**Minimally Invasive Implant Treatment Alternatives for the Edentulous Patient — Fast & Fixed and Implant Overdentures**

Elena Preoteasa, Laurentiu Iulian Florica, Florian Obadan, Marina Imre and Cristina Teodora Preoteasa

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59369

**1. Introduction**

Edentulism, defined as the loss of all natural teeth, is a severe chronic irreversible medical condition that associates extensive oral changes and has a negative impact on general health, psychological comfort, social functioning and on the overall quality of life. Despite the efforts made, edentulism still has a high prevalence, about 7 to 69% in the adult population world‐ wide, projections displaying a high rate of occurrence in the next decades, especially in the elderly population [1,2].

The most common treatment option for complete edentulism is still the conventional complete denture, an alternative which rather often does not fulfill patients' needs and is regarded as having multiple shortcomings, mainly in relation to its instability. The use of implant pros‐ theses, fixed or removable, provides a better treatment outcome, with a significant improve‐ ment of oral function and quality of life [3].

Implant prosthesis in edentulous patients, despite their increasing use, still register low prevalence, which is most probably linked to oral, systemic and social factors. Frequently, the edentulous patients are elderly and face barriers to treatment access (e.g., limited financial means, transportation difficulties, communication problems linked to loss of hearing or visual acuity) [4,5]. They show less willingness to accept complex treatment options, with major surgical interventions, such as bone grafting, or sometimes even implant placement. Often elderly have systemic comorbidities that are sometimes risk factors for developing complica‐

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

tions. Considering the previous, simpler treatments with high predictability and easy main‐ tenance procedures are preferred.

Despite these factors that limit usage of implant prosthetic rehabilitations in edentulous patients, due to their better treatment outcome compared to conventional dentures or root overdentures, in the future most likely they will be standard treatment options widely used. Supporting the previous, McGill consensus states that two-implant overdenture is the minimum standard of care for mandibular edentulism, taking into account performance, patient satisfaction, cost and clinical time [6]. Implant use for prosthetic rehabilitation will probably increase over time in relation to the advancement of research and technology in the dental field, combined with decrease of the implant treatment costs and increase of the acceptance for this treatment option by the general public.

Out of the variety of implant prosthetic options that can be used, the minimally invasive implant treatment alternatives may be more appropriate for the aged edentulous patients, considering their oral and systemic status, needs, expectations and barriers [7-9]. Usage of fewer and less invasive surgical procedures (e.g., avoiding bone grafting; using flapless technique for implant placement; using a reduced number of implants) is beneficial due to a shorter healing period and a decreased patient discomfort, represented by either pain or stress [10]. Additionally, the possibility of immediate implant loading with the regain of function‐ ality, the decreased clinical time needed for their execution and the relatively moderate treatment burden are all positive aspects that should be considered [11-13].

Subsequently, two minimally invasive implant treatment options for the edentulous patient, one fixed, namely Sky Fast & Fixed (concept derived from All-on-4), and one removable, namely implant overdentures, will be presented. These are perceived as being minimally invasive compared to other implant treatment options, with regards to the limited surgical interventions (they usually don't require bone grafting; a reduced number of implants are placed; when appropriate, flapless technique is used) and reduced clinical time, favoring rapid healing and functionality regaining through immediate implant loading. Both fixed and removable treatment option were chosen considering patient's needs and expectations. Therefore, fixed prosthetic restorations are more appropriate for younger patients, who usually don't easily accept removable prosthesis, and have better dexterity that is needed in order to properly maintain the oral hygiene. The implant overdentures are more appropriate for older edentulous patients, especially for the ones dissatisfied with the conventional dentures, ensuring a satisfying performance and esthetic rehabilitation, requiring simpler procedures for oral hygiene maintenance [14].

#### **2. SKY Fast & Fixed — Fixed-prosthetic implant restoration**

**General presentation.** Sky Fast & Fixed defines an option of immediate fixed-prosthetic implant restoration for complete edentulism, with specific protocol and materials, developed by Bredent Medical (Senden, Germany). Basically, this treatment concept is derived from Allon-4 and All-on-6 concepts, previously developed by Professor Paulo Malo, together with Nobel Biocare (Göteborg, Sweden) [15-17]. Sky Fast & Fixed differs mainly through the particularities of the system components, such as implant and abutment design.

The main characteristics of Sky Fast & Fixed treatment concept are presented below:


tions. Considering the previous, simpler treatments with high predictability and easy main‐

Despite these factors that limit usage of implant prosthetic rehabilitations in edentulous patients, due to their better treatment outcome compared to conventional dentures or root overdentures, in the future most likely they will be standard treatment options widely used. Supporting the previous, McGill consensus states that two-implant overdenture is the minimum standard of care for mandibular edentulism, taking into account performance, patient satisfaction, cost and clinical time [6]. Implant use for prosthetic rehabilitation will probably increase over time in relation to the advancement of research and technology in the dental field, combined with decrease of the implant treatment costs and increase of the

Out of the variety of implant prosthetic options that can be used, the minimally invasive implant treatment alternatives may be more appropriate for the aged edentulous patients, considering their oral and systemic status, needs, expectations and barriers [7-9]. Usage of fewer and less invasive surgical procedures (e.g., avoiding bone grafting; using flapless technique for implant placement; using a reduced number of implants) is beneficial due to a shorter healing period and a decreased patient discomfort, represented by either pain or stress [10]. Additionally, the possibility of immediate implant loading with the regain of function‐ ality, the decreased clinical time needed for their execution and the relatively moderate

Subsequently, two minimally invasive implant treatment options for the edentulous patient, one fixed, namely Sky Fast & Fixed (concept derived from All-on-4), and one removable, namely implant overdentures, will be presented. These are perceived as being minimally invasive compared to other implant treatment options, with regards to the limited surgical interventions (they usually don't require bone grafting; a reduced number of implants are placed; when appropriate, flapless technique is used) and reduced clinical time, favoring rapid healing and functionality regaining through immediate implant loading. Both fixed and removable treatment option were chosen considering patient's needs and expectations. Therefore, fixed prosthetic restorations are more appropriate for younger patients, who usually don't easily accept removable prosthesis, and have better dexterity that is needed in order to properly maintain the oral hygiene. The implant overdentures are more appropriate for older edentulous patients, especially for the ones dissatisfied with the conventional dentures, ensuring a satisfying performance and esthetic rehabilitation, requiring simpler

treatment burden are all positive aspects that should be considered [11-13].

**2. SKY Fast & Fixed — Fixed-prosthetic implant restoration**

**General presentation.** Sky Fast & Fixed defines an option of immediate fixed-prosthetic implant restoration for complete edentulism, with specific protocol and materials, developed by Bredent Medical (Senden, Germany). Basically, this treatment concept is derived from Allon-4 and All-on-6 concepts, previously developed by Professor Paulo Malo, together with

tenance procedures are preferred.

78 Current Concepts in Dental Implantology

acceptance for this treatment option by the general public.

procedures for oral hygiene maintenance [14].


Time sequence of the main phases of Sky Fast & Fixed can be observed in figure 1. appointment and with reduced costs, compared to conventional fixed-prosthetic implant restorations.

Time sequence of the main phases of Sky Fast & Fixed can be observed in figure 1.

 Sky Fast & Fixed implies the use of some specific materials, components and instruments of Bredent Medical, some of them developed especially for this concept, such as the implants and the abutments. The distal implants that are meant to be placed tilted are designed with length of 14 or 16 mm and diameters over 4 mm. The axial implants should have a length of at least 10 mm and a diameter over 3.5mm. For implant divergence, compensation

Ensures a simpler and fast oral rehabilitation, with limited surgical procedures performed during one single

Dummy Text **Clinical phases.** Sky Fast & Fixed is implemented following the regular steps of fixed-prosthetic implant

• analyze of radiographs and computed tomography

Figure 1. Sky Fast & Fixed – time sequence of the main treatment phases **Figure 1.** Sky Fast & Fixed – time sequence of the main treatment phases

restorations, with some specific aspects related to this concept and to patient features. Some of the aspects that should be accounted in treatment planning are synthetized in table 1, followed by a more detailed presentation. Diagnostic procedures • oral and systemic health assessment • facial esthetic evaluation **Clinical phases.** Sky Fast & Fixed is implemented following the regular steps of fixedprosthetic implant restorations, with some specific aspects related to this concept and to patient features. Some of the aspects that should be accounted in treatment planning are synthetized in table 1, followed by a more detailed presentation.

• wax-up • informed consent Preoperative interventions • instruction and motivation on maintaining a proper oral hygiene (antibacterial mouthwash, such as Chlorhexidine 0.12%, is recommended) **Patient evaluation** should comprise information regarding the oral and systemic health, considering anatomical and functional aspects, in order to accurately collect diagnostic data, essential for treatment planning and execution.

and instructions • record of maxillomandibular relations and occlusion • impression used for fabricating the provisional prosthesis • surgical template (guide) • medication - antibiotics (amoxicillin with clavulanic acid, administered for 5-7 days, starting 1 hour prior to surgical intervention) and sometimes Oral examination must consider, among others, the initial dental condition (as dentulous or edentulous), maxillomandibular relationship, the vertical interarch space (restorative space), bone features (quality, quantity, anatomical limitations) and plaque control. Dentate patients, compared to the edentulous ones, present an increased treatment time, linked to the proce‐ dures performed previous to implant placement (teeth extraction, bone leveling, removal of infected tissue), that may have specific complications. Even so, it may be a more favorable clinical situation considering implants associate a reduction of bone resorption, it is possible to register the maxillomandibular relationship and identify some of the patient's natural esthetic particularities. In edentulous patients, severity of bone resorption and its consequen‐


**Table 1.** Main coordinates of the clinical interventions of Sky Fast & Fixed

Time sequence of the main phases of Sky Fast & Fixed can be observed in figure 1.

80 Current Concepts in Dental Implantology

Figure 1. Sky Fast & Fixed – time sequence of the main treatment phases

• wax-up

Diagnostic procedures

in table 1, followed by a more detailed presentation.

essential for treatment planning and execution.

**Figure 1.** Sky Fast & Fixed – time sequence of the main treatment phases

Preoperative interventions and instructions

Time sequence of the main phases of Sky Fast & Fixed can be observed in figure 1.

 Sky Fast & Fixed implies the use of some specific materials, components and instruments of Bredent Medical, some of them developed especially for this concept, such as the implants and the abutments. The distal implants that are meant to be placed tilted are designed with length of 14 or 16 mm and diameters over 4 mm. The axial implants should have a length of at least 10 mm and a diameter over 3.5mm. For implant divergence, compensation abutments are designed with angulations of 0°, 17.5° and 35°, and an outer cone of 17.5° Also, the abutments have

Ensures a simpler and fast oral rehabilitation, with limited surgical procedures performed during one single

Dummy Text **Clinical phases.** Sky Fast & Fixed is implemented following the regular steps of fixed-prosthetic implant restorations, with some specific aspects related to this concept and to patient features. Some of the aspects that should be

> • instruction and motivation on maintaining a proper oral hygiene (antibacterial mouthwash, such as Chlorhexidine 0.12%, is recommended)

> • medication - antibiotics (amoxicillin with clavulanic acid, administered for 5-7 days, starting 1 hour prior to surgical intervention) and sometimes

• analyze of radiographs and computed tomography

• record of maxillomandibular relations and occlusion • impression used for fabricating the provisional prosthesis

accounted in treatment planning are synthetized in table 1, followed by a more detailed presentation.

• oral and systemic health assessment

• facial esthetic evaluation

• surgical template (guide)

• informed consent

**Patient evaluation** should comprise information regarding the oral and systemic health, considering anatomical and functional aspects, in order to accurately collect diagnostic data,

Oral examination must consider, among others, the initial dental condition (as dentulous or edentulous), maxillomandibular relationship, the vertical interarch space (restorative space), bone features (quality, quantity, anatomical limitations) and plaque control. Dentate patients, compared to the edentulous ones, present an increased treatment time, linked to the proce‐ dures performed previous to implant placement (teeth extraction, bone leveling, removal of infected tissue), that may have specific complications. Even so, it may be a more favorable clinical situation considering implants associate a reduction of bone resorption, it is possible to register the maxillomandibular relationship and identify some of the patient's natural esthetic particularities. In edentulous patients, severity of bone resorption and its consequen‐

**Clinical phases.** Sky Fast & Fixed is implemented following the regular steps of fixedprosthetic implant restorations, with some specific aspects related to this concept and to patient features. Some of the aspects that should be accounted in treatment planning are synthetized

an unique platform of 4mm and are designed for variable gingiva heights, from 0.9 mm to 3.6 mm.

appointment and with reduced costs, compared to conventional fixed-prosthetic implant restorations.

ces (e.g., deficient lip support), particularities of maxillomandibular relationship are important to be correctly acknowledged in order to obtain an aesthetic and functional outcome. Addi‐ tionally to alveolar ridge particularities (bone width, vertical ridge orientation and aspect of the surface-uniform or with irregularities), the characteristics of the mucosa, such as resilience and amount of keratinized mucosa, may be decision-factors for using either a flap or a flapless technique for implant placement. In dentate patients, registration of maxillomandibular relations for the implant prosthesis can be eased by initial records or preservation of posterior occluding teeth. Bone assessment is essential for establishing if this treatment option is viable, and if it is, it's very important for treatment planning, as for deciding upon implant number, position and design (diameter and length). In this respect, a quantitative and qualitative bone evaluation is required, which includes aspects like ridge width, ridge height, anatomical limitations and bone density, additional to panoramic radiographies, computed tomography being highly recommended. Considering that oral hygiene is an important prognosis factor for all implant prosthesis, patient's behavior in this respect should be assessed and deficiencies of it addressed by mechanisms as awareness, motivation and training.

Facial appearance with this type of prosthetic restoration must be assessed and predicted, in order to provide an adequate esthetic result. The analysis should start with the evaluation of initial situation (natural teeth or prosthetic rehabilitation), acknowledging also patient's perception and preferences. Difficulties in this regard are mainly found in edentulous patients that have severe facial changes related to tooth loss and bone resorption, especially in the maxilla due to the centripetal bone resorption. Assessment of facial and lip support can be done comparing the facial appearance with and without the dentures or using a wax try-in without the buccal flange [21]. In patients with severe ridge resorption, if between the ideal artificial teeth location and the ridge there is an increased sagittal discrepancy, in order to obtain a satisfactory esthetic outcome, a removable denture with a buccal flange may be more appropriate. For a natural appearance, vertical bone loss is addressed also through the use of pink acrylic or ceramic.

Implementing this treatment concept should be done in patients with good overall health, considering the inherent risks of the surgical intervention, but also the considerable physical and psychological stress related to the increased number of clinical procedures done in only one day. Therefore, acknowledgement of patient general health status is needed and constant monitoring of the blood pressure and pulse rate in the dental office is recommended.

**The surgical phase** mainly comprises preprosthetic procedures and implants placement.

Preprosthetic surgery aims to obtain optimal conditions for implant placement and for the prosthetic reconstruction (Figure 2). Teeth extraction and related interventions, alveolectomy, bone grafting, excision of hyperplasic lesions and bone leveling may be included.

Implant placement may be done using a flap or flapless technique. Flap technique is usually selected, due to the better assessment of available bone and thickness of the crestal area, but flapless surgery has also numerous advantages related to preservations of circulation and bone tissue volume at implant site, decrease of surgical time and accelerated healing [22]. In edentulous patients that do not require preprosthetic surgery and a flapless technique is used, the interim prosthesis can be done prior to the surgical phase, and minor adjustment are needed, contributing to a considerable decrease of the clinical time.

Implant placement should be done according to the treatment plan; for a more accurate position a surgical template can be used. Usually, the axial implants are placed first (Figure 3), and then the tilted ones (Figure 4). For verifying implant angulation, parallelizing pins can be used.

Immediate implant loading requires a good primary stability for achieving a successful osseointegration. This is related to multiple factors, such as bone density, implant diameter and length and insertion torque of 45 N cm or more. Using the long titled implants favors a good primary stability due to the fact that they follow a dense bone structure-the anterior wall of the sinus [23].

After the selected abutments are placed, the sutures follow. Therefore, there is no need for another surgical phase, as there is in the case of using healing abutments.

Figure 2. Preprosthetic surgery that included teeth extraction and bone leveling **Figure 2.** Preprosthetic surgery that included teeth extraction and bone leveling Implant placement should be done according to the treatment plan; for a more accurate position a surgical template can be used. Usually, the axial implants are placed first (Figure 3), and then the titled ones (Figure 4). For verifying implant

angulation, parallelizing pins can be used.

Implant placement may be done using a flap or flapless technique. Flap technique is usually selected, due to the better

Figure 3. Axial implant are placed first **Figure 3.** Axial implant are placed first

Figure 3. Axial implant are placed first

and amount of keratinized mucosa, may be decision-factors for using either a flap or a flapless technique for implant placement. In dentate patients, registration of maxillomandibular relations for the implant prosthesis can be eased by initial records or preservation of posterior occluding teeth. Bone assessment is essential for establishing if this treatment option is viable, and if it is, it's very important for treatment planning, as for deciding upon implant number, position and design (diameter and length). In this respect, a quantitative and qualitative bone evaluation is required, which includes aspects like ridge width, ridge height, anatomical limitations and bone density, additional to panoramic radiographies, computed tomography being highly recommended. Considering that oral hygiene is an important prognosis factor for all implant prosthesis, patient's behavior in this respect should be assessed and deficiencies

Facial appearance with this type of prosthetic restoration must be assessed and predicted, in order to provide an adequate esthetic result. The analysis should start with the evaluation of initial situation (natural teeth or prosthetic rehabilitation), acknowledging also patient's perception and preferences. Difficulties in this regard are mainly found in edentulous patients that have severe facial changes related to tooth loss and bone resorption, especially in the maxilla due to the centripetal bone resorption. Assessment of facial and lip support can be done comparing the facial appearance with and without the dentures or using a wax try-in without the buccal flange [21]. In patients with severe ridge resorption, if between the ideal artificial teeth location and the ridge there is an increased sagittal discrepancy, in order to obtain a satisfactory esthetic outcome, a removable denture with a buccal flange may be more appropriate. For a natural appearance, vertical bone loss is addressed also through the use of

Implementing this treatment concept should be done in patients with good overall health, considering the inherent risks of the surgical intervention, but also the considerable physical and psychological stress related to the increased number of clinical procedures done in only one day. Therefore, acknowledgement of patient general health status is needed and constant

monitoring of the blood pressure and pulse rate in the dental office is recommended.

bone grafting, excision of hyperplasic lesions and bone leveling may be included.

needed, contributing to a considerable decrease of the clinical time.

**The surgical phase** mainly comprises preprosthetic procedures and implants placement.

Preprosthetic surgery aims to obtain optimal conditions for implant placement and for the prosthetic reconstruction (Figure 2). Teeth extraction and related interventions, alveolectomy,

Implant placement may be done using a flap or flapless technique. Flap technique is usually selected, due to the better assessment of available bone and thickness of the crestal area, but flapless surgery has also numerous advantages related to preservations of circulation and bone tissue volume at implant site, decrease of surgical time and accelerated healing [22]. In edentulous patients that do not require preprosthetic surgery and a flapless technique is used, the interim prosthesis can be done prior to the surgical phase, and minor adjustment are

Implant placement should be done according to the treatment plan; for a more accurate position a surgical template can be used. Usually, the axial implants are placed first (Figure

of it addressed by mechanisms as awareness, motivation and training.

pink acrylic or ceramic.

82 Current Concepts in Dental Implantology

decrease of the clinical time.

angulation, parallelizing pins can be used.

Figure 3. Axial implant are placed first

Figure 2. Preprosthetic surgery that included teeth extraction and bone leveling

Implant placement may be done using a flap or flapless technique. Flap technique is usually selected, due to the better assessment of available bone and thickness of the crestal area, but flapless surgery has also numerous advantages related to preservations of circulation and bone tissue volume at implant site, decrease of surgical time and accelerated healing [22]. In edentulous patients that do not require preprosthetic surgery and a flapless technique is used, the interim prosthesis can be done prior to the surgical phase, and minor adjustment are needed, contributing to a considerable

Implant placement should be done according to the treatment plan; for a more accurate position a surgical template can be used. Usually, the axial implants are placed first (Figure 3), and then the titled ones (Figure 4). For verifying implant

Figure 4. Titled implants are placed second **Figure 4.** Tilted implants are placed second

to multiple factors, such as bone density, implant diameter and length and insertion torque of 45 N cm or more. Using the long title implants favors a good primary stability due to the fact that they follow a dense bone structure - the anterior wall of the sinus [23]. After the selected abutments are placed, the sutures follow. Therefore, there is no need for another surgical phase, as there is in the case of using healing abutments. **Interim prosthesis** is fixed, usually made from rigid acrylic material and splints the implants, protecting them from adverse loading and reducing the stress in the bone around the implant [20,24]. It is manufactured and placed in the same day with implant insertion. Therefore, it is mandatory to include a dental technician in the team that, ideally, has the dental laboratory in the same location with the dental office.

Immediate implant loading requires a good primary stability for achieving a successful osseointegration. This is related

Dummy Text **Interim prosthesis** is fixed, usually made from rigid acrylic material and splints the implants, protecting them from adverse loading and reducing the stress in the bone around the implant [20,24]. It is manufactured and placed in the same day with implant insertion. Therefore, it is mandatory to include a dental technician in the team that, ideally, has the dental laboratory in the same location with the dental office. Manufacturing the interim prosthesis basically follows the same steps as other fixed-prosthetic implant restoration. After placement of abutments and suture, an impression is taken with a closed or open tray (Figure 5). The impression copings are attached to the implant abutment without splinting, that associates the risk of positional errors that are reflected as deficiencies on all forthcoming laboratory phases. After that, maxillomandibular relationship is recorded.

The dental technician manufactures the interim prosthesis, the procedure being simpler, faster and better adapted to patient's features (e.g., maxillomandibular relationship) when a wax-up is previously made. For shortening of the laboratory phase and obtaining a better esthetic outcome, composite or acrylic prefabricated veneers can be used. The prefabricated veneers are used for a wax set-up, followed by manufacturing a positioning template for them, through the use of a silicone impression. Finishing of the interim prosthesis is achieved by transferring the set-up, adding rigid acrylic material, and fixation of only one implant coping (Figure 6).

After manufacturing of the interim prosthesis by the dental technician, fixation of the remain‐ ing implant copings and adjustments are made in the dental office. All implant copings except one are fixed insitu, directly intraorally by the dentist, in order to address coping errors and to ensure passive fit and tension-free placement. Only after that occlusal adjustments are made. Minimally Invasive Implant Treatment Alternatives for the Edentulous Patient — Fast & Fixed… http://dx.doi.org/10.5772/59369 85

Figure 5. Interim prosthesis – clinical phases **Figure 5.** Interim prosthesis – clinical phases

Figure 5. Interim prosthesis – clinical phases

Figure 2. Preprosthetic surgery that included teeth extraction and bone leveling

decrease of the clinical time.

84 Current Concepts in Dental Implantology

angulation, parallelizing pins can be used.

Figure 3. Axial implant are placed first

Figure 4. Titled implants are placed second

there is in the case of using healing abutments.

has the dental laboratory in the same location with the dental office.

anterior wall of the sinus [23].

the same location with the dental office.

**Figure 4.** Tilted implants are placed second

Implant placement may be done using a flap or flapless technique. Flap technique is usually selected, due to the better assessment of available bone and thickness of the crestal area, but flapless surgery has also numerous advantages related to preservations of circulation and bone tissue volume at implant site, decrease of surgical time and accelerated healing [22]. In edentulous patients that do not require preprosthetic surgery and a flapless technique is used, the interim prosthesis can be done prior to the surgical phase, and minor adjustment are needed, contributing to a considerable

Implant placement should be done according to the treatment plan; for a more accurate position a surgical template can be used. Usually, the axial implants are placed first (Figure 3), and then the titled ones (Figure 4). For verifying implant

Immediate implant loading requires a good primary stability for achieving a successful osseointegration. This is related to multiple factors, such as bone density, implant diameter and length and insertion torque of 45 N cm or more. Using the long title implants favors a good primary stability due to the fact that they follow a dense bone structure - the

**Interim prosthesis** is fixed, usually made from rigid acrylic material and splints the implants, protecting them from adverse loading and reducing the stress in the bone around the implant [20,24]. It is manufactured and placed in the same day with implant insertion. Therefore, it is mandatory to include a dental technician in the team that, ideally, has the dental laboratory in

Manufacturing the interim prosthesis basically follows the same steps as other fixed-prosthetic implant restoration. After placement of abutments and suture, an impression is taken with a closed or open tray (Figure 5). The impression copings are attached to the implant abutment without splinting, that associates the risk of positional errors that are reflected as deficiencies on all forthcoming laboratory phases. After that, maxillomandibular relationship is recorded.

The dental technician manufactures the interim prosthesis, the procedure being simpler, faster and better adapted to patient's features (e.g., maxillomandibular relationship) when a wax-up is previously made. For shortening of the laboratory phase and obtaining a better esthetic outcome, composite or acrylic prefabricated veneers can be used. The prefabricated veneers are used for a wax set-up, followed by manufacturing a positioning template for them, through the use of a silicone impression. Finishing of the interim prosthesis is achieved by transferring the set-up, adding rigid acrylic material, and fixation of only one implant coping (Figure 6).

After manufacturing of the interim prosthesis by the dental technician, fixation of the remain‐ ing implant copings and adjustments are made in the dental office. All implant copings except one are fixed insitu, directly intraorally by the dentist, in order to address coping errors and to ensure passive fit and tension-free placement. Only after that occlusal adjustments are made.

After the selected abutments are placed, the sutures follow. Therefore, there is no need for another surgical phase, as

Dummy Text **Interim prosthesis** is fixed, usually made from rigid acrylic material and splints the implants, protecting them from adverse loading and reducing the stress in the bone around the implant [20,24]. It is manufactured and placed in the same day with implant insertion. Therefore, it is mandatory to include a dental technician in the team that, ideally,

After manufacturing of the interim prosthesis by the dental technician, fixation of the remaining implant copings and Figure 6. Interim prosthesis – laboratory phases **Figure 6.** Interim prosthesis – laboratory phases

Figure 6. Interim prosthesis – laboratory phases

the changes desired for the definitive prosthesis.

the changes desired for the definitive prosthesis.

Therefore, during the osseointegration phase, a comfortable fixed interim restoration is used, that ensures esthetic and functional rehabilitation, which can be used for a moderate period of time. Also, during this interim phase, the patient has the time to analyze and form his own opinion about the esthetic outcome, and declare his own requirements about the changes desired for the definitive prosthesis. adjustments are made in the dental office. All implant copings except one are fixed insitu, directly intraorally by the dentist, in order to address coping errors and to ensure passive fit and tension-free placement. Only after that occlusal adjustments are made. Therefore, during the osseointegration phase, a comfortable fixed interim restoration is used, that ensures esthetic and functional rehabilitation, which can be used for a moderate period of time. Also, during this interim phase, the patient has the time to analyze and form his own opinion about the esthetic outcome, and declare his own requirements about After manufacturing of the interim prosthesis by the dental technician, fixation of the remaining implant copings and adjustments are made in the dental office. All implant copings except one are fixed insitu, directly intraorally by the dentist, in order to address coping errors and to ensure passive fit and tension-free placement. Only after that occlusal adjustments are made. Therefore, during the osseointegration phase, a comfortable fixed interim restoration is used, that ensures esthetic and functional rehabilitation, which can be used for a moderate period of time. Also, during this interim phase, the patient

adjustments should be done, considering their impact on treatment prognostic.

adjustments should be done, considering their impact on treatment prognostic.

Dummy Text **Postoperative instructions** target mainly postoperative medications, the adequate plaque control and using a soft diet during the first weeks. In the next appointment, scheduled in the following days after surgery, occlusal

Dummy Text **Postoperative instructions** target mainly postoperative medications, the adequate plaque control and using a soft diet during the first weeks. In the next appointment, scheduled in the following days after surgery, occlusal

has the time to analyze and form his own opinion about the esthetic outcome, and declare his own requirements about

the mandible.

Figure 6. Interim prosthesis – laboratory phases

the changes desired for the definitive prosthesis.

adjustments should be done, considering their impact on treatment prognostic.

adjustments are made.

After manufacturing of the interim prosthesis by the dental technician, fixation of the remaining implant copings and adjustments are made in the dental office. All implant copings except one are fixed insitu, directly intraorally by the dentist, in order to address coping errors and to ensure passive fit and tension-free placement. Only after that occlusal

Therefore, during the osseointegration phase, a comfortable fixed interim restoration is used, that ensures esthetic and functional rehabilitation, which can be used for a moderate period of time. Also, during this interim phase, the patient has the time to analyze and form his own opinion about the esthetic outcome, and declare his own requirements about

Dummy Text **Postoperative instructions** target mainly postoperative medications, the adequate plaque control and using a soft diet during the first weeks. In the next appointment, scheduled in the following days after surgery, occlusal

Dummy Text **The definitive prosthesis** is a splinted implant fixed restoration, by a rigid metal-based ceramic or acrylic prosthesis. It is manufactured after at least 4 months after surgery in the maxilla, respectively after at least 3 months in

Clinical phase of definitive prosthesis manufacture are similar to those used for fixed-prosthetic implant restorations (Figure 7). If desired, implant abutments can be replaced with others, with different angulation or gingival height. Special attention must be given to accurately register the implant abutment position. In this respect, a preliminary

laboratory is sectioned in the area between the implants and then splinted intraorally with acrylic resin. Using this procedure for custom tray impression ensures an accurate tension-free registration of implant abutment position.

Figure 7. Definitive prosthesis execution **Figure 7.** Definitive prosthesis execution

**Postoperative instructions** target mainly postoperative medications, the adequate plaque control and using a soft diet during the first weeks. In the next appointment, scheduled in the following days after surgery, occlusal adjustments should be done, considering their impact on the prognosis..

**The definitive prosthesis** is a splinted implant fixed restoration, by a rigid metal-based ceramic or acrylic prosthesis. It is manufactured after at least 4 months after surgery in the maxilla, respectively after at least 3 months in the mandible.

Clinical phase of definitive prosthesis manufacture are similar to those used for fixedprosthetic implant restorations (Figure 7). If desired, implant abutments can be replaced with others, with different angulation or gingival height. Special attention must be given to accurately register the implant abutment position. In this respect, a preliminary impression is taken in order to fabricate an acrylic splint and a custom tray. The acrylic splint manufactured in the dental laboratory is sectioned in the area between the implants and then splinted intraorally with acrylic resin. Using this procedure for custom tray impression ensures an accurate tension-free registration of implant abutment position.

Definitive prosthetic design, as the length of dental arch and decision upon using cantilever extensions depends on the site of the most distal implant abutment and patient features, as number of teeth exposed during smile. It is best to use cantilever extension with reduced length, below 6-8 mm in the maxilla and 10 mm in the mandible [25].

Definitive prostheses are screw-retained, the screw-access opening being placed on the occlusal or the lingual side of the prosthesis. Through this method of retention, removal of prosthesis and professional hygiene procedures are easy to perform.

Metal or zirconium-based ceramic, metal-based acrylic or composite, are all options that can be used for manufacturing the definitive prosthesis. In the mandible, metal based acrylic and composite restorations are preferred when opposed by maxillary ceramic prosthesis, as prevention factor of negative complication that may appear in relation to occlusal or parafuc‐ tional forces. In order to obtain a natural aspect, pink material is used for replacing the lost hard and soft tissue and for restoring the artificial gingival contour.

**Indications.** Sky Fast & Fixed treatment concept addresses rehabilitation of complete edentu‐ lism, as current or imminent condition, through an immediate fixed-prosthetic implant restoration. It is especially indicated in the cases with severe ridge resorption in the posterior regions of the jaws that prohibit the axial placement of dental implants, in patients for whom extensive bone grafting procedures are not an option. It can be used for either dentate patients that are soon to be edentulous and absolutely refuse interim or definitive removable prosthesis, or for edentulous patients extremely dissatisfied by their conventional or implant removable prosthesis who desire a fixed prosthetic restoration. In some systemic conditions or elderly patients, this treatment option may be more indicated compared to conventional fixed implant restorations (that usually require major grafting procedures), considering that there are fewer and less invasive surgical procedures, that cause less trauma and stress, shorter healing period and a lower risk of developing complications [26, 27].

**Contraindications.** This treatment alternative basically has the same contraindications as all implant based restorations, mainly in relation to the risks associated to surgical procedures. Even so, there are few absolute contraindications (e.g., recent myocardial infarction, stroke, cardiovascular surgery, and transplant; profound immunosuppression; radiotherapy or bisphosphonate use), the degree of disease-control being far more important than the nature of systemic disorder itself [27,28]. Additionally, there are complications or behavioral aspects that may increase the treatment failure or complication rate, which should be acknowledged (e.g., diabetes, oral hygiene status, smoking, decreased frequency of using the dental services).

**Postoperative instructions** target mainly postoperative medications, the adequate plaque control and using a soft diet during the first weeks. In the next appointment, scheduled in the following days after surgery, occlusal adjustments should be done, considering their impact

**The definitive prosthesis** is a splinted implant fixed restoration, by a rigid metal-based ceramic or acrylic prosthesis. It is manufactured after at least 4 months after surgery in the

Clinical phase of definitive prosthesis manufacture are similar to those used for fixedprosthetic implant restorations (Figure 7). If desired, implant abutments can be replaced with others, with different angulation or gingival height. Special attention must be given to accurately register the implant abutment position. In this respect, a preliminary impression is taken in order to fabricate an acrylic splint and a custom tray. The acrylic splint manufactured in the dental laboratory is sectioned in the area between the implants and then splinted intraorally with acrylic resin. Using this procedure for custom tray impression ensures an

Definitive prosthetic design, as the length of dental arch and decision upon using cantilever extensions depends on the site of the most distal implant abutment and patient features, as number of teeth exposed during smile. It is best to use cantilever extension with reduced

maxilla, respectively after at least 3 months in the mandible.

Figure 6. Interim prosthesis – laboratory phases

the changes desired for the definitive prosthesis.

adjustments should be done, considering their impact on treatment prognostic.

adjustments are made.

the mandible.

86 Current Concepts in Dental Implantology

After manufacturing of the interim prosthesis by the dental technician, fixation of the remaining implant copings and adjustments are made in the dental office. All implant copings except one are fixed insitu, directly intraorally by the dentist, in order to address coping errors and to ensure passive fit and tension-free placement. Only after that occlusal

Therefore, during the osseointegration phase, a comfortable fixed interim restoration is used, that ensures esthetic and functional rehabilitation, which can be used for a moderate period of time. Also, during this interim phase, the patient has the time to analyze and form his own opinion about the esthetic outcome, and declare his own requirements about

Dummy Text **Postoperative instructions** target mainly postoperative medications, the adequate plaque control and using a soft diet during the first weeks. In the next appointment, scheduled in the following days after surgery, occlusal

Dummy Text **The definitive prosthesis** is a splinted implant fixed restoration, by a rigid metal-based ceramic or acrylic prosthesis. It is manufactured after at least 4 months after surgery in the maxilla, respectively after at least 3 months in

Clinical phase of definitive prosthesis manufacture are similar to those used for fixed-prosthetic implant restorations (Figure 7). If desired, implant abutments can be replaced with others, with different angulation or gingival height. Special attention must be given to accurately register the implant abutment position. In this respect, a preliminary impression is taken in order to fabricate an acrylic splint and a custom tray. The acrylic splint manufactured in the dental laboratory is sectioned in the area between the implants and then splinted intraorally with acrylic resin. Using this procedure for custom tray impression ensures an accurate tension-free registration of implant abutment position.

accurate tension-free registration of implant abutment position.

length, below 6-8 mm in the maxilla and 10 mm in the mandible [25].

on the prognosis..

Figure 7. Definitive prosthesis execution **Figure 7.** Definitive prosthesis execution

Using this specific treatment concept is limited to cases with severe ridge resorption in the anterior region of the jaws, in patients for whom extensive bone grafting procedures are not an option.

**Advantages.** Sky Fast & Fixed has the general advantages of immediately loaded fixed implant prosthesis, provided through a less invasive treatment compared to the conventional option.

As an immediately-loaded implant-prosthesis, it ensures immediate functional and esthetic rehabilitation, with a positive impact on patient's wellbeing and quality of life. Even more, for the dentate patients it is possible to avoid the edentulism condition treated by removable prosthesis, the imminence of this situation being frequently a major stressor for patients.

Compared to conventional fixed implant prosthesis, Sky Fast & Fixed is considered to be less invasive. The surgical procedure used is simpler, by avoiding extensive bone grafting, placement of fewer implants, using when appropriate a flapless technique, no need for a second stage implant surgery. Also, there is only one-day of surgery. Minor preprosthetic surgery, if required, is done in the same appointment with implant placement, and there is no need of a second stage implant surgery. Correspondently, the less the surgical trauma is, the faster the healing and recovery of the patient is.

Using a reduced number of implants, avoiding some procedures like bone grafting, the possibility of using metal-based acrylic prosthesis, decrease of the number of clinical appoint‐ ments required, are all factors that may contribute to a decrease of the treatment cost. This may be an important aspect for the edentulous patient that is often aged and has limited financial means.

This treatment concept has advantages also for the dental team. Aspects like the standardized treatment protocol, the reduced number of clinical appointments, the relatively easy way of manufacturing and placement of the interim prosthesis, patient's satisfaction, all have a positive impact.

**Complications.** This treatment option basically has the same complications with any imme‐ diately loaded fixed implant prosthesis. Some aspects, mainly related to Sky Fast & Fixed particularities will be highlighted.

The acrylic interim prosthesis can fracture, this occurring mainly after the ten week period of recommendation of eating soft diet, when patients fell confident to chew harder food. If unmanaged, it can lead to implant failure, due to the alteration of the splinting process. Therefore, the interim prosthesis should not be reinforced, because it may mask the fracture and delay the patient's addressing to the dental office.

If chipping of the ceramic of the definitive prosthesis occurs, this being a relative frequent complication, the interim prosthesis can be used for the time needed for laboratory repairing.

One important risk factor for all implant prosthesis, including this treatment option, that is linked to sometimes severe complications, is the correctness of the registration of maxillo‐ mandibular relations (respecting the coincidence of maximal intercuspal position and centric relation, and the functional vertical dimension of occlusion). Acknowledging that, in a dentate patient with posterior occluding teeth it is recommended their preservation until after the interim prosthesis is manufactured, in order to ensure a correct registration.

#### **3. Implant overdentures**

**General presentation.** An implant overdenture is a removable dental prosthesis supported or retained by dental implants, through various attachment systems (e.g., ball, locator, magnets, bar). Benefits of overdentures include increased retention and stability of the prosthesis, improved mastication and phonation, decrease of the rate of ridge resorption, all having a positive impact on patients' well-being and quality of life.

An increased usage of this treatment option occurred as a reaction to the relatively frequent retention and stability deficiencies of complete dentures that are addressed at more affordable costs compared to the ones of fixed implant prosthesis [29]. Moreover, nowadays two implant overdentures are considered the minimum standard of care for mandibular edentulism, taking into account performance, patient satisfaction, cost and clinical time [6]. Most probably, overdenture use will increase even more, in relation to its indications, being most appropriate for the aged population segment that is estimated to be increasing.

Implant overdenture treatment concept has the following main features:

placement of fewer implants, using when appropriate a flapless technique, no need for a second stage implant surgery. Also, there is only one-day of surgery. Minor preprosthetic surgery, if required, is done in the same appointment with implant placement, and there is no need of a second stage implant surgery. Correspondently, the less the surgical trauma is, the

Using a reduced number of implants, avoiding some procedures like bone grafting, the possibility of using metal-based acrylic prosthesis, decrease of the number of clinical appoint‐ ments required, are all factors that may contribute to a decrease of the treatment cost. This may be an important aspect for the edentulous patient that is often aged and has limited financial

This treatment concept has advantages also for the dental team. Aspects like the standardized treatment protocol, the reduced number of clinical appointments, the relatively easy way of manufacturing and placement of the interim prosthesis, patient's satisfaction, all have a

**Complications.** This treatment option basically has the same complications with any imme‐ diately loaded fixed implant prosthesis. Some aspects, mainly related to Sky Fast & Fixed

The acrylic interim prosthesis can fracture, this occurring mainly after the ten week period of recommendation of eating soft diet, when patients fell confident to chew harder food. If unmanaged, it can lead to implant failure, due to the alteration of the splinting process. Therefore, the interim prosthesis should not be reinforced, because it may mask the fracture

If chipping of the ceramic of the definitive prosthesis occurs, this being a relative frequent complication, the interim prosthesis can be used for the time needed for laboratory repairing. One important risk factor for all implant prosthesis, including this treatment option, that is linked to sometimes severe complications, is the correctness of the registration of maxillo‐ mandibular relations (respecting the coincidence of maximal intercuspal position and centric relation, and the functional vertical dimension of occlusion). Acknowledging that, in a dentate patient with posterior occluding teeth it is recommended their preservation until after the

**General presentation.** An implant overdenture is a removable dental prosthesis supported or retained by dental implants, through various attachment systems (e.g., ball, locator, magnets, bar). Benefits of overdentures include increased retention and stability of the prosthesis, improved mastication and phonation, decrease of the rate of ridge resorption, all having a

An increased usage of this treatment option occurred as a reaction to the relatively frequent retention and stability deficiencies of complete dentures that are addressed at more affordable

interim prosthesis is manufactured, in order to ensure a correct registration.

faster the healing and recovery of the patient is.

88 Current Concepts in Dental Implantology

means.

positive impact.

particularities will be highlighted.

**3. Implant overdentures**

and delay the patient's addressing to the dental office.

positive impact on patients' well-being and quality of life.


Figure 8. Different type of implants, according to their diameter and attachment system **Figure 8.** Different type of implants, according to their diameter and attachment system

splinted and unsplinted implant overdentures regarding the peri-implant outcome and patients' satisfaction. Therefore, considering unsplinted implants prostheses have simpler manufacturing and repairing procedure, these may be more indicated for aged edentulous patients [31]. The number of dental implants placed in the case of implant overdentures vary between 1 to 4 for mandibular overdenture, and 2 to 6 for maxillary overdenture. Selection of the dental implant, as type, diameter and length and establishing their number and position must consider the bone features (ridge width and length; bone density) and treatment objectives (e.g., enhance only overdenture retention, or retention and support). Usually, implant placement without bone grafting can be done

**•** There are many types of attachment system that can be used for implant overdentures, e.g., ball, bar, locator, magnets, telescope, TiSiSnap. Selecting the attachment system must consider their role, such as only improving overdenture retention (e.g., ball attachment), or retention and stability (e.g., round bar attachment with non-rigid anchorage), or retention, stability and support (e.g., milled bars with rigid anchorage). Aspects related to patient's features (bone resorption, interarch vertical space, patient ability to perform maintenance procedures and expectations), situation of the opposite jaw (dentate or edentulous patient, treated by fixed or removable conventional or implant prosthesis), financial costs, should be all considered. anteriorly to the mental foramen in the mandible, and anteriorly to the maxillary sinus in the maxilla. Frequently, for the implants placed in the posterior area of the jaws, bone grafting is required. In order to avoid bone grafting, narrow dental implants can be used in narrow ridges, and short dental implants can be used in reduced ridge height. Bone density, according to Misch classification, should be D1, D2 or D3, not D4 because it is usually accompanied by implant failure [30]. Depending on patient's features and the material and treatment option chosen, implant placement can be done with or without a flap, using one-stage or two-stage implantation protocol. Implants can be unsplinted (e.g., with ball as attachment system) or splinted (e.g., with bar as attachment system). In the first case, implant problems can be more easily addressed by implant replacement or by placing an additional implant. In case of implants splinted by a bar, implant failure may be followed by treatment failure. There is no difference between splinted and unsplinted implant overdentures regarding the peri-implant outcome and patients'

procedure, these may be more indicated for aged edentulous patients [31].

satisfaction. Therefore, considering unsplinted implants prostheses have simpler manufacturing and repairing

 There are many types of attachment system that can be used for implant overdentures, e.g., ball, bar, locator, magnets, telescope, TiSiSnap. Selecting the attachment system must consider their role, such as only improving


There are many treatment planning options when considering treatment of edentulism with implant overdentures, some being more invasive than other. Selection of one of them depends mainly on patient's preferences and needs, and on oral and general health status and partic‐ ularities.

Among implant overdenture treatment options, those requiring easier and less invasive interventions for execution and maintenance will be detailed further on. There will be addressed mainly the alternatives that require the minimum necessary surgery (mainly implant placement, according to the anatomical limitations), preferably with immediate implant loading (ensures rapid functional reestablishment), and unsplinted implants (give more flexibility in managing future complications, that usually are less severe; maintenance is simpler). These overdentures mainly improve the retention of the prosthesis, and are implemented at moderate biological, financial and time costs.

#### **Clinical phases**.

splinted and unsplinted implant overdentures regarding the peri-implant outcome and patients' satisfaction. Therefore, considering unsplinted implants prostheses have simpler manufacturing and repairing procedure, these may be more indicated for aged edentulous

The number of dental implants placed in the case of implant overdentures vary between 1 to 4 for mandibular

 Selection of the dental implant, as type, diameter and length and establishing their number and position must consider the bone features (ridge width and length; bone density) and treatment objectives (e.g., enhance only overdenture retention, or retention and support). Usually, implant placement without bone grafting can be done anteriorly to the mental foramen in the mandible, and anteriorly to the maxillary sinus in the maxilla. Frequently, for the implants placed in the posterior area of the jaws, bone grafting is required. In order to avoid bone grafting, narrow dental implants can be used in narrow ridges, and short dental implants can be used in reduced ridge height. Bone density, according to Misch classification, should be D1, D2 or D3, not D4 because it is usually

Depending on patient's features and the material and treatment option chosen, implant placement can be done with

 Implants can be unsplinted (e.g., with ball as attachment system) or splinted (e.g., with bar as attachment system). In the first case, implant problems can be more easily addressed by implant replacement or by placing an additional implant. In case of implants splinted by a bar, implant failure may be followed by treatment failure. There is no difference between splinted and unsplinted implant overdentures regarding the peri-implant outcome and patients' satisfaction. Therefore, considering unsplinted implants prostheses have simpler manufacturing and repairing

 There are many types of attachment system that can be used for implant overdentures, e.g., ball, bar, locator, magnets, telescope, TiSiSnap. Selecting the attachment system must consider their role, such as only improving

Figure 8. Different type of implants, according to their diameter and attachment system

or without a flap, using one-stage or two-stage implantation protocol.

procedure, these may be more indicated for aged edentulous patients [31].

overdenture, and 2 to 6 for maxillary overdenture.

**Figure 8.** Different type of implants, according to their diameter and attachment system

accompanied by implant failure [30].

**•** There are many types of attachment system that can be used for implant overdentures, e.g., ball, bar, locator, magnets, telescope, TiSiSnap. Selecting the attachment system must consider their role, such as only improving overdenture retention (e.g., ball attachment), or retention and stability (e.g., round bar attachment with non-rigid anchorage), or retention, stability and support (e.g., milled bars with rigid anchorage). Aspects related to patient's features (bone resorption, interarch vertical space, patient ability to perform maintenance procedures and expectations), situation of the opposite jaw (dentate or edentulous patient, treated by fixed or removable conventional or implant prosthesis), financial costs, should

patients [31].

90 Current Concepts in Dental Implantology

be all considered.

**Patient evaluation** should comprise the common diagnostic data collection for complete dentures, and implant prosthesis, some of the aspects mentioned below being very important for treatment planning in case of implant overdenture.

Patient's needs, expectations and chief complaints related to the previous prosthetic treatment should be well-acknowledged. Most often, previous complete denture wearers are dissatisfied by its retention, aspect that is usually well addressed by implant overdentures. Dentate patients are often frightened by the idea of removable denture, and have psychological difficulties in accepting it. Therefore, explaining to the patient the main treatment options, with their benefits, limitations and cost, is mandatory.

Considering that often edentulous patients are aged, with multiple comorbidities, less invasive surgery is beneficial. Therefore, bone offer needs to be accurately analyzed, in order to establish implants type, position, diameter and length. Frequently, sufficient natural bone for implant placement is found anteriorly to the mental foramen in the mandible, and anteriorly to the maxillary sinus in the maxilla. In the mandible, bone deficiencies are mostly related to severe ridge resorption and decreased ridge width. In the maxilla, bone deficiencies are mostly related to decreased ridge height and reduced bone density. Consequently, when conventional dental implants cannot be applied without bone grafting, narrow or mini dental implants may be used in the mandible, and an increased number of conventional diameter implants are recommended in the maxilla [32]. In the mandible, two conventional diameter implants (diameter greater than 3.5mm), two narrow diameter implants (diameter below 3.5mm), or four mini dental implants (diameter below 3mm) are usually placed. In the maxilla four conventional diameter implants, four narrow diameter implants or six mini dental implants, of minimum 10 mm length are usually placed.

Thickness of keratinized mucosa should be evaluated in order to properly select the implant and attachment system that are usually designed with alternatives for different gingiva height.

Treatment planning should consider the condition and treatment of the opposite jaw. For example, planning an implant overdenture in the mandible should consider if teeth or fixed restoration, or edentulism treated by conventional denture are found in the maxilla. If teeth or fixed prosthesis are found in the maxilla, it is recommended to increase the number of mandibular implants and special consideration should be given to the vertical prosthetic space that is frequently reduced. If a complete denture is found in the maxilla, signs of combination syndrome may appear due to anterior movement of the masticatory field, favoring the instability of the maxillary denture and the increased bone resorption rate in the anterior maxilla. Consequently, this iatrogenic effect can be managed by using implant overdenture also in the maxilla [33].

Previous denture analysis may offer diagnostic data and further on, depending on their correctness, can be transformed or not into the future overdenture. Aspects like registration of an increased vertical dimension of occlusion or errors in artificial teeth mounting should lead to the decision of manufacturing a new denture, because these may become risk factors for implant overdenture complications.

**Surgical procedure** includes teeth extractions, preprosthetic interventions and implants placement.

Preprosthetic surgery aims towards obtaining favorable conditions for denture execution and improving the treatment prognosis. It may include intervention on the bone (for exostosis, tori) or the soft tissue (for frenum, hyperplasia). Sometimes, major surgical interventions, such as bone grafting, sinus lift or mental nerve relocation, are needed. Decision regarding the preprosthetic surgical intervention used is linked to patient features and treatment parameters (e.g., using narrow dental implants usually requires less invasive preprosthetic surgical interventions compared to conventional diameter implants). Preprosthetic surgery can be performed before or during implant placement.

Patient's needs, expectations and chief complaints related to the previous prosthetic treatment should be well-acknowledged. Most often, previous complete denture wearers are dissatisfied by its retention, aspect that is usually well addressed by implant overdentures. Dentate patients are often frightened by the idea of removable denture, and have psychological difficulties in accepting it. Therefore, explaining to the patient the main treatment options, with

Considering that often edentulous patients are aged, with multiple comorbidities, less invasive surgery is beneficial. Therefore, bone offer needs to be accurately analyzed, in order to establish implants type, position, diameter and length. Frequently, sufficient natural bone for implant placement is found anteriorly to the mental foramen in the mandible, and anteriorly to the maxillary sinus in the maxilla. In the mandible, bone deficiencies are mostly related to severe ridge resorption and decreased ridge width. In the maxilla, bone deficiencies are mostly related to decreased ridge height and reduced bone density. Consequently, when conventional dental implants cannot be applied without bone grafting, narrow or mini dental implants may be used in the mandible, and an increased number of conventional diameter implants are recommended in the maxilla [32]. In the mandible, two conventional diameter implants (diameter greater than 3.5mm), two narrow diameter implants (diameter below 3.5mm), or four mini dental implants (diameter below 3mm) are usually placed. In the maxilla four conventional diameter implants, four narrow diameter implants or six mini dental implants,

Thickness of keratinized mucosa should be evaluated in order to properly select the implant and attachment system that are usually designed with alternatives for different gingiva height. Treatment planning should consider the condition and treatment of the opposite jaw. For example, planning an implant overdenture in the mandible should consider if teeth or fixed restoration, or edentulism treated by conventional denture are found in the maxilla. If teeth or fixed prosthesis are found in the maxilla, it is recommended to increase the number of mandibular implants and special consideration should be given to the vertical prosthetic space that is frequently reduced. If a complete denture is found in the maxilla, signs of combination syndrome may appear due to anterior movement of the masticatory field, favoring the instability of the maxillary denture and the increased bone resorption rate in the anterior maxilla. Consequently, this iatrogenic effect can be managed by using implant overdenture

Previous denture analysis may offer diagnostic data and further on, depending on their correctness, can be transformed or not into the future overdenture. Aspects like registration of an increased vertical dimension of occlusion or errors in artificial teeth mounting should lead to the decision of manufacturing a new denture, because these may become risk factors

**Surgical procedure** includes teeth extractions, preprosthetic interventions and implants

Preprosthetic surgery aims towards obtaining favorable conditions for denture execution and improving the treatment prognosis. It may include intervention on the bone (for exostosis, tori)

their benefits, limitations and cost, is mandatory.

92 Current Concepts in Dental Implantology

of minimum 10 mm length are usually placed.

also in the maxilla [33].

placement.

for implant overdenture complications.

Implant placement, as implant number and position, is done according to the treatment plan previously established. In order to obtain the desired implant position and angulation, a surgical guide or template can be used.

Surgical steps of implant placement vary according to patient's features, implant placement protocol and implant type, respecting the manufacturer's instructions.

Case particularities are determinant for choosing a specific treatment conduct. Alveolar ridge width and height, bone density, cortical bone thickness, mucosal resilience and width of keratinized mucosa are decision factors for using flap or flapless technique, one-stage or twostage implantation protocol with immediate or delayed loading [30].

Implant surgical protocol is achieved using the main following steps, with variation depending on the implant type used (e.g., mini, narrow or conventional diameter implant). Firstly, a surgical exposure of the implant site is done, through flap elevation or mucosal punch, with a flapless technique. Using a flap technique has the advantage of a better assessment of available bone and thickness of the crestal area, information deficiently acknowledged when only clinical examination and panoramic radiographs are used. Flapless technique is mostly used for narrow dental implants (Figure 9). It has the advantage of reduced bleeding and decrease of the clinical time required (avoiding incision and flap elevation in the beginning, and suture in the end), is less invasive compared to the previous therefore promoting a shortened healing period. Afterwards, initial osteotomy is done with the marking or trepan drill, this aiming to pierce the cortical bone and define the implant site. With the same or another drill, usually called pilot drill, the implant osteotomies is initiated, in this stage being important to verify the implant angulation with a parallel pin. Implant placed with an unfavorable divergent angle may associate difficulties related to abutment and attachment system selection and exertion of excessive pressure on the implant during overdenture placement or removal. Osteotomy depth varies according to bone density, being approxi‐ mately 2/3 of implant length in low bone density (D3) and as implant length in increased bone density (D1, D2). The implant osteotomy is enlarged as necessary using the twist drills. All previous drilling procedures need to be accompanied by irrigation with refrigerated sterile saline. Consequently, implant is placed with the ratchet and handpiece. After that, depending on the implant type and the treatment plan, if the surgical phase is over, placement of cover screw, healing abutment or prosthetic abutment, with suturing flap, are necessary. The surgical appointment usually ends with giving the patient the postoperative instructions regarding care (hygiene, diet and medication), also being scheduled for the next appointment. When needed, a second stage implant surgery is applied for removal of the cover screw and abutment placement [34,35].

**Figure 9.** Flapless surgical technique used for placement of mini and narrow dental implants

Considering that generally edentulous patients are aged, with systemic comorbidities and less availability to complex surgical intervention, simpler one-stage surgical interventions are usually preferred [36].Considering that, mini or narrow dental implants may be preferred for increasing the denture retention, due to the simpler and shorter medical intervention [37-39].

**The overdenture** can be executed before or after implant placement. If applicable, the previous complete denture can be used as interim prosthesis or can be transformed into the new overdenture.

Overdentures that aim only towards improvement of retention, should be designed as a conventional denture, with proper support, retention and stability. If previous dentures are preserved, their correctness should be assessed in order to decide to either keep or replace them.

Using an implant overdenture associates more frequently a less accurate extension of over‐ denture bearing area, due to the misconception that the attachment system will provide all the retention needed. Overextended flanges dislodge the overdenture during chewing or speak‐ ing. Short flanges enhance food and plaque accumulation and retention. Existence of a space between the overdenture and the oral mucosa in the implant site is a risk factor for periimplantitis or peri-implant mucositis. Therefore, a complete coverage of the overdenture support area, reaching the anatomical and functional borders, with complete peripheral seal should be obtained. For the maxillary denture, complete palatal coverage, with posterior palatal seal is recommended. In order to correctly register the functional limits of the denture bearing area, a mucodynamic functional impression technique can be used.

**Figure 10.** The worn denture was modified as overdenture, and used as an interim prosthesis during the osseointegra‐ tion period

**Figure 9.** Flapless surgical technique used for placement of mini and narrow dental implants

overdenture.

94 Current Concepts in Dental Implantology

them.

Considering that generally edentulous patients are aged, with systemic comorbidities and less availability to complex surgical intervention, simpler one-stage surgical interventions are usually preferred [36].Considering that, mini or narrow dental implants may be preferred for increasing the denture retention, due to the simpler and shorter medical intervention [37-39].

**The overdenture** can be executed before or after implant placement. If applicable, the previous complete denture can be used as interim prosthesis or can be transformed into the new

Overdentures that aim only towards improvement of retention, should be designed as a conventional denture, with proper support, retention and stability. If previous dentures are preserved, their correctness should be assessed in order to decide to either keep or replace

Using an implant overdenture associates more frequently a less accurate extension of over‐ denture bearing area, due to the misconception that the attachment system will provide all the retention needed. Overextended flanges dislodge the overdenture during chewing or speak‐ ing. Short flanges enhance food and plaque accumulation and retention. Existence of a space between the overdenture and the oral mucosa in the implant site is a risk factor for periimplantitis or peri-implant mucositis. Therefore, a complete coverage of the overdenture

Registration of maxillomandibular relations aims towards recording the correct functional vertical dimension of occlusion and centric relation. Correctness of this clinical procedure has a major impact of the treatment outcome. Registration of an increased vertical dimension of occlusion can lead to prosthesis intolerance and implant loss, consecutive to the high pressure exerted on them.

In order to obtain a good esthetic outcome, the overdenture can be manufactured first, according to the esthetic principles and patient wishes, followed by implant placement using a surgical template.

For implant overdentures, immediate or delayed implant loading protocols can be used. Delayed implant loading is mainly used for conventional diameter implants. After implant placement, the healing abutments are placed for 10 to 13 weeks; in this period it is important to verify the denture, in order not to exert excessive pressure on implant site and interfere with implant osseointegration. Immediate implant loading is always used for one-piece mini dental implants, and sometimes used for narrow and conventional diameter implants. Using it requires a good primary stability of the implant, linked to a high insertion torque, of 35-40 Ncm. When the value of insertion torque is reduced, immediate implant loading can be done using soft acrylic or silicone materials [40]. In this respect, there are silicone materials especially developed to be used as matrices, such as Retension.Sil (Bredent), that offer three retention levels, i.e., 200, 400, 600 gf (Figure 11).

**Figure 11.** Immediate implant loading with silicone materials.

Attachment systems ensure stable balance (support, retention, stability) of the overdenture. The usual attachment systems used are: round, ovoid or parallel wall shaped bar; ball; Locator; magnets; telescopes. Selection of the attachment system depends on oral and prosthesis features, such as:


**Figure 12.** Placement of the metal matrices in the overdenture base

implant osseointegration. Immediate implant loading is always used for one-piece mini dental implants, and sometimes used for narrow and conventional diameter implants. Using it requires a good primary stability of the implant, linked to a high insertion torque, of 35-40 Ncm. When the value of insertion torque is reduced, immediate implant loading can be done using soft acrylic or silicone materials [40]. In this respect, there are silicone materials especially developed to be used as matrices, such as Retension.Sil (Bredent), that offer three retention

Attachment systems ensure stable balance (support, retention, stability) of the overdenture. The usual attachment systems used are: round, ovoid or parallel wall shaped bar; ball; Locator; magnets; telescopes. Selection of the attachment system depends on oral and prosthesis

**•** overdenture type (partial or complete) and the role of connection systems (to improve

**•** the implant number, site, angulation and their parallelism (two implant overdenture can be splinted with a bar, or used unsplinted with ball attachment; the selection of the attachment system must take into account the parallelism of the implants, ball attachments can be used

levels, i.e., 200, 400, 600 gf (Figure 11).

96 Current Concepts in Dental Implantology

**Figure 11.** Immediate implant loading with silicone materials.

support, stability and/or retention of the prosthesis);

up to 30° divergence while Locator allows up to 40° divergence);

features, such as:

**Postoperative instructions** usually target the postoperative medications, the adequate plaque control, having a soft diet and wearing the overdentures as little as possible until the next appointment. It is mandatory to schedule the next appointment in the following days, in order to verify if the overdenture is supported only by the oral mucosa and to make occlusal adjustments. During osseointegration phase, pressure exercised on the implants is a major risk factor for implant failure. Additionally, in overdentures with immediate implant loading, patients have difficulties in assessing the cause of a perceived discomfort (implant pain is usually mistaken for trauma related to the prostheses or healing after surgery). Therefore, regular check-ups are recommended and the denture should not be worn overnight.

**Indications.** Implant overdentures are removable prostheses designed for treatment of edentulism, considered as the minimum standard of care for this condition. They are indicated for unsatisfied complete denture wearers, because by a relative simple intervention patient's complaints can be addressed, usually solving the problem of ill-fitting dentures. Also, they can be used as preventive factor for alveolar ridge resorption in high risk patients (e.g., patients with tooth loss due to periodontitis, with diabetes, during the menopause and postmeno‐ pause). Overdenture can be used as palliative treatment in patients with sensitive mucosa or hyposialia. They are particularly recommended in the older completely edentulous patients, which show a more frequent rate of denture intolerance, this way favoring a better adaptability with the prosthesis. Implant overdenture are recommended to be used when there are objective reasons that favor instability of the conventional denture (e.g., mandibular implant overden‐ tures are indicated in skeletal class II patients; maxillary overdentures are indicated in skeletal class III patients). They are also recommended in oral and maxillofacial defects (clefts; after tumors removal, trauma) and in those with poor neuro-muscular coordination.

**Contraindications.** Implant overdentures have contraindications, mainly in relation to the risks associated to the surgical procedures, even if in some cases in can be regarded as a minimally invasive one. Additionally, using this specific treatment concept is limited to cases with reduced prosthetic vertical space that makes it impossible to apply the attachment systems and also provide adequate prosthesis resistance (e.g., using Locators requires a minimum of 8.5 mm vertical space and 9 mm horizontal space; bar attachments require 10 to 12 mm vertical space) [41]. Implant overdentures are not recommended when there is a decreased D4 bone density, in bruxism and in severe oral hygiene deficiency.

**Advantages.** Implant overdentures are a viable alternatives to conventional dentures, being considered the optimal solution for the edentulous seniors. Its main advantages are related to the improved retention, stability and support, depending on the attachment system that is used (e.g., improved chewing efficiency, speaking and comfort, with positive consequences on the quality of life). Using it associates a lower bone resorption rate, compared to conven‐ tional dentures, due to dental implants and improved denture stability, thus limiting the magnitude of pressures to a biological tolerance level. For the upper arch, if a vomiting reflex exists, the extension of the maxillary base can be reduced. Plaque control for implant over‐ denture is easier compared to implant fixed prostheses, but more difficult compared to conventional dentures. Considering the relatively easy surgical intervention and the reduced number of implants used, it is better accepted by patients with fear of complex medical interventions. Their execution and maintenance implies lower costs compared to the fixed implant prosthesis, and even if they are not the gold standard treatment, they can be considered as being cost effective due to their obvious benefits.

**Complications.** The implant overdenture complications occur in relation to patient's features, to surgical procedures or to prosthetic factors, during or after treatment execution. Some of them are considered as being more specific to this treatment option.

The implants' failure, as lack of osseointegration or peri-implantitis, can be linked to factors that affect healing of the bone, such as diabetes, steroids or bisphosphonates treatment, and smoking, to inadequate bone site and poor quality of the bone, to implant trauma exercised by the denture, to poor oral hygiene and decreased patient compliance. Prosthetic complica‐ tions occur mainly within the first year of functioning [42]. Biomechanical or technical complications of the overdentures or attachment system used can be encountered, such as overdenture fracture, retention loss, aging of the material, teeth wear and attachment system loosening, loss or damage.

Addressing overdenture complications should take into account their nature, etiology and severity. Acknowledgement of patient's general and local features, respecting the removable implant prosthodontic principles, additional to regular check-ups, represent the basis of their prevention and control.

#### **4. Conclusion**

which show a more frequent rate of denture intolerance, this way favoring a better adaptability with the prosthesis. Implant overdenture are recommended to be used when there are objective reasons that favor instability of the conventional denture (e.g., mandibular implant overden‐ tures are indicated in skeletal class II patients; maxillary overdentures are indicated in skeletal class III patients). They are also recommended in oral and maxillofacial defects (clefts; after

**Contraindications.** Implant overdentures have contraindications, mainly in relation to the risks associated to the surgical procedures, even if in some cases in can be regarded as a minimally invasive one. Additionally, using this specific treatment concept is limited to cases with reduced prosthetic vertical space that makes it impossible to apply the attachment systems and also provide adequate prosthesis resistance (e.g., using Locators requires a minimum of 8.5 mm vertical space and 9 mm horizontal space; bar attachments require 10 to 12 mm vertical space) [41]. Implant overdentures are not recommended when there is a

**Advantages.** Implant overdentures are a viable alternatives to conventional dentures, being considered the optimal solution for the edentulous seniors. Its main advantages are related to the improved retention, stability and support, depending on the attachment system that is used (e.g., improved chewing efficiency, speaking and comfort, with positive consequences on the quality of life). Using it associates a lower bone resorption rate, compared to conven‐ tional dentures, due to dental implants and improved denture stability, thus limiting the magnitude of pressures to a biological tolerance level. For the upper arch, if a vomiting reflex exists, the extension of the maxillary base can be reduced. Plaque control for implant over‐ denture is easier compared to implant fixed prostheses, but more difficult compared to conventional dentures. Considering the relatively easy surgical intervention and the reduced number of implants used, it is better accepted by patients with fear of complex medical interventions. Their execution and maintenance implies lower costs compared to the fixed implant prosthesis, and even if they are not the gold standard treatment, they can be considered

**Complications.** The implant overdenture complications occur in relation to patient's features, to surgical procedures or to prosthetic factors, during or after treatment execution. Some of

The implants' failure, as lack of osseointegration or peri-implantitis, can be linked to factors that affect healing of the bone, such as diabetes, steroids or bisphosphonates treatment, and smoking, to inadequate bone site and poor quality of the bone, to implant trauma exercised by the denture, to poor oral hygiene and decreased patient compliance. Prosthetic complica‐ tions occur mainly within the first year of functioning [42]. Biomechanical or technical complications of the overdentures or attachment system used can be encountered, such as overdenture fracture, retention loss, aging of the material, teeth wear and attachment system

Addressing overdenture complications should take into account their nature, etiology and severity. Acknowledgement of patient's general and local features, respecting the removable

tumors removal, trauma) and in those with poor neuro-muscular coordination.

decreased D4 bone density, in bruxism and in severe oral hygiene deficiency.

as being cost effective due to their obvious benefits.

loosening, loss or damage.

98 Current Concepts in Dental Implantology

them are considered as being more specific to this treatment option.

Sky Fast & Fixed is one of the less invasive fixed-prosthetic implant restoration for edentulism. It is a relatively simple and quick approach to the patient's medical problem, implemented through a decreased number of appointments, using limited surgery and reduced number of implants. The interim prosthesis is fixed, applied in the same day as implant placement, therefore the removable prosthesis is avoided. This rapid, less invasive, cost-effective fixed implant restoration usually ensures rapid regaining of functionality and resumption of social activities.

The implant overdenture is acknowledged as having a high predictability and numerous advantages compared to the most widely used treatment alternative, namely complete denture. It is important to identify the simpler and less invasive options of implant overdenture when considering the trends of decreasing tooth loss that associate an increasing of the age when edentulism occurs. Elderly patients require prosthetic rehabilitations that ensure good functionality, but considering their multiple systemic comorbidities and reduced availability to complex medical interventions, less invasive treatments with limited surgery, with easy maintenance procedures and that are cost-effective are more realistic and appropriate to their expectations. Therefore, the frequent problem of ill-fitting dentures can be relatively simply approached through placement of a reduced number of conventional diameter, narrow, or even mini implants, this requiring one clinical appointment, a relatively simple medical procedure and moderate costs.

Identifying and presenting to the reluctant edentulous patient the less invasive implant treatment strategies, fixed and removable, with their advantages, disadvantages and limita‐ tion, may help overcome their misconceptions and fears towards the implant prosthesis and lead to applying a treatment with a better outcome that promotes higher satisfaction and improved quality of life.

#### **Author details**

Elena Preoteasa1 , Laurentiu Iulian Florica2 , Florian Obadan3 , Marina Imre1 and Cristina Teodora Preoteasa4\*

\*Address all correspondence to: cristina\_5013@yahoo.com

1 Department of Prosthodontics, Faculty of Dental Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania

2 Private Practice, Bucharest, Romania

3 Private Practice, Alexandria, Romania

4 Department of Oral Diagnosis, Ergonomics, Scientific Research Methodology, Faculty of Dental Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania

#### **References**


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3 Private Practice, Alexandria, Romania

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4 Department of Oral Diagnosis, Ergonomics, Scientific Research Methodology, Faculty of Dental Medicine, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania

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[10] Esposito M, Grusovin MG, Chew YS, Coulthard P, Worthington HV. One-stage ver‐ sus two-stage implant placement. A Cochrane Systematic Review of Randomised Controlled Clinical Trials. European Journal of Oral Implantology 2009;2(2):91-9. [11] Visser A, de Baat C, Hoeksema AR, Vissink A. Oral Implants in Dependent Elderly

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[25] Armellini D, von Fraunhofer JA. The Shortened Dental Arch: a Review of the Litera‐

[26] Preoteasa E, Imre M, Preoteasa CT. A 3-Year Follow-up Study of Overdentures Re‐ tained by Mini–Dental Implants. The International Journal of Oral & Maxillofacial

[27] Diz P, Scully C, Sanz M. Dental Implants in the Medically Compromised Patient.

[28] Gomez-de Diego R, Mang-de la Rosa M, Romero-Pérez MJ, Cutando-Soriano A, Lo‐ pez-Valverde-Centeno A. Indications and Contraindications of Dental Implants in Medically Compromised Patients: Update. Medicina Oral Patologia Oral y Cirugia

[29] Attard NJ, Zarb GA, Laporte A. Long-Term Treatment Costs Associated with Im‐ plant-Supported Mandibular Prostheses in Edentulous Patients. The International

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[33] Kreisler M, Behneke N, Behneke A, d´Hoedt B. Residual Ridge Resorption in the Edentulous Maxila in Patients With Implant-Supported Mandibular Overdentures: An 8-Years Retrospective Study. International Journal of Prosthodontics 2003;16(3):

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## **Dental Implant Placement in Inadequate Posterior Maxilla**

Umit Karacayli, Emre Dikicier and Sibel Dikicier

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59458

#### **1. Introduction**

Hard tissue defects resulting from trauma, infection, or tooth loss often lead to an unfavorable anatomy of maxillary and mandibular alveolar processes. Dental implant placement in the edentulous posterior maxilla can present difficulties because of a horizontal or vertical alveolar ridge deficiency, unfavorable bone quality, or increased pneumatization of the maxillary sinus. The posterior maxilla has been known as the most difficult and problematic intraoral area for implant dentistry, requiring a maximum of attention for the achievement of successful surgery. Both anatomical structures and mastication dynamics contribute to the long term survival rates of endosseous dental implants in this region [1]. During the past 25 years, surgical procedures have been developed to increase the local bone volume, thus enabling the placement of implants [2]. The hard tissue augmentation techniques were separated into two anatomic sites, the maxillary sinus and alveolar ridge. Within the alveolar ridge augmentation procedures, different surgical approaches were developed and are currently used, including guided bone regeneration, onlay grafting, distraction osteogenesis, ridge splitting, free and vascularized autografts for discontinuity defects, and socket preservation. Among the variety of techniques have been described, the three that are the most widely used in maxilla are lateral approach, osteotome technique and ridge splitting [3].

#### **2. Anatomy of the posterior maxilla**

The maxillary sinus is a pyramid shaped cavity with an anterior wall corresponding to the facial surface of the maxilla. The size of the sinus is minimal until the eruption of permanent teeth. The average dimensions of the adult sinus are 2.5 to 3.5cm wide, 3.6 to 4.5 cm tall, and

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3.8 to 4.5 cm deep. The size of the sinus will increase with age after extraction of the maxillary molar teeth. The extent of pneumatization varies from person to person and from side to side. The inner walls of the maxillary sinus is lined with the sinus membrane, also known as the Schneiderian membrane. This membrane consists of ciliated epithelium cells resting of the basement membrane. It is continuous with, and connects to, the nasal epithelium through the ostium in the middle meatus. The blood circulation to the maxillary sinus is primarily obtained from the posterior superior alveolar artery and the infraorbital artery, both being branches of the maxillary artery. Many anastomoses are occureed between these 2 arteries in the lateral antral wall. Among these arteries, the posterior superior alveolary artery and the infra-orbital artery also supply the buccal part of the maxillary sinus. However, because the blood supplies to the maxillary sinus are from terminal branches of peripheral vessels, to avoid bleeding complications, the branches of the maxillary artery should be taken into consideration. Nerve supply to the sinus is derived from the superior alveolar branch of the maxillary division of the trigeminal nerve [4].

The objective of sinus lift procedure is to compensate the bone loss by creating increased bone volume in the maxillary sinus and thus permitting the installation of implants in the posterior maxilla [4,5]. Membrane perforations and bleeding are procedure-related complications, seen in lateral wall sinus approach [6]. Therefore, the anatomy of the area should be carefully examined before surgical interventions.

#### **3. Augmentation procedures**

#### **3.1. Vertical ridge augmentation**

#### *3.1.1. Sinus lifting procedure*

Implant placement in the posterior maxilla is a challenging procedure when vertical deficien‐ cies are occured. Maxillary sinus elevation technique is a main surgical procedure which permits to augment the sufficient bone volume in posterior maxilla in order to place implants.

To increase the amount of bone in the posterior maxilla, the sinus lift procedure, or subantral augmentation, originally presented in 1977 and subsequently published in 1980 [4]. After modifications of the surgical procedure, access was accomplished through the lateral wall of the maxilla. It is preferable techniques to adjust the low residual bone height in the posterior maxilla performed in two ways: A lateral window technique and an osteotome sinus floor elevation technique and placing bone-graft material in the maxillary sinus to increase the height and width of the available bone. Autogenic bone graft is often used in this method. The bone usually seems to be harvested from the iliac crest, although several anatomic areas have been used.

When the ridge bone height is more than 6 mm, the osteotome technique can be performed. In that case, implant placement is usually carried out simultaneously with elevation of the sinus floor.

#### *3.1.1.1. Lateral approach*

3.8 to 4.5 cm deep. The size of the sinus will increase with age after extraction of the maxillary molar teeth. The extent of pneumatization varies from person to person and from side to side. The inner walls of the maxillary sinus is lined with the sinus membrane, also known as the Schneiderian membrane. This membrane consists of ciliated epithelium cells resting of the basement membrane. It is continuous with, and connects to, the nasal epithelium through the ostium in the middle meatus. The blood circulation to the maxillary sinus is primarily obtained from the posterior superior alveolar artery and the infraorbital artery, both being branches of the maxillary artery. Many anastomoses are occureed between these 2 arteries in the lateral antral wall. Among these arteries, the posterior superior alveolary artery and the infra-orbital artery also supply the buccal part of the maxillary sinus. However, because the blood supplies to the maxillary sinus are from terminal branches of peripheral vessels, to avoid bleeding complications, the branches of the maxillary artery should be taken into consideration. Nerve supply to the sinus is derived from the superior alveolar branch of the maxillary division of

The objective of sinus lift procedure is to compensate the bone loss by creating increased bone volume in the maxillary sinus and thus permitting the installation of implants in the posterior maxilla [4,5]. Membrane perforations and bleeding are procedure-related complications, seen in lateral wall sinus approach [6]. Therefore, the anatomy of the area should be carefully

Implant placement in the posterior maxilla is a challenging procedure when vertical deficien‐ cies are occured. Maxillary sinus elevation technique is a main surgical procedure which permits to augment the sufficient bone volume in posterior maxilla in order to place implants.

To increase the amount of bone in the posterior maxilla, the sinus lift procedure, or subantral augmentation, originally presented in 1977 and subsequently published in 1980 [4]. After modifications of the surgical procedure, access was accomplished through the lateral wall of the maxilla. It is preferable techniques to adjust the low residual bone height in the posterior maxilla performed in two ways: A lateral window technique and an osteotome sinus floor elevation technique and placing bone-graft material in the maxillary sinus to increase the height and width of the available bone. Autogenic bone graft is often used in this method. The bone usually seems to be harvested from the iliac crest, although several anatomic areas have

When the ridge bone height is more than 6 mm, the osteotome technique can be performed. In that case, implant placement is usually carried out simultaneously with elevation of the

the trigeminal nerve [4].

106 Current Concepts in Dental Implantology

examined before surgical interventions.

**3. Augmentation procedures**

**3.1. Vertical ridge augmentation**

*3.1.1. Sinus lifting procedure*

been used.

sinus floor.

Lateral approach is also known as lateral antrostomy which is a predictable technique to increase vertically available bone volume of the edentulous posterior maxilla giving the possibility to place osseointegrated implants. The sinus floor is elevated and it can be aug‐ mented with either autologous or xenogeneic bone grafts following an opening bone window prepared on the facial buccal wall of the sinus.

The 2-step antrostomy is the treatment of choice when the residuel ridge bone height is less than 4 mm. As part of this approach, the implants are usually placed after a healing period of 6 to 18 months following sinus floor elevation [7]. The 1-step antrostomy is applied when the ridge bone height ranges from 4 to 6 mm. In this situation, implant placement is performed simultaneously with sinus floor elevation.

With respect to the grafting procedure, several grafting materials have successfully been used for elevating and stabilizing the sinus membrane: autogenous bone, allografts, xenografts and combination of these materials. Sinus floor elevation by lateral antrostomy has provided good implant survival rates, as reported in several studies. However, it is a demanding surgical procedure and is quite invasive. The 1-step antrostomy, in which implants are placed during the same surgical visit as elevation of sinus floor is performed, is similar to the 2-step technique with regard to advantages and disadvantages. The most important difference is that less time elapses before initiation of prosthetic therapy [7,8].

**Figure 1.** (a) Panoramic image before sinus augmentation procedure (b) Cone beam computerized image of the residu‐ al alveolar bone

**Figure 2.** (a) Preparation of the bony window with a round bur (b) Medial rotation of the bone flap, elevation of the mucosa of the maxillary sinus and implant placement

**Figure 3.** Postoperative radiographic view

**Figure 4.** (a) Clinical view of the implants (b) Final prosthetic restoration

#### *3.1.1.2. Osteotome sinus floor elevation technique*

When the ridge bone height is more than 6 mm, the osteotome technique can be performed. In that case, implant placement is usually carried out simultaneously with elevation of the sinus floor. In the original approach, implants were placed after the controlled fracture of sinus floor and were submerged during the healing phase (Figure 5) [9].

Although the transcrestal approach is decided more conservative than the lateral approach, the main disadvantage is that the sinus lifting procedure must be performed blindly because of the impossibility to visualize the sinus floor [10]. In spite of this limitation, membrane perforation was reported to be less frequent in the osteotome-mediated procedure than in the lateral approach, for which such complication was occured in 7-35% of cases [11].

Osteotome-mediated sinus lift surgery may be performed with or without using many type of bone graft material as allograft, autogenous bone, or xenogeneic bone material [12]. No significant differences in terms of implant survival and surgical success rates were reported comparing the two methods [13]. Also, the use of platelet derivatives without any bone substitute is described in literature with the aim of allowing a better control of forces during sinus floor elevation and reducing the incidence of complications [13].

**Figure 5.** Osteotome sinus floor elevation technique

#### *3.1.2. Titanium mesh*

**Figure 2.** (a) Preparation of the bony window with a round bur (b) Medial rotation of the bone flap, elevation of the

mucosa of the maxillary sinus and implant placement

108 Current Concepts in Dental Implantology

**Figure 3.** Postoperative radiographic view

**Figure 4.** (a) Clinical view of the implants (b) Final prosthetic restoration

Natural hard and soft tissue contours allow both ideal implant placement and the emergence of a restoration. If there is large or small volume hard and soft tissue defects in these contours, these are prevent three-dimensional implant placement and aesthetic results [14]. Reconstruc‐ tive efforts at aesthetic implant sites usually involve more than replacing missing hard and soft tissue. For reconstruction of these type of defects, the surgeon uses different techniques: (1) Distraction osteogenesis, which describes the surgical induction of a fracture and the subsequent gradual separation of the two bone ends to create spontaneous bone regeneration between the two fragments; (2) Osteoinduction, which employs appropriate growth factors and/or stem/osteoprogenitor cells to encourage new bone formation [15, 16]; (3) Osteocon‐ duction, in which a grafting material serves as a scaffold for new bone formation; and (4) Guided bone regeneration (GBR), which provides spaces using barrier membranes that are to be subsequently filled with new bone [17, 18]. Guided bone regeneration was introduced as a therapeutic modality to achieve bone regeneration, via the use of barrier membranes and titanium mesh. Titanium mesh has been used for a variety of clinical applications in recon‐ structive implant surgery and reported positive results. Titanium mesh has excellent mechan‐ ical properties for the stabilization of bone grafts beneath the membrane [19]. Its rigidity provides extensive space maintenance and prevents contour collapse; its elasticity prevents mucosal compression; its stability prevents graft displacement; and its plasticity permits bending, contouring, and adaptation to any unique bony defect [20]. The common feature of commercially available titanium mesh membranes is its macroporosity (in the millimeter range). This is thought to play a critical role in maintaining blood supply and is believed to enhance regeneration by improving wound stability through tissue integration and allowing diffusion of extracellular nutrients across the membrane [21]. The most important advantage of this macroporosity is related to the attachment of soft tissues, which may stabilize and restrict the migration of epithelial cells. However, this makes the material difficult to remove at the second surgery. These macro- and multi-porous characteristics also create sharp spots when the material is cut or bent, and may provide an easy pathway for microbial contamination into the healing site. Thus, the development of less porous and micropore-sized titanium mesh membrane could alleviate some of the current difficulties associated with titanium mesh in dental applications [22].

Although many relevant articles have reported good clinical results without using resorbable membrane over titanium mesh, it can be considered that the combination of titanium mesh and resorbable membrane can demonstrate satisfying results. Thus, it was achieved space creation by using titanium mesh and prevention of fibroblastic cell migration into the defect site by using resorbable membrane.

**Figure 6.** Pre-operative intraoral view

**Figure 7.** (a) Severe atrophy of right maxillar alveolar process (b) Titanium mesh

**Figure 8.** Post-operative 12 months intraoral view

between the two fragments; (2) Osteoinduction, which employs appropriate growth factors and/or stem/osteoprogenitor cells to encourage new bone formation [15, 16]; (3) Osteocon‐ duction, in which a grafting material serves as a scaffold for new bone formation; and (4) Guided bone regeneration (GBR), which provides spaces using barrier membranes that are to be subsequently filled with new bone [17, 18]. Guided bone regeneration was introduced as a therapeutic modality to achieve bone regeneration, via the use of barrier membranes and titanium mesh. Titanium mesh has been used for a variety of clinical applications in recon‐ structive implant surgery and reported positive results. Titanium mesh has excellent mechan‐ ical properties for the stabilization of bone grafts beneath the membrane [19]. Its rigidity provides extensive space maintenance and prevents contour collapse; its elasticity prevents mucosal compression; its stability prevents graft displacement; and its plasticity permits bending, contouring, and adaptation to any unique bony defect [20]. The common feature of commercially available titanium mesh membranes is its macroporosity (in the millimeter range). This is thought to play a critical role in maintaining blood supply and is believed to enhance regeneration by improving wound stability through tissue integration and allowing diffusion of extracellular nutrients across the membrane [21]. The most important advantage of this macroporosity is related to the attachment of soft tissues, which may stabilize and restrict the migration of epithelial cells. However, this makes the material difficult to remove at the second surgery. These macro- and multi-porous characteristics also create sharp spots when the material is cut or bent, and may provide an easy pathway for microbial contamination into the healing site. Thus, the development of less porous and micropore-sized titanium mesh membrane could alleviate some of the current difficulties associated with titanium mesh in

Although many relevant articles have reported good clinical results without using resorbable membrane over titanium mesh, it can be considered that the combination of titanium mesh and resorbable membrane can demonstrate satisfying results. Thus, it was achieved space creation by using titanium mesh and prevention of fibroblastic cell migration into the defect

dental applications [22].

110 Current Concepts in Dental Implantology

site by using resorbable membrane.

**Figure 6.** Pre-operative intraoral view

**Figure 9.** (a) Titanium mesh post-operative 12 months (b) Removal of titanum mesh.

**Figure 10.** Implant placement

#### **3.2. Lateral ridge augmentation**

#### *3.2.1. Ridge splitting*

Alveolar bone splitting technique and immediate implant placement have been proposed for patients with narrow alveoalar ridge in the horizontal dimension. When the alveolar ridge is narrower than the optimally planned implant diameter, onlays of bone grafting material or guided bone regeneration are indicated [23]. This technique provides a selective cutting, minimal operative invasion and provides an acceptable inter-cortical gap for the placement of particulate bone grafting [24]. The obvious advantage of this technique is the absence of donor site morbidity associated to autologous bone harvesting. Crestal split augmentation involved a surgical osteotomy that was followed by alveolar crest split and augmentation after buccolingual bony plate expansion, prior to implantation [25].

Specific disadvantages have also been reported for each technique: resorption, limited amount of bone, damaging soft tissues, such as sinus floor membrane, nerves and vessels in bone grafting; tissue dehiscence, membrane displacement and membrane collapse in guided bone regeneration; and insufficiency of the distraction line, bone resorption, deficiency of bone formation and increased healing time for implant placement, in alveolar distraction [26-28].

50-year-old male patient referred to our clinic with atrophy of the alveolar rim in the posterior maxilla, which had inadequate width and height for implant placement (Figure 11).

A pre-operative computerized tomographic (CT) scan revealed 2.5-3 mm. of bone weightand‐ height of themolarareawas 5.64 mm. between the alveolar crest and maxillary sinus (Figures. 12a,b, 13a). We planned segmental split osteotomy, socket lifting and three dental implant placement at the same section without using any graft materials.

**Figure 11.** Pre-operative radiograph of the left posterior edentulous maxilla

**Figure 10.** Implant placement

112 Current Concepts in Dental Implantology

*3.2.1. Ridge splitting*

**3.2. Lateral ridge augmentation**

lingual bony plate expansion, prior to implantation [25].

placement at the same section without using any graft materials.

Alveolar bone splitting technique and immediate implant placement have been proposed for patients with narrow alveoalar ridge in the horizontal dimension. When the alveolar ridge is narrower than the optimally planned implant diameter, onlays of bone grafting material or guided bone regeneration are indicated [23]. This technique provides a selective cutting, minimal operative invasion and provides an acceptable inter-cortical gap for the placement of particulate bone grafting [24]. The obvious advantage of this technique is the absence of donor site morbidity associated to autologous bone harvesting. Crestal split augmentation involved a surgical osteotomy that was followed by alveolar crest split and augmentation after bucco-

Specific disadvantages have also been reported for each technique: resorption, limited amount of bone, damaging soft tissues, such as sinus floor membrane, nerves and vessels in bone grafting; tissue dehiscence, membrane displacement and membrane collapse in guided bone regeneration; and insufficiency of the distraction line, bone resorption, deficiency of bone formation and increased healing time for implant placement, in alveolar distraction [26-28].

50-year-old male patient referred to our clinic with atrophy of the alveolar rim in the posterior

A pre-operative computerized tomographic (CT) scan revealed 2.5-3 mm. of bone weightand‐ height of themolarareawas 5.64 mm. between the alveolar crest and maxillary sinus (Figures. 12a,b, 13a). We planned segmental split osteotomy, socket lifting and three dental implant

maxilla, which had inadequate width and height for implant placement (Figure 11).

**Figure 12.** (a-b) Pre-operative CT scan (c-d) Post-operative CT scan

The surgical procedure was performed under local anesthesia. Full thickness muco-periostal flap was elevated with vertical and crestal incisions. Ridge splitting was applied with osteo‐ tome 8 mm/Obwegeser (Ace Surgical Supply Co., Brockton, MA, USA), after the crest being prepared with surgical diamond disc in straight high speed handpiece (Figure 14-15). One centimeter penetration of the osteotome blade in ridge crest would automatically expand the ridge. Since osteotome thickness increases from tip toward shaft further the osteotome penetrates, more the ridge will expand. Slight bucco-lingual movement of the osteotome increases the expansion. 3.5x12 mm implants were placed in the canine and first premolar region into the ridge splitted crest (Figure 16-17). Muco-periostal flap were sutured primerly by using 3.0 silk suture (Starmedix LLC, Miami, FL, USA).

The present study reports that the clinical results of narrow ridge splitting. Post-operative panoramic radiograph (Figure 8) and CT scan (Figure 13b) showed therewas not any compli‐ cations around the implants and maxillary sinus. Five months after surgery, final fixed prosthetic restorations were accomplished.

**Figure 13.** (a) Pre-operative CT scan (b) Post-operative CT scan

**Figure 14.** Pre-operative view of alveolar ridge

**Figure 15.** Ridge splitting procedure with diamond disc

Dental Implant Placement in Inadequate Posterior Maxilla http://dx.doi.org/10.5772/59458 115

**Figure 16.** Implant placement

**Figure 13.** (a) Pre-operative CT scan (b) Post-operative CT scan

114 Current Concepts in Dental Implantology

**Figure 14.** Pre-operative view of alveolar ridge

**Figure 15.** Ridge splitting procedure with diamond disc

**Figure 17.** Post-operative view after implant placement

**Figure 18.** Post-operative panoramic radiograph

#### *3.2.2. Autogenous block graft*

Currently, various augmentation procedures have been introduced to rehabilitate of atrophic maxillary ridges in literature [29-32]. The grafting procedure using autogenous bone block is considered ideal by many researchers, as it shows osteogenic capability and deformation resistance [33]. A wide range of bone grafts and synthetic bone graft materials have been used in the last two decades for augmentation of inadequate alveolar ridge to facilitate the placement of dental implants of partially and completely edentulous patients. Various bone graft types, including autogenous, allogeneic (human), xenogeneic (porcine, equine, or bovine, and synthetic calcium-based materials (calcium phosphates [β-tricalcium phosphate/β-TCP, hydroxyapatite/HA], bioactive glasses), calcium sulfate, calcium hydroxide), and a combina‐ tion of these with or without the use of membrane and screws have been employed for grafting procedure [34-37]. Although, allogeneic bone grafts do not have the drawbacks of autografts, the procedure is more delicate and less successful in clinical practice. They also display several other disadvantages: risk of disease transmission of the donour site, infection, difficulties in obtaining and processing, possible rapid resorption [38,39], and partial loss of mechanical strength after sterilization [40]. Xenogenic bone substitutes of porcine, bovine, or, more recently, equine origin are used because of their chemical and structural composition similarity when compared to human bone [32]. They represent an unlimited supply of available material and may reduce morbidity by eliminating the donor site [31]. Heat or other treatments are used to deproteinate bone particles and eliminate immunogenicity risks [40]. Synthetic calcium phosphate ceramics with their excellent biocompatibility are common alternatives to autoge‐ nous bone [41]. Autogenous bone grafts have been widely accepted as "gold standard" due to their compatibility and osteogenic potentials to form the new bone by processes of osteogen‐ esis, osteoinduction, and osteoconduction. A particulate and block autogenous bone has been used to compensate of alveolar ridge deficiency [42]. Extraoral sites of autogenous block grafts are ilium, calvarium, tibia, rib, and others. The most widely used intraoral potential sites of autogenous block grafts include symphysis and retromolar-ramus areas. In the clinical practice, a maxillary tuberosity bone graft has been also used as a particulate graft for aug‐ mentation procedures in posterior maxilla prior to or simultaneously with implant insertion [43]. Some of advantages about the autogenous block graft procedure such as; intra- and extraoral donor site morbidity, potential complications and risks associated with the harvesting procedures may have been reported [44].

**Figure 19.** Pre-operative view

9 

10 

Figure 20. Operation site of the rib

Figure 19. Pre-operative view

Currently, various augmentation procedures have been introduced to rehabilitate of atrophic maxillary ridges in literature [29-32]. The grafting procedure using autogenous bone block is considered ideal by many researchers, as it shows osteogenic capability and deformation resistance [33]. A wide range of bone grafts and synthetic bone graft materials have been used in the last two decades for augmentation of inadequate alveolar ridge to facilitate the placement of dental implants of partially and completely edentulous patients. Various bone graft types, including autogenous, allogeneic (human), xenogeneic (porcine, equine, or bovine, and synthetic calcium-based materials (calcium phosphates [β-tricalcium phosphate/β-TCP, hydroxyapatite/HA], bioactive glasses), calcium sulfate, calcium hydroxide), and a combination of these with or without the use of membrane and screws have been employed for grafting procedure [34-37]. Although, allogeneic bone grafts do not have the drawbacks of autografts, the procedure is more delicate and less successful in clinical practice. They also display several other disadvantages: risk of disease transmission of the donour site, infection, difficulties in obtaining and processing, possible rapid resorption [38,39], and partial loss of mechanical strength after sterilization [40]. Xenogenic bone substitutes of porcine, bovine, or, more recently, equine origin are used because of their chemical and structural composition similarity when compared to human bone [32]. They represent an unlimited supply of available material and may reduce morbidity by eliminating the donor site [31]. Heat or other treatments are used to deproteinate bone particles and eliminate immunogenicity risks [40]. Synthetic calcium phosphate ceramics with their excellent biocompatibility are common alternatives to autogenous bone [41]. Autogenous bone grafts have been widely accepted as "gold standard" due to their compatibility and osteogenic potentials to form the new bone by processes of osteogenesis, osteoinduction, and osteoconduction. A particulate and block autogenous bone has been used to compensate of alveolar ridge deficiency [42]. Extraoral sites of autogenous block grafts are ilium, calvarium, tibia, rib, and others. The most widely used intraoral potential sites of autogenous block grafts include symphysis and retromolar-ramus areas. In the clinical practice, a maxillary tuberosity bone graft has been also used as a particulate graft for augmentation procedures in posterior maxilla prior to or simultaneously with implant insertion [43]. Some of advantages about the autogenous block graft procedure such as; intra- and extra-oral donor site morbidity, potential complications and risks associated with the harvesting procedures

#### **Figure 20.** Operation site of the rib

may have been reported [44].

**3.2.2. Autogenous block graft** 

*3.2.2. Autogenous block graft*

116 Current Concepts in Dental Implantology

procedures may have been reported [44].

**Figure 19.** Pre-operative view

Currently, various augmentation procedures have been introduced to rehabilitate of atrophic maxillary ridges in literature [29-32]. The grafting procedure using autogenous bone block is considered ideal by many researchers, as it shows osteogenic capability and deformation resistance [33]. A wide range of bone grafts and synthetic bone graft materials have been used in the last two decades for augmentation of inadequate alveolar ridge to facilitate the placement of dental implants of partially and completely edentulous patients. Various bone graft types, including autogenous, allogeneic (human), xenogeneic (porcine, equine, or bovine, and synthetic calcium-based materials (calcium phosphates [β-tricalcium phosphate/β-TCP, hydroxyapatite/HA], bioactive glasses), calcium sulfate, calcium hydroxide), and a combina‐ tion of these with or without the use of membrane and screws have been employed for grafting procedure [34-37]. Although, allogeneic bone grafts do not have the drawbacks of autografts, the procedure is more delicate and less successful in clinical practice. They also display several other disadvantages: risk of disease transmission of the donour site, infection, difficulties in obtaining and processing, possible rapid resorption [38,39], and partial loss of mechanical strength after sterilization [40]. Xenogenic bone substitutes of porcine, bovine, or, more recently, equine origin are used because of their chemical and structural composition similarity when compared to human bone [32]. They represent an unlimited supply of available material and may reduce morbidity by eliminating the donor site [31]. Heat or other treatments are used to deproteinate bone particles and eliminate immunogenicity risks [40]. Synthetic calcium phosphate ceramics with their excellent biocompatibility are common alternatives to autoge‐ nous bone [41]. Autogenous bone grafts have been widely accepted as "gold standard" due to their compatibility and osteogenic potentials to form the new bone by processes of osteogen‐ esis, osteoinduction, and osteoconduction. A particulate and block autogenous bone has been used to compensate of alveolar ridge deficiency [42]. Extraoral sites of autogenous block grafts are ilium, calvarium, tibia, rib, and others. The most widely used intraoral potential sites of autogenous block grafts include symphysis and retromolar-ramus areas. In the clinical practice, a maxillary tuberosity bone graft has been also used as a particulate graft for aug‐ mentation procedures in posterior maxilla prior to or simultaneously with implant insertion [43]. Some of advantages about the autogenous block graft procedure such as; intra- and extraoral donor site morbidity, potential complications and risks associated with the harvesting

Figure 21. Autogenous rib block graft

**Figure 21.** Autogenous rib block graft

**Figure 22.** Lateral augmentation procedure of the maxilla with autogenous rib graft

Figure 24. Post-operative panoramic radiograph of the graft

Figure 25. Implant placement four months after the augmentation procedure

**Figure 23.** Post-operative intraoral view after rib grafting

**Figure 24.** Post-operative panoramic radiograph of the graft

**Figure 25.** Implant placement four months after the augmentation procedure

**Figure 26.** Post-operative intraoral view after implant surgery

#### **4. Zygomatic implants**

Maxillary posterior defects that occur after tumor resection or trauma are challenging to reconstruct and rehabilitate. The aim of rehabilitation is not only to provide a cosmetically acceptable appearance, but also to restore oral functions, such as deglutition, mastication, and phonation [45]. The impossibility of placing conventional implants in posterior maxilla due to maxillectomy, maxillary sinus pneumatization or the lack of bone volume is currently the main indication for the usage of zygomatic implants [46].

Various reconstructive approaches, involving differing surgical procedures, graft materials and endosseous implant systems, have been described for reconstruction of patients with severe resorption of alveolar bone, and also patients who have undergone maxillary resection for neoplastic disease. Restorative techniques have been emphasized such as; microvascular free flaps, local flaps, and obturator prosthesis [47,48]. However, significant obturator retention and stability problems occur when extensive defects remain following a maxillectomy. Zygomatic implants are an effective treatment alternative to limit free or vascularized bone graft procedures, employing the zygomatic bone as anchorage. When determining zygomatic implant rehabilitation, the patient must present not only resorbtion of posterior maxilla preventing the placement of additional fixations for supporting the prosthesis, but also sufficient bone volume in the anterior maxilla -with a 10 mm in height and a 4 mm in widthto allow the placement of 2-4 conventional fixations [49].

Zygomatic implants were firstly introduced by Branemark in 1998 to rehabilitate the mastica‐ tory and aesthetic functions in severe atrophied maxilla caused by trauma, congenital condi‐ tions, tumour resection or increased sinus pneumatization. Given the high success rate reported for zygomatic implant placement, this surgical technique can be considered as a valid alternative therapeutic approach to bone grafting and invasive surgery to restore function and improve the esthetic results for patients with atrophic edentulous maxilla [50,51]. The surgical manipulation may lead to potential risk because of the drill way is close to critical anatomical vital structures, such as the maxillary sinus, the nasal cavity, and the eyes [52]. However the limited intraoperative visibility, especially given the anatomical intricacies of the curved zygomatic bone, makes this kind of surgery a demanding procedure. Traditional complica‐ tions of this surgery are secondary infection, sinusitis, pain, periimplantitis and bone resorp‐ tion related to implant function [46,53]. The surgical approach consists of using the frontal part of the zygomatic bone as an anchorage for zygomatic implant, with support from the maxillary palatal or alveolar bone, without any bone augmentation. This offers a more simplified treatment approach, a decrease in biological impact and a more comfortable post-surgical period for the patient thanks to a quicker recovery time [49].

#### **5. Angulated implants**

**Figure 24.** Post-operative panoramic radiograph of the graft

118 Current Concepts in Dental Implantology

**Figure 25.** Implant placement four months after the augmentation procedure

**Figure 26.** Post-operative intraoral view after implant surgery

Maxillary posterior defects that occur after tumor resection or trauma are challenging to reconstruct and rehabilitate. The aim of rehabilitation is not only to provide a cosmetically acceptable appearance, but also to restore oral functions, such as deglutition, mastication, and

**4. Zygomatic implants**

Angulated implant treatment of the maxilla requires presurgical prosthetic treatment planning for high smile line esthetics to be acceptable [54]. This requires bone removal in the vast majority of dentate or edentulous patients who undergo full arch treatment.The use of angulated implants for short-span bridges or even long-span reconstructions to avoid bone grafts has been used for 10 years, although many of these were not immediately loaded [55]. However, with the advent of the angulated implant immediate function, this became consis‐ tently possible using a graftless protocol [56]. Angulated implant concept consists that to avoid the anatomical structures in the posterior regions by using implants just anterior to the maxillary sinus in the maxilla and anterior to mental foramen in the mandible by having them placed on a 30-45 degree angle. This concept solves the problem of insufficient bone and reduces the need for sinus and ridge augmentation.

Angulated implant treatment concept may not be considered or adopted as a conventional treatment modality by many clinicians. This treatment concept refers four implants to support a fixed prosthesis. However, long-term clinical results are inadequate on the effects of angulation on the development and distrubition of the loading stress within the implant [57].

#### **Author details**

Umit Karacayli1\*, Emre Dikicier2 and Sibel Dikicier3

\*Address all correspondence to: ukaracayli@gmail.com

1 Department of Oral and Maxillofacial Surgery, Gulhane Military Medical Academy, Ankara, Turkey

2 Department of Oral and Maxillofacial Surgery, Corlu Military Hospital, Tekirdag, Turkey

3 Department of Prosthodontics, Corlu Military Hospital, Tekirdag, Turkey

#### **References**


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maxillary sinus in the maxilla and anterior to mental foramen in the mandible by having them placed on a 30-45 degree angle. This concept solves the problem of insufficient bone and

Angulated implant treatment concept may not be considered or adopted as a conventional treatment modality by many clinicians. This treatment concept refers four implants to support a fixed prosthesis. However, long-term clinical results are inadequate on the effects of angulation on the development and distrubition of the loading stress within the implant [57].

and Sibel Dikicier3

3 Department of Prosthodontics, Corlu Military Hospital, Tekirdag, Turkey

1 Department of Oral and Maxillofacial Surgery, Gulhane Military Medical Academy, Ankara,

2 Department of Oral and Maxillofacial Surgery, Corlu Military Hospital, Tekirdag, Turkey

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## **Immediate Loading in Implant Dentistry**

Ilser Turkyilmaz and Ashley Brooke Hoders

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59321

#### **1. Introduction**

Planning for immediate implant placement requires an accurate diagnosis and specific case selection [1-3]. Adequate planning can be accomplished using the various technologies that are available to us today, and it is important to remember that any alteration to position in relationship to the prosthesis used during planning can compromise the final result with alteration of occlusion, esthetics and biomechanics resulting. In order to accurately plan, a thorough clinical evaluation will be necessary and should include assessment of smile line, gingival morphology, the inter-arch relationship, condition and gingival margin positions of adjacent teeth, as well as supporting tissue conditions [4-6].

If the presenting conditions are deemed unfavorable, it is important that corrections be made via reconstruction of soft tissue, bone, and tooth positioning. An adequate amount of bone is important because a deficiency can jeopardize stability and lead to recession, loss of papilla and inadequate positioning; an inadequate amount of soft tissue will lead to a poor esthetic outcome [7-9]. Therefore, when bone quality and quantity are not sufficient, you must use regeneration techniques during the initial phase of treatment such as guided bone regenera‐ tion, orthodontics, and/or grafting. Other important things to be considered for immediate loading include the implant having primary stability [10,11]. Things that would contraindicate immediate loading include lack of primary stability, parafunction, pathology in the region of implant placement, and systemic alterations such as severe periodontal disease, poor oral hygiene, and smoking. Careful evaluation must be completed before immediate placement and loading be considered.

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

### **2. Immediate loading**

#### **2.1. Concepts and protocols**

Ever since dental implants were first successfully employed in restoring completely edentu‐ lous mandibles in 1951, implant supported dental rehabilitations of various designs and complexity have been shown to be a reliable and predictable treatment option for both partially and fully edentulous patients [12-14]. The original Branemark protocol dictated that the initial phase of implant integration be at least 4 to 6 months before any restoration was placed [15]. "Conventional loading", as it is now known, is a reliable, safe, predictable, and accepted treatment modality that has been used as a point of comparison for other dental implant loading protocols.

Within the last decade, clinicians have increasingly begun to explore the possibilities of decreasing treatment time by early placement of the implant-supported restoration, or by placing implants in extraction sockets at the time of extraction [16-18]. Investigators are now increasingly reporting protocols designed to promote shortened treatment periods for implant-supported prostheses.

The concept of implant immediate loading includes all of the advantages of a one stage surgical approach. Also, during the osseointegration process, the patient does not have to use a removable denture, which increases function, speech, stability, comfort and improves certain psychological factors [19]. Splinted implants can decrease the risk of overload to each implant because of the greater surface area and improved biomechanical distribution [20,21].

The primary goal for immediate loading is establishment of direct bone implant contact. The terminology when it comes to immediate loading can sometimes be ambiguous and there many classifications in the literature, so it is important to understand the different techniques that can be used [22]:

#### *2.1.1. Terminology for the timing of implant loading*

**Immediate loading:** The placement of implants and insertion of restorations are completed in the same day.

**Early loading:** The restoration is connected to the implants at a second procedure but earlier than the conventional healing period of 3 to 6 months; time of loading should be considered in days/weeks.

**Delayed loading:** The restoration is connected at a second procedure after a conventional healing period of 3 to 6 months.

#### *2.1.2. Terminology for implant loading*

**Occlusal loading:** The crown/bridge is in contact with opposing dentition in centric occlusion.

**Nonocclusal loading:** The crown/bridge is not in contact in centric occlusion with opposing dentition in centric occlusion.

The concept of an immediate restoration includes a nonsubmerged first stage surgery and also implies that the occlusal surfaces and implants are loaded with a provisional of definitive restoration [23-25]. A delayed or staged loading refers to an implant prosthesis with occlusal load after more than 3 months (mandible) or 6 months (maxilla) post-implant insertion. Using a delayed approach allows you to use a 2 stage surgical procedure that covers implants with tissue or one stage approach that exposes a portion of the implant at the initial surgery.

#### **2.2. Factors affecting time of loading**

**2. Immediate loading**

128 Current Concepts in Dental Implantology

**2.1. Concepts and protocols**

loading protocols.

implant-supported prostheses.

that can be used [22]:

the same day.

in days/weeks.

healing period of 3 to 6 months.

dentition in centric occlusion.

*2.1.2. Terminology for implant loading*

*2.1.1. Terminology for the timing of implant loading*

Ever since dental implants were first successfully employed in restoring completely edentu‐ lous mandibles in 1951, implant supported dental rehabilitations of various designs and complexity have been shown to be a reliable and predictable treatment option for both partially and fully edentulous patients [12-14]. The original Branemark protocol dictated that the initial phase of implant integration be at least 4 to 6 months before any restoration was placed [15]. "Conventional loading", as it is now known, is a reliable, safe, predictable, and accepted treatment modality that has been used as a point of comparison for other dental implant

Within the last decade, clinicians have increasingly begun to explore the possibilities of decreasing treatment time by early placement of the implant-supported restoration, or by placing implants in extraction sockets at the time of extraction [16-18]. Investigators are now increasingly reporting protocols designed to promote shortened treatment periods for

The concept of implant immediate loading includes all of the advantages of a one stage surgical approach. Also, during the osseointegration process, the patient does not have to use a removable denture, which increases function, speech, stability, comfort and improves certain psychological factors [19]. Splinted implants can decrease the risk of overload to each implant

The primary goal for immediate loading is establishment of direct bone implant contact. The terminology when it comes to immediate loading can sometimes be ambiguous and there many classifications in the literature, so it is important to understand the different techniques

**Immediate loading:** The placement of implants and insertion of restorations are completed in

**Early loading:** The restoration is connected to the implants at a second procedure but earlier than the conventional healing period of 3 to 6 months; time of loading should be considered

**Delayed loading:** The restoration is connected at a second procedure after a conventional

**Occlusal loading:** The crown/bridge is in contact with opposing dentition in centric occlusion. **Nonocclusal loading:** The crown/bridge is not in contact in centric occlusion with opposing

because of the greater surface area and improved biomechanical distribution [20,21].

Some of the variables that can impact your ability to immediately load include surgical trauma, bone loading trauma, and treatment plans related to implant number. Alveolar and residual bone has a cortical and trabecular component that can be modified by modeling and remod‐ eling. Remodeling allows the bone to respond to its local environment or allows bone repair after traumatic situation [26]. The bone is generally lamellar bone but woven bone might occur during the repair process. Typically, lamellar bone and woven bone are the primary bone tissue types observed around a dental implant. Lamellar bone and woven bone are the primary bone tissue types found around a dental implant. Lamellar bone is organized, highly mineralized and is the strongest bone type. Woven bone is unorganized, less mature, less mineralized and has lower strength and is more flexible [26]. Woven bone can form at a rate of 60µm (micro‐ meters) per day, whereas lamellar bone forms at a rate of up to 10µm per day.

The rationale behind immediate loading is not only to reduce the risk of fibrous tissue formation but also to promote lamellar bone maturation to sustain a continued occlusal load. So when compared to the 2 stage approach, the repair of the implant is separated from the early loading response by 3-6 months. The process of osteotomy preparation and implant insertion causes a regional acceleratory phenomenon of bone repair around the implant interface [26]. Therefore, the organized lamellar bone in the preparation site becomes woven and unorganized next to the implant and at 4 months the bone is still only 60% mineralized lamellar bone- this is sufficient in most bone types and situation for implant loading.

The concept of immediate loading challenges the conventional load-free healing time of 3-6 months before the insertion of restoration. The bone in the thread design is stronger on the day of implant placement as opposed to 3 months later as more mature lamellar bone exists in the implant threads. However, the cellular connection between the implant surface and bone cells does not exist yet [26,27]. On the day of implant placement, there is residual cortical and trabecular bone around the implant and the implant has some contact with this prepared bone. Surgical trauma triggers early cellular repair and increased vascularization to stimulate repair process to injured bone [26,27]. Woven bone formation by appositional growth may start to form as early as the second week after implant placement at a rate of 30-50µm per day. Approximately 3-5 weeks after implant placement, the implant bone interface is weakest and at highest risk of overload since the implant-bone interface is least mineralized and unorgan‐ ized during this time.

#### **2.3. Risk factors for immediate loading**

It has been found that immediate loaded failure occurred between 3-5weeks post-operative from mobility without infection [28-29]. The risk of immediate occlusal overload can be decreased by utilizing some techniques such as having more vital bone in contact with the implant interface, minimizing the surgical trauma at implant placement, including thermal injury and mechanical trauma that may result in microfracture of bone during implant placement. In addition, the microfracture of bone may lead to osteonecrosis and possible fibrous and granulation tissue encapsulation around the implant. Death of osteoblasts has been reported to occur at 40 °C [30-31].

Sharawy et al. [32], reported that heat generated in bone next to implant drills depends on design and revolutions of the drill. It was found that the drill rpm of 2500 generated less heat than 2000 rpm and 1250 rpm caused the highest heat and the longest recovery period regardless of drill design. Some other factors that need to be entertained to keep heat minimum may include the drill sharpness, the depth of the osteotomy, the amount of bone prepared, the variation in cortical thickness and the temperature and solution chemistry of the irrigant.

When the implant is substantially compressed against the bone, the interface between implant and bone has a greater area of repair. Self-tapping via implant itself, meaning the implant cuts the bone during placement, can result in greater bone remodeling/woven bone around the implant in initial healing compared to bone tapping before implant placement. The implant should not have any mobility on insertion; excess strain within the bone from torque and space filling may also increase risk of microdamage at the interface [33-35].

The recommended protocol for immediate load is to insert the implant with a torque of 45-60 Ncm [36-37]. This stability helps to ensure that the implant has a relatively rigid fixation in good quality bone. Additional torque may result in pressure necrosis and increase the strain magnitude at the interface and increase amount of damage and remodeling which could decrease strength of bone implant interface.

An alternate approach is to use a reverse torque test of 20Ncm to evaluate the quality of the bone and the interface at initial fixation for evaluating delayed healing. If the implant does not unthread at 20Ncm the resistance indicates that the bone is sufficient density to consider immediate loading.

Once the bone begins to receive occlusal loads by the implant restoration, the interface begins to remodel again. However, the trigger is strain transfer from occlusal function rather than trauma of implant placement. *Repair bone* is woven bone from surface trauma but *reactive woven bone is* woven bone formed from mechanical or loading response. The remodeling from mechanical strain can be called *bone turnover* and not only repairs damaged bone but also allows the implant interface to adapt to its biomechanical situation. The *interface remodeling rate* is the period of time for bone at the implant interface to be replaced with new bone [26].

*Strain* is the change in length of material/original length measured as % change [26]. The loaded bone next to an implant changes its shape, which is measured as strain. Micro‐ strain conditions 100 times less than the ultimate strength of bone may trigger a cellular response. Bone fractures at strain levels of 1-2% but bone begins to disappear or form fibrous tissue, which is named the *pathologic overload zone* when strain levels of 20-40%*.* There‐ fore, the mechanical load is too severe, fibrous tissue may form at the implant interface rather than bone. Fibrous tissue at an implant interface may cause clinical mobility instead of rigid connection called osseointegration.

The ideal microstrain level for bone is the *adapted zone* and is called *ideal load bearing zone* [26]*.* The remodeling rate of bone in the jaws is in the physiologic zone of 40% of each year; the bone can remodel and remain an organized, mineralized, lamellar structure at these levels. The intermediate level of microstrain with the ideal load bearing zone and pathologic overload is called the *mild overload zone* [26]*.* In this strain region, bone begins its healing process to repair microfractures and the bone that is in a fatigue risk of failure. Bone in this range is reactive woven bone. Microstrain from overload or trauma causing accelerated bone repair causes less mineralized bone to form and less organized bone that is weaker [26]*.*

Localized overload and possible implant failure might be possible due to excess stresses along the implant interface. However, immediate loading does not cause excessive stresses neces‐ sarily [26]. Initial response of bone at the implant interface has been evaluated on immediately loaded implants: direct bone-implant-contact with favorable bone quality around the implant has been reported. Brunski showed that a direct bone-implant interface may develop as long as the implant moves less than 100 µm and micromotion beyond 150 resulted in fibrous tissue encapsulation instead of a osseointegration [38]. Studies have shown that immediate loading of an implant interface did not increase risk of fibrous tissue formation. Long term results suggest that loaded implants have less marrow spaces and more compact bone. Greater direct bone contact was noted at the interface, suggesting that early occlusal loading may enhance bone remodeling and further increase bone density compared with unloaded implants [38].

Canullo et al., reported that the extension of bone remodeling was less extensive in cases of immediate placement (1.7mm) rather than delayed placement (3.0mm) [39]. Despite this limit in the healing zone, it has been shown that bone can fill osseous defects around implants if they are 3-walled in nature and <1.5-2.0mm wide. Other interventions such as autogenous bone grafts have been shown to be more osteogenic when used in conjunction with immedi‐ ately placed implants. However, immediate placement does present some disadvantages. These can include unpredictable site morphology, a potentially limited amount of soft tissue, and risk of failure due to residual periosteal infection. Despite these potential disadvantages, immediate implant placement and immediate implant loading have shown to be favorable in maintaining or increasing bone heights around implants [1-4].

#### **2.4. Biomechanical considerations**

decreased by utilizing some techniques such as having more vital bone in contact with the implant interface, minimizing the surgical trauma at implant placement, including thermal injury and mechanical trauma that may result in microfracture of bone during implant placement. In addition, the microfracture of bone may lead to osteonecrosis and possible fibrous and granulation tissue encapsulation around the implant. Death of osteoblasts has been

Sharawy et al. [32], reported that heat generated in bone next to implant drills depends on design and revolutions of the drill. It was found that the drill rpm of 2500 generated less heat than 2000 rpm and 1250 rpm caused the highest heat and the longest recovery period regardless of drill design. Some other factors that need to be entertained to keep heat minimum may include the drill sharpness, the depth of the osteotomy, the amount of bone prepared, the variation in cortical thickness and the temperature and solution chemistry of the irrigant.

When the implant is substantially compressed against the bone, the interface between implant and bone has a greater area of repair. Self-tapping via implant itself, meaning the implant cuts the bone during placement, can result in greater bone remodeling/woven bone around the implant in initial healing compared to bone tapping before implant placement. The implant should not have any mobility on insertion; excess strain within the bone from torque and space

The recommended protocol for immediate load is to insert the implant with a torque of 45-60 Ncm [36-37]. This stability helps to ensure that the implant has a relatively rigid fixation in good quality bone. Additional torque may result in pressure necrosis and increase the strain magnitude at the interface and increase amount of damage and remodeling which could

An alternate approach is to use a reverse torque test of 20Ncm to evaluate the quality of the bone and the interface at initial fixation for evaluating delayed healing. If the implant does not unthread at 20Ncm the resistance indicates that the bone is sufficient density to consider

Once the bone begins to receive occlusal loads by the implant restoration, the interface begins to remodel again. However, the trigger is strain transfer from occlusal function rather than trauma of implant placement. *Repair bone* is woven bone from surface trauma but *reactive woven bone is* woven bone formed from mechanical or loading response. The remodeling from mechanical strain can be called *bone turnover* and not only repairs damaged bone but also allows the implant interface to adapt to its biomechanical situation. The *interface remodeling rate* is the period of time for bone at the implant interface to be replaced with new bone [26].

*Strain* is the change in length of material/original length measured as % change [26]. The loaded bone next to an implant changes its shape, which is measured as strain. Micro‐ strain conditions 100 times less than the ultimate strength of bone may trigger a cellular response. Bone fractures at strain levels of 1-2% but bone begins to disappear or form fibrous tissue, which is named the *pathologic overload zone* when strain levels of 20-40%*.* There‐ fore, the mechanical load is too severe, fibrous tissue may form at the implant interface

filling may also increase risk of microdamage at the interface [33-35].

decrease strength of bone implant interface.

immediate loading.

reported to occur at 40 °C [30-31].

130 Current Concepts in Dental Implantology

Any treatment plans involving immediate loading should have the goal to minimize the occlusal overload risk and its resultant increase in the remodeling rate of bone. The regional acceleratory phenomenon may replace the bone interface without the additional risk of biomechanical overload. The lower the stress applied to the bone, the lower the microstrain in the bone [26]. This provides conditions that increase the functional surface area to the implant bone interface. The surface area of load may be increased by variables including implant number, implant size, implant design, and body surface conditions. Force applied to the implant bone interface is related to the strain observed and some other factors such as patient conditions, implant position and direction of occlusal load.

Two approaches for immediate occlusal loading with edentulous patient include: overengineering by placing more implants than the usual treatment plan for the conventional healing period; using selected implants around the arch (3+) to immediately restore with a transitional fixed prosthesis. In this approach, enough number of implants, which are needed to support a fixed prosthesis, are left submerged for the healing period. So, even if all imme‐ diately loaded implants fail, a fixed restoration can still be provided to the patient. If any immediately loaded implants survive, then they are also used in the final restoration [40]. This technique can be used where moderate to abundant bone is present in the posterior and anterior to the mental foramen. A study by Scortecci, involved loading all implants initially and splinting all for increased area of load transfer which could decrease stresses along the developing multiple interfaces and increases the stability, retention, and strength of transi‐ tional prosthesis during initial healing phase [41]. This technique allows you to use additional implants.

The functional surface area of occlusal load transfer along implant interface may be increased by increasing the implant number, especially when the devices are splinted through bridge‐ work. The biomechanical approach loads additional implants when immediate loading is planned. The lowest percentage of survival for a full arch restoration corresponded to a fewer number of loaded implants.

A rule in traditional prosthetics is that 3 pontics in the posterior of the mouth are contraindi‐ cated for a fixed prosthesis because of the amount of force and the flexibility and fatigue strength of the restoration [27]. When only 3 are used to support an immediate restoration there are often 3-4 pontics cantilevered. It has been suggested that additional implants should be placed with the staged healing approach in case one or more fails during the initial loading period. They can then be used in the final restoration to decrease the number of pontics and increase retention of final restoration

An increased number of implants reduces the risk of overload due to the increased implant surface area but also increases the retention of the restoration and decreases the number of pontics [27]. If fracture to a prosthesis or partially unretained restorations occur, the portion that is retained may act as a lever and overload the implants. The increased retention minimizes the occurrence of partially unretained restorations during healing which would be another source of overload to the implants supporting the restoration [27]. Decreases in pontic number also reduce the risk of fracture of the transitional restoration that could be a source of additional load to the remaining implants supporting the prosthesis. As a general rule, more implants should be inserted in maxilla to compensate for less dense bone and increased directions of force often found in the upper arch [27].

The most common number of implants used for a mandibular overdenture is 4-6 splinted in anterior mandible [5,24,42]. In a partially edentulous patient missing multiple teeth, ideally 1 implant should be placed for each missing tooth. For missing single teeth, the implant size, design or surface may be more important. Load may be reduced by reducing occlusal the contact and having a nonfunctional scheme.

The greater the benefit:risk ratio or the lower the risk, the more immediate loading should be considered. For example, a completely edentulous mandible restored with an overdenture supported by 4+ implants is a very low risk condition. If the patient can not tolerate a man‐ dibular denture and does not wear it, the immediate load protocol would be a high benefit. An example of a high risk for immediate load would be posterior single tooth implant- the implant number can not be increased and you can not engage cortical bone; this would be of low benefit when out of the esthetic zone. Additional studies to evaluate risks especially in maxilla are expected [43].

#### **2.5. Factors related to implant type/design**

Two approaches for immediate occlusal loading with edentulous patient include: overengineering by placing more implants than the usual treatment plan for the conventional healing period; using selected implants around the arch (3+) to immediately restore with a transitional fixed prosthesis. In this approach, enough number of implants, which are needed to support a fixed prosthesis, are left submerged for the healing period. So, even if all imme‐ diately loaded implants fail, a fixed restoration can still be provided to the patient. If any immediately loaded implants survive, then they are also used in the final restoration [40]. This technique can be used where moderate to abundant bone is present in the posterior and anterior to the mental foramen. A study by Scortecci, involved loading all implants initially and splinting all for increased area of load transfer which could decrease stresses along the developing multiple interfaces and increases the stability, retention, and strength of transi‐ tional prosthesis during initial healing phase [41]. This technique allows you to use additional

The functional surface area of occlusal load transfer along implant interface may be increased by increasing the implant number, especially when the devices are splinted through bridge‐ work. The biomechanical approach loads additional implants when immediate loading is planned. The lowest percentage of survival for a full arch restoration corresponded to a fewer

A rule in traditional prosthetics is that 3 pontics in the posterior of the mouth are contraindi‐ cated for a fixed prosthesis because of the amount of force and the flexibility and fatigue strength of the restoration [27]. When only 3 are used to support an immediate restoration there are often 3-4 pontics cantilevered. It has been suggested that additional implants should be placed with the staged healing approach in case one or more fails during the initial loading period. They can then be used in the final restoration to decrease the number of pontics and

An increased number of implants reduces the risk of overload due to the increased implant surface area but also increases the retention of the restoration and decreases the number of pontics [27]. If fracture to a prosthesis or partially unretained restorations occur, the portion that is retained may act as a lever and overload the implants. The increased retention minimizes the occurrence of partially unretained restorations during healing which would be another source of overload to the implants supporting the restoration [27]. Decreases in pontic number also reduce the risk of fracture of the transitional restoration that could be a source of additional load to the remaining implants supporting the prosthesis. As a general rule, more implants should be inserted in maxilla to compensate for less dense bone and increased directions of

The most common number of implants used for a mandibular overdenture is 4-6 splinted in anterior mandible [5,24,42]. In a partially edentulous patient missing multiple teeth, ideally 1 implant should be placed for each missing tooth. For missing single teeth, the implant size, design or surface may be more important. Load may be reduced by reducing occlusal the

The greater the benefit:risk ratio or the lower the risk, the more immediate loading should be considered. For example, a completely edentulous mandible restored with an overdenture

implants.

number of loaded implants.

132 Current Concepts in Dental Implantology

increase retention of final restoration

force often found in the upper arch [27].

contact and having a nonfunctional scheme.

The area of load may also be increased by considering implant size, design, and surface. You can decrease stress by decreasing force applied to the prosthesis. These forces are influenced by patient factors, implant position, cantilever forces, occlusal load direction, occlusal contact positions, and diet.

Implant diameter and length are often emphasized in reports as these values give insight into the bone-to-implant surface area that an implant will provide. Avila et al., described that larger implants provided greater bone-to-implant contact and less susceptibility to cantilever forces following restoration [44]. More importantly, thread design and dimensions dictate the functional bone-to-implant surface area that will resist forces when a given implant is loaded along a given functional axis. Tapered implants offer a conical shape that is consistent with a natural root form but have less surface area which in turn results in increased crestal bone stresses and less primary stability.

For each 3mm increase in length beyond 10mm, you can increase the surface area by more than 20% for a cylinder implant design. Most stresses to an implant bone interface are concentrated at crestal bone. Therefore, increased implant length does little to decrease stress that occurs at the transosteal region around implant. But because immediately restored implant loads the interface before the establishment of a cellular connection, the implant length is more relevant especially in softer bone.

Benefits of increased length are found in the initial stability of the bone implant interface. Remodeling of the interface does not occur uniformly around implant- one region of interface remodels and other remains stable. Added length may allow remodeling in one region while other can stabilize implant. Added length can also allow implant to engage opposing cortical plate which can increase initial stability. Cortical bone has a lower remodeling rate and ensures stable condition during early loading. When trying to evaluate what length implant should be placed, it is important to consider that the survival rate of 10mm or less implants drops to less than 85% in traditional healing; Schnitman et al., found a 50% failure rate in immediately loaded implants with length of 10mm or less [45]. However, recent literature suggests that a high degree of survivability can be reproduced with implants that are at least 3mm in diameter and 8mm in length when splinted with other implants [46,47]. These findings, along with the innovations in implant design, suggest that these values should be revisited.

The functional surface area of each implant support system is related to the width and shape of the implant. Wider root form implants of the same length provide greater bone contact than narrower implants. Occlusal stresses are greatest in concentration at the crest of the ridge after the implant has integrated, so the width may be more important to the length of the implant to decrease the risk of crestal bone overload. Overload can cause early crestal bone loss in immediately loaded implants. The diameter of the implant increases in the molar area for immediate loading, especially when the density is less or the forces are greater. Increasing the width of the implant in molar sites or adding additional implants to increase the surface area in the posterior region can help alleviate overload that may result in crestal bone loss.

The implant body design needs to be more specific for immediate load because maximum stability is needed at the time of placement. After placement, bone has not had time to grow into the recesses or undercuts in the implant body or attach to the conditioned surface before occlusal load is applied. A threaded implant body and insertion process provides a better chance of stabilization. The implant design has a greater impact on the functional surface area than the implant size. The functional surface area is greater during immediate load, and a threaded implant presents many advantages over a pressfit type of implant for immediate load because the design features do not require integration to resist loads and have a greater surface area to resist occlusal forces [48].

The number, spacing, and orientation of the threads affect the amount of area available to resist the forces during immediate loading [49,50]. A greater number of threads means a greater functional surface area at the time of immediate load. The smaller the distance between threads, the greater the thread number corresponds to the surface area. Thread depth is also a variable to consider. Greater depth means a greater functional surf area for immediate load application. Functional surface area is more important when the number of implants cannot increase (less than 4 adjacent teeth are being replaced).

Thread geometry can affect the strength of early osseointegration and bone implant interface. A V- shaped thread design withstands a 10x greater shear force applied to bone compared to a square thread shape. Bone is strongest in compression and weakest in shear loading. Compressive force transfer would decrease microstrain to bone as compared to shear force. Therefore, a square thread design may provide a benefit in immediate load protocols.

The higher the remodeling rate of a loaded interface creates a higher woven bone ratio and weaker bone interface. A square threaded implant design with deeper threads has a 10x reduction in resorption rate. When considering a tapered implant design for immediate load, consider that this type of design allows for a less overall surface area compared to a straight design of the same length, width, and thread number. A tapered design will also have less thread depth near the apical portion of the implant, which reduces the surface area but decreases initial fixation. Thread depth and a tapered body can combine to improve initial stability, and may be a good option in lower density bone when less than 4 teeth are replaced and implant position and number can not be manipulated. Implant number, position and patient factors are more relevant to success and there have been few trials that compare immediate load with different implant thread designs and tapered implant bodies in the edentulous patient [50,51].

When the implant surface is modified with a roughened texture, this increases the bone to implant contact [52,53]. The shear strength of an implant with a roughened texture has been shown to be 5x greater than implants with smooth surface. The surface condition also affects the rate and percentage of bone contact, and lamellar bone formation. Surface coatings and conditions of the implant have been shown to be most beneficial during the initial healing and early loading conditions. For immediate loading, the most desirable surface is one that will allow the greatest percent of bone formation, has the highest bone-implant contact percentage with the highest mineralization rate, and the fastest lamellar bone formation.

A rough surface will initially increase stability; a machined surface is less successful to do so, especially in low density bone. A hydroxyapatite (HA) coating has been shown to decrease resorption rates during occlusal loading, which can increase the percentage of lamellar bone formation at the interface. If the bone is not an ideal density for immediate loading, the surface condition of the implant body may decrease the risk of occlusal overload. In summary, a rough surface provides a better condition than a machine surface; and in good quality bone, the types of surface condition is less relative to the overall implant survival [54].

Strain placed on the bone is influenced by the stress directed to the implant interface [26]. Ways that stress can be reduced include increasing the surface area that supports the occlusal load or by decreasing the force that is applied to the prosthesis. It has been recommended to not remove the prosthesis once it is delivered within first 2 weeks, and that resorbable sutures may be beneficial.

#### **3. General considerations for treatment planning**

the implant has integrated, so the width may be more important to the length of the implant to decrease the risk of crestal bone overload. Overload can cause early crestal bone loss in immediately loaded implants. The diameter of the implant increases in the molar area for immediate loading, especially when the density is less or the forces are greater. Increasing the width of the implant in molar sites or adding additional implants to increase the surface area in the posterior region can help alleviate overload that may result in crestal bone loss.

The implant body design needs to be more specific for immediate load because maximum stability is needed at the time of placement. After placement, bone has not had time to grow into the recesses or undercuts in the implant body or attach to the conditioned surface before occlusal load is applied. A threaded implant body and insertion process provides a better chance of stabilization. The implant design has a greater impact on the functional surface area than the implant size. The functional surface area is greater during immediate load, and a threaded implant presents many advantages over a pressfit type of implant for immediate load because the design features do not require integration to resist loads and have a greater surface

The number, spacing, and orientation of the threads affect the amount of area available to resist the forces during immediate loading [49,50]. A greater number of threads means a greater functional surface area at the time of immediate load. The smaller the distance between threads, the greater the thread number corresponds to the surface area. Thread depth is also a variable to consider. Greater depth means a greater functional surf area for immediate load application. Functional surface area is more important when the number of implants cannot increase (less

Thread geometry can affect the strength of early osseointegration and bone implant interface. A V- shaped thread design withstands a 10x greater shear force applied to bone compared to a square thread shape. Bone is strongest in compression and weakest in shear loading. Compressive force transfer would decrease microstrain to bone as compared to shear force. Therefore, a square thread design may provide a benefit in immediate load protocols.

The higher the remodeling rate of a loaded interface creates a higher woven bone ratio and weaker bone interface. A square threaded implant design with deeper threads has a 10x reduction in resorption rate. When considering a tapered implant design for immediate load, consider that this type of design allows for a less overall surface area compared to a straight design of the same length, width, and thread number. A tapered design will also have less thread depth near the apical portion of the implant, which reduces the surface area but decreases initial fixation. Thread depth and a tapered body can combine to improve initial stability, and may be a good option in lower density bone when less than 4 teeth are replaced and implant position and number can not be manipulated. Implant number, position and patient factors are more relevant to success and there have been few trials that compare immediate load with different implant thread designs and tapered implant bodies in the

When the implant surface is modified with a roughened texture, this increases the bone to implant contact [52,53]. The shear strength of an implant with a roughened texture has been

area to resist occlusal forces [48].

134 Current Concepts in Dental Implantology

than 4 adjacent teeth are being replaced).

edentulous patient [50,51].

Patient factors such as bruxism and clenching parafunction are forces that are high in magni‐ tude, extensive in duration, and generate primarily horizontal forces to the implant. Paraf‐ unction presents a considerable risk and potential contraindication for immediate load due to this resulting in the poorest implant survival data [55]. There is an increased risk of abutment screw loosening, unretained prostheses, fracture of the transitional restoration used in immediate loading when a lever forms and increasing the risk of occlusal overload.

Implant position is an important factor for the edentulous patient. In the partially edentulous patient it is important to eliminate cantilevers on two implants supporting 3 teeth rather than position the implants next to each other with a cantilever. There will be less stress directed towards the implant interface when implants are not in a straight line in an edentulous site [24,36]. Cross-arch splinting is a very effective way to reduce stress within the entire implant support system, especially when there is an antero-posterior (AP) distance between the splinted implants. The splinted arch concept for the completely edentulous patient is advan‐ tageous for the immediate load transitional restoration. A line is drawn from the distal of each posterior implant. The distance from this line to the center of the most anterior implant is called the *anteroposterior distance* (A-P spread). The greater the A-P spread is between the center of the most anterior implant or implants and the most distal aspect of the posterior implants, the smaller is the resultant loads on the implant system from cantilevered forces because of the stabilizing effect of the A-P distance [27].

less relative to the overall implant survival [54].

**3. General Considerations for Treatment Planning** 

resorbable sutures may be beneficial.

surface provides a better condition than a machine surface; and in good quality bone, the types of surface condition is

Strain placed on the bone is influenced by the stress directed to the implant interface [26]. Ways that stress can be reduced include increasing the surface area that supports the occlusal load or by decreasing the force that is applied to the prosthesis. It has been recommended to not remove the prosthesis once it is delivered within first 2 weeks, and that

Patient factors such as bruxism and clenching parafunction are forces that are high in magnitude, extensive in duration, and generate primarily horizontal forces to the implant. Parafunction presents a considerable risk and potential contraindication for immediate load due to this resulting in the poorest implant survival data [55]. There is an increased risk of abutment screw loosening, unretained prostheses, fracture of the transitional restoration used in

Implant position is an important factor for the edentulous patient. In the partially edentulous patient it is important to eliminate cantilevers on two implants supporting 3 teeth rather than position the implants next to each other with a cantilever. There will be less stress directed towards the implant interface when implants are not in a straight line in an edentulous site [24,36]. Cross-arch splinting is a very effective way to reduce stress within the entire implant support system, especially when there is an antero-posterior (AP) distance between the splinted implants. The splinted arch

called the *anteroposterior distance* (A-P spread). The greater the A-P spread is between the center of the most anterior implant or implants and the most distal aspect of the posterior implants, the smaller is the resultant loads on the implant

A square arch form involves smaller A-P spreads between splinted implants and should have shorter-length cantilevers. **Figure 1.** A-P spread and length of cantilever for framework (a) and final restoration (b).

Figure 1: A-P spread and length of cantilever for framework (a) and final restoration (b).

immediate loading when a lever forms and increasing the risk of occlusal overload.

system from cantilevered forces because of the stabilizing effect of the A-P distance [27].

cantilever design [27]. **3.1 Treatment Planning of Mandible**  The mandible should be divided into three sections when planning for implant placement: canine to canine; bilateral A square arch form involves smaller A-P spreads between splinted implants and should have shorter-length cantilevers. A tapered arch form has the largest distance between anterior and posterior implants and may have the longest cantilever design [27].

posterior. This is different from the maxilla, which needs more implant support because the bone is less dense and the

A tapered arch form has the largest distance between anterior and posterior implants and may have the longest

#### direction of force is outside of the arch in all excursive movements; here you must consider the maxilla in at least 4 sections depending on the magnitude of force and the shape of the arch. These sections include the bilateral canine area and the bilateral posterior areas; at least 1 implant should be inserted into each section and splinted during immediate **3.1. Treatment planning of mandible**

6 load for the completely edentulous patient. Concerns about medial mandibular flexure with cross-arch splinting suggests that the final restoration should be fabricated in at least 2 sections when implants are placed in both posterior quadrants and fewer than 3 adjacent pontics are present [56]. The following photos show the restoration of an mandible with a 2-piece implant-supported fixed restoration. The mandible should be divided into three sections when planning for implant placement: canine to canine; bilateral posterior. This is different from the maxilla, which needs more implant support because the bone is less dense and the direction of force is outside of the arch in all excursive movements; here you must consider the maxilla in at least 4 sections depending on the magnitude of force and the shape of the arch. These sections include the bilateral canine area and the bilateral posterior areas; at least 1 implant should be inserted into each section and splinted during immediate load for the completely edentulous patient.

Concerns about medial mandibular flexure with cross-arch splinting suggests that the final restoration should be fabricated in at least 2 sections when implants are placed in both posterior quadrants and fewer than 3 adjacent pontics are present [56]. The following photos show the restoration of an mandible with a 2-piece implant-supported fixed restoration.

**Figure 2.** Panoramic radiograph of patient before treatment.

**Figure 3.** Scanning of tissue surface of mandibular wax pattern by using CAD/CAM.

**Figure 4.** Final design of mandibular framework.

6

surface provides a better condition than a machine surface; and in good quality bone, the types of surface condition is

Strain placed on the bone is influenced by the stress directed to the implant interface [26]. Ways that stress can be reduced include increasing the surface area that supports the occlusal load or by decreasing the force that is applied to the prosthesis. It has been recommended to not remove the prosthesis once it is delivered within first 2 weeks, and that

Patient factors such as bruxism and clenching parafunction are forces that are high in magnitude, extensive in duration, and generate primarily horizontal forces to the implant. Parafunction presents a considerable risk and potential contraindication for immediate load due to this resulting in the poorest implant survival data [55]. There is an increased risk of abutment screw loosening, unretained prostheses, fracture of the transitional restoration used in

Implant position is an important factor for the edentulous patient. In the partially edentulous patient it is important to eliminate cantilevers on two implants supporting 3 teeth rather than position the implants next to each other with a cantilever. There will be less stress directed towards the implant interface when implants are not in a straight line in an edentulous site [24,36]. Cross-arch splinting is a very effective way to reduce stress within the entire implant support system, especially when there is an antero-posterior (AP) distance between the splinted implants. The splinted arch concept for the completely edentulous patient is advantageous for the immediate load transitional restoration. A line is drawn from the distal of each posterior implant. The distance from this line to the center of the most anterior implant is called the *anteroposterior distance* (A-P spread). The greater the A-P spread is between the center of the most anterior implant or implants and the most distal aspect of the posterior implants, the smaller is the resultant loads on the implant

(a) (b)

A square arch form involves smaller A-P spreads between splinted implants and should have shorter-length cantilevers. A tapered arch form has the largest distance between anterior and posterior implants and may have the longest

A square arch form involves smaller A-P spreads between splinted implants and should have shorter-length cantilevers. A tapered arch form has the largest distance between anterior and

The mandible should be divided into three sections when planning for implant placement: canine to canine; bilateral posterior. This is different from the maxilla, which needs more implant support because the bone is less dense and the direction of force is outside of the arch in all excursive movements; here you must consider the maxilla in at least 4 sections depending on the magnitude of force and the shape of the arch. These sections include the bilateral canine area and the bilateral posterior areas; at least 1 implant should be inserted into each section and splinted during immediate

Concerns about medial mandibular flexure with cross-arch splinting suggests that the final restoration should be fabricated in at least 2 sections when implants are placed in both posterior quadrants and fewer than 3 adjacent pontics are present [56]. The following photos show the restoration of an mandible with a 2-piece implant-supported fixed

The mandible should be divided into three sections when planning for implant placement: canine to canine; bilateral posterior. This is different from the maxilla, which needs more implant support because the bone is less dense and the direction of force is outside of the arch in all excursive movements; here you must consider the maxilla in at least 4 sections depending on the magnitude of force and the shape of the arch. These sections include the bilateral canine area and the bilateral posterior areas; at least 1 implant should be inserted into each section

Concerns about medial mandibular flexure with cross-arch splinting suggests that the final restoration should be fabricated in at least 2 sections when implants are placed in both posterior quadrants and fewer than 3 adjacent pontics are present [56]. The following photos show the

less relative to the overall implant survival [54].

**3. General Considerations for Treatment Planning** 

immediate loading when a lever forms and increasing the risk of occlusal overload.

system from cantilevered forces because of the stabilizing effect of the A-P distance [27].

Figure 1: A-P spread and length of cantilever for framework (a) and final restoration (b).

**Figure 1.** A-P spread and length of cantilever for framework (a) and final restoration (b).

posterior implants and may have the longest cantilever design [27].

and splinted during immediate load for the completely edentulous patient.

restoration of an mandible with a 2-piece implant-supported fixed restoration.

resorbable sutures may be beneficial.

cantilever design [27].

136 Current Concepts in Dental Implantology

restoration.

**3.1 Treatment Planning of Mandible** 

load for the completely edentulous patient.

**Figure 2.** Panoramic radiograph of patient before treatment.

**3.1. Treatment planning of mandible**

**Figure 5.** Clinical fit of mandibular framework verified after it was sectioned in two pieces.

**Figure 6.** Implant-supported screw-retained fixed dental prosthesis, in two pieces, was fabricated in the laboratory.

**Figure 7.** Occlusal view of mandibular implant- supported screw-retained fixed dental prosthesis at delivery.

**Figure 8.** Intra-oral view after inserting mandibular restoration.

**Figure 5.** Clinical fit of mandibular framework verified after it was sectioned in two pieces.

138 Current Concepts in Dental Implantology

**Figure 6.** Implant-supported screw-retained fixed dental prosthesis, in two pieces, was fabricated in the laboratory.

**Figure 9.** Panoramic radiograph at delivery.

**Figure 10.** Intra-oral view after inserting interim maxillary removable partial denture.

#### **3.2. Factors influencing restorative plans**

Cantilevers increase moment loads to implant bone interface and can increase the amount of crestal bone loss observed, increase abutment screw loosening, increased implant body fracture, and increase the risk of implant failure. The immediate load transitional should not have a posterior cantilever -not in esthetic zone- and bite forces are greater posteriorly; especially in the partially edentulous patients without a cross-arch support system. Partially uncemented restorations may result in a cantilever along the remaining implants; considering a definitive cement for transitional restoration to decrease the risk of partially retained restorations can be considered.

An occusal load direction along the implant interface may affect the resorption rate. Axial load has been shown to maintain the lamellar bone and has a lower resorption rate. The crown height can also serve as a vertical cantilever when angled forces or cantilevers placed. Flat occlusal planes in the posterior decrease risk of angled loads. The amount of force can be decreased by modifying the occlusal contacts so as to decrease or eliminate contact on the restoration. In the completely edentulous patient, parafunction may be eliminated by restoring with an immediate load overdenture and having the patient remove it at night. Having a stress relief attachment to implants can decrease the force transferred while the prosthesis is in function.

The patient's diet should also be a factor to consider and can lead to the fracture or loosening of the transitional due to overload. The patient should be instructed to eat only soft foods during the immediate loading period. The mechanical properties of bone should be considered as a less dense bone type has a lower strength. The bone-implant contact decreases for less dense bone, and the strength of the bone is directly related to its density, with the less dense bone type being weaker. The rate of resorption of dense cortical bone is slower than trabecular resorption rates; cortical bone is more likely to remain lamellar during the immediate load process than trabecular bone.

In summary, the greater number of implants, the greater length and width of implants, rough surfaces that provide greater surface area; placement of implants to maximize antero-posterior spread and decrease cantilevers should be considered in lower density bone types when planning for immediate load. The bone in the anterior is cortical bone at the crestal and apical areas; root forms implants should be placed to engage the opposing cortical plate when immediate load is contemplated to maximize primary stability and optimize mechanical conditions.

The posterior maxilla has a thin sinus floor and the mandibular canal location does not always allow engagement of the opposing cortex; the posterior maxilla is the area that caries the highest risk of implant failure when a 2 stage healing approach is used [57,58]. The implant number, width, and design are methods to decrease stresses to the interface in these regions. Use of conventional healing for type 3 or 4 bone quality when less than 10mm height exists. Bone grafting depends on many factors to be predictable: blood supply and lack of micro‐ movement [57-60]. Developing woven bone is at more risk of overload, and grafting is more predictable when soft tissue covers the graft and membranes are used. Immediately loaded implants should be placed in an existing bone volume that is adequate for both early load and that has the proper prosthetic design. Bone grafting before implant placement and then implant insertion and immediate loading after graft maturation is suggested when inadequate bone volume is present for proper reconstructive procedures.

#### **3.3. Restoratively-driven treatment planning**

**Figure 10.** Intra-oral view after inserting interim maxillary removable partial denture.

Cantilevers increase moment loads to implant bone interface and can increase the amount of crestal bone loss observed, increase abutment screw loosening, increased implant body fracture, and increase the risk of implant failure. The immediate load transitional should not have a posterior cantilever -not in esthetic zone- and bite forces are greater posteriorly; especially in the partially edentulous patients without a cross-arch support system. Partially uncemented restorations may result in a cantilever along the remaining implants; considering a definitive cement for transitional restoration to decrease the risk of partially retained

An occusal load direction along the implant interface may affect the resorption rate. Axial load has been shown to maintain the lamellar bone and has a lower resorption rate. The crown height can also serve as a vertical cantilever when angled forces or cantilevers placed. Flat occlusal planes in the posterior decrease risk of angled loads. The amount of force can be decreased by modifying the occlusal contacts so as to decrease or eliminate contact on the restoration. In the completely edentulous patient, parafunction may be eliminated by restoring with an immediate load overdenture and having the patient remove it at night. Having a stress relief attachment to implants can decrease the force transferred while the prosthesis is in

The patient's diet should also be a factor to consider and can lead to the fracture or loosening of the transitional due to overload. The patient should be instructed to eat only soft foods during the immediate loading period. The mechanical properties of bone should be considered as a less dense bone type has a lower strength. The bone-implant contact decreases for less dense bone, and the strength of the bone is directly related to its density, with the less dense bone type being weaker. The rate of resorption of dense cortical bone is slower than trabecular resorption rates; cortical bone is more likely to remain lamellar during the immediate load

**3.2. Factors influencing restorative plans**

restorations can be considered.

140 Current Concepts in Dental Implantology

process than trabecular bone.

function.

Implant rehabilitation should always be prosthodontically driven [6]. This philosophy promotes a reduction in implant micromovement through appropriately positioned and loaded restorations. If restorations are inappropriately designed, a loss of osseointegration and/or prosthetic failure is more likely to occur. Axial implant loading is a desirable treatment goal since lateral forces greater than 30Ncm have been shown to produce micromotions greater than 100µm. Non-axial loading can also contribute to the loosening of abutment screws, a major cause of prosthodontic failure. Nordin et al., described that a high precision and passively fitting prosthesis reduced stresses and strains that could be detrimental to a healing implant [61]. In their study, they utilized the "Cresco Precision Method" to allow a high precision passive fit, intended to reduce stress and strain on the implant-bone interface during prosthetic fixation. Some researchers have implemented splinting and cross-arch stabilization on implants that are not loaded along their long axis. In an effort to avoid the maxillary sinus, Bevilacqua et al., placed distal implants in an angulated manner [62]. This technique has shown bone loss around the distal implants that is similar to more conventionally placed implants. Others have demonstrated 100% survivability using a similar concept called V-II-V, where 6 implants are placed into the maxilla at 30-45 degree angulations to the occlusal plane in the posterior maxilla to avoid the maxillary sinus.

Some researchers have reported that a similar prognosis could be expected whether or not the splinting of implants was utilized [63,64]. Especially when evaluating implant treatment in the maxilla, it is more common to find reports supporting reductions in micromovement and increases in overall survivability and success when splinting and cross-arch stabilization are used. Various combinations of prosthodontic materials are available, including: all-resin, metal reinforced resins and ceramics and all-ceramics. Literature describing the ability of each type of restoration to adequately splint immediately loaded implants to permit osseointegration suggests that stability, rather than the material used, is the critical factor. However, Collaert and De Bruyn reported resin fractures leading to prosthodontic failure and they subsequently altered their protocol to utilize metal reinforced fixed prostheses [65]. Nordin et al., reported failures of distal implants supporting all resin full-arch prostheses [61]. This failure is consis‐ tent with both Ibanez et al. [66], who reported that stability from splinting is the primary concern for success rather than other factors such as implant length, and Bergkvist et al.[67], who described impaired healing of implants under a removable prosthesis. Nordin et al., subsequently cited material thinness as the likely cause of inadequate rigidity, suggesting that if adequately thick, an all-resin fixed prosthesis would provide adequate splinting and crossarch stabilization. Since implants are susceptible to overload with excessive micromotion and since they do not possess a periodontal ligament, pathologic bone strain and fibrotic healing are more likely to occur with poor occlusal management. An occlusal scheme that is perpen‐ dicular to the long axis of the implant, has freedom in centric relation, avoids cantilever forces, does not have interferences during excursive or protrusive movements and is in group function where possible also reduces non-axial forces on the implant and screw fixation components.

#### **4. Conclusion**

The more current reports suggest that the prevalence of implant survivability has increased and that previous recommendations may not reflect the survivability that current treatment planning and delivery options afford. Careful surgical preparation and performance, consid‐ erations in restoration design and maintenance, a regular recall regimen and good oral hygiene can predictably and consistently yield successful results. This has been proven continuously in the literature for the mandible. Although the maxilla has yet to prove itself in long term evidence based studies, the interim results of various investigations suggests that by carefully following guidelines and respecting the biology of the "softer" maxillary alveolar bone and the anatomic limitations of the upper jaw, clinicians may achieve long term success rates similar to those consistently realized in the mandible.

#### **Author details**

Ilser Turkyilmaz\* and Ashley Brooke Hoders

\*Address all correspondence to: ilserturkyilmaz@yahoo.com

Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, Texas, USA

#### **References**

used. Various combinations of prosthodontic materials are available, including: all-resin, metal reinforced resins and ceramics and all-ceramics. Literature describing the ability of each type of restoration to adequately splint immediately loaded implants to permit osseointegration suggests that stability, rather than the material used, is the critical factor. However, Collaert and De Bruyn reported resin fractures leading to prosthodontic failure and they subsequently altered their protocol to utilize metal reinforced fixed prostheses [65]. Nordin et al., reported failures of distal implants supporting all resin full-arch prostheses [61]. This failure is consis‐ tent with both Ibanez et al. [66], who reported that stability from splinting is the primary concern for success rather than other factors such as implant length, and Bergkvist et al.[67], who described impaired healing of implants under a removable prosthesis. Nordin et al., subsequently cited material thinness as the likely cause of inadequate rigidity, suggesting that if adequately thick, an all-resin fixed prosthesis would provide adequate splinting and crossarch stabilization. Since implants are susceptible to overload with excessive micromotion and since they do not possess a periodontal ligament, pathologic bone strain and fibrotic healing are more likely to occur with poor occlusal management. An occlusal scheme that is perpen‐ dicular to the long axis of the implant, has freedom in centric relation, avoids cantilever forces, does not have interferences during excursive or protrusive movements and is in group function where possible also reduces non-axial forces on the implant and screw fixation components.

The more current reports suggest that the prevalence of implant survivability has increased and that previous recommendations may not reflect the survivability that current treatment planning and delivery options afford. Careful surgical preparation and performance, consid‐ erations in restoration design and maintenance, a regular recall regimen and good oral hygiene can predictably and consistently yield successful results. This has been proven continuously in the literature for the mandible. Although the maxilla has yet to prove itself in long term evidence based studies, the interim results of various investigations suggests that by carefully following guidelines and respecting the biology of the "softer" maxillary alveolar bone and the anatomic limitations of the upper jaw, clinicians may achieve long term success rates

Department of Comprehensive Dentistry, University of Texas Health Science Center at San

**4. Conclusion**

142 Current Concepts in Dental Implantology

**Author details**

Ilser Turkyilmaz\*

Antonio, Texas, USA

similar to those consistently realized in the mandible.

and Ashley Brooke Hoders

\*Address all correspondence to: ilserturkyilmaz@yahoo.com


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### **CAD/CAM Technology in Implant Dentistry**

Ilser Turkyilmaz, Caroline Corrigan Eskow and Gokce Soganci

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/59322

#### **1. Introduction**

sealant in maxillary sinus floor elevation for delayed dental implant. Clinical Oral

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5-13.

When a patient presents with a need and a desire for implants to replace missing teeth, correct execution will only occur with thorough planning [1-4]. Recently introduced technology may benefit both the dentist and the patient when restoring with dental implants, in that the implants will be placed in an ideal, predictable, and planned location [4-7]. Implant dentistry is constantly challenging the practitioner to be aware of recent advances. Though it may feel overwhelming for a practitioner to stay informed with the continuous introduction of new technologies, implant dentistry is undergoing an exciting time, and in order to take full advantage of it, the practitioner has a duty to practice at the highest level. This chapter aims to inform the practitioner about the latest technologies, their history and importance, and the current options on the market.

#### **2. Computerized tomography**

Computerized tomography is a tool that is based on the original concept of conventional tomography [8,9]. Tomography is a type of image in which a 2-D slice is captured and the surrounded slices are blurred. This works by the sensor and the x-ray tube moving in opposite directions around the source. During this movement, the plane of interest remains fixed, and the surrounding planes become blurred due to constantly changing positions on the sensor. A panoramic image is a single tomographic image [9]. Panoramic radiographs cover large anatomical areas, have low radiation doses, and are easily and quickly done, though their distortion and 2-D quality limits their diagnostic value.

Computed tomography (CT) was introduced in 1973 by Godfrey Hounsfield. It works by an x-ray tube and a series of detectors which rotate in synchronous directions, as the x-ray tube

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

emits fan-shaped beams through the region of interest and onto the detectors. The data captured is processed in a computer which displays the resulting image in voxels, or volume elements [10]. Benefits of CT include high resolution and absence of superimposed images, but they emit large radiation doses and are expensive.

More recently, a new technology called cone-beam computed tomography (CBCT) has become popular [1,10-13]. This works by the x-ray tube emitting beams onto a 2-D sensor. The x-ray tube and sensor rotate around the region of interest and expose an image at each degree of rotation. These slices can subsequently be arranged into a 3-D image which can provide detailed and accurate information which has been reported to be within 2% of geometric accuracy. Benefits of CBCT include cost effectiveness, ease of use, low radiation dose, and accurate gathering of information [14,15].

#### **3. Cone-Beam Computed Tomography (CBCT)**

When utilizing CBCT technology, the practitioner should be aware of several features [14,15]. The resolution of a CBCT image acquired is measured by voxel size. The majority of CBCT's used for dental implant planning has a voxel size of 0.4 mm, and the accuracy of measurements made on the CBCT are directly related to this size. When reading a CBCT, one way to analyze bone density is through the Hounsfield index. This index was named after the inventor of computed tomography, as previously mentioned. The scale ranges from-1,000 to+1,000, in which air reads at-1,000, water reads at 0, and extremely dense bone reads at+1,000 [16]. Different anatomical structures have varying Hounsfield units. It is important to know how to apply the Hounsfield scale because the differences in bone densities will alter the chosen surgical protocol. For instance, if the CBCT scan shows very dense bone, more implant preparation drills will be required. Each implant system has a unique protocol for soft and dense bone. The average Hounsfield units for human tissues are shown in Table 1 [16].


**Table 1.** Average Hounsfield units for human tissues.

Most implant planning software is structured from the images produced by medical computed tomography. The conversion of a cone beam computed tomography image into a medical computed tomography image has not been studied, though it is hypothesized that there is no difference in linear measurement between the two.

When planning for implant surgery, few complications should occur when utilizing cone beam computed tomography. The most common complication, called beam hardening, occurs when the patient already has implants or a large amount of metal restorations [17,18]. This is a phenomenon that occurs when the metal causes the x-ray to increase in energy and become "hard" as it passes through an object. Beam hardening makes it difficult to visualize sur‐ rounding structures, thus altering the accuracy of measurements of crucial anatomical sites, such as the inferior alveolar nerve and the buccal plate thickness [17,18].

When ordering a scan, clear written instructions should be communicated from the practi‐ tioner to the radiologist. The practitioner should specify the reason for the scan (i.e., implant placement, sites), the size of the scan (small or large), and any additional anatomical regions that should be included (such as a TMJ or sinus evaluation). A small volume scan should be ordered for single tooth implants, and a large volume scan should be ordered for full-arch implants, inclusion of sinuses, or evaluation of TMJ or OSA.

#### **4. Surgical guides**

emits fan-shaped beams through the region of interest and onto the detectors. The data captured is processed in a computer which displays the resulting image in voxels, or volume elements [10]. Benefits of CT include high resolution and absence of superimposed images,

More recently, a new technology called cone-beam computed tomography (CBCT) has become popular [1,10-13]. This works by the x-ray tube emitting beams onto a 2-D sensor. The x-ray tube and sensor rotate around the region of interest and expose an image at each degree of rotation. These slices can subsequently be arranged into a 3-D image which can provide detailed and accurate information which has been reported to be within 2% of geometric accuracy. Benefits of CBCT include cost effectiveness, ease of use, low radiation dose, and

When utilizing CBCT technology, the practitioner should be aware of several features [14,15]. The resolution of a CBCT image acquired is measured by voxel size. The majority of CBCT's used for dental implant planning has a voxel size of 0.4 mm, and the accuracy of measurements made on the CBCT are directly related to this size. When reading a CBCT, one way to analyze bone density is through the Hounsfield index. This index was named after the inventor of computed tomography, as previously mentioned. The scale ranges from-1,000 to+1,000, in which air reads at-1,000, water reads at 0, and extremely dense bone reads at+1,000 [16]. Different anatomical structures have varying Hounsfield units. It is important to know how to apply the Hounsfield scale because the differences in bone densities will alter the chosen surgical protocol. For instance, if the CBCT scan shows very dense bone, more implant preparation drills will be required. Each implant system has a unique protocol for soft and dense bone. The average Hounsfield units for human tissues are shown in Table 1 [16].

Most implant planning software is structured from the images produced by medical computed tomography. The conversion of a cone beam computed tomography image into a medical

but they emit large radiation doses and are expensive.

**3. Cone-Beam Computed Tomography (CBCT)**

**Tissue Hounsfield Unit**

Trabecular bone 150-900 Cortical bone 900-1800 Dentin 1600-2400 Enamel 2500-3000 Muscle 35-70 Fibrous tissue 60-90 Cartilage 80-130

**Table 1.** Average Hounsfield units for human tissues.

accurate gathering of information [14,15].

150 Current Concepts in Dental Implantology

Not only does cone-beam technology provide valuable information for evaluation before placing dental implants, but it also translates into completely digital planning of surgical cases. Utilizing a CBCT scan as a template, a surgical guide may be fabricated based on the precise location of a planned implant [1,4,19,20]. All of the major implant companies offer software which can be used for planning the specific location of implants in the CBCT image, and eventually a guide can be ordered and fabricated. The software allows the virtual placement of implants into the CBCT scan at the precise location you choose, while taking into account considerations such as anatomic landmarks, adjacent dentition, type of restoration to be fabricated, and occlusal scheme.

It is beneficial, and many times essential, to utilize a radiographic guide in order to aid in choosing the correct position of the implants. If a patient is missing several teeth, a radiographic guide should be worn by the patient during the CBCT scan. The guide allows the practitioner to locate where the future teeth will be restored in space. Radiographic guides can be fabricated in many ways, and one must consider the protocol of the implant planning software one chooses to use. For example, the Nobel Clinician prescribes a dualscan protocol in which the patient wears the guide during the patient's scan, and then the guide is scanned separately [21,22]. Fiduciary markers, or small gutta percha points placed into the radiographic guide, allow the software to overlap the two scans and merge the two files together. In this way, the guide may be virtually removed and replaced on the patient's scan in the computer. Another way to fabricate a radiographic guide is by placing radiopaque denture teeth into the guide. These teeth will ultimately be visible in the scan so that the implants may be planned accordingly.

Regardless of which system is chosen, the practitioner must be able to understand when it is important to utilize a radiographic guide. When planning for single implant replacements, with adjacent teeth on both sides, it is often not necessary to use a radiographic guide because enough adjacent landmarks exist in order to surmise the future location of the single crown. In an edentulous patient, the decision to use a radiographic guide depends largely upon the type of restoration that will be fabricated. For a mandibular locator overdenture with two implants, it is often unnecessary to use a radiographic guide because the clinician has some freedom in the positioning of these implants. This is unlike an edentulous patient that is planned to receive metal ceramic restorations in which the abutment-screw access hole must open through the occlusal surface of the posterior teeth and the cingula of the anterior teeth. In this case, it is paramount to plan for the precise implant positioning, and the radiographic guide must have the identical anticipated tooth positions of the final prosthesis. If the patient is unhappy with the tooth position or shape on the radiographic guide, this must be fixed before utilizing it as the guide.

#### **5. Virtual implant planning**

The purpose of utilizing virtual implant software is to plan the placement of the implants in prosthodontically driven positions [22,23]. Of course an implant may be placed anywhere the bony anatomy allows, but in order to build a successful prosthesis for that implant, the correct planning must be done. In the past, a panoramic tomography scan was performed while the patient wore a radiographic template with integrated metal spheres at the implant site. In this manner, the magnification of the radiograph was able to be calculated, and the approximate placement of the implant was planned. This conventional model was flawed in that it did not convey any 3-D information [24].

The most contemporary technique utilizes cone-beam CT technology which provides the essential 3-D information. The technique begins with fabrication of a radiographic guide with ideal tooth positions. This guide may be a duplicate of the patient's exiting denture, only if that denture offers tooth positions that are acceptable by the patient and practitioner. If the denture is not ideal, a new one should be fabricated until the esthetics and functional demands are met. It is not until this point that a CBCT scan should be taken. The next step involves interpretation of the scan and possibly a re-working of the original treatment plan. This may include an additional surgery for bone grafting, or a different prosthesis choice. For example, if metal ceramic restorations were originally planned for, but the scan clearly shows that an implant cannot be placed in the proposed position, either a new design or a new prosthesis must be chosen. Lastly, the practitioner can virtually place the implants into the bone at the exact position that optimizes prosthodontic benefit as well as osseointegration potential. These positions are then translated into the surgical guide which will be used on the day of surgery for the placement of the implants.

The benefits of virtual planning and fabricating surgical guides from the planning are numerous. The patient's chair time is decreased, the surgery is more predictable and less stressful, the implants are placed in a restoratively driven manner, and the case difficulty is learned ahead of time [6,25]. These factors allow the dentist to plan accordingly in regards to time and fees. Increased lab costs due to customized abutments may be realized during planning, and extra surgical procedures may be foreseen. The patient will know what to expect and will appreciate the dentist for the knowledge rendered.

#### **5.1. Indications**

Regardless of which system is chosen, the practitioner must be able to understand when it is important to utilize a radiographic guide. When planning for single implant replacements, with adjacent teeth on both sides, it is often not necessary to use a radiographic guide because enough adjacent landmarks exist in order to surmise the future location of the single crown. In an edentulous patient, the decision to use a radiographic guide depends largely upon the type of restoration that will be fabricated. For a mandibular locator overdenture with two implants, it is often unnecessary to use a radiographic guide because the clinician has some freedom in the positioning of these implants. This is unlike an edentulous patient that is planned to receive metal ceramic restorations in which the abutment-screw access hole must open through the occlusal surface of the posterior teeth and the cingula of the anterior teeth. In this case, it is paramount to plan for the precise implant positioning, and the radiographic guide must have the identical anticipated tooth positions of the final prosthesis. If the patient is unhappy with the tooth position or shape on the radiographic guide, this must be fixed

The purpose of utilizing virtual implant software is to plan the placement of the implants in prosthodontically driven positions [22,23]. Of course an implant may be placed anywhere the bony anatomy allows, but in order to build a successful prosthesis for that implant, the correct planning must be done. In the past, a panoramic tomography scan was performed while the patient wore a radiographic template with integrated metal spheres at the implant site. In this manner, the magnification of the radiograph was able to be calculated, and the approximate placement of the implant was planned. This conventional model was flawed in that it did not

The most contemporary technique utilizes cone-beam CT technology which provides the essential 3-D information. The technique begins with fabrication of a radiographic guide with ideal tooth positions. This guide may be a duplicate of the patient's exiting denture, only if that denture offers tooth positions that are acceptable by the patient and practitioner. If the denture is not ideal, a new one should be fabricated until the esthetics and functional demands are met. It is not until this point that a CBCT scan should be taken. The next step involves interpretation of the scan and possibly a re-working of the original treatment plan. This may include an additional surgery for bone grafting, or a different prosthesis choice. For example, if metal ceramic restorations were originally planned for, but the scan clearly shows that an implant cannot be placed in the proposed position, either a new design or a new prosthesis must be chosen. Lastly, the practitioner can virtually place the implants into the bone at the exact position that optimizes prosthodontic benefit as well as osseointegration potential. These positions are then translated into the surgical guide which will be used on the day of surgery

The benefits of virtual planning and fabricating surgical guides from the planning are numerous. The patient's chair time is decreased, the surgery is more predictable and less

before utilizing it as the guide.

152 Current Concepts in Dental Implantology

**5. Virtual implant planning**

convey any 3-D information [24].

for the placement of the implants.

As mentioned before, not all cases are advocated for radiographic guides. Similarly, not all patients are candidates for surgical guides. There are several limiting factors involving surgical guides. Firstly, the patient must have adequate opening. Depending on the guide, length of implant, and drill system used, the normal minimal opening is 35 mm at the first molar. This must be evaluated before ordering the guide, as the guides are custom made and nonreturnable. Secondly, the patient must be aware that this is an added cost to the treatment. Surgical guides range anywhere from \$200 to \$1,000 depending on the complexity of the case and the company chosen to fabricate the guide.

Surgical guides allow prosthodontically driven implant placement, which ultimately will give the patient the best prosthesis to satisfy esthetic and functional needs. Surgical guides also allow more accuracy during implant placement. Not only are the implants placed in the exact pre-determined positions, but the surgery may take less time and ultimately will be more comfortable for the patient.

#### **5.2. Steps for the practitioner**

Some of the steps involved in virtual implant planning are different depending on which company you choose to utilize, but they are all based on the same principles. As mentioned before, the first step is to fabricate trial dentures for the completely edentulous patient or a trial tooth arrangement for the partially edentulous patient. Once this is approved by the patient and practitioner, the denture may be converted into a radiographic guide.

#### **5.3. Fabrication methods**

There are three basic methods of fabricating a radiographic guide. The generic method involves any type of scan template that has radiopaque material to indicate the desired implant positions. There are many radiopaque materials that may be used. These include radiopaque denture teeth (SR vivo TAC, Ivoclar, Vivadent, Amherst, NY), radiopaque acrylic (Biocryl X, Great Lakes, Tonawanda, NY), and triphenylbismuth added to denture acrylic.

Another type of guide, termed a dual density radiographic guide, is fabricated as a duplicate denture utilizing denture teeth of a high radiopacity and denture base of a lesser radiopacity. This type of guide prescribes a single scan protocol.

Lastly, the dual-scan protocol requires a radiographic guide with fiduciary markers placed into it. These are small divets 1.5 mm in diameter that are filled with gutta percha. Eight markers must be placed in each guide at different horizontal, vertical, and transverse levels. The term "dual-scan" comes from the way in which the patient is first scanned while wearing the radiographic guide, and then the guide is secondarily scanned alone on a plexi-glass table.

#### **5.4. CBCT scan**

Once the type of guide is chosen, the CBCT scan may be performed. During this procedure, that patient's occlusion must be opened at least 5 mm. This may be done by injecting PVS material on the patient's occlusal surface and having the patient bite down at an open vertical dimension. A radiopaque material should never be used for this, as it will obscure the region of interest on the scan. This opened bite allows us to distinguish the maxillary teeth from the mandibular teeth in the radiograph.

#### **5.5. Digital planning**

Next, the case may be planned using the software of your choice. Most major implant com‐ panies sell their own software, but there are also universal software companies available which allow you to place any implant of your choosing. These will be reviewed later in the chapter.

### **6. Surgical guide support**

The type of surgical guide must be chosen at this point. Three types exist based on the type of supporting tissue: bone, mucosal, and tooth [1,19,26,27].

#### **6.1. Bone-based guides**

Bone-based guides are indicated for the fully or partially edentulous arch, when immediate implants are being placed, when alveoloplasty is required, and when anatomic limitations exist which require visualization of the bone. Bone-based guides may provide a more accurate seating of the guide because of the rigidness of the bony base. Sufficient bone support is essential for a stable guide positioning. During surgery, an incision is made along the alveolar ridge and mucoperiosteal flaps are elevated. The guide sits directly on the bone and complete visibility is acquired. Limitations of bone-based guides include a lengthier surgical appoint‐ ment, longer healing times for the patient, and difficulties gaining adequate palatal reflection in certain patients. Some argue that they may be a poor choice in a patient with a thin buccal plate which can be prone to resorption after tissue reflection.

#### **6.2. Mucosal-based guides**

Flapless implant surgery is an alternative method for implant placement. Advantages of a flapless surgery include less trauma to the hard and soft tissues during surgery, shortened procedure, rapid healing, fewer postoperative complications, decreased infection risk, and increased patient comfort [28-31]. A significant advantage of the flapless implant surgery is the decreased amount of bone loss as well as the preservation of the gingival margin of the adjacent teeth and interdental papillae [31]. More bone loss occurs during flapped procedures since the gingiva is unable to provide nutrients to the bone during the surgery. The preserva‐ tion of tissues will help prevent the appearance of black triangles after healing.

Though flapless surgery offers many advantages, many surgeries still require a flap to be elevated. Reasons for this include the need for more visualization, bone grafting, and alveo‐ loplasty. If the patient's alveolar bone is thin, it is wise to elevate a flap and visualize the bone before placing an implant.

A mucosal-based guide is a good choice for a fully edentulous arch with a minimum of 2 mm of bone buccal and lingual to the proposed implant site. This amount of bone is necessary because of the increased risk of cortical bone perforation related to implant placement without direct visualization of the bone. The conventional flapless surgery relies on the experience of the surgeon to correctly predict the shape of the underlying bone when placing an implant. Recently it has been suggested that using a surgical guide fabricated virtually utilizing a CBCT may be beneficial in these cases.

Mucosal-based guides are good choices in the maxilla due to difficulty in reflection of the soft tissue of the palate which is necessary for a bone-based guide [32]. A mucosal-based guide can also be used in conjunction with osteotome sinus lifts [33]. Limitations include error when seating the guide due to the mobility of mucosa which ultimately can affect the implant positions. Furthermore, a mucosal-based guide will mimic the fit of the radiographic guide, which is most often fabricated as a duplicate of the denture. So it is important that the denture be very stable before utilizing it as a radiographic guide.

Three retention pins are required to be placed in these guides to stabilize them on the eden‐ tulous arch. The retention pins must be spread out, must not protrude into the vestibule, and must be an adequate distant from the implant sites so as not to hinder their placement.

The literature shows conflicting results when comparing mucosa-based versus bone-based guides. Some say that mucosa-based guides may have a decreased accuracy as compared to bone-and tooth-borne guides [27,34] and some say that mucosa-based guides have increased accuracy as compared to bone-and tooth-borne guides [20]. In the end, the literature shows that mucosal-based guides offer adequate accuracy of implant placement. Several studies have displayed a mean of about 1.0mm deviation at the apical aspect of the implant from the planned placement on the CBCT [20,35]. Some authors recommend a certain safety zone (2.0mm) due to the inevitable deviation of the planned versus actual osteotomy site [35].

#### **6.3. Tooth-based guides**

The term "dual-scan" comes from the way in which the patient is first scanned while wearing the radiographic guide, and then the guide is secondarily scanned alone on a plexi-glass table.

Once the type of guide is chosen, the CBCT scan may be performed. During this procedure, that patient's occlusion must be opened at least 5 mm. This may be done by injecting PVS material on the patient's occlusal surface and having the patient bite down at an open vertical dimension. A radiopaque material should never be used for this, as it will obscure the region of interest on the scan. This opened bite allows us to distinguish the maxillary teeth from the

Next, the case may be planned using the software of your choice. Most major implant com‐ panies sell their own software, but there are also universal software companies available which allow you to place any implant of your choosing. These will be reviewed later in the chapter.

The type of surgical guide must be chosen at this point. Three types exist based on the type of

Bone-based guides are indicated for the fully or partially edentulous arch, when immediate implants are being placed, when alveoloplasty is required, and when anatomic limitations exist which require visualization of the bone. Bone-based guides may provide a more accurate seating of the guide because of the rigidness of the bony base. Sufficient bone support is essential for a stable guide positioning. During surgery, an incision is made along the alveolar ridge and mucoperiosteal flaps are elevated. The guide sits directly on the bone and complete visibility is acquired. Limitations of bone-based guides include a lengthier surgical appoint‐ ment, longer healing times for the patient, and difficulties gaining adequate palatal reflection in certain patients. Some argue that they may be a poor choice in a patient with a thin buccal

Flapless implant surgery is an alternative method for implant placement. Advantages of a flapless surgery include less trauma to the hard and soft tissues during surgery, shortened procedure, rapid healing, fewer postoperative complications, decreased infection risk, and increased patient comfort [28-31]. A significant advantage of the flapless implant surgery is the decreased amount of bone loss as well as the preservation of the gingival margin of the adjacent teeth and interdental papillae [31]. More bone loss occurs during flapped procedures

**5.4. CBCT scan**

154 Current Concepts in Dental Implantology

**5.5. Digital planning**

mandibular teeth in the radiograph.

**6. Surgical guide support**

**6.1. Bone-based guides**

**6.2. Mucosal-based guides**

supporting tissue: bone, mucosal, and tooth [1,19,26,27].

plate which can be prone to resorption after tissue reflection.

A tooth-borne guide is indicated for the partially edentulous arch with adequate remaining sound dentition. A plaster cast or an optical scan of the cast is necessary for the laboratory fabrication of this type of guide. The remaining teeth will determine how stable a tooth-borne guide will be, so this must be evaluated carefully. It is recommended to use this type of guide when placing a single implant or several implants when minimally invasive surgery is required. Often times, a flapless surgery may be performed with a tooth-borne guide. In a partially edentulous patient, the treatment planning may be more difficult due to anatomical limitations, so utilizing computer-aided techniques can optimize the efficiency and accuracy of implant placement [36].

#### **6.4. Surgical preparation**

When preparing for surgery, several steps must be taken when utilizing a surgical guide. First, the guide should be disinfected according to the instructions provided from the company who fabricated the guide. Many guides may be placed in a chemical disinfectant for 10 to 12 minutes, and most guides will not tolerate heat disinfection. Also, if utilizing a mucosal-based guide, it is a good idea to place holes into the guide before the surgery begins, so that anesthesia may be administered throughout the surgical procedure. If this step is missed, the practitioner must remove the mucosal based guide, after removing the retention pins, administer anesthesia, and replace the guide in the exact same position. Or the practitioner must drill through the guide to gain access to the anesthesia locations. Lastly, when seating a mucosal-based guide on the day of surgery, the same interocclusal record which was used during the CBCT scan should be placed in the patients mouth along with the guide. At that point the retention pins can be placed into the bone to lock the guide into place while using the patients occlusion to stabilize the guide in the correct location.

#### **6.5. Stereolithographic versus conventional guides**

Surgical guides can be made through many techniques and several different materials. Recently, stereolithography has become a popular method of fabricating surgical guides [5,19]. Stereolithography is an additive manufacturing process. This process utilizes a bath of lightsensitive liquid resin which is cured one layer at a time by a laser which traces the 3-D model which the computer demands of it. Guides made from stereolithography are light sensitive as well as heat sensitive. These guides should always be kept in their original packaging in a cool dry environment.

Stereolithographic guides are very rigid in comparison to a conventional resin cured guide. When restoring a large edentulous area in which the guide has the potential to flex under pressure of the implant drill, it may be a wise decision to choose a stereolithographic guide so that the implant positions are not compromised. Stereolithographic guides also allow more precision when placing implants as compared with conventional guides. One study compared the difference between the planned implant position and the actual osteotomy at the apex. The conventional guides had an average of 2.1mm difference whereas the stereolithographic guides had an average of 1.0mm difference [37].

Surgical guides may be fabricated from the radiographic guide. The radiographic guide can be sent to a manufacturer which will convert it, through a mechanized process, into a surgical guide with included guide sleeves. If this technique is chosen, the radiographic guide must incorporate the correct orientation and placement of the implant into the guide. This can be accomplished either by using a radiographically opaque denture tooth, gutta percha markers through the long access of the tooth, or any other radio-opaque material which can orient the planned implant into the radiographic guide.

Alternatively, a mapping technique may be used to fabricate a computer generated surgical guide. This is a technique which eliminates the need for a radiographic guide. The patient is scanned while wearing a radiolucent interocclusal record to disclude the patient's posterior teeth by about 5 mm. Then a cast of the patient is scanned and a diagnostic wax-up is scanned. The computer is then able to orient these images to each other and the practitioner can digitally plan the implant placement in reference to the patients alveolar bone and planned tooth positions. A surgical guide can then be fabricated from the digital design.

All of these choices are viable options for fabricating a surgical guide. Each situation is unique and depending on the practitioners resources and relationship with their radiologist, the practitioner may choose any option he or she prefers.

#### **7. Companies**

limitations, so utilizing computer-aided techniques can optimize the efficiency and accuracy

When preparing for surgery, several steps must be taken when utilizing a surgical guide. First, the guide should be disinfected according to the instructions provided from the company who fabricated the guide. Many guides may be placed in a chemical disinfectant for 10 to 12 minutes, and most guides will not tolerate heat disinfection. Also, if utilizing a mucosal-based guide, it is a good idea to place holes into the guide before the surgery begins, so that anesthesia may be administered throughout the surgical procedure. If this step is missed, the practitioner must remove the mucosal based guide, after removing the retention pins, administer anesthesia, and replace the guide in the exact same position. Or the practitioner must drill through the guide to gain access to the anesthesia locations. Lastly, when seating a mucosal-based guide on the day of surgery, the same interocclusal record which was used during the CBCT scan should be placed in the patients mouth along with the guide. At that point the retention pins can be placed into the bone to lock the guide into place while using the patients occlusion to

Surgical guides can be made through many techniques and several different materials. Recently, stereolithography has become a popular method of fabricating surgical guides [5,19]. Stereolithography is an additive manufacturing process. This process utilizes a bath of lightsensitive liquid resin which is cured one layer at a time by a laser which traces the 3-D model which the computer demands of it. Guides made from stereolithography are light sensitive as well as heat sensitive. These guides should always be kept in their original packaging in a cool

Stereolithographic guides are very rigid in comparison to a conventional resin cured guide. When restoring a large edentulous area in which the guide has the potential to flex under pressure of the implant drill, it may be a wise decision to choose a stereolithographic guide so that the implant positions are not compromised. Stereolithographic guides also allow more precision when placing implants as compared with conventional guides. One study compared the difference between the planned implant position and the actual osteotomy at the apex. The conventional guides had an average of 2.1mm difference whereas the stereolithographic

Surgical guides may be fabricated from the radiographic guide. The radiographic guide can be sent to a manufacturer which will convert it, through a mechanized process, into a surgical guide with included guide sleeves. If this technique is chosen, the radiographic guide must incorporate the correct orientation and placement of the implant into the guide. This can be accomplished either by using a radiographically opaque denture tooth, gutta percha markers through the long access of the tooth, or any other radio-opaque material which can orient the

of implant placement [36].

156 Current Concepts in Dental Implantology

**6.4. Surgical preparation**

stabilize the guide in the correct location.

dry environment.

**6.5. Stereolithographic versus conventional guides**

guides had an average of 1.0mm difference [37].

planned implant into the radiographic guide.

The aim of this section is not to advertise any specific company, and we just want to share our experiences with these surgical guides. Surgical guides are fabricated by many manufactures, most notable the major implant companies. Each company has a unique planning software program as well as various choices for scanning protocol, guide materials, and design of the guide. Depending on the case, different manufacturers must be considered in certain situa‐ tions. For example, if dual-scan protocol was desired, only NobelBiocare and Anatomage offer this option.

#### **Things to Consider When Choosing a System**


These are all considerations that must be taken into account before investing in any imaging software because once you do, you will be limited by that companies available options.

Another consideration is that different implant-planning softwares allow different levels of resolution of the CBCT data. So even if the CBCT machine is capable of taking high resolution images, the planning software you choose may not be able to open the full resolution which was recorded. When placing implants, any fraction of a millimeter in the wrong direction may have a significant compromise on the outcome.

three, depending on the case?

a separate radiographic guide for the scan?

you do, you will be limited by that companies available options.

in the wrong direction may have a significant compromise on the outcome.

can then be fabricated from the digital design.

Dummy Text **Things to Consider When Choosing a System**

implant planning for you?

prefers.

**7. Companies**


record to disclude the patient's posterior teeth by about 5 mm. Then a cast of the patient is scanned and a diagnostic wax‐up is scanned. The computer is then able to orient these images to each other and the practitioner can digitally plan the implant placement in reference to the patients alveolar bone and planned tooth positions. A surgical guide

All of these choices are viable options for fabricating a surgical guide. Each situation is unique and depending on the practitioners resources and relationship with their radiologist, the practitioner may choose any option he or she

The aim of this section is not to advertise any specific company, and we just want to share our experiences with these surgical guides. Surgical guides are fabricated by many manufactures, most notable the major implant companies. Each company has a unique planning software program as well as various choices for scanning protocol, guide materials, and design of the guide. Depending on the case, different manufacturers must be considered in certain situations. For example, if dual‐scan protocol was desired, only NobelBiocare and Anatomage offer this option.

‐ How well can you maneuver the software program? Or will your radiologist be manipulating most of the digital

‐ If you plan on doing the virtual placement yourself, make sure you are comfortable with the program. Each

‐ What kind of radiographic scanning protocol to you plan on using? Do you prefer the dual‐scan protocol in which a denture can be quickly converted into a radiographic guide? Or do you prefer to have your lab fabricate

‐ Do you plan on using bone, mucosa, or tooth supported guides? Or do you want to have the option of using all

These are all considerations that must be taken into account before investing in any imaging software because once

Another consideration is that different implant‐planning softwares allow different levels of resolution of the CBCT

may not be able to open the full resolution which was recorded. When placing implants, any fraction of a millimeter

company offers a different program and these are not all as user‐friendly as the next.
