**1. Introduction**

In 2018, The Global Cancer Statistics reported just over 18 million new cases worldwide. Lip and oral cavity cancer is ranked 18th with 354,864 new cases (2.0%) and 177,384 deaths (1.9%). However, if we analyze the main cancers that affect the upper digestive tract (salivary glands, hypopharynx, oropharynx, nasopharynx, larynx, lip, and oral cavity), we obtain approximately 887,659 new cases (4.9%) of cancers that could leave important sequelae in the maxillofacial region [1].

Maxillectomy is defined as the partial or total surgical removal of the maxilla and was designed as a surgical treatment for tumors that affect the middle third of the face. During oncological ablative surgery complex maxillofacial defects result that involve the loss of anatomical structures such as dental elements, facial cavities, sense organs, bone tissue and facial soft tissue. Although reconstruction

with local and microvascular flaps is sometimes a viable alternative, maxillofacial rehabilitation with osseointegrated implants has been a well-reported treatment with a high success rate [2].

Various techniques and anatomical locations have been described in the facial region for the placement of osseointegrated implants and its reason is based on the bone buttress where a skeletal anchorage is possible to support the functional load of the implants. In general, maxillofacial rehabilitation with osseointegrated implants uses anchors in the zygomatic, pterygoid, nasomaxillary and alveolar zones [3–5].

## **2. Buttress implant concept and classification**

Based on the anatomical zones of the bony buttresses of the facial middle third, we designed a classification system that allows determining the therapeutic options where the placement and functional loading of osseointegrated implants is feasible: zone I or alveolar, zone II or nasomaxillary, zone III or zygomatic, zone IV or pterygoid (**Figure 1**)**.**

#### **2.1 Zone I/maxillary alveolar buttress**

#### *2.1.1 Tilted and axially positioned implants*

The use of endosseous osseointegrated implants was introduced to North America in 1982. At that conference, Branemark presented the data from 15 years of work, which was highly evidence-based with long-term clinical follow-up findings setting the guidelines for contemporary implantology [6].

Currently implantology has improved considerably; dental implants have incorporated advances in their anatomy, surface and types of connections, achieving a higher success rate and predictable results [7, 8].

Implants angled between 30 and 45° were described as an alternative surgical technique in order to avoid nearby anatomical structures or to achieve an adjacent bone position. Thus, we avoid advanced bone regeneration procedures and minimize the cantilever of prosthetic rehabilitation [9].

#### **Figure 1.**

*Anatomical zones of the bony buttresses of the facial middle third and placement of osseointegrated implants with their positions in the prosthetic arch.*

**165**

15 years [4].

*A Review of Maxillofacial Rehabilitation Using Osseointegrated Implants in Oncological…*

viability for the functional load of osseointegrated implants [10].

failed in healthy patients, yielding a success rate of 84.6% [11].

In 1994 Scher. describes the use of the nasopalatine canal as a receptor site for a dental implant, since then controlled studies have been carried out that confirm its

Peñarrocha et al. treated 13 patients with 78 osseointegrated implants in the rehabilitation of the atrophic maxilla. Of 78 implants, 13 were implanted in the nasopalatine canal, 6 patients had reversible sensory alteration, and 2 implants

Occasionally, when performing a partial maxillectomy, bone is available throughout the Maxillary alveolar buttress. In these cases, it is possible to use conventional dental implants anchored even in contralateral anatomical structures.

Although the term "Nasomaxillary implant" has not been defined in the Glossary of Oral and Maxillofacial Implants (GOMI) [12]. We define it as "Implant placement through the alveolar process and into the nasomaxillary buttress". The nasomaxillary buttress has been well described in facial trauma as it is a key anatomic zone in the reconstruction of fractures of the middle third. This area offers a cortical bone suitable for the anchorage and functional load of osseointegrated implants. However, there are few implant-oriented anatomical studies and

Some authors have described the placement of posterior tilted implants between 30 and 45° that reach an apical anchorage in the nasomaxillary buttress [9, 17, 18]. However, this type of implant is not frankly a nasomaxillary implant because they are retained from an apical portion and are not strictly into the buttress as in the

Nasomaxillary implants can be used as an anchorage point in a location anterior to the prosthetic arch. With this, we achieve anterior stability and the reduction of

In 1998 Dr. P. I Branemark described zygomatic implants as a bone anchorage alternative with a design between 30 and 52.5 mm long that are inserted into the body of the malar bone [19]. Since then, Branemark and other authors have described various surgical techniques and approaches for zygomatic implant placement that could be used to rehabilitate atrophic jaws or in patients with partial or total maxillectomy [20–22]. Scott et al. rehabilitated 28 patients after undergoing rhinectomy for malignant pathological processes, a total of 56 zygomatic implants were used as retainers of maxillofacial prostheses, 1 failed after radiotherapy having a success rate of 98% in

In general, most authors agree that zygomatic implants are more than 95% successful [23] and in radiated patients the success rate of implants is highly variable

Zygomatic implants offer adequate bone quality and quantity. Sometimes when the maxillectomy is extensive, it compromises the malar bone. Performing regenerative procedures with autografts or xenografts are a viable option to improve site conditions.

*DOI: http://dx.doi.org/10.5772/intechopen.93224*

**2.2 Zone II/nasomaxillary buttress**

some are anthropometric studies [13–16].

work forces in posterior implants.

with a range between 72 and 98% [2].

*2.3.1 Zygomatic implants*

case of a long implant with an axial orientation.

**2.3 Zone III/zygomaticomaxillary buttress**

*2.2.1 Nasomaxillary implants*

*2.1.2 Nasopalatine implants*

*A Review of Maxillofacial Rehabilitation Using Osseointegrated Implants in Oncological… DOI: http://dx.doi.org/10.5772/intechopen.93224*

#### *2.1.2 Nasopalatine implants*

*Oral and Maxillofacial Surgery*

with a high success rate [2].

pterygoid (**Figure 1**)**.**

**2.1 Zone I/maxillary alveolar buttress**

*2.1.1 Tilted and axially positioned implants*

**2. Buttress implant concept and classification**

setting the guidelines for contemporary implantology [6].

higher success rate and predictable results [7, 8].

mize the cantilever of prosthetic rehabilitation [9].

with local and microvascular flaps is sometimes a viable alternative, maxillofacial rehabilitation with osseointegrated implants has been a well-reported treatment

Various techniques and anatomical locations have been described in the facial region for the placement of osseointegrated implants and its reason is based on the bone buttress where a skeletal anchorage is possible to support the functional load of the implants. In general, maxillofacial rehabilitation with osseointegrated implants uses anchors in the zygomatic, pterygoid, nasomaxillary and alveolar zones [3–5].

Based on the anatomical zones of the bony buttresses of the facial middle third, we designed a classification system that allows determining the therapeutic options where the placement and functional loading of osseointegrated implants is feasible: zone I or alveolar, zone II or nasomaxillary, zone III or zygomatic, zone IV or

The use of endosseous osseointegrated implants was introduced to North America in 1982. At that conference, Branemark presented the data from 15 years of work, which was highly evidence-based with long-term clinical follow-up findings

Currently implantology has improved considerably; dental implants have incorporated advances in their anatomy, surface and types of connections, achieving a

Implants angled between 30 and 45° were described as an alternative surgical technique in order to avoid nearby anatomical structures or to achieve an adjacent bone position. Thus, we avoid advanced bone regeneration procedures and mini-

*Anatomical zones of the bony buttresses of the facial middle third and placement of osseointegrated implants* 

**164**

**Figure 1.**

*with their positions in the prosthetic arch.*

In 1994 Scher. describes the use of the nasopalatine canal as a receptor site for a dental implant, since then controlled studies have been carried out that confirm its viability for the functional load of osseointegrated implants [10].

Peñarrocha et al. treated 13 patients with 78 osseointegrated implants in the rehabilitation of the atrophic maxilla. Of 78 implants, 13 were implanted in the nasopalatine canal, 6 patients had reversible sensory alteration, and 2 implants failed in healthy patients, yielding a success rate of 84.6% [11].

Occasionally, when performing a partial maxillectomy, bone is available throughout the Maxillary alveolar buttress. In these cases, it is possible to use conventional dental implants anchored even in contralateral anatomical structures.

### **2.2 Zone II/nasomaxillary buttress**

#### *2.2.1 Nasomaxillary implants*

Although the term "Nasomaxillary implant" has not been defined in the Glossary of Oral and Maxillofacial Implants (GOMI) [12]. We define it as "Implant placement through the alveolar process and into the nasomaxillary buttress".

The nasomaxillary buttress has been well described in facial trauma as it is a key anatomic zone in the reconstruction of fractures of the middle third. This area offers a cortical bone suitable for the anchorage and functional load of osseointegrated implants. However, there are few implant-oriented anatomical studies and some are anthropometric studies [13–16].

Some authors have described the placement of posterior tilted implants between 30 and 45° that reach an apical anchorage in the nasomaxillary buttress [9, 17, 18]. However, this type of implant is not frankly a nasomaxillary implant because they are retained from an apical portion and are not strictly into the buttress as in the case of a long implant with an axial orientation.

Nasomaxillary implants can be used as an anchorage point in a location anterior to the prosthetic arch. With this, we achieve anterior stability and the reduction of work forces in posterior implants.

#### **2.3 Zone III/zygomaticomaxillary buttress**

#### *2.3.1 Zygomatic implants*

In 1998 Dr. P. I Branemark described zygomatic implants as a bone anchorage alternative with a design between 30 and 52.5 mm long that are inserted into the body of the malar bone [19]. Since then, Branemark and other authors have described various surgical techniques and approaches for zygomatic implant placement that could be used to rehabilitate atrophic jaws or in patients with partial or total maxillectomy [20–22].

Scott et al. rehabilitated 28 patients after undergoing rhinectomy for malignant pathological processes, a total of 56 zygomatic implants were used as retainers of maxillofacial prostheses, 1 failed after radiotherapy having a success rate of 98% in 15 years [4].

In general, most authors agree that zygomatic implants are more than 95% successful [23] and in radiated patients the success rate of implants is highly variable with a range between 72 and 98% [2].

Zygomatic implants offer adequate bone quality and quantity. Sometimes when the maxillectomy is extensive, it compromises the malar bone. Performing regenerative procedures with autografts or xenografts are a viable option to improve site conditions.

### **2.4 Zone IV/pterygomaxillary buttress**

#### *2.4.1 Pterygomaxillary implants*

Tulasne and Tessier in 1989 were the first to describe the technique for the placement of pterygoid implants [24]. This technique wanted to resolve the difficulties caused by the presence of the maxillary sinus and the poor characteristics of the bone in the maxillary tuberosity.

Pterygoid implants are implants between 15 and 20 mm long that allow a bone anchorage of up to 9 mm in the pterygoid process [25]. However, in the maxilectomized patient this length may vary because the posterior segment of the maxilla is not found.

Araujo et al. in 2019 performed a systematic review from January 1995 to January 2018. A total of 634 patients received 1893 pterygoid implants, with a 10-year survival rate of 94.85%.

Pterygoid implants are a viable option and if their main advantage is to decrease the prosthetic distal cantilever [26].

#### **3. Buttress implant concept: advantages and disadvantages**

Maxillofacial reconstruction with osseointegrated implants placed in bony buttresses is indicated in patients who have suffered loss of mid-facial anatomical structures due to benign and malignant pathological processes, trauma, and severe maxillary atrophy.

There are few contraindications to the use of osseointegrated implants and they are mostly relative. Their reason is that they decrease the success rate compared to implantation in healthy patients. The most important contraindications suggest bone healing disorders such as bisphosphonate treatment, radiotherapy, chemotherapy and active infection. However, for each situation there are protocols that help maintain a high success rate and some of them are discussed in this chapter [20, 23, 27].

The main advantages in this type of rehabilitation are the decrease in the number of reconstructive surgeries, avoiding the use of donor sites and a shorter hospital stay. By performing a single-phase reconstruction, the patient recovers the phonation, swallowing and chewing lost due to the oncological defect. in addition, the patients present a timely and less morbid treatment compared to local and microvascular grafts. To achieve these results, prosthetically guided reconstruction is key [28].

#### **4. Virtual prosthetic and surgical planning**

Three-dimensional (3D) planning in oral and maxillofacial surgery has become a standard in the treatment of multiple conditions of the facial region. Multiple Programs have been designed to perform 3D virtual planning and surgery in the reconstruction with osseointegrated implants (DTX Studio Implant®, SIMPLANT®, DDS-pro®, 3Shape Dental System®). Most of them are equipped with numerous software complements that allow the preparation of surgical guides and prosthetic reconstructions with different attachments through CAD/CAM [29].

Some of the multiple advantages offered by 3D virtual surgery are: simulating different approaches and types of procedures, avoiding damage to neurovascular and anatomical structures, reducing operating time and improving postoperative recovery, reducing complications and obtaining more predictable results.

**167**

**Figure 3.**

*planned positions.*

**Figure 2.**

*anatomical zone.*

*A Review of Maxillofacial Rehabilitation Using Osseointegrated Implants in Oncological…*

For preoperative evaluation and planning, a CT scan of the head and neck is the Gold standard [3, 23]. The planning of the placement of osseointegrated implants must be prosthetically guided. This means that planning must precede the surgical act of implant placement and these must be located where it best suits prosthetic rehabilitation and biomechanical demands. The objective should be a surgical and prosthetic planning with at least four osseointegrated implants with their distributed emergencies in a polygonal manner over the prosthetic arch. In this way, we were able to tripodize and stabilize the prosthetic reconstruction in the face of the

*DOI: http://dx.doi.org/10.5772/intechopen.93224*

functional demands of chewing (**Figure 2**) [28, 30].

**5. Simulated surgery in stereolithographic biomodels**

increasingly important in medicine and surgery [31].

Stereolithography is a solid three-dimensional prototype obtained through the processing of data obtained from computed tomography or magnetic resonance imaging. In recent years, stereolithographic manufacturing has made great strides in the quality, resolution, and precision of manufactured parts and is becoming

*Simulated surgery in stereolithographic biomodel. Zygomatic and Pterygomaxillary implants placed in the* 

*3-dimensional computed prosthetic and surgical planning and bone availability in the peri-implant* 

#### *A Review of Maxillofacial Rehabilitation Using Osseointegrated Implants in Oncological… DOI: http://dx.doi.org/10.5772/intechopen.93224*

For preoperative evaluation and planning, a CT scan of the head and neck is the Gold standard [3, 23]. The planning of the placement of osseointegrated implants must be prosthetically guided. This means that planning must precede the surgical act of implant placement and these must be located where it best suits prosthetic rehabilitation and biomechanical demands. The objective should be a surgical and prosthetic planning with at least four osseointegrated implants with their distributed emergencies in a polygonal manner over the prosthetic arch. In this way, we were able to tripodize and stabilize the prosthetic reconstruction in the face of the functional demands of chewing (**Figure 2**) [28, 30].

**Figure 2.**

*Oral and Maxillofacial Surgery*

*2.4.1 Pterygomaxillary implants*

bone in the maxillary tuberosity.

10-year survival rate of 94.85%.

the prosthetic distal cantilever [26].

**4. Virtual prosthetic and surgical planning**

not found.

maxillary atrophy.

**2.4 Zone IV/pterygomaxillary buttress**

Tulasne and Tessier in 1989 were the first to describe the technique for the placement of pterygoid implants [24]. This technique wanted to resolve the difficulties caused by the presence of the maxillary sinus and the poor characteristics of the

Pterygoid implants are implants between 15 and 20 mm long that allow a bone anchorage of up to 9 mm in the pterygoid process [25]. However, in the maxilectomized patient this length may vary because the posterior segment of the maxilla is

Pterygoid implants are a viable option and if their main advantage is to decrease

Araujo et al. in 2019 performed a systematic review from January 1995 to January 2018. A total of 634 patients received 1893 pterygoid implants, with a

Maxillofacial reconstruction with osseointegrated implants placed in bony buttresses is indicated in patients who have suffered loss of mid-facial anatomical structures due to benign and malignant pathological processes, trauma, and severe

There are few contraindications to the use of osseointegrated implants and they are mostly relative. Their reason is that they decrease the success rate compared to implantation in healthy patients. The most important contraindications suggest bone healing disorders such as bisphosphonate treatment, radiotherapy, chemotherapy and active infection. However, for each situation there are protocols that help maintain a high success rate and some of them are discussed in this chapter [20, 23, 27]. The main advantages in this type of rehabilitation are the decrease in the number of reconstructive surgeries, avoiding the use of donor sites and a shorter hospital stay. By performing a single-phase reconstruction, the patient recovers the phonation, swallowing and chewing lost due to the oncological defect. in addition, the patients present a timely and less morbid treatment compared to local and microvascular grafts. To achieve these results, prosthetically guided reconstruction is key [28].

Three-dimensional (3D) planning in oral and maxillofacial surgery has become a standard in the treatment of multiple conditions of the facial region. Multiple Programs have been designed to perform 3D virtual planning and surgery in the reconstruction with osseointegrated implants (DTX Studio Implant®, SIMPLANT®, DDS-pro®, 3Shape Dental System®). Most of them are equipped with numerous software complements that allow the preparation of surgical guides and prosthetic reconstructions with different attachments

Some of the multiple advantages offered by 3D virtual surgery are: simulating different approaches and types of procedures, avoiding damage to neurovascular and anatomical structures, reducing operating time and improving postoperative

recovery, reducing complications and obtaining more predictable results.

**3. Buttress implant concept: advantages and disadvantages**

**166**

through CAD/CAM [29].

*3-dimensional computed prosthetic and surgical planning and bone availability in the peri-implant anatomical zone.*
