**Abstract**

To assess the effect of LIPUS on marginal bone regeneration during insertion and following loading using CBCT scan imaging, a trial of RCT of 22 subjects needing dental implant was conducted. The participants were randomly allocated into 2 groups; both groups underwent similar two-stage implant surgery of one maxillary dental implant. The control group (n = 11) of the implant site was allowed to heal in a conventional way, while the intervention group (n = 11) was subjected to LIPUS therapy at the implant site (twice a week, 20-minute duration, from week 2 after stage I implant surgery and continued for 10 weeks). Similar ultrasound protocol was repeated 2 weeks after crown installation and again continued for another 10 weeks. The assessment of marginal bone loss around dental implants was carried out at three different views (coronal, sagittal, and axial) of the implant site immediately after surgery, 3 and 6 months later. Statistical analysis of ANOVA within and between two-group analysis that was applied followed by pairwise comparison with confidence interval adjustment showed that there is a significant difference among the groups (p < 0.05). The CBCT imaging (coronal view) values suggested that bucccal bone regeneration around the dental implant has significantly increased during the early osseointegration period in the LIPUS-treated subjects than in the control group. LIPUS enhances bone formation in particular buccal bone plate around the dental implant as confirmed by the coronal view.

**Keywords:** LIPUS, coronal, sagittal, axial, osseointegration

## **1. Introduction**

The introduction of osseointegration, in 1969, by Professor Per-Ingvar Brånemark, at the Institute of Applied Biotechnology, University of Goteborg, [1] opened new avenues in the dental implant treatment for the partially or fully edentulous patients [2]. Titanium endosseous implants are widely used successfully in association with this treatment modality. Various investigations proved this method to be superior for long-term prognosis for dental implant treatment [3, 4].

Osseointegration is a process of connecting structurally and functionally an ordered living bone with load-carrying implant [5]. When histologic features of the osseointegration were observed, functional ankylosis was found without any intrusion of connective or fibrous tissues between the implant surface and bone [6]. However, in some situations, osseointegration does not take place adequately and

at times leads to implant failure. Continuous investigations looking into implant's chemical and physical characteristics, structures, and the biological responses from the surrounding bone are being conducted to identify its cause.

Implant success depends upon successful osseointegration. Evaluation of the bone surrounding the implant is a common method for observing the implant prognosis [7–9]. Care of the bone that supports the implant is vital for the beneficial results of the implant treatment [10].

Various studies have shown that there were changes in the marginal bone level and loss of different amount of bone that occur mostly during the first year of dental implant placement [11–13]. Assessment of changes in marginal bone height is considered an important parameter in evaluating implant success [14, 15]. Excessive marginal bone loss after implant or following prosthesis may be seen in the first year. However, in the early phase of osseointegration, the process of bone healing is not well understood [16].

One of the etiological factors of marginal bone loss is the disruption of the periosteum and blood supply during flap elevation and placement of implant [17]. Some studies showed that less marginal bone loss was noticed when flapless technique is used as compared with full-thickness flap technique that showed more marginal bone loss during healing period [18–21].

Other studies showed that periosteum disruption not only affects marginal bone level but also has other effects on bone formation around the implant during the healing period that compromise the stability of the implant and delay healing [21, 22].

Previous studies [19, 23] reported that the decreased blood supply to the bone after periosteum elevation has the same effect of flapless technique on the level of marginal bone and bone formation rhythm.

Continuous bone resorption affects function and esthetic. There are several ways to restore and regenerate bone such as advocating bone grafting procedures, usage of growth factors, laser therapy in low levels, and therapeutic ultrasound.

Low-intensity pulsed ultrasound (LIPUS) stimulation is a classical therapeutic modality for bone regeneration. Its efficiency has been widely reported over the years. LIPUS stimulation can be used as a tool to enhance tooth and periodontal regeneration [24].

Della Rocca [25] in her study on the effect of LIPUS on bone regeneration on Wistar rats confirmed that LIPUS can consolidate fractures and reduce bone healing time. It is also shown that LIPUS enhances bone regeneration based on its angiogenic and osteogenic values both before and after dental implant placement [26, 27].

#### **1.1 Ultrasound**

#### *1.1.1 History and development of ultrasound*

Ultrasound has been discovered 50 years ago for therapeutic and diagnostic uses in the medical field. Ultrasound refers to the sound with frequency greater than that audible by the human ear. It is a mechanical compression-rarefaction wave that travels through the tissue, producing both thermal and nonthermal effects [28].

The thermal effects of ultrasound can increase the temperature of deep tissue with high collagen content to increase the extensibility of the tissue or to control pain. The nonthermal effects of ultrasound can alter cell membrane permeability, thus facilitating tissue healing and transdermal drug penetration. Therapeutic ultrasound may also facilitate calcium resorption. To achieve these treatment outcomes, appropriate frequency, intensity, duty cycle, and duration of ultrasound must be selected and applied.

**5**

*Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study*

In evaluating an ultrasound device for the clinical application, one should consider the appropriateness of the available heads and BNRs for the types of problems

Transthoracic ultrasound (US) examination can be used for (1) chest wall lesions; (2) pleural lesions such as pleural effusion, pleural thickening, or pleural tumors; (3) peridiaphragmatic lesions; (4) peripheral pulmonary lesions which abut the pleura; (5) pulmonary lesions with an accessible US window; and (6)

On US, pleural effusion is characterized by an echo-free or hypo echoic space between the visceral and parietal pleurae that can change shape with respiration. On US, peripheral lung tumors appear as well-defined, homogeneous, hypo echoic,

Diagnostic US is efficiently used for the visceral examinations, e.g., the liver, pancreas, kidneys, etc., at 3 MHz frequency. The neck, breast, and children are examined using a frequency of 5–7 MHz. The increase in the frequency in the ultrasound examination increases the visibility and discrimination of details of the image. Diagnosis of benign or malignant growth in the uterus, fallopian tubes, and ovary is routinely made in the obstetrics using ultrasound. It is also used for the

Harris [32] claimed that therapeutic ultrasound increases the blood supply and the deposition of new healthy callus replacing the necrotic bone. Therefore, therapeutic ultrasound can be used as conservative method of management of osteora-

Ultrasound and some other physical factors stimulate the bone healing process by increasing the intracellular calcium levels. Deposition of intracellular calcium enhances the formation of bone [33]. In vivo and in vitro studies have shown that ultrasound treatment increases the activity of alkaline phosphatase in spontaneous and experimental fractures in rats and rabbits as compared with untreated

Animal and clinical studies conducted in two phases by John et al. [37] reported that ultrasound-treated groups have increased formation of callus. Increased activity of the osteoblasts was observed cytologically in the ultrasound-treated group.

General guidelines of parameters for ultrasound therapy are given for different

• Duty cycle: The proportion of the total treatment time that the ultrasound is on. This can be expressed as a percentage or a ratio: 20 or 1:5 duty cycle, that is,

*DOI: http://dx.doi.org/10.5772/intechopen.87220*

expected to be treated with the device [28].

mediastinal tumors in contact with the chest wall [29–31].

or echogenic nodules with posterior acoustic enhancement.

*1.1.2 Diagnostic uses of ultrasound*

progressive assessment of pregnancy.

*1.1.3 Therapeutic uses of ultrasound*

*1.1.3.1 Osteoradionecrosis*

dionecrosis of the mandible.

animals [34–36].

*1.1.3.2 In vitro and in vivo bone regeneration*

*1.1.4 Ultrasound treatment setting parameters*

20% of the time on and 80% of the time off.

clinical applications as follow [28]:

*Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study DOI: http://dx.doi.org/10.5772/intechopen.87220*

In evaluating an ultrasound device for the clinical application, one should consider the appropriateness of the available heads and BNRs for the types of problems expected to be treated with the device [28].

### *1.1.2 Diagnostic uses of ultrasound*

*Clinical Implementation of Bone Regeneration and Maintenance*

results of the implant treatment [10].

marginal bone loss during healing period [18–21].

marginal bone and bone formation rhythm.

*1.1.1 History and development of ultrasound*

must be selected and applied.

not well understood [16].

regeneration [24].

**1.1 Ultrasound**

the surrounding bone are being conducted to identify its cause.

at times leads to implant failure. Continuous investigations looking into implant's chemical and physical characteristics, structures, and the biological responses from

Implant success depends upon successful osseointegration. Evaluation of the bone surrounding the implant is a common method for observing the implant prognosis [7–9]. Care of the bone that supports the implant is vital for the beneficial

Various studies have shown that there were changes in the marginal bone level and loss of different amount of bone that occur mostly during the first year of dental implant placement [11–13]. Assessment of changes in marginal bone height is considered an important parameter in evaluating implant success [14, 15]. Excessive marginal bone loss after implant or following prosthesis may be seen in the first year. However, in the early phase of osseointegration, the process of bone healing is

One of the etiological factors of marginal bone loss is the disruption of the periosteum and blood supply during flap elevation and placement of implant [17]. Some studies showed that less marginal bone loss was noticed when flapless technique is used as compared with full-thickness flap technique that showed more

Other studies showed that periosteum disruption not only affects marginal bone level but also has other effects on bone formation around the implant during the healing period that compromise the stability of the implant and delay healing [21, 22]. Previous studies [19, 23] reported that the decreased blood supply to the bone after periosteum elevation has the same effect of flapless technique on the level of

Continuous bone resorption affects function and esthetic. There are several ways to restore and regenerate bone such as advocating bone grafting procedures, usage of growth factors, laser therapy in low levels, and therapeutic ultrasound. Low-intensity pulsed ultrasound (LIPUS) stimulation is a classical therapeutic modality for bone regeneration. Its efficiency has been widely reported over the years. LIPUS stimulation can be used as a tool to enhance tooth and periodontal

Della Rocca [25] in her study on the effect of LIPUS on bone regeneration on Wistar rats confirmed that LIPUS can consolidate fractures and reduce bone healing time. It is also shown that LIPUS enhances bone regeneration based on its angiogenic and osteogenic values both before and after dental implant placement [26, 27].

Ultrasound has been discovered 50 years ago for therapeutic and diagnostic uses in the medical field. Ultrasound refers to the sound with frequency greater than that audible by the human ear. It is a mechanical compression-rarefaction wave that travels through the tissue, producing both thermal and nonthermal effects [28]. The thermal effects of ultrasound can increase the temperature of deep tissue with high collagen content to increase the extensibility of the tissue or to control pain. The nonthermal effects of ultrasound can alter cell membrane permeability, thus facilitating tissue healing and transdermal drug penetration. Therapeutic ultrasound may also facilitate calcium resorption. To achieve these treatment outcomes, appropriate frequency, intensity, duty cycle, and duration of ultrasound

**4**

Transthoracic ultrasound (US) examination can be used for (1) chest wall lesions; (2) pleural lesions such as pleural effusion, pleural thickening, or pleural tumors; (3) peridiaphragmatic lesions; (4) peripheral pulmonary lesions which abut the pleura; (5) pulmonary lesions with an accessible US window; and (6) mediastinal tumors in contact with the chest wall [29–31].

On US, pleural effusion is characterized by an echo-free or hypo echoic space between the visceral and parietal pleurae that can change shape with respiration. On US, peripheral lung tumors appear as well-defined, homogeneous, hypo echoic, or echogenic nodules with posterior acoustic enhancement.

Diagnostic US is efficiently used for the visceral examinations, e.g., the liver, pancreas, kidneys, etc., at 3 MHz frequency. The neck, breast, and children are examined using a frequency of 5–7 MHz. The increase in the frequency in the ultrasound examination increases the visibility and discrimination of details of the image.

Diagnosis of benign or malignant growth in the uterus, fallopian tubes, and ovary is routinely made in the obstetrics using ultrasound. It is also used for the progressive assessment of pregnancy.

#### *1.1.3 Therapeutic uses of ultrasound*

#### *1.1.3.1 Osteoradionecrosis*

Harris [32] claimed that therapeutic ultrasound increases the blood supply and the deposition of new healthy callus replacing the necrotic bone. Therefore, therapeutic ultrasound can be used as conservative method of management of osteoradionecrosis of the mandible.

#### *1.1.3.2 In vitro and in vivo bone regeneration*

Ultrasound and some other physical factors stimulate the bone healing process by increasing the intracellular calcium levels. Deposition of intracellular calcium enhances the formation of bone [33]. In vivo and in vitro studies have shown that ultrasound treatment increases the activity of alkaline phosphatase in spontaneous and experimental fractures in rats and rabbits as compared with untreated animals [34–36].

Animal and clinical studies conducted in two phases by John et al. [37] reported that ultrasound-treated groups have increased formation of callus. Increased activity of the osteoblasts was observed cytologically in the ultrasound-treated group.

#### *1.1.4 Ultrasound treatment setting parameters*

General guidelines of parameters for ultrasound therapy are given for different clinical applications as follow [28]:

• Duty cycle: The proportion of the total treatment time that the ultrasound is on. This can be expressed as a percentage or a ratio: 20 or 1:5 duty cycle, that is, 20% of the time on and 80% of the time off.


## *1.1.5 Mechanism of action of ultrasound therapy*

Although the exact mechanism of LIPUS interaction with the viable tissues and stimulation of bone healing is still unclear, there are several studies that showed that LIPUS stimulates regeneration of the bone and decreases the osseointegration time and promotion of the quality of osseointegration [38].

The mechanism behind the effect of LIPUS on bone regeneration might start from the mechanotransduction pathways of LIPUS on bone wound healing which is considered a complex process as numerous cell types respond to this stimulus involving several pathways. Mechanotransduction refers to the processes through which cells sense and respond to mechanical stimuli by converting them to biochemical signals that elicit specific cellular responses [39]. Typically the mechanical stimulus gets filtered in the conveying medium before reaching the site of mechanotransduction. Cellular responses to mechanotransduction are variable and give rise to a variety of changes and sensations. From definition of mechanotransduction, LIPUS promotes activation of osteoblast and other necessary cells' function which are considered decisive elements in bone healing by increasing proliferation, migration, and differentiation of these cells and changing it from inactive phase to active cells. The cellular responses underlying this mechanism are termed mechanotransduction [40].

Ingber [41] demonstrated in his work that the integrins are the most important key in the transduction of the ultrasound signals with evolutionary conserved mechanoreceptors, are expressed by various cell types, and convert mechanical signal into biochemical response. This form of sensory transduction is responsible for a

**7**

*Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study*

synthesis, which had been upregulated in response to ultrasound before.

tors of intracellular calcium signaling in osteoblasts for bone formation [40].

tion by a low-intensity ultrasound (1 MHz, 30 mW/cm<sup>2</sup>

RUNX2, and OSX—indicating accelerated differentiation.

Most recently, Kang et al. [52] studied the effects of 20 minutes a day stimula-

combination with cyclic vibratory strain (1 Hz, 10% strain) on MC3T3-E1 cells in a 3D scaffold. The stimulation did not change the cell proliferation over a period of 10 days, but significantly upregulated several gene expressions—COL-I, OC,

continuous sine wave) in

Ren et al. [50] has reported that p38 MAPK kinase is crucial for LIPUS to induce and enhance differentiation of human periodontal ligament cells (HPDLC) which are similar to mesenchymal stem cells and can undergo osteogenic differentiation. Treatment of cells with the p38 inhibitor significantly reduced ALP activity, osteocalcin concentration, and matrix mineralization in response to LIPUS, compared to the control group, where no inhibitor was added [44]. Whitney et al. [51] also explained in his study that the LIPUS in continuous mode caused more intense phosphorylation of FAK, Src, p130Cas, CrkII, and Erk1/Erk2 in primary human chondrocyte culture, suggesting that this pathway is involved in US-induced mechanotransduction mechanism. However, several studies in mechanotransduction suggested that voltage-sensitive calcium channels (VSCCs) have been reported to be the key regula-

number of senses and physiological processes in the body, including proprioception, touch, balance, and hearing. Mechanotransduction involves various signal transduction pathways, including the activation of ion channels and other mechanoreceptors in the membrane of the bone cell, resulting in gene regulation in the nucleus [42]. Identification and functional characterization of the mechanotransduction components may improve bone tissue engineering. In this process, a mechanically gated ion channel makes it possible for sound, pressure, or movement to cause a change in the excitability of specialized sensory cells and sensory neurons [43]. The stimulation of a mechanoreceptor causes mechanically sensitive ion channels to open and produce a transduction current that changes the membrane potential of the cell. Padilla et al. [44] and Sato et al. [45] updated the information in this area of interest that the mechanotransduction pathways involved in cell responses include integrin/mitogen-activated protein kinase (MAPK) and other kinase signaling pathways, gap-junctional intercellular communication, upregulation and clustering of integrins, involvement of the COX-2/PGE2 and iNOS/NO pathways, and activation of mechanoreceptor. Along with the direct effect of ultrasound, sensitizing mechanosensitive receptors, channels of the cell and the indirect effect of acoustic streaming-governed-shear stress on the cell surface (**Figure 1**). Acoustic streaming, giving rise to a unidirectional bulk fluid movement, can improve the circulation of molecules within the extracellular matrix in the culture wall, or trigger fluid flow in vivo, and thereby increase the delivery of cytokines secreted by other cell participants or other essential nutrients, and remove cellular waste products [46]. Tang et al. [47] stressed with his co-worker that the transmembrane mechanoreceptors increased surface expression in rat primary osteoblasts (in vitro study) of a2, a5, b1, and b3 integrins and clustering of b1 and b3 integrins have been shown to be upregulated within 24 hours after 20-minute treatment with LIPUS. In the same cell type, but using continuous ultrasound exposure, enhanced expression of a2, a5, and b1 integrins has also been reported and also showed upregulated expression [36]. After ultrasound exposure in mouse, osteoblasts isolated from long bones, gene expression was also significantly upregulated of a2, a5, and b1 integrins, whereas Watabe et al. [48] revealed in his vitro study that only expression of a5 was enhanced in mouse mandibular and calvaria-derived osteoblasts stimulated with LIPUS. Zhou et al. [49] explained in his amazing work that inhibiting b1 integrin by blocking antibody or RGD peptide in human primary skin fibroblasts led to restoring basal levels of DNA

*DOI: http://dx.doi.org/10.5772/intechopen.87220*

#### *Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study DOI: http://dx.doi.org/10.5772/intechopen.87220*

number of senses and physiological processes in the body, including proprioception, touch, balance, and hearing. Mechanotransduction involves various signal transduction pathways, including the activation of ion channels and other mechanoreceptors in the membrane of the bone cell, resulting in gene regulation in the nucleus [42]. Identification and functional characterization of the mechanotransduction components may improve bone tissue engineering. In this process, a mechanically gated ion channel makes it possible for sound, pressure, or movement to cause a change in the excitability of specialized sensory cells and sensory neurons [43]. The stimulation of a mechanoreceptor causes mechanically sensitive ion channels to open and produce a transduction current that changes the membrane potential of the cell.

Padilla et al. [44] and Sato et al. [45] updated the information in this area of interest that the mechanotransduction pathways involved in cell responses include integrin/mitogen-activated protein kinase (MAPK) and other kinase signaling pathways, gap-junctional intercellular communication, upregulation and clustering of integrins, involvement of the COX-2/PGE2 and iNOS/NO pathways, and activation of mechanoreceptor. Along with the direct effect of ultrasound, sensitizing mechanosensitive receptors, channels of the cell and the indirect effect of acoustic streaming-governed-shear stress on the cell surface (**Figure 1**). Acoustic streaming, giving rise to a unidirectional bulk fluid movement, can improve the circulation of molecules within the extracellular matrix in the culture wall, or trigger fluid flow in vivo, and thereby increase the delivery of cytokines secreted by other cell participants or other essential nutrients, and remove cellular waste products [46]. Tang et al. [47] stressed with his co-worker that the transmembrane mechanoreceptors increased surface expression in rat primary osteoblasts (in vitro study) of a2, a5, b1, and b3 integrins and clustering of b1 and b3 integrins have been shown to be upregulated within 24 hours after 20-minute treatment with LIPUS. In the same cell type, but using continuous ultrasound exposure, enhanced expression of a2, a5, and b1 integrins has also been reported and also showed upregulated expression [36]. After ultrasound exposure in mouse, osteoblasts isolated from long bones, gene expression was also significantly upregulated of a2, a5, and b1 integrins, whereas Watabe et al. [48] revealed in his vitro study that only expression of a5 was enhanced in mouse mandibular and calvaria-derived osteoblasts stimulated with LIPUS. Zhou et al. [49] explained in his amazing work that inhibiting b1 integrin by blocking antibody or RGD peptide in human primary skin fibroblasts led to restoring basal levels of DNA synthesis, which had been upregulated in response to ultrasound before.

Ren et al. [50] has reported that p38 MAPK kinase is crucial for LIPUS to induce and enhance differentiation of human periodontal ligament cells (HPDLC) which are similar to mesenchymal stem cells and can undergo osteogenic differentiation. Treatment of cells with the p38 inhibitor significantly reduced ALP activity, osteocalcin concentration, and matrix mineralization in response to LIPUS, compared to the control group, where no inhibitor was added [44]. Whitney et al. [51] also explained in his study that the LIPUS in continuous mode caused more intense phosphorylation of FAK, Src, p130Cas, CrkII, and Erk1/Erk2 in primary human chondrocyte culture, suggesting that this pathway is involved in US-induced mechanotransduction mechanism. However, several studies in mechanotransduction suggested that voltage-sensitive calcium channels (VSCCs) have been reported to be the key regulators of intracellular calcium signaling in osteoblasts for bone formation [40].

Most recently, Kang et al. [52] studied the effects of 20 minutes a day stimulation by a low-intensity ultrasound (1 MHz, 30 mW/cm<sup>2</sup> continuous sine wave) in combination with cyclic vibratory strain (1 Hz, 10% strain) on MC3T3-E1 cells in a 3D scaffold. The stimulation did not change the cell proliferation over a period of 10 days, but significantly upregulated several gene expressions—COL-I, OC, RUNX2, and OSX—indicating accelerated differentiation.

*Clinical Implementation of Bone Regeneration and Maintenance*

the treatment head.

in the tissues.

Organization.

• Effective radiating area (ERA): The area of the transducer that radiates ultrasound energy is known as ERA. ERA is smaller in comparison with the area of

• Frequency: Frequency is the measure of compression-refraction cycles per unit of time. It can be expressed in Hertz (Hz) or cycle per second. Frequency used for therapeutic purposes ranges from 1 to 3 MHz. Increment in the frequency decreases the concentration and depth of penetration of the ultrasound energy

• Intensity: Intensity demonstrates power per unit area of the sound head. It

• Power: It is the amount of aural energy per unit time. It is expressed in watts (W).

• Spatial average intensity: The average intensity of the ultrasound output over

• Spatial average temporal average (SATA) intensity: The spatial average intensity of the ultrasound averaged over the on time and the off time of the pulse.

• Spatial average temporal peak (SATP) intensity: The spatial average intensity of the ultrasound during the on time of the pulse. This is a measure of the

Although the exact mechanism of LIPUS interaction with the viable tissues and stimulation of bone healing is still unclear, there are several studies that showed that LIPUS stimulates regeneration of the bone and decreases the osseointegration

The mechanism behind the effect of LIPUS on bone regeneration might start from the mechanotransduction pathways of LIPUS on bone wound healing which is considered a complex process as numerous cell types respond to this stimulus involving several pathways. Mechanotransduction refers to the processes through which cells sense and respond to mechanical stimuli by converting them to biochemical signals that elicit specific cellular responses [39]. Typically the mechanical stimulus gets filtered in the conveying medium before reaching the site of mechanotransduction. Cellular responses to mechanotransduction are variable and give rise to a variety of changes and sensations. From definition of mechanotransduction, LIPUS promotes activation of osteoblast and other necessary cells' function which are considered decisive elements in bone healing by increasing proliferation, migration, and differentiation of these cells and changing it from inactive phase to active cells. The cellular responses underlying this mechanism are termed mechano-

Ingber [41] demonstrated in his work that the integrins are the most important

key in the transduction of the ultrasound signals with evolutionary conserved mechanoreceptors, are expressed by various cell types, and convert mechanical signal into biochemical response. This form of sensory transduction is responsible for a

• Pulsed ultrasound: During the treatment, periodic or sporadic supply of

). The recommended

by the World Health

is expressed in watts per centimeter squared (W/cm<sup>2</sup>

ultrasound is known as pulsed ultrasound.

amount of energy delivered to the tissue.

time and promotion of the quality of osseointegration [38].

*1.1.5 Mechanism of action of ultrasound therapy*

the area of the transducer.

limit of the intensity for therapeutic purposes is 3 W/cm2

**6**

transduction [40].

#### **Figure 1.**

*Summary of hypothetical LIPUS effects on bone cellular events in vitro data. The columns represent the four phases during in vivo endochondral bone fracture healing: phase 1, early events soon after the bone injury: hematoma formation, inflammation, and migration of osteogenic precursors; phase 2, angiogenesis, proliferation of mesenchymal stem cells (MSCs), and osteoblasts and osteogenic differentiation; phase 3, chondrogenesis and maturation of osteoblast; and phase 4, maturation of chondrocytes, woven bone formation, and remodeling [44].*

The accessibility of the crucial factors to the compromised cells supports their viability and maintains the indispensable microenvironment in the healing fracture through the regulation of pH and oxygenation, which may be enhanced by the ultrasound treatment. A mechanism of improved oxygen and nutrient transport in response to ultrasound has been suggested by Pitt and Ross [53].

These studies suggest that LIPUS are able to enhance osteogenesis and angiogenesis in vivo and in vitro as was well documented by literature review that angiogenesis precedes osteogenesis process [54]. Angiogenesis is closely associated with osteogenesis where reciprocal interactions between endothelial and osteoblast cells play an important role in bone regeneration [55].

Angiogenesis has a key role in bone repair by not only facilitating the supply of oxygen and nutrients required for bone repair and the removal of waste products but also by providing conduits for the invasion of osteoblast and osteoclast

**9**

*Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study*

progenitors into the healing site [56]. Vascular endothelial growth factor (VEGF) is a potent and vital angiogenic cytokine. It is a specific mitogen for vascular endothelial cells (ECs) [57]. Shiraishi et al. [58] demonstrated in his vitro study that the application of LIPUS led to the upregulation of interleukin-8, basic fibroblast growth factor, vascular endothelial growth factor, and non-collagenous bone proteins, and the downregulation of osteoclasts resulted in bone regeneration. El-Bialy et al.'s [59] study in vivo has demonstrated that therapeutic LIPUS can promote bone repair and regeneration, accelerate bone fracture healing, and enhance osteogenesis at the distraction site on rabbits ultimately offering long-term benefits

Low-intensity pulsed ultrasound technique is used for the evaluation of bone growth in the permeable implant surface [60]. Pulsed ultrasound produces a pressure wave which serves as a noninvasive mechanical stimulus and promotes the growth at the site of injury. Amplitude of the pulse is kept as low as 0.3 mm showing no ill effects on the process of recovery. However, mechanism of cellular response produced by ultrasound is not well defined [61, 62]. Low-intensity pulsed ultrasound, which is used for only few minutes in routine, has shown beneficial role

The intensity of ultrasound used for soft tissue application ranges from 500

therapy have been attributed to the controlled heating of the tissue. Because heating bone may also have significant deleterious effects, intensity used for bone applica-

1.Ultrasound is widely used for fracture detection in dentistry. Fractures of the nasal bone, orbital rim, maxilla, and mandible zygomatic arch are commonly detected by ultrasound. The position of the mandibular condyles is also located by ultrasound. To observe the healing fractures after surgery can be easily

2.Focal disease or parotid lesions can be observed easily using an ultrasound.

This study was a randomized controlled clinical trial (RCT) in which patients who visited the University Dental Hospital Sharjah (UDHS) for dental treatment and requested for oral rehabilitation of their missing teeth were selected for dental implant therapy. Those patients were examined in the oral surgery implant clinic and provided with new registration serial number. All the odd number patients were in the trial (ultrasound) group, and the even numbers were in the control group. The aims and objectives of this study were to evaluate the effect of ultrasound therapy on osseointegration using clinical assessments, measurements of RFA values, and radiological assessments using linear measurement of marginal bone loss around the dental implant-supported prostheses using CBCT. The selected age groups were between 20 and 40 years old. All patients were recruited following specific criteria

. Much of the clinical benefits from the ultrasound in physical

, which does not induce applicable

in the healing evidenced by experimental and clinical trials [62, 63].

tion is much lower, in the range 30 mW/cm<sup>2</sup>

heating of treated hard and soft tissues [64].

*1.1.6.1 Applications of ultrasound in dentistry*

performed by ultrasound [66].

**2. Materials and methods**

**2.1 Study design**

*DOI: http://dx.doi.org/10.5772/intechopen.87220*

to patients.

to 3000 mW/cm2

*1.1.6 Ultrasound in dentistry*

#### *Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study DOI: http://dx.doi.org/10.5772/intechopen.87220*

progenitors into the healing site [56]. Vascular endothelial growth factor (VEGF) is a potent and vital angiogenic cytokine. It is a specific mitogen for vascular endothelial cells (ECs) [57]. Shiraishi et al. [58] demonstrated in his vitro study that the application of LIPUS led to the upregulation of interleukin-8, basic fibroblast growth factor, vascular endothelial growth factor, and non-collagenous bone proteins, and the downregulation of osteoclasts resulted in bone regeneration. El-Bialy et al.'s [59] study in vivo has demonstrated that therapeutic LIPUS can promote bone repair and regeneration, accelerate bone fracture healing, and enhance osteogenesis at the distraction site on rabbits ultimately offering long-term benefits to patients.

### *1.1.6 Ultrasound in dentistry*

*Clinical Implementation of Bone Regeneration and Maintenance*

The accessibility of the crucial factors to the compromised cells supports their viability and maintains the indispensable microenvironment in the healing fracture through the regulation of pH and oxygenation, which may be enhanced by the ultrasound treatment. A mechanism of improved oxygen and nutrient transport in

*Summary of hypothetical LIPUS effects on bone cellular events in vitro data. The columns represent the four phases during in vivo endochondral bone fracture healing: phase 1, early events soon after the bone injury: hematoma formation, inflammation, and migration of osteogenic precursors; phase 2, angiogenesis, proliferation of mesenchymal stem cells (MSCs), and osteoblasts and osteogenic differentiation; phase 3, chondrogenesis and maturation of osteoblast; and phase 4, maturation of chondrocytes, woven bone formation, and remodeling [44].*

These studies suggest that LIPUS are able to enhance osteogenesis and angiogen-

esis in vivo and in vitro as was well documented by literature review that angiogenesis precedes osteogenesis process [54]. Angiogenesis is closely associated with osteogenesis where reciprocal interactions between endothelial and osteoblast cells

Angiogenesis has a key role in bone repair by not only facilitating the supply of oxygen and nutrients required for bone repair and the removal of waste products but also by providing conduits for the invasion of osteoblast and osteoclast

response to ultrasound has been suggested by Pitt and Ross [53].

play an important role in bone regeneration [55].

**8**

**Figure 1.**

Low-intensity pulsed ultrasound technique is used for the evaluation of bone growth in the permeable implant surface [60]. Pulsed ultrasound produces a pressure wave which serves as a noninvasive mechanical stimulus and promotes the growth at the site of injury. Amplitude of the pulse is kept as low as 0.3 mm showing no ill effects on the process of recovery. However, mechanism of cellular response produced by ultrasound is not well defined [61, 62]. Low-intensity pulsed ultrasound, which is used for only few minutes in routine, has shown beneficial role in the healing evidenced by experimental and clinical trials [62, 63].

The intensity of ultrasound used for soft tissue application ranges from 500 to 3000 mW/cm2 . Much of the clinical benefits from the ultrasound in physical therapy have been attributed to the controlled heating of the tissue. Because heating bone may also have significant deleterious effects, intensity used for bone application is much lower, in the range 30 mW/cm<sup>2</sup> , which does not induce applicable heating of treated hard and soft tissues [64].

#### *1.1.6.1 Applications of ultrasound in dentistry*


### **2. Materials and methods**

#### **2.1 Study design**

This study was a randomized controlled clinical trial (RCT) in which patients who visited the University Dental Hospital Sharjah (UDHS) for dental treatment and requested for oral rehabilitation of their missing teeth were selected for dental implant therapy. Those patients were examined in the oral surgery implant clinic and provided with new registration serial number. All the odd number patients were in the trial (ultrasound) group, and the even numbers were in the control group.

The aims and objectives of this study were to evaluate the effect of ultrasound therapy on osseointegration using clinical assessments, measurements of RFA values, and radiological assessments using linear measurement of marginal bone loss around the dental implant-supported prostheses using CBCT. The selected age groups were between 20 and 40 years old. All patients were recruited following specific criteria

### *Clinical Implementation of Bone Regeneration and Maintenance*

of inclusion and exclusion. Patients of this study were divided into two groups, namely, ultrasound and control; each patient received one dental implant to replace single missing maxillary first or second premolar teeth. In the first trial group (ultrasound), the ultrasound therapy was applied twice a week for 20 minutes that commenced 2 weeks after stage I implant surgery and continued for 10 weeks. At 2 months, uncovery and placement of gingival former for 10 days were carried on for all patients in both groups (ultrasound and control), then the impression taking was done for all patients, and installation of screw-retained porcelain to fused crown was performed 2 weeks later after the impression was taken. The same ultrasound therapy protocol was repeated 2 weeks after the crown installation for another 10 weeks. In the control group, patients were not subjected to application of ultrasound therapy. Clinical data collections composed of measurements of resonance frequency analysis (RFA) values using Osstell ISQ device and linear measurements of different variables using CBCT images taken immediately after the placement of the implant and during follow-up clinical examinations at 3 and 6 months postoperatively.

**11**

*Marginal Bone Changes around Dental Implants after LIPUS Application: CBCT Study*

Thorough medical and dental histories were taken from all patients presented in the study project. General clinical assessment of oral hygiene and gingival and periodontal health in terms of gingival color, contour, size, and consistency was documented. The height and width of the available bone around the potential site

An orthopantomogram (OPG) and intraoral periapical radiograph (IOPA) were taken preoperatively during patient selection and were kept in the patient's record; they gave an indication about the location and proximity of the vital structures and anatomical landmarks, bone quality, quantity and the presence of sufficient bone height and width in terms of mesiodistal dimension around the dental implant, absence of pathological lesions that may affect the outcome of dental implant success (periapical cysts, granulomas, osteomyelitis), and the angulation and position of the potential dental implant in relation to the

All patients underwent two stages of implant surgeries. Stage I implant surgery was performed in which one SPI dental implant (THOMMEN Medical SPI ELEMENT MC INICELL) bone level type with a length of 9.5 mm and a diameter of 4 mm was positioned in the maxillary edentulous premolar area in each patient of the 22 sample size. A stage II implant surgery was carried on after 2 months of implant placement in which the dental implant had to be uncovered and impression

1.The ultrasound group patients (n = 11) were then subjected to the application of low-intensity pulsed ultrasound 2 weeks following stage I implant surgery placement. The machine employed was Gymna Pulson® 330 Belgium

(**Figure 2**). The intensity of ultrasound therapy used was 30 mW/cm2

a frequency of 1.5 MHz and temporal average power of 20 mW (**Table 1**). The therapy was delivered intraorally on the buccal part of the implant site for duration of 20 minutes twice a week starting 2 weeks after dental implant placement for the subsequent 10 weeks (**Figure 3**). At 2 months, uncovery and placement of gingival former for 10 days were carried on, then the impression taking was done for all patients, and installation of screw-retained porcelain to fused crown was performed 2 weeks later after the impression was taken. The same ultrasound therapy protocol was repeated 2 weeks after the crown

2.Clinical data collections composed of resonance frequency analysis (RFA) value measurements using Osstell ISQ device (**Figure 4**) and linear measurements of CBCT images at three different views were taken immediately after the placement of the implant and in the follow-up clinical examinations at 3

with

*DOI: http://dx.doi.org/10.5772/intechopen.87220*

of the dental implant were assessed using a bone caliper.

*2.3.2 Preoperative radiological screening assessment*

**2.3 Clinical methods**

*2.3.1 Clinical assessment*

adjacent teeth.

*2.3.3 Operative techniques*

was taken for crown installation.

*2.3.3.1 Group I (ultrasound) group*

installation for another 10 weeks.

and 6 months postoperatively.
