Distraction Osteogenesis Of Mandible Research Articles

Distraction Osteogenesis as a reliable method in management of Obstructive Sleep Apnoea (OSA) secondary to TMJ Ankylosis: A Case Report.

Obstructive sleep apnoea (OSA) is identified as repetitive and intermittent upper airway collapse or narrowing during sleep. Skeletal advancement through maxillomandibular surgery remains the most effective surgical treatment for OSA but is radical with certain relapse rate. Distraction Osteogenesis of mandible is a single-jaw surgical treatment alternative to bi-jaw surgeries having lesser complications. This case report describes successful management of a 46-year-old patient who reported with a chief complain of obstruction in breathing while sleeping since one year. Obstructive Sleep Apnoea (OSA) secondary to a retrognathic mandible was the final diagnosis, which was successfully treated by Distraction Osteogenesis (DO) of the mandible. The case showed enhancement in airway by 13mm and marked forward movement of Point-B (SNB increased by 6 degrees). The Epworth Sleepiness Scale value decreased from 19mm to 8 mm indicating substantial increase in the airway with stable results after 18 months of follow-up (elimination of symptoms and subsequent sound sleep). Distraction osteogenesis is an effective and reliable method to treat obstructive sleep apnoea secondary to retrognathic mandible.

Bone Density of the Condyle of Children with Craniofacial Microsomia and its Correlation with Condylar Resorption After Mandible Distraction Osteogenesis.

To investigate condylar bone density (BD) in children with craniofacial microsomia (CFM) and identify factors that contribute to early stage condylar resorption (CR) after mandibular distraction osteogenesis (MDO). Retrospective study. Craniofacial department of a plastic surgery hospital. Fifty-one children with CFM classified as Pruzansky IIa based on complete pre-(T0) and post-MDO (T1) computed tomography (CT) data. Mimic 21.0 (Materialise Inc., Belgium) was used to measure bilateral BD and condylar height (CH) and volume (CV) of affected side. Children were split into groups based on either affected side BD or the distraction length (DL,25 mm as cutoff) .Bilateral BD was compared using a paired t-test in each group. The CH and CV of affected side at T0 and T1 were compared. The relative values of the CH and CV (CH ratio) and the volume (CV ratio) of the affected side were compared across the groups. The BD was lower on affected side than on unaffected side. Regarding BD, CH and CV decreased after MDO in group I, while the CH ratio and CV ratio of group I was lower than that of groups II and III. Regarding DL, the CV ratio was lower in Group L than Group S. The condylar bone quality on affected side is compromised in type IIa CFM. A low BD in combination with a larger distraction distance may increase the risk of CR; therefore, MDO in patients with such characteristics should be postponed.

Study on the Effect of Bilateral Mandible Distraction Osteogenesis About the Nutrition Status of Infants With Pierre-Robin Sequence.

Objective: By comparing and studying the changes of food intake, weight, body length, BMI, blood albumin level and other indicators of infants with Pierre-Robin Sequence (PRS) before and after Bilateral Mandible Distraction Osteogenesis operation, to explore the effect of distraction osteogenesis on PRS patients about the improvement of nutrition status.Methods: The children with PRS who admitted to the Oral and Maxillofacial Surgery Department of Guangzhou Women and Children's Medical Center from July 2015 to December 2020 were selected. All patients accepted bilateral mandible distraction osteogenesis surgery, and the pre- and post-operative indicators were recorded, such as food intake, weight, length, blood albumin level and others. BMI was calculated based on the indicators mentioned above, and comparative statistical analysis was performed.Results: 1. All patients were fed with whole milk before the first surgery, and the average calorie per kg was 91.8 kcal/kg, significantly lower than the standard (100–150 kcal/kg), suggesting the overall nutritional intake of PRS patients is low; 2. t tests for independent samples were used to analyze the pre-operative and post-operative indicators. The WFA percentile increased from 14.16 ± 2.17 to 15.01 ± 1.85% (P = 0.0048), WFA z score increased from −2.40 ± 0.18 to −1.90 ± 0.14 after the surgery (P = 0.0010), LFA percentile increased from 20.04 ± 3.48 to 33.67 ± 4.29% (P = 0.0098), LFA z score increased from −2.09 ± 0.19 to −1.42 ± 0.23 (P = 0.0009), BMI z score increased from −1.95 ± 0.22 to −1.39 ± 0.16 (P = 0.0408), ALB raised from 37.06 ± 0.51 to 42.85 ± 0.30 g/L (P < 0.001), which indicating that the physique of patients improved after the distraction osteogenesis surgery, mainly was reflected by the lifting of weight and length growth curves; the body shape also improved, indicating that the patients' nutrition status after the surgery is also improved.Conclusion: Bilateral mandible distraction osteogenesis surgery has a positive effect on the nutrition status of children with PRS. This effect is mainly reflected by the improvements of the body physical indicators after surgery.

Early Adverse Events Following Pediatric Mandibular Advancement: Analysis of the ACS NSQIP-Pediatric Database.

This study aims to assess early adverse events and patient factors associated with complications following mandible distraction osteogenesis (MDO). The American College of Surgeons National Surgical Quality Improvement Program-Pediatric (NSQIP-Pediatric) database, years 2012 to 2019, was queried for patients undergoing mandible advancement via relevant Current Procedural Terminology and postoperative diagnosis codes. Thirty-day adverse events and co-morbidities are assessed. A total of 208 patients were identified with 17.3% (n = 36) experiencing an adverse event, reoperation (n = 14), and readmission (n = 11) being most common. Patients < 365 days old at the time of operation were more likely to experience an adverse event (26.1% vs 10.8%; P = .005). However, among patients less than 1 year of age, differences in the complication rates between patients ≤ 28 days and >28 days (30.2% vs 22.2%; P = .47) and those weighing ≤ 4 kg and >4 kg (31.7% vs 11.5%; P = .063) did not reach statistical significance. Adverse events following mandible advancement are relatively common, though often minor. In our analysis of the NSQIP-Pediatric database, neonatal age ( ≤ 28 days) or weight ≤ 4 kg did not result in a statistically significant increase in complications among patients less than 1 year of age. Providers should consider early intervention in patients who may benefit from MDO.

Qualitative assesement of newly formed bone after distraction osteogenesis of mandible in patients with facial asymmetry using 3 dimensional computed tomography

IntroductionDistraction osteogenesis is a surgical technique of new bone formation between the osteotomized bone segments with the help of gradual incremental traction. As distraction osteogenesis is slow biologic process, soft tissue changes gradually follow the new bone formation. Mandibular distraction is one of the accepted modalities to treat the triad of TMJ ankylosis, obstructive sleep apnoea & micrognathia and also for facial asymmetry cases like hemifacial microsomia, mandibular hypoplasia etc. After the distraction osteogenesis, some relapse has been noticed in patients. Therefore, this study was conducted to assess the quality of the newly formed bone after distraction osteogenesis of mandible using 3 dimensional computed tomography (3DCT Scan) to evaluate its relation with relapse if any. Objectives1) To objectively analyse the quality of bone formed after mandibular distraction osteogenesis.2) To observe the site & architecture of newly formed bone after distraction is complete. Material and methodsTotal 5 patients of facial asymmetry reported to the Department of Oral and Maxillofacial Surgery were enrolled. Distraction osteogenesis of mandible was carried out in all the patients. Radiographic analysis (CT Scan) was done after 1 year of surgery for further planning and management of deformity. The non-distracted site was considered as a control side and it was compared with newly formed bone at distraction site. The standard & universally accepted radio density measuring Hounsfield Unit (HU) in 3DCT scan was calculated in axial,coronal, sagittal sections from distraction site and it was compared with non-distraction site, as Hounsfield unit is considered as a standard tool for measuring the bone density to evaluate the quality as well as quantity of newly formed bone. ResultsThe total mean Hounsfield Unit of distracted site of all three sections was 359.8 HU and non-distracted site was 545.2 HU. Statistical analysis was carried out using students paired ttest and p value was obtained which was <0.01 suggestive of statistically significant difference between the quality of bone in distracted site and non-distracted site. ConclusionThe findings of our study concluded that the quality of bone formed after distraction osteogenesis was satisfactory but it was less mineralized with less dense trabecular pattern compared to non-distracted bone region of mandible which leads to some relapse. Therefore it was advisable to reinforce the distracted bone segment by cutting the activation arm of distractor itself or mini plate or reconstruction plate to prevent relapse.

Thirty Years Later: What Has Craniofacial Distraction Osteogenesis Surgery Replaced?

After studying this article and viewing the video, the participant should be able to: 1. Compare the relative stability and neurosensory changes following mandible distraction osteogenesis with those after traditional advancement and fixation. 2. Describe the condylar changes that can occur after mandible distraction osteogenesis and list three ways to mitigate these changes. 3. Propose clinical situations where segmental or rotational movements of the midface may allow improved outcomes compared to en bloc linear distraction advancement. 4. Summarize the advantages and risks associated with anterior and posterior cranial distraction osteogenesis compared to traditional one-stage expansion. Over the past 30 years, distraction forces have been applied to the spectrum of craniofacial osteotomies. It is now time to assess critically the current understanding of distraction in craniofacial surgery, identifying both traditional procedures it has replaced and those it has not. This article provides a review of comparative studies and expert opinion on the current state of craniofacial distraction compared with traditional operations. Through this critical evaluation, the reader will be able to identify when distraction techniques are appropriate, when traditional techniques are more favorable, and what the future of distraction osteogenesis is.

S7B-05 SESSION 7B: HFM ROBIN - PART II VIVODOGMA PROJECT MAGNETIC ACTIVATION OF MANDIBULAR DISTRACTION OSTEOGENESIS: FIRST CADAVERIC STUDY

Introduction: Here we present the result of a cadaveric study incorporating 10 cadavers. On each, a partial or complete magnetically activated mandible distraction osteogenesis has been performed. Several designs of magnetic distractors have been tested with a resulting improvement between each design. Classical mandibular distraction is performed thanks to devices comprising activation rods protruding in the mouth, therefore, occasioning poor occlusion and discomfort. Our main goal is to free patients of this rod. For that, we used a system of two permanent magnets in interaction. Therefore we work on optimizing the design a functional magnetically activated device for distraction osteogenesis. Methods: A 10 cadavers study was performed. Our devices were implanted on horizontal branches and one on a vertical branch. The surgical procedure was performed on non-pathological adult corpses according to Necker Hospital standards. The devices implanted were the magnetic distractor prototypes. The distraction was tested with and without soft-tissues sutured. The external activator consisted of either a simple magnet or an automatic activating device. To evaluate the distraction’s activation success, we focused on measuring real advancement, the number of turns for activation and activation ratio. Results: Fully-closed distractions were successful with a low activating ratio while rotating the simple external magnet by hand. Both horizontal and vertical activations were successful without suture of soft-tissues, achieving an activation ratio of sixty-six percent (two millimeters for sixty turns) using the automatic activating device. The same results were obtained with soft tissues sutured back into position while making an opening for the internal magnet edge to be exposed on the jaw. Conclusion: As a first step, this cadaveric study demonstrates the relevancy of a rod-less magnetic activation of mandibular distraction osteogenesis. The next objective will be to refine our design of both the internal and external devices to increase the activation ratio and fully control it.

Cranial Anchored Mandible Distraction Osteogenesis

Multiple or large distance mandibular distraction osteogenesis (MDO) in the older child is often complicated by iatrogenic temporomandibular joint (TMJ) pathology. The transmission of significant force to the TMJ in these particular patients is due to the greater distance of distraction required and the relative inelasticity of the soft tissue envelope. The authors present a clinical report of a successful asymmetrically vectored large distance MDO in a 13-year-old female with bilateral craniofacial microsomia with Goldenhar syndrome. During distraction, the TMJ joints were effectively unloaded from the forces of distraction using external bilateral cranial anchored devices (Cranio-Mandibular Fixator; KLS Martin, Jacksonville, FL). Angle's occlusion, facial angle, and evidence of TMJ pathology were assessed.

Efficacy of distraction osteogenesis of mandible in adult patients with hemifacial deformity

Objective To evaluate recurrence after mandibular distraction osteogenesis in adult patients with hemifacial microsomia using the digital three dimensional measurement. Methods Nine adult hemifacial microsomia patients were evaluated using the method of digital measurements with three dimensional computed tomography. Three observation points were studied: pre-operation (T0), post-operation (T1) and follow-up (T2). The length of ramus (H for normal side and h for affected side), the length of body (L for normal side and l for affected side) and distance between pogonion and facial midline (D) were measured and the recurrence rate (R) was calculated. Results Percentages of h/H at T0, T1, T2 were (58.19±12.06)%, (87.09±17.92)%and (81.13±30.57)%, which had statistical significance respectively. 2. Percentage of l/L at T0, T1, T2 were (87.70±7.86)%, (90.69±5.77)% and (90.11±5.62)%, respectively, which had statistical significance between T0 and T1. 3. Lengths of D at T0, T1, T2 were (13.66±3.28) mm, (4.926±1.75) mm and (6.616±1.82) mm, respectively, which had statistical significance between T0, T1 and T0, T1. 4. Average R was (22.80±9.73)%. Conclusions Varying degrees of recurrence do happen in both ramus and body of mandibular after distraction osteogenesis. While it is demonstrated that the mandible grows obviously after operation compared to that pre-operation, Meanwhile, the facial symmetry is also improved significiantly. Key words: Adult; Hemifacial microsomia; Distraction osteogenesis; Three-dimensional measurement; Recrudescence

Comparison of the adult three-dimensional craniofacial features of patients with unilateral craniofacial microsomia with and without early mandible distraction

This study was conducted to analyze the long-term facial growth of patients with craniofacial microsomia (CFM) after early mandible distraction osteogenesis (DO), and compared adult three-dimensional (3D) craniofacial features of patients with and without early mandibular DO for Pruzansky grade II deformities. The study included 20 patients: 9 with early mandible DO (the DO group) and 11 without previous treatment (the NDO group). Longitudinal radiographs were measured for growth changes after DO. The 3D craniofacial images were constructed to compare the craniofacial forms between the two groups. The patients with early DO presented 8 to 9mm forward and downward maxillary growth and 4.6mm limited forward and 17.3mm substantial downward mandibular growth. The ramus length ratio (affected/nonaffected) was 90.8% at DO completion and decreased to 69.5% at growth completion during 13 years of follow-up. Both groups showed obvious craniofacial asymmetry, as indicated by occlusal plane canting, chin deviation, transverse and vertical condyle positions, and mandibular contours. Although all the bilateral differences were higher in the NDO group than in the DO group, no statistical differences were found. Early mandible distraction could not alter the inherent facial growth pattern in patients with grade II CFM. Limited changes are derived for definitive facial correction with early DO.

Mandibular distractions in jaws deformations - as a sufficient method or in combination with orthognatic surgery

Aim: improvement of mandibular distraction osteogenesis and rehabilitation algorithm of patients with combined jaws deformities caused by mandible hypoplasia. Matherial and methods: we report treatment results of 6 patients with the combined jaws deformities and mandible hypoplasia (developmental and congenital). All of the patients have undergone Steiner cephalometric analysis on the presurgical stage, after mandible distraction osteogenesis (DO) and after orthognathic surgery. The assessment of callus formation was done by ultrasound. All patients have undergone orthodontic treatment during retention period after distraction. The need of orthognathic surgery was defined at the end of retention period. Final evaluation was provided accordingly to functional and esthetic results. Results. Distration speed adjustments were the case in 5 patients to get normotrophic type of bone regeneration. Mean allongation was 175 mm. All of the patients had fully matured bony regenerate after mandibular distraction. That gave the opportunity to provide bimaxillary ortognathic surgery and genioplasty simultaneously with distractors removement in 3 patients. In 2 patients was performed only genioplasty with distractors removement. In 1 case with preoperative distraction computer planning there was no need of any additional surgical procedures. Acceptable functional and esthetic results were achieved after DO and orthodontic treatment. Conclusion. The combination of surgical methods (DO and ortognathic surgery) and early orthodontic treatment allow complete recovery. Use of sophisticated algorithm of DO, including computer planning, conservative surgical methods and curvilinear distractors as well as the ultrasonic assessment of distraction, allow to get fully matured bone regenerate and predictable treatment results in all cases. Sometimes the DO alone permits to avoid additional surgical procedures.

Effects of Piezoelectric Surgery on Bone Regeneration Following Distraction Osteogenesis of Mandible.

The aim of this study is to compare the bone healing in the distraction gap following the osteotomy performed with piezoelectric and conventional devices for the distraction osteogenesis in the rabbit mandibles. Twelve rabbits were randomly divided into 2 groups; 6 for piezoelectric device and 6 for rotary instruments. After 3 days of latency period, distraction was started at a rate of 1 mm per day for 10 days. All the animals were sacrificed after 4 weeks of consolidation phase for histological and histomorphological evaluation. Histological evaluation revealed thick trabecular bone formation in all of the specimens. Inflammation scores were chronic minimal. The mean percentages of the bone area in distraction gap are 62% in group P and 57% in group R. However, the difference between 2 groups was not statistically significant (P > 0.05). Our results revealed a slight increase in bone formation in the distraction gap in piezo-osteotomy groups histologically though not statistically supported. However, there is still a need for more histological studies with larger sample sizes evaluating the bone structure following piezo-osteotomies.

Piezoelectric Osteotomy for Distraction Osteogenesis of the Pediatric Mandible

Distraction osteogenesis of the mandible requires a complete osteotomy so that the proximal and distal segments may be separated, thereby producing length. One of the main complications of this technique is lingual nerve injury due to trauma induced by either the saw or the osteotome. The purpose of this article was to suggest the use of piezosurgery in performing near-complete osteotomy of either the body or ramus of the mandible. Surgical procedure was performed under general anesthesia, and it lasted approximately 90 minutes. After the buccal cortex of the mandible was dissected, a piezosurgical device was used for the planned osteotomy. The gap created by the device allowed visualization of the nerve, thereby permitting completion osteotomy of the lingual cortex. The patient did not show any neurological postoperative complication. The use of piezoelectric surgery appears to be a safer option in performing distraction osteogenesis of the pediatric mandible. The presumed disadvantage of this technique, notably an increased operating time due to the lower power cut of the piezoelectric device, was not encountered.

Beneficial Role of Periosteum in Distraction Osteogenesis of Mandible: Its Preservation Prevents the External Bone Resorption

Distraction osteogenesis (DO) is a surgical process of new bone generation through the gradual extension of two segments of existing bone. DO is applied for maxillofacial surgeries to manage defects in mandibular continuity. Vertical DO with an oral device is often employed to augment the alveolar bone height for better implant anchorage for esthetic purposes or functional prosthetic requirements. To determine how the periosteum affects the vertical DO in mandibular reconstruction, we extracted the teeth and resected the alveolar parts of the mandible on both sides of dogs, along with removal of the surrounding periosteum in the right, but not left side. Three months later, box-shaped bone segments (vectors) were prepared from the resected alveolar part, and the segments were vertically elongated using a distraction device on both sides at 0.9 mm/day for one week. The extent of bone formation after distraction was determined with micro-focused computed tomography and by measuring incorporation of tetracycline and calcein with confocal laser scanning microscopy. During the initial two months after distraction, new bone formation was observed more prominently in the left side than in the right side of mandible with the periosteum. However, this difference was less clear during the bone-remodeling period. One notable change was the reduced height of the alveolar part of the right-side mandible, a sign of external bone resorption, observed in two out of three dogs at 6-month post-consolidation. These findings suggest that preservation of periosteum prevents the external bone resorption during the vertical DO of mandible.

Effects of Nerve Growth Factor Delivery Via a Gel to Inferior Alveolar Nerve in Mandibular Distraction Osteogenesis

Inferior alveolar nerve (IAN) injury is a concern in mandible distraction osteogenesis (DO). We have previously demonstrated that repeated local injections of human nerve growth factor beta (NGF-beta) have significantly enhanced the histologic recovery of the IAN in a rabbit model of DO. This study was to further test the effect of a single injection of human NGF-beta delivered via a collagen/nanohydroxyapatite/kappa-carrageenan gel to the recovery of the IAN in DO. Rabbits underwent mandibular DO at a rate of 0.75 mm/12 h for 6 days. At the end of the distraction period, injections were performed near the IAN percutaneously as follows: group 1, human NGF-beta in the gel; group 2, human NGF-beta in saline; group 3, the gel alone; and group 4, saline alone. At 14 days after the end of distraction, IAN histologic findings and histomorphometric parameters were evaluated. Histologically, there were less myelin debris and more abundant regenerating nerve fibers in group 1 than the other groups. Both the myelinated fiber density and the myelinated axon area in group 1 were significantly higher than groups 3 and 4 (P < 0.01); the myelinated axon area in the group 1 was significantly higher than group 2 (P < 0.01). In conclusion, the delivery of human NGF-beta in the gel leads to a better acceleration of the IAN injury recovery over the saline delivery. It provides a possible way to enhance the recovery of nerve injuries in craniofacial DO clinically.

Effect of Low-Intensity Pulsed Ultrasound on Bone Formation During Mandible Distraction Osteogenesis in a Canine Model—A Preliminary Study

To make a preliminary study of the effect of low-intensity pulsed ultrasound on new bone formation during mandible distraction osteogenesis in dogs. Bilateral surgical cuts were made in mandibles of 7 dogs between the first and second premolar regions. Anterior mandibles were lengthened by 20 mm at the rate of 1 mm/day twice a day. During the distraction period 1 lateral distraction gap was irradiated by low-intensity pulsed ultrasound for 10 minutes twice a day and the other side was sham irradiated as control. After distraction was completed, the dogs were sacrificed at 0, 1, 2, 4, 6, 8, and 12 weeks. Before sacrifice, dynamic bone imaging with technetium (99)m-methylene diphosphonate ((99)mTc-MDP) single-photon emission computed tomography was performed. Mandible samples were harvested. Then plain x-ray, dual-energy x-ray bone mineral density measurement, 3-dimensional computed tomography, and regular histologic examination were performed. The (99)mTc-MDP bone imaging showed that uptake of (99)mTc-MDP in the experimental side was higher than in the control side at the early period of the consolidation time, but the outcome was later reversed. Plain x-ray showed that new bone of the experimental side was mature sooner than that of the control side. Bone mineral density in the experimental side was higher than that of the control side. Volume of new bone of the 2 sides had no significant difference. Histologic examination showed that trabeculae of the experimental side were more numerous and thicker than those of the control side at the early period of the consolidation time. Endochondral bone formation was observed in the experimental side. Low-intensity pulsed ultrasound could accelerate bone formation during mandibular distraction osteogenesis and increase bone mineral density but had no effect on the volume of new bone.

DETERMINATION OF TIME-DEPENDENT FORCES IN HUMAN MANDIBLE DISTRACTION OSTEOGENESIS

Distraction Osteogenesis (DO) is often used for the treatment of traumas with important bone defects as ballistic wounds. External bone transport devices are thus preferred, mainly in reason of the forces encountered [Labbe, 2005]. Bone callus participates in these resisting forces and its mechanical response strongly depends on time [Richards, 1999]. Mandibular DO forces have already been studied but without considerations about immediate timedependency [Robinson, 2001]. In this context, the aim of this study was to determine the time-dependent forces supported by a distraction device (DEOS, OBL, France), see figure 1. From these measurements, the time-dependent force-displacement behaviour of bone regenerate during the early phases of human mandible DO has been evaluated.

Therapeutic Ultrasound Applications in Craniofacial Growth, Healing and Tissue Engineering

Previous reports have shown that therapeutic ultrasound enhances healing of fractured bone as well as cut tendons. Moreover, it has been shown that therapeutic ultrasound enhances bone formation during distraction osteogenesis that is also known as Ilizarove technique. It has been recently reported that therapeutic ultrasound enhances tooth formation and eruption during mandible distraction osteogenesis in rabbits. This enhanced tooth formation and eruption was caused by new dental tissue formation, known as dentin and cementum. This led to a clinical trial in human that showed that therapeutic ultrasound can enhance repairing tooth root resorption caused by orthodontic treatment. This discovery can lead to many applications of ultrasound in the dental as well as in the craniofacial reconstructions. This paper provides an overview of the molecular basis of the achieved clinical results. Moreover, potential future application will be elaborated.

Effect of Recombinant Human Bone Morphogenetic Protein 7 on Bone Density during Distraction Osteogenesis of the Rabbit Mandible

To examine whether the quality of bone generation in distraction osteogenesis of the rabbit mandible is enhanced by administering recombinant human bone morphogenetic protein 7 (rhBMP-7) to the lengthened site at the end of the distraction phase. Prospective randomized study of 24 rabbits undergoing distraction osteogenesis of the mandible, followed by injection of rhBMP-7 or a lactate buffer. McGill University animal care facility. Twenty-four white New Zealand rabbits underwent unilateral mandibular osteotomy and application of an Orthofix uniplanar M-100 fixator (Orthofix Inc., Verona, Italy) to the mandible. Mandibular distraction was carried out for 3 weeks. The animals were divided into three groups: group 1 (eight rabbits), control group: distraction, no injection; group 2 (eight rabbits), study group: distaction + injection of 200 microg of rhBMP7-lactate buffer; group 2 (eight rabbits), comparison group: distraction + injection of lactate buffer. All rabbits were sacrificed 7 weeks after surgery. The mandibles underwent radiology and bone densitometry analysis. Radiology assessment of bone generation within distracted segments and objective analysis of bone mineral density. Radiology confirmed the presence of bone generate within distraction sites. Densitometry showed a difference in bone mineral density among the three groups (p < .05). Local injection of a single dose of 200 microg of rhBMP-7 did enhance bone density when compared with the control group, although not in a statistically significant way when analyzed by an x-ray bone densitometer. This study serves as a starting point for future studies in bone tissue engineering by guiding the strategic administration of rhBMPs and the use of new state-of-the-art technologies, such as micro CT scanning, to analyze in a more detailed way, the effects of rhBMP administration.

Volumetric change of the medial pterygoid following distraction osteogenesis of the mandible: an example of the associated soft-tissue changes.

Mandibular distraction osteogenesis lengthens not only the affected skeleton but also the associated muscles of mastication. The purpose of this study was to determine medial pterygoid volume before and after distraction by using computed tomography. Using computed tomographic scans, the volume of the medial pterygoid muscle was determined before and after mandibular distraction in six pediatric patients. In four unilateral distraction patients (average age, 65 months), the average increase of the medial pterygoid muscle on the distracted side of the mandible was 29 percent, and on the contralateral nondistracted side, 10 percent. The average increase in medial pterygoid muscle volume in two bilateral distraction patients (each aged 8 months) was 75 percent. Results of this study demonstrate that distraction osteogenesis of the human mandible not only lengthens deficient bone, but it also increases the volume of the attached musculature.