Mandibular Lengthening Research Articles

Distraction Osteogenesis with complimentary Herbst Appliance and Activator therapy to produce significant mandibular lengthening in bilateral Tessier 7 clefts

Distraction Osteogenesis with complimentary Herbst Appliance and Activator therapy to produce significant mandibular lengthening in bilateral Tessier 7 clefts

Mandibular Lengthening by Distraction Osteogenesis in Retrognathic Temporomandibular Joint Ankylosis Patients Suffering From Obstructive Sleep Apnea

Mandibular Lengthening by Distraction Osteogenesis in Retrognathic Temporomandibular Joint Ankylosis Patients Suffering From Obstructive Sleep Apnea

Alveolar Reconstruction by Distraction Osteogenesis Under Unfavorable Conditions

We present a patient who underwent alveolar reconstruction using vertical mandibular lengthening by distraction osteogenesis under unfavorable conditions. Part of the alveolar bone in the center of the mandible was resected, together with a squamous cell carcinoma located on the oral floor. We used vertical mandibular lengthening from the region of the remaining mandible inferior to the bony defect to reconstruct the alveolus, combined with a free musculocutaneous flap as a cover. However, the transferred flap underwent complete necrosis and was replaced with another flap on the seventh postoperative day. Radiotherapy at a total dose of 50 Gy was administered from day 75 to day 109 after completion of the distraction, because of suspected residual tumor. Despite the severe conditions, most of the distraction gap became filled with new bone. This case indicates that distraction osteogenesis can be used even in irradiated or poorly vascularized areas, as in our patient.

Effect of Platelet-Rich Plasma on a Rabbit Model of Nicotine-Compromised Bone Healing

This study aimed to evaluate the effects of platelet-rich plasma (PRP) on nicotine-compromised bone healing. Fifteen adult New Zealand white rabbits were implanted with 1.5-g time-release nicotine pellets. Bilateral mandibular distraction osteogenesis was then performed. Autologous PRP was injected into 1 side of the distraction regenerate, whereas physiologic saline solution was injected into the contralateral side as a control. Five rabbits were killed on day 5 of active distraction, on day 11 of active distraction, and in week 2 of consolidation, respectively. In the PRP the platelet enrichment was 14.63 ± 3.081-fold of that in whole blood. Plain radiography and micro-computed tomography assessment showed no significant difference between the PRP injection and control sides. Histologic examination showed more disorganized distraction tissue on the PRP injection side. PRP injection at an early stage of active distraction does not significantly enhance bone healing in the nicotine-compromised rabbit model of mandibular lengthening.

Mandibular Body Lengthening by Distraction Osteogenesis for Correction of Skeletal Class II Problems With an Impacted Premolar

Mandibular Body Lengthening by Distraction Osteogenesis for Correction of Skeletal Class II Problems With an Impacted Premolar

Transcription factor osterix modified bone marrow mesenchymal stem cells enhance callus formation during distraction osteogenesis

This study was designed to investigate the effects of local delivery of bone marrow mesenchymal stem cells (BMMSCs) with or without osterix (OSX) gene transfected on bone regeneration in the distracted zone using a rabbit model of mandibular lengthening. Fifty-four New Zealand white rabbits underwent osteodistraction of the left mandible and were then randomly divided into group A, group B, and group C (n = 18 for each group). At the end of distraction BMMSCs transfected with OSX, autologous BMMSCs and physiological saline were injected into the distraction gaps in groups A, B, and C, respectively. Nine animals from each group were humanely killed at 2 and 6 weeks after completion of distraction. The distracted mandibles were harvested and processed for radiographic, histological, and immunohistochemical examination. Excellent bone formation in the distracted callus was observed in group A and group B; the former showed better bone formation and highest bone mineral density (BMD), thickness of new trabeculae (TNT, mm) and volumes of the newly formed bone area (NBV) in the distraction zones. Group C animals showed poor bone formation in the distracted callus when compared with groups A and B. Positive immunostaining of bone sialoprotein (BSP) was observed in the distracted callus in all groups; however, BSP expression was much stronger in group A than in groups B and C. The results of this study suggest transplantation of BMMSCs can promote bone formation in DO; OSX-mediated ex vivo gene therapy was more effective during bone deposition and callus formation in distraction osteogenesis.

Serial Histologic and Immunohistochemical Changes in Anterior Digastric Myocytes in Response to Distraction Osteogenesis

Statement of the Problem: Expansion or lengthening of the craniomaxillofacial skeleton, by standard osteotomies and bone grafts, may result in skeletal relapse due to soft tissue resistance. To potentially avoid these problems, gradual bone and soft tissue expansion by distraction osteogenesis (DO) has become a frequently used technique. We hypothesize that the muscle response to mandibular lengthening will be proliferation rather than degeneration and fibrosis. The purpose of this study was to document anterior digastric muscle changes as a result of mandibular DO.

Experimental evaluation of acute molding of the regenerate in mandibular distraction osteogenesis in a rabbit model

The aim of this study was to investigate the possible effect of acute regenerate molding (ARM) on bone healing in mandibular distraction osteogenesis (DO). Nine white New Zealand rabbits underwent unilateral mandibular lengthening via DO. Three groups were created: The first underwent 15° ARM, the second group underwent 30° ARM after the distraction period, and the third group served as control without molding. After 1 month of consolidation, all of the animals were killed and histomorphometric evaluation was performed. New bone formation was uneventful in all of the groups. In the ARM groups, the amounts of osteoblasts and newly formed bone areas were higher in compressed areas than in stretched ones (P < .05). The regenerates in the control group and stretched regenerate areas of the ARM groups were similar regarding new bone formation (P > .05). Acute regenerate molding could be safely applied immediately after the distraction period to correct postdistraction deformities without compromising bone healing.

BFGF-Modified BMMSCs enhance bone regeneration following distraction osteogenesis in rabbits

Distraction osteogenesis (DO), which induces new bone formation along the vector of pull without requiring the use of bone graft, has become a valuable surgical method for patients with limb discrepancy or craniofacial microsomia. However, the long treatment period and possible fibrous union or nonunion hampers its further clinical application. Bone marrow mesenchymal stem cells (BMMSCs) have been widely used as a source of cell therapy or a vector for gene transfer. Basic fibroblast growth factor (bFGF) has high potential for promotion of bone regeneration. However, bFGF has a short half value period in vivo. In this study, osteodistraction was applied in craniofacial bone of rabbit to observe the effects of BMMSCs with or without bFGF gene transfected on bone regeneration in the distracted zone. Mandibular lengthening (10 mm) was performed in 42 New Zealand white rabbits using a rapid distraction rate (2 mm/day). The animals were then randomly divided into group A, group B and group C ( n = 14 for each group). At the end of distraction, physiological saline, autologous BMMSCs and BMMSCs transfected with bFGF were injected into the distraction gaps in groups A, B, and C, respectively. Eight weeks after DO, the rabbits were sacrificed, and the distracted mandibles were harvested and processed for radiography, dual energy x-ray absorptiometry (DXA), micro-CT, histology and three-point bend testing. Under a rapid distraction, immature or poor bone healing was observed in the distracted callus from group A. However, better bone formation and higher bone mineral density (BMD) and bone mineral content (BMC) in the distracted callus were observed in group B and group C, the latter showed excellent bone formation and highest BMD and BMC. Such finding was confirmed by histological and micro-CT examinations. The values of BT/TV in group C were highest and the micro-architecture presented more mature characteristics. The mechanical strength in group C was 1.63-fold and 1.28-fold greater than that in group A and B by three-point bending testing. The results of this study suggest that BMMSCs transplantation can promote bone formation in DO, and bFGF-modified BMMSCs were more effective in this enhancement.

Staged Reconstruction for Adult Complete Treacher Collins Syndrome

Treacher Collins syndrome is a congenital craniofacial malformation affecting the structures derived from the first and second brachial arches. For the complete form, the deformities can be severe; both the orbital-zygomatic region and mandible as well as the soft tissues should be reconstructed. To explore the surgical management of this kind of deformities, we proposed our protocol for the staged reconstruction: (1) upper-facial reconstruction with specially designed outer calvarial table, (2) mandibular lengthening by distraction osteogenesis technique and orthognathic surgery to correct the birdlike facial appearance and anterior open bite after distraction, and (3) lipofilling for the correction of residual depressive deformities. Two adult patients have undergone this protocol, and the results were satisfactory. Even though many authors advised using pedicled bone flap for the reconstruction of the orbit and zygomatic complex in young patient because free bone graft has the tendency of bone resorption and multiple onlay bone graft may need to be added in later stage, for adult patient, however, the reconstructed bone framework using outer cranial table can well maintain the bony facial contour of the orbital zygomatic region. The residual depressive deformities in the temporal and cheek regions can be treated with lipofilling. Compared with the technique of mandibular advancement osteotomy, bilateral mandibular lengthening by gradual distraction is relatively safe and can effectively elongate the mandible and the surrounding soft tissues. After the distraction, the open bite can be closed with subapical osteotomy, and the chin projection can be further added by advancement genioplasty.

Comparison of gene expression of osteogenic factors between continuous and intermittent distraction osteogenesis in rabbit mandibular lengthening

This study aimed to evaluate the effect of distraction frequency on the gene expression of osteogenic mediators in mandibular distraction osteogenesis. Forty adult New Zealand white rabbits were randomly assigned to the continuous and intermittent distraction groups. Unilateral mandibular osteotomy was performed and custom-designed manual-driven or autodriven distractor was bridged over the osteotomy segments. Animals were humanely killed at day 6, day 10, day 14, and day 21 after osteotomy. mRNA expression of the osteogenic mediators in the distraction regenerate was examined by real-time polymerase chain reaction. The expression of transforming growth factor-beta(1) was significantly higher at day 6, and the expression of the bone morphogenetic protein-2 was significantly higher from day 6 to day 14, in the continuous distraction group. High-frequency traction up-regulates the expression of osteogenic mediators contributing to the enhanced bone formation.

Endoscopically assisted sagittal split osteotomy for mandibular lengthening: Technical note and initial experience

To demonstrate the feasibility of carrying out a sagittal split osteotomy with rigid osteosynthesis via a small oral incision, working in two distinct tunnels and one corridor, using a standard 30 degrees 4-mm Ø endoscope. The procedure can be classified as minimally invasive, allowing for ambulatory treatment and return to daily activities within a week. Thirty-one bilateral procedures were performed on selected patients, all of whom needed mandibular lengthening to obtain a functional occlusion and enhanced facial profile. Transoral osteosynthesis was performed in all but one patient, in whom a transbuccal approach was required to fix the beginning of a "bad" split. Three screws were placed in each of 50 mandibular sides; two screws were placed in each of 10 sides (six screws along the upper border, and four above and below the mandibular canal). Two sides required additional plate osteosynthesis. In four patients, there was fixation instability, either bilaterally with opening of the bite, or unilaterally with protrusion of the mandible; these instabilities were managed conservatively with intermaxillary elastics. In the cases of mandibular lengthening only, oedema was minimal after one week, allowing patients to return to normal daily activities. Endoscopically assisted mandibular lengthening with bilateral sagittal split osteotomies and transoral osteosynthesis reduces periosteal degloving and consequent oedema. The minimal surface available for screw osteosynthesis contributes to the difficulty of the procedure.

Effect of oil-based calcium hydroxide (Osteoinductal) on distraction osteogenesis in rabbit mandible

The objective of this study was to evaluate the effects of oil-based calcium hydroxide on mandibular lengthening during distraction osteogenesis. Twenty-four New Zealand white rabbits underwent unilateral mandibular osteotomy. The rabbits were divided into 4 groups containing 6 each: groups 1 and 3 were control groups and groups 2 and 4 were test groups. Oil-based calcium hydroxide suspension was applied to test groups' corticotomy gap after osteotomy during operation. No treatment was applied to the control groups. After 5 days' latency period, distraction was commenced at a rate of 0.8 mm/day for 10 days via custom-made distractor. Groups 1 and 2 were killed 14 days after distraction and groups 3 and 4 were killed 28 days after distraction. Quantitative computerized tomography evaluation did not demonstrate a difference mean the density and the area of the regeneration between groups 1 and 3, but there was a significant difference groups 2 and 4. Histomorphometric evaluation demonstrated that there was a significant difference between test and control groups in new bone volume formation during distraction osteogenesis. Application of oil-based calcium hydroxide paste during the osteotomy phase of distraction osteogenesis increased regeneration and new bone volume formation.

A case of first and second brachial arch syndrome treated using Le Fort I osteotomy and unilateral vertical distraction osteogenesis of the ramus of the mandible

Treatment for hemifacial microsomia caused by first and second brachial arch syndrome must be appropriately selected based on the site and degree of the defect. Distraction osteogenesis of the mandible is a useful method for improving malocclusion and facial asymmetry caused by mandibular hypoplasia, and produces more reliable results than conventional osteotomy. In the present study, we preoperatively planned surgery by conducting a detailed simulation using a computer and a three-dimensional model, then performed mandibular lengthening and occlusal reconstruction by using mandibular lengthening using a mandibular distractor (a device for intraoral distraction osteogenesis) for the affected side, sagittal split ramus osteotomy for the healthy side, and Le Fort I osteotomy for the upper jaw. As favourable outcomes were obtained, we report the treatment and course of the present patient.

Effects of hyperbaric oxygen therapy on an accelerated rate of mandibular distraction osteogenesis

Distraction osteogenesis has become a standard therapy for lengthening of the human craniofacial skeleton. Because the technique is used predominately in a paediatric population, limiting the treatment protocol is beneficial. Twenty-four animals were divided into four groups with distraction rates of 1mm and 2mm/day with and without hyperbaric oxygen (HBO) therapy. Following a 5-day latency period, mandibular lengthening of 15mm was performed with a uniaxial distractor along the body of the mandible. Consolidation period was 4 weeks in all groups. HBO therapy was administered to one of the 1 and 2mm/day groups 1 day preoperatively, throughout the latency and distraction phases and 2 weeks into the consolidation period. Animals were euthanised after consolidation and the mandibles harvested for bone mineral densitometry evaluation. The mean bone mineral density (BMD) (g/cm(2)) was 0.208+/-0.04 in Group 1 (1mm/day distraction, no HBO therapy), 0.228+/-0.09 in Group 2 (1mm/day distraction, + HBO therapy), 0.180+/-0.1 in Group 3 (2mm/day distraction, no HBO therapy), and 0.269+/-0.05 in Group 4 (2mm/day distraction, + HBO therapy). Using the Student's t-test for equality of means and the one-way analysis of variance (ANOVA), we found that the mean BMD was significantly higher in the groups that were administered HBO (Groups 2 and 4) than not (P=< 0.05). For the groups that had distraction of 1mm/day and 2mm/day, those that underwent HBO therapy had significantly higher BMD than those without HBO therapy (P=< 0.05). We have found that HBO therapy may serve to augment the healing process in distraction osteogenesis, allowing for more rapid distraction in order to decrease the overall treatment time.

CT analysis after distraction osteogenesis in Pierre Robin Sequence

Early mandibular lengthening by distraction osteogenesis provides an alternative to traditional methods of airway management in infants with Pierre Robin sequence (PRS). Little evidence in the medical literature quantitatively demonstrates the changes in skeletal, soft tissue, and hypopharyngeal spaces with mandibular distraction. Prospective analysis of a cohort of three patients with PRS. We reviewed a series of infants with PRS and severe upper airway obstruction who underwent mandibular distraction. The infants underwent mandibular lengthening with the same internal, unidirectional distraction osteogenesis device. Standardized serial computed tomography (CT) scans were obtained according to established protocol. Computed tomography data were extracted and analyzed with medical image analysis software for mandibulo-maxillary arch harmony, symmetry, hypopharyngeal airway volume, geniohyoid distance, distraction osteogenesis bone volume, and mandibular length. Mandibulo-maxillary alveolar ridge distances were corrected to 0.5 mm after distraction. Clinical examination showed good arch harmony without open-bite or cross-bite deformities. Mandibular ramus was lengthened by 19.5%; the body, 43.4%. After distraction, total mandibular length was increased by 26.2%; hypopharyngeal airway volume, 192%; posterior distance from pharyngeal wall to tongue base, 198.9%; and geniohyoid distance, 14.1%. Unidirectional internal microdistractors can achieve good mandibulo-maxillary arch harmony. Hypopharyngeal airway volume increases substantially, with an even greater increase in distance between tongue base and posterior pharyngeal wall. As the distal mandibular segment is distracted, the hyoid moves anteriorly, with minor increase in geniohyoid relationship. Internal mandibular microdistraction devices represent a substantial advance in airway obstruction management in infants with micrognathia.

Ten-year follow-up of a patient with hemifacial microsomia treated with distraction osteogenesis and orthodontics: An implant analysis

Distraction osteogenesis (DO) has become an accepted treatment method for patients requiring mandibular lengthening because of congenital malformations. However, the skeletal growth pattern of a distracted mandible in the long term has still not been clearly shown in the literature. The purpose of this report was to analyze the dentofacial changes observed during a 10-year follow-up period in a patient treated with mandibular DO. The patient was a 12-year-old girl with hemifacial microsomia who had undergone DO with an external device. Morphologic changes during the observation period were evaluated on panoramic radiographs and posteroanterior and lateral cephalograms. Six Björk-type titanium implants were placed bilaterally in the mandible under local anesthesia to analyze the mandibular skeletal changes over time. Marked lengthening was achieved during the active phase of mandibular distraction. The ratio between the ramus heights of the affected and normal sides improved significantly in the affected side's favor as the mandible was lengthened, but this ratio returned to its initial value after 10 years. Although there was some growth on the affected side during the follow-up period, it was not enough to catch up with the growth on the normal side. The original asymmetry recurred as a consequence of the growth pattern in this patient with hemifacial microsomia.

Poster 042: Histomorphometric Examination of Long Term Changes in Temporomandibular Joints After Mandibular Lengthening by Distraction Osteogenesis in Rabbits

Poster 042: Histomorphometric Examination of Long Term Changes in Temporomandibular Joints After Mandibular Lengthening by Distraction Osteogenesis in Rabbits

High-rhythm automatic driver for bone traction: an experimental study in rabbits

The distractors currently used in clinics are activated manually by intermittent advancement. An automatic driver has been developed to attach to custom-made or commercially available distractors and activate advancement at a high rhythm of 8 steps per second. One 1.5-V lithium button battery is used as the power source to drive a step motor and the driving torque is transmitted to the distractor through a flexible shaft at a rate of 2 revolutions per day. This automatic driver was tested in 5 rabbits for mandibular lengthening. Osteotomy was performed on one side of the mandible and the custom-made distractor was adapted. After a latency period of 3 days, the automatic driver was attached to the distractor's arm and mandibular lengthening was activated. After 11 days of continuous distraction the automatic driver was detached from the distractor's arm. All the rabbits were euthanized after 4 weeks of consolidation. The distraction regenerates were analysed by plain radiography, micro-computerized tomography and histological examination. All 5 rabbits completed the experimental process and healed uneventfully. The mandibles were confirmed to have lengthened successfully and the distraction gap was filled with newly formed bone.

Changes in blood perfusion and bone healing induced by nicotine during distraction osteogenesis

Nicotine is the main chemical in cigarettes responsible for the tobacco's pathological effects. The influence of nicotine on bone healing remains controversial. Distraction osteogenesis provides an ideal model to study bone healing and regeneration. The present study aims to evaluate the effects of nicotine on blood perfusion, angiogenesis and bone formation using a rabbit model of mandibular lengthening. Twenty adult New Zealand white rabbits were randomly assigned to the control group and nicotine group. The total nicotine or placebo exposure time for all animals was 7 weeks. After 2- or 4-week of consolidation following osteotomy, 3-day of latency and 11-day of active distraction, the animals were sacrificed and the mandibles were harvested. Blood perfusion and vascularization were evaluated by Laser Doppler monitoring and Collagen IV immunohistochemistry staining respectively. Bone formation was assessed by radiological, histological and immunohistochemical examination. Results showed that nicotine exposure increased microvessel density, whereas inhibited blood flow and bone formation. The expression of bone morphogenetic protein (BMP)-2 in osteoblasts was also decreased. Frequent appearance of cartilage islands suggested ischemia and low oxygen tension in the distraction regenerate. We concluded that nicotine compromises bone regeneration possibly by causing ischemia and directly inhibitory effect on osteoblastic cells. Nicotine exposure enhances angiogenesis but cannot compensate for the adverse effect of vasoconstriction.