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Fibrous ankylosis after distraction osteogenesis of a costochondral neomandible in a patient with grade III hemifacial microsomia.

Distraction osteogenesis has recently become a mainstay for treatment of craniofacial syndromes with mandibular hypoplasia. This article presents the difficult case of a patient with a previous costochondral rib graft who underwent mandibular distraction and developed a fibrous pseudoarthrosis at the distraction site. This was attributed in part to an associated temporomandibular joint ankylosis. Resorption of the pseudoarthrosis occurred once the distractor was removed. It appears that distraction osteogenesis of a mandible with an ankylosed temporomandibular joint can result in healing with a fibrous union, presumably because of movement at the distraction site when masticating. This can result in a pseudo "temporomandibular joint" at the distraction site. A temporomandibular joint arthroplasty was performed, followed by repeat distraction. We conclude that if there is an ankylosed temporomandibular joint or a stiff temporomandibular joint that may ankylose during the course of the distraction process, then a temporomandibular joint arthroplasty should be performed before or at the time the distractor is placed.

Adolescent↗

Clinical application of distraction osteogenesis for traumatic maxillofacial deformities.

Treatment including occlusal function is important for maxillofacial fractures. Because distraction osteogenesis is now used frequently for the treatment of various types of congenital maxillary hypoplasia, the authors applied this technique to six cases of traumatic maxillofacial deformity caused by old maxillofacial fractures. Several kinds of devices were used for the various deformities associated with severe malocclusion, resulting in extension of both bone and soft tissues. In each case, favorable facial aesthetics and occlusion were achieved. Distraction osteogenesis also appears to be an extremely effective method for repair of traumatic maxillofacial deformities.

Adolescent↗

Bone formation is enhanced by thrombin-related peptide TP508 during distraction osteogenesis.

The thrombin-related peptide, TP508, has been shown to promote soft tissue healing and fracture repair. One possible clinical application of TP508 is to accelerate bone regeneration during distraction osteogenesis, which is a lengthy procedure involving significant complications. In this study, we tested the ability of TP508 to accelerate the consolidation phase of distraction osteogenesis in a rabbit model of leg lengthening. Twenty-three rabbits had left tibiae lengthened for 1 cm over a period of 6 days. TP 508 (0, 30 and 300 microg in 300 microl saline) was injected into the distraction gaps at the beginning and the end of the lengthening phase, and all the animals were killed 2 weeks after lengthening. By the end of experiment, more animals in the TP508 treated groups had complete bony union of the distraction gaps when compared to the saline treated group. pQCT examination of the regenerates demonstrated a significantly greater bone mineral density (BMD) in the TP508 treated groups relative to the saline control group, but no statistical difference in the BMD was found between the two dosages of TP508. Bone consolidation and bone remodeling was far advanced in the TP508 300 microg treated group, and the regenerates mainly consisted of well-vascularized woven bone. In contrast, in the group that received the 30 microg TP508 treatment, focal bone defects and discontinuities of the new cortices were evident in some but not all animals. In the saline control group a majority of the animals showed large amounts of fibrous and cartilaginous tissues in the regenerates, and none of the regenerates had completed consolidation. This study has demonstrated that local application of TP508 enhanced bone formation and consolidation during distraction osteogenesis in the rabbit. The findings indicate that TP508 may be useful in promoting osteogenesis in situations when augmentative treatment for bone formation and consolidation are needed.

Animals↗

Bite force and occlusal contact area changes following mandibular widening using distraction osteogenesis.

OBJECTIVE: To examine changes in bite force and occlusal contact area after mandibular widening by distraction osteogenesis using pressure-sensitive sheet (Dental-Prescale; Fuji Photo Film, Tokyo, Japan). STUDY DESIGN: Fifteen patients with transverse mandibular deficiency (6 to 9 mm, mean distraction interval: 8 mm) were examined. They were measured just before the operation and at 1 week, 1 month, 3 months, 6 months, and 1 year after the operation. Ten control subjects with normal occlusion were also measured. RESULTS: Both bite force and occlusal contact area were lowest at 1 month postoperatively. The values of bite force and occlusal contact area steadily increased thereafter. The bite force and occlusal contact area reached to the preoperative levels at 6 months after operation and slightly above the preoperative level at 12 months after operation. There were no statistically significant differences between 12 months and the control values for bite force measurements (P > .05). CONCLUSION: Although statistically not significant, this study suggests that mandibular symphyseal distraction osteogenesis increases the bite force and occlusal contact area in patients with transverse mandibular deficiency.

Adolescent↗

[Using TiNi-SMA distractor for mandibular alveolar ridge augmentation by distraction osteogenesis: a preliminary study].

OBJECTIVE: To study the possibility of mandibular alveolar ridge augmentation by distraction osteogenesis using TiNi-SMA (shape memory alloy) distractor. METHODS: All of the mandibular premolars and the first molar were extracted from ten adult mongrel canines. One month later, box-shaped osteotomies of the alveolar bone were performed out and TiNi-SMA distractors were buried in experimental group. The bone height was measured before and 1, 5, 13 weeks after the operation. The radiographs were taken on the day of, and 1, 5, 13 weeks after operation. The animals were killed at one or three months after distraction and examined histologically. RESULTS: The bone segments were lifted up immediately after the insertion of distractors and the height achieved 7.5 - 11.5 mm one week after the operation. One month after distraction, the radiographs showed there was regeneration of bone in distraction gap. The new bone and the normal bone could not be differentiated clearly three months after distraction. No bone resorption was found during this period. In histological sections, there were collagen bundles in early distraction, then these bundles were calcified and became traeculaes. CONCLUSION: It suggests that the canine mandibular posterior alveolar ridge can be augmented by distraction osteogenesis using TiNi-SMA distractor, and the new bone is formed by intramembranous ossification.

Alloys↗

Histomorphometry of distraction osteogenesis in a caprine tibial lengthening model.

Standardized histomorphometry of bone formation and remodeling during distraction osteogenesis (DO) has not been well characterized. Increasing the rhythm or number of incremental lengthenings performed per day is reported to enhance bone formation during limb lengthening. In 17 skeletally immature goats, unilateral tibial lengthenings to 20 or 30% of original length were performed at a rate of 0.75 mm/day and rhythms of 1, 4, or 720 times per day using standard Ilizarov external fixation and an autodistractor system. Two additional animals underwent frame application and osteotomy without lengthening and served as osteotomy healing controls. Histomorphometric indices were measured at predetermined regions from undecalcified tibial specimens. Within the distraction region, bone formation and remodeling activity were location dependent. Intramembranous bone formed linearly oriented columns of interconnecting trabecular plates of woven and lamellar type bone. Total new bone volume and bone formation indices were significantly increased within the distraction and osteotomy callus regions (Tb.BV/TV, 226% [p < 0.05]; BFR/BS, 235-650% [p < 0.01]) respectively, compared with control metaphyseal bone. Bone formation indices were greatest adjacent to the mineralization zones at the center of the distraction gap; mineral apposition rate 96% (p < 0.01); mineralized bone surfaces 277% [p < 0.001]); osteoblast surfaces 359% [p < 0.001]); and bone formation rate (650% [p < 0.01]). There was no significant difference (p < 0.14; R = 0.4) in the bone formation rate of the distracted callus compared with the osteotomy control callus. Within the original cortices of the lengthened tibiae, bone remodeling indices were significantly increased compared with osteotomy controls; activation frequency (200% [p < 0.05]); osteoclast surfaces (295% [p < 0.01]); erosion period (75%); porosity (240% [p < 0.001]). Neither the rhythm of distraction nor the percent lengthening appeared to significantly influence any morphometric parameter evaluated. Distraction osteogenesis shares many features of normal fracture gap healing. The enhanced bone formation and remodeling appeared to result more from increased recruitment and activation of bone forming and resorbing cells rather than from an increased level of individual cellular activity.

Animals↗

A multidisciplinary approach to restoring an acquired palatal defect using distraction osteogenesis: a clinical report.

Prosthetic and surgical procedures can be applied to rehabilitate acquired palatal defects. Distraction osteogenesis may be used to narrow the defect to facilitate bone and soft tissue closure. This clinical report describes a multidisciplinary approach to the closure of a palatal defect with distraction osteogenesis, comprehensive orthodontic treatment, surgical soft tissue flap reconstruction of the residual soft tissue defect, implant placement in the newly created edentulous ridge, and restoration with an implant-supported prosthesis.

Adult↗

Colocalization of c-Src (pp60src) and bone morphogenetic protein 2/4 expression during mandibular distraction osteogenesis: in vivo evidence of their role within an integrin-mediated mechanotransduction pathway.

Craniofacial distraction osteogenesis (DO) is an evolving reconstructive technique with expanding applications for the treatment of bony deficiencies of the facial skeleton. Mechanical force has been known to play a fundamental role in modulating sustained osteogenic response and therefore is believed to function as a critical regulator of DO. We hypothesize that key clustering components of an integrin-mediated signaling pathway, including c-Src (pp60), are necessary for mediating the response to mechanical force. The specific aim of this study is to demonstrate up-regulation of a key focal adhesion molecule, c-Src, selectively in new bone formation subject to the mechanical forces of distraction and to demonstrate a lack of that same up-regulation in new bone formation associated with simple fracture healing. An additional specific aim is to demonstrate colocalization of c-Src expression and bone morphogenetic protein (BMP 2/4) expression during mandibular DO. Using a rat model of mandibular DO, c-Src and BMP 2/4 expression were evaluated in critical size defects, subcritical size defects, and mandibles undergoing gradual distraction. Osseous regeneration was observed in the course of gradual distraction; this process was associated with increased expression of c-Src. Furthermore, the presence of BMP 2/4 closely approximated c-Src expression spatially and temporally, suggesting a link between cytoplasmic focal adhesion activation and the resultant nuclear regulation of osteogenic protein expression. In significant contradistinction, minimal c-Src expression was found in the subcritical-sized defects where the fractures healed secondarily but where no gradual distraction was performed. Instead, the new bone formation inherent in the secondarily healed subcritical-sized defects demonstrated expected BMP 2/4 expression but was devoid of an up-regulation of c-Src. Finally, as expected, minimal expression of both c-Src and BMP was found in fibrous nonunion specimens. C-src expression was observed during gradual distraction; furthermore, minimal c-Src expression was visualized during subacute and critical-size defect fracture healing. C-Src expression also closely approximated BMP expression during DO. These findings that c-Src expression is found primarily only during conditions of cyclic distraction forces strongly implicates that mechanical force during gradual distraction is associated with c-Src expression. These results provide in vivo support for previous in vitro evidence that mechanical force profoundly influences osseous regeneration during distraction osteogenesis by means of a c-Src dependent mechanotransduction pathway, resulting in increased expression of osteogenic proteins, including BMP 2/4.

Animals↗

The effects of electromagnetic field on distraction osteogenesis.

The effects of electromagnetic field on distraction osteogenesis and new bony tissue were investigated. Twenty-five New Zealand rabbits were divided into an experimental (12 rabbits) and a control (13 rabbits) group. An osteotomy was performed on the right tibia in the diaphyseal region in both groups. The experimental group was exposed to a magnetic field of 50 Hz 1.0 mT for 3 hours a day for 13 weeks. The control group was kept in a similar environment but with no electromagnetic field. The distraction was continued until an increase of 10 mm was achieved. At weeks 4, 8, and 13, radiography, scintigraphy, and a biopsy were performed in both groups, and the results were statistically analyzed. The X-ray results were similar in both groups at all times. On the other hand while the scintigraphic and histopathological results were similar at weeks 4 and 13 in both groups, the osteoblastic activity was significantly greater in the experimental group at week 8 (p < 0.01). In conclusion an electromagnetic field increases the osteoblastic activity and osteogenesis, but has little effect during the remodeling phase.

Animals↗

Effects of mandibular symphyseal distraction osteogenesis on mandibular structures.

INTRODUCTION: The purpose of this study was to evaluate the effects of mandibular symphyseal distraction osteogenesis on dental and mandibular skeletal structures with a tooth- and bone-borne distraction device. METHODS: The sample comprised 20 patients, ranging in age from 15.8 to 23.3 years (mean, 20.1 +/- 2.3 years) at the start of treatment. The distraction device was activated 1 mm per day. The device was usually maintained in position about 90 days after surgery. Records were obtained at the start of treatment, at the end of distraction (11.4 +/- 2.2 days after surgery), and at follow-up periods (24.1 +/- 4.2 months after surgery). The records included posteroanterior cephalograms and study casts. The data were analyzed statistically by using the repeated measure analysis of variance and paired t test. RESULTS: Posteroanterior cephalometric analysis demonstrated no significant changes in bigonial widths and ramal angles at the end of distraction period. On the other hand, bimolar widths were significantly increased, whereas bicondylar widths were markedly decreased. The dental cast analysis indicated that the maximum amount of increase was found between the mandibular canines, and the widening effect gradually decreased from the mandibular canines to the second molars. The follow-up data confirmed that the treatment results were stable. CONCLUSIONS: The long-term findings indicate that mandibular symphyseal distraction osteogenesis is an efficient nonextraction treatment alternative for mandibular dental crowding to increase mandibular skeletal and dental arch widths.

Adolescent↗

Management of alveolar clefts using dento-osseous transport distraction osteogenesis.

This article evaluates the usage of distraction osteogenesis (DO) in the treatment of cleft alveoli. The procedure was carried out on eight alveolar clefts of five patients between the ages of 17 and 25 years. Three patients had bilateral alveolar clefts (BAC) and two patients had unilateral alveolar clefts (UAC). DO was carried out bilateral to the palatal segments for the BAC patients and unilateral to the lesser segment for the UAC patients. A custom-made tooth-borne distractor was used. The average amount of distraction was eight mm (range, 5-11.5 mm). The average amount of distal movement of the anchorage teeth was 0.8 mm (range, 0-2 mm). The average amount of inclination changes of the transport segments and anchorage teeth was 7.6 degrees (range, 2-17.5 degrees) and 3.3 degrees (range, 0-9 degrees), respectively. Two important problems were observed attributable to the method. First, the transport segment was docked in a more superior position at the end of distraction process. This undesirable movement also changed the inclination of the teeth in the transport segment and increased tooth tipping. Removing the device in the second week of the consolidation period and retracting the segment to its ideal position orthodontically solved these problems. Second, the bony defect on the nasal side of the alveolar cleft could not be completely closed. This method for repairing small or large alveolar clefts is a simple, cost-effective, and useful treatment option. However, repairing the alveolar cleft without grafts seems to be impossible when using a tooth-borne device.

Adolescent↗

Endoscopically assisted intraoral mandibular distraction osteogenesis.

Correct placement of intraoral devices for mandibular distraction osteogenesis is important to achieve the ideal vector of distraction. As visual inspection and intraoperative management in the inferior mandibular border or at the posterior ascending ramus is impaired, an endoscopically assisted method is presented. Since the introduction of this new technique operation time and ease have been significantly improved.

Adult↗

[Evaluation of potential damage to the regenerate during callus molding after mandibular distraction osteogenesis. Experimental study using an animal model].

BACKGROUND: Molding the regenerate created by distraction osteogenesis has clinically been shown to be an efficient lifeboat, good enough that for complex three-dimensional deformities final adjustments by molding the regenerate may be part of the treatment plan. The study assessed the limits of molding a regenerate, taking into consideration compressive and tensile forces acting simultaneously on the fresh callus. MATERIAL AND METHODS: Distraction osteogenesis was performed in 15 beagle mandibles using custom-made devices which allowed for lengthening as well as for angulation. After linear distraction of 10 mm, a defined 20 degrees angulation was performed in one acute step. The position of the fulcrum of the device allowed the regenerate to be compressed and stretched simultaneously. The effects on bone healing were assessed after 6 or 13 weeks of consolidation and compared to a control group where only linear distraction was performed. RESULTS: Radiological and histological investigations demonstrated that no significant difference between the biological behavior of the compressed and the stretched zone of the regenerate could be found. However, there were signs, showing the more critical character of the stretched area. After 6 weeks of consolidation, some specimens revealed delayed ossification of the stretched zone. Under stable conditions, this delay was compensated after 13 weeks of consolidation and complete osseous healing occurred. CONCLUSIONS: Under stable conditions, a fresh regenerate can be molded to a considerable extent without endangering osseous healing permanently. Nevertheless, tensile forces acting on the regenerate should be minimized to prevent damage to the new bone. This can be achieved by overdistraction prior to callus molding or by gradually changing the vector of distraction during the lengthening process.

Animals↗

A new method for vector control during alveolar distraction osteogenesis: a case report.

We report a case of dentoalveolar rehabilitation employing the technique of alveolar distraction osteogenesis in a 25-year-old male patient with a right posterior mandibular defect that was a result of previous tooth extractions and consequent severe loss of alveolar bone. A new method for vector control during alveolar distraction osteogenesis was used. This method consisted of placing an orthodontic wire on an immediately loaded implant (in the right third molar position) and securing it by means of resin composite to the implant and the adjacent tooth. Implant positioning and soft tissue management were performed successfully. The described treatment strategy appears to have good potential for providing an ideal final position of the regenerated bone in cases where major tissue defects exist in the posterior mandible.

Adult↗

Histomorphometric evaluation of short-term changes in masseter muscle after lengthening the rabbit mandible by distraction osteogenesis.

PURPOSE: Structural changes in muscles may affect the process during and after distraction osteogenesis (DO) of the mandible. However, the response of the masticatory muscles is still not well defined after gradual lengthening of the mandible. In this experimental study, short-term structural changes in masseter muscles of the rabbits are evaluated after mandibular DO. MATERIALS AND METHODS: Left mandibles of 10 New Zealand rabbits were lengthened by DO for 7 days in the rate of 1 mm/day. Mandibles of all animals were removed at the end of the consolidation period. Muscle biopsy samples of distracted and contralateral sides were histopathologically investigated, and histomorphometric results were statistically analyzed. RESULTS: Atrophy, hypertrophy, regeneration, and concomitant mild interstitial edema and fibrosis were found more evident in experimental side biopsy samples 30 days after distraction. Histomorphometric analysis revealed a statistically significant decrease in the mean regions of masseter muscle fibers of the distracted sides compared with the control sides (P <.05). CONCLUSION: This experimental study showed that the structure of masseter muscle is influenced during and shortly after mandibular distraction osteogenesis. Atrophic changes of the ipsilateral masseter muscles may be regarded as regenerative response that occurs during and shortly after distraction period.

Animals↗

Angiogenesis is required for successful bone induction during distraction osteogenesis.

UNLABELLED: The role of angiogenesis during mechanically induced bone formation is incompletely understood. The relationship between the mechanical environment, angiogenesis, and bone formation was determined in a rat distraction osteogenesis model. Disruption of either the mechanical environment or endothelial cell proliferation blocked angiogenesis and bone formation. This study further defines the role of the mechanical environment and angiogenesis during distraction osteogenesis. INTRODUCTION: Whereas successful fracture repair requires a coordinated and complex transcriptional program that integrates mechanotransductive signaling, angiogenesis, and osteogenesis, the interdependence of these processes is not fully understood. In this study, we use a system of bony regeneration known as mandibular distraction osteogenesis (DO) in which a controlled mechanical stimulus promotes bone induction after an osteotomy and gradual separation of the osteotomy edges to examine the relationship between the mechanical environment, angiogenesis, and osteogenesis. MATERIALS AND METHODS: Adult Sprague-Dawley rats were treated with gradual distraction, gradual distraction plus the angiogenic inhibitor TNP-470, or acute distraction (a model of failed bony regeneration). Animals were killed at the end of distraction (day 13) or at the end of consolidation (day 41) and examined with muCT, histology, and immunohistochemistry for angiogenesis and bone formation (n = 4 per time-point per group). An additional group of animals (n = 6 per time-point per group) was processed for microarray analysis at days 5, 9, 13, 21, and 41. RESULTS AND CONCLUSIONS: Either TNP-470 administration or disruption of the mechanical environment prevented normal osteogenesis and resulted in a fibrous nonunion. Subsequent analysis of the regenerate showed an absence of angiogenesis by gross histology and immunohistochemical localization of platelet endothelial cell adhesion molecule in the groups that failed to heal. Microarray analysis revealed distinct patterns of expression of genes associated with osteogenesis, angiogenesis, and hypoxia in each of the three groups. Our findings confirm the interdependence of the mechanical environment, angiogenesis, and osteogenesis during DO, and suggest that induction of proangiogenic genes and the proper mechanical environment are both necessary to support new vasculature for bone induction in DO.

Angiogenesis Inhibitors↗

Study of mandibular alveolar distraction osteogenesis using a three-dimensional computed tomography measurement method: report of four patients, a preliminary study.

OBJECTIVE: This study was conducted to show dimensional and volumetric changes after vertical alveolar distraction osteogenesis using a three-dimensional computed tomography measurement method. MATERIALS: Four patients with mandibular alveolar ridge atrophy were evaluated. Three-dimensional computed tomography reconstructions were obtained 2 weeks before and 3 months after the operation. The results of the three-dimensional computed tomography measurements were used for preoperative planning and for quantitative assessment of the mandibular alveolar distraction. The results of the preoperative and postoperative three-dimensional computed tomography measurements were compared statistically using paired t-test. RESULTS: The increase in distracted mandibular segment volume and surface area, height, and width of each slice after distraction were statistically significant (P < 0.001). CONCLUSION: In atrophic jaw cases, the dimensions of the present alveolar bone were clearly measured so that the amount of augmentation needed could be estimated. Three-dimensional computed tomography provided better understanding of the effects of distraction osteogenesis on the anterior mandible. Newly formed bone can be viewed as close to its real dimensions after distraction osteogenesis.

Adult↗

[The expression of activin A and transforming growth factor-beta 1 during rabbit mandibual distraction osteogenesis].

OBJECTIVE: To examine the expression of activin A (ACT A) and transforming growth factor-beta 1 (TGF-beta 1) during mandibular lengthening and elucidate the difference between the role of ACT A and TGF-beta 1 during mandibular distraction osteogenesis. METHOD: Skeletally mature white new zealand rabbits were established right mandibular distraction osteogenesis model. The regenerating tissue of animals' lengthened mandibes were harvested at different time points to have immunohistochemistric research of ACT A, TGF-beta 1 protein and analysis ACT A, TGF-beta 1 mRNA by using RT-PCR semiquantitative mean. RESULTS: AT the end of latency period day, positive stain of ACT A were found in the osteoblasts while positive stain of TGF-beta 1 was found in mesenchymal cells. At the end of distraction phase, fibrosis tissue had no stain of ACT A, but had strong stain of TGF-beta 1. At the period of fixation days of 20 days, both cytoplasm of osteoblasts and extracellular matrix in primary mineralization front were strongly stained of ACT A. The osteoblasts, osteoid and osteocytes in peripheral new bone zone were moderately stained of ACT A. TGF-beta 1 had strongly positive stained in fibrosis zone and weekly positive stained in primary mineralization front and peripheral new bone zone. There were also broad activin A stains in cytoplasm of osteoblasts, osteoid and cytoplasm of ACT A, TGF-beta 1 in osteocytes after distraction for 30 days. Activin A mRNA began to express at the end of latency period. Expression for activin A mRNA increased gradually along with the beginning of distraction and at the peak in distraction of 10 days and 20 days, while TGF beta 1 mRNA increased at the peak at the end of latency period. CONCLUSION: ACT A and TGF beta 1 have different role during rabbit mandibular distraction osteogenesis.

Activins↗