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PubMed2002

[Evaluation of inferior alveolar nerve function with trigeminal somatosensory evoked potential during mandibular distraction osteogenesis in monkeys].

OBJECTIVE: To assess sensory function of inferior alveolar nerve in monkeys with mandibular distraction osteogenesis by use of trigeminal somatosensory evoked potential (TSEP). METHOD: Seven young monkeys, 4 approximately 6 kg, were undergone a 13.5 mm bilateral or right-side mandibular lengthening with mandibular angle osteotomy and intraoral bone-born appliance. The inferior alveolar nerve function was assessed with TSEP before surgery, at the completion of distraction, and after four weeks of fixation. RESULTS: No significant differences in latencies and amplitudes of TSEP between the left and right inferior alveolar nerves before surgery. At the completion of distraction, latencies of TSEP showed significant elongation (P < 0.01, P < 0.001) and amplitudes also significantly decreased (P < 0.001). After four weeks of fixation, various degrees of TSEP recovery were identified. The latencies and the amplitude were slightly improved. CONCLUSIONS: Mandibular distraction osteogenesis affects sensory function of inferior alveolar nerves in studied monkeys evaluated with SEP, but recovery is observed four weeks after surgery.

Alveolar Process↗
PubMed2002

Distraction osteogenesis for nonunion after high tibial osteotomy.

The purpose of this study was to determine whether distraction osteogenesis can be used to treat hypertrophic nonunion associated with angular deformity and shortening after Coventry style high tibial osteotomy. Five consecutive patients were retrospectively reviewed. In all patients the alignment had collapsed into excessive varus or valgus and leg length discrepancy was present. The leg length discrepancy, malalignment, and nonunion were treated simultaneously with distraction. Union was achieved by the time of fixator removal, which averaged 4.4 months. The Hospital for Special Surgery knee score significantly improved from 42 to 89. The mechanical axis deviation significantly improved by 5 cm. The coronal plane deformity significantly improved by 13 degrees, and leg length discrepancy improved significantly from 2.3 to 0.5 cm. Metaphyseal bone stock increased by 43%, and the Insall-Salvati ratio increased from 1.1 to 1.2 and remained within normal limits. All patients were satisfied with the procedure, and none have had or need a total knee replacement at an average followup of 4 years. Distraction osteogenesis of nonunion after high tibial osteotomy is a minimally invasive and successful procedure. It leads to bony union with correction of deformity and leg length discrepancy and prevents the need for total knee replacement at intermediate-term followup. The increase in metaphyseal bone stock may make total knee replacement technically easier.

Adult↗
PubMed2004

[Recombinant human BMP-2 accelerates bone formation of mandibular distraction osteogenesis in rabbits].

OBJECTIVE: To study the effects of rhBMP-2 on bone formation of mandibular distraction osteogenesis in rabbits. METHODS: Bilateral mandibular osteotomies were performed in 12 mature rabbits. 5 mg rhBMP-2 with the collagen carrier was implanted in the osteotomy site of one side of the mandibles. Only the collagen sponge was placed in the contra-lateral side as control. The mandibles of 8 rabbits were lengthened by 6mm using a custom-made distractor. At 4 weeks after the end of distraction, all animals were killed and the distracted calluses were harvested and processed for histological, scanning electron microscopic, as well as Ca/P ratio analysis. RESULTS: The regenerated bone was found in the distraction gap after mandibular lengthening. The mandibular side treated with rhBMP-2 had greater amounts of new bone formation and earlier mineralization than contra-lateral side (non-rhBMP-2 treated). CONCLUSION: Recombinant human BMP-2 appears to be able to accelerate bone formation of mandibular distraction osteogenesis in rabbits.

Animals↗
PubMed2000

Quantitative assessment of in vivo bone regeneration consolidation in distraction osteogenesis.

We present a new method for quantitatively assessing the consolidation of bone regeneration by performing distraction osteogenesis in micropigs. We measured in vivo stiffness using a newly developed, revolving, bone-healing meter. After the micropigs were killed, we obtained maximum torsional moment data for the regenerated bones by destructive mechanical testing, and we then correlated these data with the data for stiffness. We found a highly significant regression between in vivo stiffness and maximum torsional moment (r2 = 0.80), suggesting that monitoring stiffness may be useful for the prediction of bone regeneration in distraction osteogenesis. Therefore, our method may be a reliable tool for future quantitative monitoring of healing progress in patients with healing bones or in animal studies addressing treatments to increase bone formation in long-bone defects.

Animals↗
PubMed1995

Distraction osteogenesis of the human craniofacial skeleton: initial experience with new distraction system.

Application of distraction osteogenesis to the human craniofacial skeleton in properly selected cases represents a major advance in the treatment of craniofacial deformities. We report our initial clinical experience with a system of miniature distraction devices that permitted maxillary, orbital, and mandibular distraction in a 4-month-old boy with unilateral craniofacial microsomia and anophthalmia. At 6 months of age, after maxillary repositioning and orbital expansion, a costochondral rib graft was used to construct the missing left mandibular ramus and condyle.

Bone Lengthening↗
PubMed1999

The role of distraction osteogenesis in the management of craniofacial disorders.

Since its introduction in the medical literature in 1992 by McCarthy, distraction osteogenesis of the craniofacial skeleton has become a standard surgical therapy. The present report attempts to trace the development of craniofacial distraction from the perspective of one of the early proponents of the technique. Although the earliest application of distraction was in children with severe unilateral or bilateral mandibular deficiency, its use for functional abnormalities such as apnoea were especially appealing. Distraction osteogenesis for the midface began with external appliances that were attached to the teeth. Newer, buried devices have eliminated the need for external devices in all LeFort III and monobloc cases. For LeFort I and mandibular cases, the ideal internal device has not been manufactured.

Child↗
PubMed2002

Value of measuring bone density serial changes on a picture archiving and communication systems (PACS) monitor in distraction osteogenesis.

Serial changes of bone density in 26 femora and 22 tibiae that underwent leg lengthening by distraction osteogenesis were investigated by measuring the pixel value shown on a picture archiving and communication systems (PACS) monitor. The pixel value of the original cortex did not change significantly until the external fixator was removed. The pixel value of the distraction sites did not change significantly for the first 5-6 weeks/cm, but rapidly increased after 7 weeks/cm in the femur and tibia, then slowly increased after 8 weeks/cm. The serial changes of the pixel value of the distracted bone showed a sigmoid curve, rather than a straight increasing line. The relative pixel values of the lengthening sites were >95% in three of the four cortices at external fixator removal. Thus, the pixel value of PACS is a rapid and easy method for the detection of bone density changes in distraction osteogenesis.

Absorptiometry, Photon↗
PubMed2004

[Distraction osteogenesis of the maxilla in cleft patients. Worth considering].

Three cleft patients were treated with RED-distraction for maxillary hypoplasia. In all patients, the desired advancement could be achieved easily. The occlusion, the lip relation and the facial profile improved remarkably post treatment. Although the treatment was well tolerated by the patients, some limitations of the treatment were also noted, such as a nasal speech and discomfort by the head frame. Distraction osteogenesis in the maxilla has several advantages when compared to the conventional Le Fort 1-osteotomy: atraumatic advancement of the maxilla, absence of need for an autogeneous bone transplant, and applicability at relatively young age. The advantages and disadvantages of distraction osteogenesis must be considered for each individual patient.

Adolescent↗
PubMed2005

Possible problems of moulding the regenerate in mandibular distraction osteogenesis -- experimental aspects in a canine model.

INTRODUCTION: Moulding of the regenerate created by distraction osteogenesis has been shown clinically to be efficient and good enough so that for complex three-dimensional deformities, final adjustments by moulding the regenerate may be part of the treatment plan. This study assessed possible drawbacks of moulding a regenerate, taking into consideration compressive and tensile forces acting simultaneously on the fresh callus. METHOD: Distraction osteogenesis in 15 Beagle mandibles was performed 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 step. The position of the fulcrum of the device allowed simultaneously compression and stretching of the regenerated bone. Effects on bone healing were assessed after 6 and 13 weeks of consolidation respectively and compared with a control group where only linear distraction was performed. RESULTS: Radiological and histological investigations demonstrated that no significant differences between the biological behaviour of the compressed and the stretched zones 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 for after 13 weeks of consolidation and complete osseous healing occurred. CONCLUSION: Under stable conditions, a fresh regenerate can be moulded to a considerable extent without permanently endangering osseous healing. 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 moulding or by gradually changing the vector of distraction during the lengthening process.

Animals↗
PubMed2002

[Mode of new bone formation following distraction osteogenesis in mandibular lengthening].

OBJECTIVE: To investigate the mode and influential factor of new bone formation following distraction osteogenesis in mandibular lengthening. METHODS: Corticotomy was performed on bilateral mandibles in twelve adult male goats. A custom-made distractor was used to lengthen the mandible at a rate of 1 mm/day for 10 days (total 10 mm elongation). Four goats were sampled respectively at 2, 4 and 8 weeks after completion of distraction. The lengthening mandibles were examined by roentgenography and histology. RESULTS: Newly formed callus was observed in the distraction gap after mandibular lengthening. The new bone exhibited intramembranous ossification generally, but cartilage islands could be found in the specimen that distractor loosed. CONCLUSION: The above findings indicate that the mode of new bone formation in mandibular lengthening following distraction osteogenesis appears to be intramembranous ossification and that endochondral ossification takes place in case distractor has loosened.

Animals↗
PubMed2002

Experimental tooth movement through mature and immature bone regenerates after distraction osteogenesis in dogs.

The purpose of this study was to verify the influence of tooth movement on tooth roots and periodontal tissues when teeth were moved into mature, well-organized, and mineralized regenerate bone created after distraction osteogenesis compared with immature, fibrous, and less-mineralized bone. Six 15-month-old male beagles underwent 10 mm of bilateral mandibular distraction osteogenesis. After 2-week (group 1) and 12-week (group 2) consolidation periods, third premolars were moved distally into the regenerate bone with 100 g of orthodontic force for 12 weeks. Simultaneously, second premolars were also moved distally as controls. After completion of tooth movement, the experimental animals were killed, and their tissues were harvested for histological evaluation. When premolars in groups 1 and 2 were compared, group 1 showed higher rates of tooth movement until the eighth week of experimental tooth movement (P <.05). The amount of tooth movement was significantly greater in group 1 than in group 2 or in the control teeth (P <.05). In group 1, we observed considerable root resorption extending into the dentin, and the thickness of the dentin became approximately half that of the controls at the compression side adjacent to the distraction gap. This root resorption extended from the cementoenamel junction to the root apex. In group 2, root resorption on the compression side reached the dentin, but the root resorption was less than in group 1. These results indicated that heavy force and early orthodontic tooth movement are not recommended when teeth are moved through regenerated bone created by distraction osteogenesis, to avoid tipping and severe root resorption.

Alveolar Process↗
PubMed1999

Identification of apoptotic cell death in distraction osteogenesis.

The purpose of this experimental work was to investigate whether apoptosis contributes to tissue remodelling during distraction bone healing. In a rabbit model of mandibular distraction osteogenesis, we quantitatively analysed the extent of apoptotic cell death in relation to differently applied mechanical loadings. Apoptotic cells were identified by means of an in situ detection assay for nuclear DNA fragmentation using a modified TUNEL procedure and by electron microscopical examination for typical morphological features of programmed cell death. TUNEL-positive cells were frequently detected in samples distracted at higher strain magnitudes. Ultrastructurally, these apoptotic cells displayed a condensed chromatin and fragmented nuclei, while the continuity of their plasma membranes remained intact. Our results clearly indicated that the discontinuous traction of osteotomized mandibles induced enhanced apoptosis. In contrast to non-distracted samples and mandibles distracted at low strain magnitudes, in which only minimal evidence of apoptotic cell death was detected, the application of hyperphysiological strain magnitudes resulted in an increased apoptosis rate. Thus, mechanical loading seems to be a triggering factor for apoptotic changes in osteoblastic cells. These findings suggest a pathophysiological role of apoptotic cell death in the control of tissue integrity during distraction osteogenesis.

Animals↗
PubMed2003

Dual midfacial distraction osteogenesis: Le Fort III minus I and Le Fort I for syndromic craniosynostosis.

Midfacial hypoplasia has been corrected by Le Fort III or monobloc forward advancement in one stage in syndromic craniosynostosis, but recently developed distraction osteogenesis has been in use. Whereas the amount of forward mobilization in Le Fort III conventional osteotomy is determined by the preplanned fabricated interdental splint, that in Le Fort III distraction is determined by the positions of the inferior orbital rim, malar complex, and nose. Therefore, the forward mobilization of the upper part of the midface may sometimes be insufficient when one focuses on the final occlusion, and the occlusion might not be satisfied when the forward mobilization is sufficient. Correction of the midfacial hypoplasia should be considered differently in the upper and lower portions of the midface. The upper portion contains the inferior orbit and nose, and the lower portion contains the occlusal structure of the maxillary dentoalveolar portion with the mandible. Separating the midface into two portions and conducting the distraction osteogenesis in both portions separately in different amounts and vectors of distraction is described in this article. Although distraction of the upper portion of the midface can be conducted in one direction with an internal device, distraction of the lower portion of the midface is preferred for conduction by a controllable device because of the need to obtain the preferred occlusion. To obtain better functional and aesthetic results in midfacial distraction in adults and adolescents with syndromic craniosynostosis, dual Le Fort III minus I and Le Fort I midfacial distraction osteogenesis was performed in four cases (in two patients with Crouzon syndrome and in two patients with Apert syndrome). Two females and two males are described (age range, 13 to 26 years). An internal device was used for the upper portion of the midface and an external device was used for the lower portion. The amount of distraction ranged from 14 to 21 mm in the upper portion of the midface and from 11 to 18 mm in the lower portion. No particular complications were noticed over a follow-up period of 10 to 38 months (average follow-up, 19.8 months).

Adolescent↗
PubMed2005

Additional distraction osteogenesis after conventional fronto-orbital advancement.

In the conventional fronto-orbital advancement method, there is a limit to advancement because of scalp skin tension and an absence of a supraorbital bar fixating point. In a case of insufficient advancement after the primary operation, a secondary re-advancement must be performed. In such a condition, additional fronto-orbital advancement by distraction osteogenesis has proved to be very useful. The authors used additional distraction osteogenesis in three infant cases: two of nonsyndromic craniosynostosis and one of Apert's syndrome. They were able to perform these operations safely using their original internal devices. Distraction was started 3 days after the operation. The rate of advancement was 0.5 to 1.0 mm per day. The distraction distances ranged from 16 to 22 mm. They were able to gain enough advancement in all three cases. A reoperation of a fronto-orbital advancement is more difficult than the primary operation because of possible infection, much loss of blood, low blood supply to advanced bones, a tendency of advanced bones to relapse, increased scalp skin tension, and the existence of bone defects. In these poor conditions, distraction osteogenesis has many advantages: good vascularization, no relapsing, a low infection rate, and no need for bony fixating points in the bone defects. Although it is necessary to have a secondary operation to remove the devices and prolonged hospitalization is required, the disadvantages are far outweighed by the many advantages when performing additional fronto-orbital advancement.

Acrocephalosyndactylia↗
PubMed1999

Coronal suture response to distraction osteogenesis in rabbits with delayed-onset craniosynostosis.

Recent studies have identified a subpopulation of persons with craniosynostosis who exhibit progressive or delayed-onset synostosis and mild cranial vault deformities. These persons may be good candidates for nonextirpation distraction osteogenesis. The present studies were designed to determine force-displacement parameters and assess the effects of distraction osteogenesis on coronal suture growth and morphologic characteristics in a rabbit model with congenital, delayed-onset craniosynostosis. Data were collected from a total of 178 rabbits: 71 normal controls; 16 normal controls with distraction; 72 with delayed-onset coronal suture synostosis; and 19 with delayed-onset coronal suture synostosis and distraction. At 10 days of age, all rabbits had amalgam markers placed on both sides of the coronal suture. In the force-displacement study, force-displacement distractors were placed across the coronal suture and distracted acutely for 1.0 mm at 42 days of age. Force-displacement curves for the coronal suture were best described by a third-order polynomial regression equation for both normal and synostosed groups. Significant differences (P < 0.05) were found in the mean force necessary to distract a normal suture 1 mm in distance (13.72 kg) compared with a suture with delayed-onset synostosis (48.39 kg). A significant (P < 0.05) relationship was also found between the extent of synostosis and the distractive force in rabbits with delayed-onset synostosis. In the distraction study, internal distractors were fixed across the coronal suture at 25 days of age and percutaneously and intermittently activated at an average of 0.11 mm/day for 42 days (4.54 mm total). Serial radiographs were taken at 10, 25, 42, and 84 days of age. Results revealed that rabbits with delayed-onset synostosis and distraction had significantly (P < 0.01) more coronal suture growth rates compared with rabbits with delayed-onset synostosis and no distraction. Coronal sutures were harvested at 84 days of age for qualitative histologic examination. Normal, distracted coronal sutures showed widened sutural ligaments and thin, active osteogenic fronts. In contrast, distracted coronal sutures from rabbits with delayed-onset synostosis showed narrowed sutural ligaments, thickened and blunt osteogenic fronts, and increased collagen and bony matrix deposition compared with controls. Results suggest that distraction osteogenesis without corticotomy may be a treatment alternative in persons with progressive, delayed-onset synostosis. However, these preliminary data also suggest that distractive forces may accelerate or stimulate osteogenesis differentially in persons with craniosynostosis, possibly through an underlying genetic disorder of bone and cytokine regulation. These differential osteogenic responses to distraction, if validated clinically, will need to be taken into account when planning distraction rate and rhythm protocols for patients with craniosynostosis.

Age of Onset↗
PubMed2006

A retrospective study of the potential complications during alveolar distraction osteogenesis in 55 patients.

The aim of this retrospective study was to analyse the outcome of alveolar distraction osteogenesis for the correction of vertical defects in a large series of 55 cases. The existing bone deficiencies were secondary to atrophy after periodontal disease or tooth extraction. The overall success rate of this technique was 89.1%. The complications presented during treatment were divided into minor (no effect on final result, but immediate intervention required) 14/55 patients (25.4%), and major (lead to technique failure) 6/55 patients (10.9%). The frequency of minor complications was 8/27 in the anterior maxillary region, 1/27 in the anterior mandibular region and 15/27 in the posterior mandibular region. The frequency of major complications was 5/6 in the posterior mandibular region and 1/6 in the anterior maxillary region. The mean alveolar height achieved was 6mm. The overall rate was 36.3%. On the basis of these results it was concluded that alveolar distraction osteogenesis is an effective technique to treat vertical alveolar ridge deficiencies.

Adult↗
PubMed2002

Matrix metalloproteinases and their inhibitors in bone remodelling following distraction osteogenesis of the sheep mandible.

AIM: Matrix metalloproteinases (MMPs), together with their tissue inhibitors (TIMPs), are responsible for the controlled degradation of collagen and other matrix substrates in bone and other tissues. This study evaluated the expression of MMPs and TIMPs in bony remodelling in a bilateral sheep mandible model up to 12 months following lengthening by distraction osteogenesis. METHODOLOGY: Sheep mandibles were harvested 3, 6, 9 or 12 months following lengthening by bilateral mandibular distraction (1 mm/day for 20 days). Undistracted sheep mandibles were used as controls. The tissues underwent routine histology and immunohistochemical staining with monoclonal antibodies specific to MMPs 1-3 and TIMP-1, 2. Matrix and cell staining was assessed using a semi-quantitative analysis. RESULTS: Matrix metalloproteinases and their tissue inhibitors (TIMPs) expression levels were marked at 3 months and decreased thereafter becoming similar to undistracted controls by 12 months. The histologic development of mature lamellar cortical bone was similar to undistracted controls by 9 months following distraction. CONCLUSIONS: A temporal expression of MMPs and TIMPs was found in distraction osteogenesis. MMPs and TIMPS may, in part, reflect the state of bony remodelling following mandibular lengthening by distraction osteogenesis. Matrix metalloproteinases and TIMP expression were comparable to undistracted controls by 12 months, suggesting that equilibrium had been achieved and that bony relapse is unlikely.

Animals↗
PubMed2004

Mechanobiology of mandibular distraction osteogenesis: experimental analyses with a rat model.

We analyzed mechanobiological influences on successful distraction osteogenesis (DO). Mandibular distraction surgeries were performed on 15 adult male Sprague-Dawley rats. Animals underwent gradual distraction (GD), progressive lengthening by small increments (5-day latency followed by 0.25 mm distractions twice daily for 8 days followed by 28-day maturation period). Distracted hemimandibles were harvested on postoperative days (POD) 5, 7, 10, 13, and 41. Load-displacement curves were then recorded for ex vivo distractions of 0.25 mm and stresses determined. Histologically, new bone formation appeared in GD specimens on distraction day 2 (POD 7), filling 50-60% of the gap by distraction day 8 (POD 13), with nearly complete bony bridging at end maturation (POD 41). Average tensile strains imposed by each incremental distraction ranged from approximately 10% to 12.5% during distraction days 2-8 and were associated with bone apposition rates of about 260 microm/day. Because this GD protocol was previously determined to be optimal for DO, we conclude that strains within this range provide an excellent environment for de novo bone apposition. Distraction caused tissue damage in distraction day 2, 5, and 8 specimens as evidenced by distinct drops in the load/displacement curves. Taken together, our interpretation of these data is that daily distractions cause daily tissue damage which triggers new mesenchymal tissue formation.

Animals↗