Intermittent loading improves results in mandibular alveolar distraction osteogenesis

AIM: To evaluate clinical and morphological effects on distractive callus after application of an original protocol of bone stimulation. MATERIAL AND METHODS: Traditional or mechanically stimulated alveolar-distraction osteogenesis was studied on 16 highly selected subjects subdivided into two groups. Clinical, radiological, densitometric and histological (on biopsies) analyses were performed 6, 8 and 12 weeks after distraction was completed. RESULTS: In subjects undergoing stimulated alveolar-distraction osteogenesis, bone density was higher and at histology, bone with ordered structure was observed after 6 weeks. Moreover, bone trabeculae with oriented architecture and greater amounts of lamellar bone were observed after 8 and 12 weeks in the same subjects. DISCUSSION AND CONCLUSIONS: In conclusion, although osteogenic processes were similar in both groups, they were induced earlier and were better structured in subjects undergoing stimulated alveolar-distraction osteogenesis. These encouraging results can only be achieved and preserved by strict monitoring of distractive vectors.     

Morphofunctional and clinical study on mandibular alveolar distraction osteogenesis

Alveolar Distraction Osteogenesis (ADO) is a process which forms new alveolar bone to correct alveolar deformities in ridge height and width. This work aims (a). to verify the predictability of the augmentation of height of atrophic alveolar ridges using an extra-alveolar distraction device and (b). to study the bone processes in order to optimize implanto-prosthetic rehabilitation. ADO was performed on 10 patients with ridge deformities to obtain the required ridge augmentation. Clinical and radiological (OPT and CT with densitometric assay) evaluations were carried out during the following 12 weeks, before implant insertion. Biopsies at 40, 60 and 88 days were studied after general, specific and histochemical staining of slides; microradiographs were analyzed to evaluate the Trabecular Bone Volume. Forty days after the end of distraction, soft callus indicated the start of ossification. Sixty days after the end of distraction, the soft callus was largely converted into a network of trabecular woven bone; osteogenic activity was high and TBV was about 50%. Eighty-eight days after the end of distraction, the amount of bone appeared reduced, with a more ordered structure; bone formation activity and TBV also diminished, whereas osteoclast erosion was active. The densitometric assay shows values increasing from the end of distraction, particularly after implant insertion. Histological results show a regression in bone deposition processes 88 days after the end of distraction culminating in a virtual steady-state after a certain time. The results suggest that early implant insertion may be desirable to avoid bone loss due to mechanical unloading.     

Neurosensory and functional evaluation in distraction osteogenesis of the anterior mandibular alveolar process

Neurosensory status and craniomandibular function of 19 patients (mean age 35.2 years, range 17.8–58.8 years) treated by combined surgical orthodontic treatment with distraction osteogenesis of the mandibular anterior alveolar process (DO group) was compared with that in 41 orthodontically treated patients (mean age 22.9 years, range 15.1–49.0 years; control group). Clinical examination took place on average 5.9 years (DO group) and 5.4 years (control group) after treatment ended. Neurosensory status was determined by two-point discrimination (2-pd) and the pointed and blunt test. Lateral cephalograms evaluated advancement of the mandibular alveolar process and possible relapse. There was no significant difference in craniomandibular function and neurosensory status between the groups. Age was significantly correlated with 2-pd at the lips (DO: p = 0.01, R = 0.575; control group: p = 0.039, R = 0.324) and chin (DO: p = 0.029, R = 0.501; control group: p = 0.008, R = 0.410). Younger patients had smaller 2-pd values. Gender, age, the amount of advancement, and relapse at point B or incision inferior show no correlation with craniomandibular function and neurosensory impairment. DO of the mandibular anterior alveolar process is a valuable and safe method with minor side effects regarding neurosensory impairment.     

Simultaneous maxillary and mandibular distraction osteogenesis with a semiburied device

Distraction osteogenesis is a technique utilizing natural healing mechanisms to generate new bone; it is commonly used to lengthen the hypoplastic mandible. Distraction of the maxilla and mandible as a unit is an obvious extension of the technique. We describe the application of a semiburied distractor to simultaneously lengthen the mandible and maxilla and level a canted occlusal plane in three cases. The indications for bimaxillary distraction are reviewed, including its advantages, disadvantages and limitations.     

MS-1型内置式下颌骨骨牵引延长器及其动物实验

目的：报告自行研究开发的内置式下颌骨骨牵引延长器,探讨其用于动物实验的可行性。方法：１５只犬采用ＭＳ－１型下颌骨牵引延长器,并进行单、双侧下颌骨体部牵引延长２０ｍｍ,并进行Ｘ线与组织学观察。结果：实验犬下颌骨牵引延长效果肯定,器械均未见断裂或松动变形,牵引区成骨明显。结论：ＭＳ－１型内置式牵引器具有临床应用可能性。     

Posterior mandibular alveolar distraction osteogenesis utilizing an extraosseous distractor: a prospective study

BACKGROUND: The aim of this clinical study was to evaluate bone elongation and the effectiveness of distraction osteogenesis when utilizing an extraosseous distractor to treat cases of atrophic posterior mandible. METHODS: Fourteen surgical sites were evaluated in 10 healthy, non-smoking, female patients, with varying degrees of atrophic posterior mandible, who underwent surgery by alveolar bone distraction. The patients presented between 6 and 10 mm above the mandibular, inferior alveolar nerve. Panoramic radiographs were taken before surgery and at the beginning and end of the consolidation period. The extraosseous distractor was fixed to both the basal and the osteotomized bone. After a 7-day latency period, the patients rotated the distractor rod three times a day for 3 to 10 days (1 mm per day). The mobile segment was held in place for 8 to 12 weeks for bone consolidation. RESULTS: The results revealed a distraction range of 2.32 to 8.11 mm (mean distraction +/- standard deviation, 5.12 +/- 1.67 mm), which was less than the real, measured distance between the upper and lower miniplates of the distractor (5.58 +/- 1.62 mm). The bone segments showed between 0.03 and 2.53 mm (mean, 0.88 +/- 0.59 mm) resorption above the upper miniplate. The efficacy of the extraosseous distractor was calculated as between 30.41% and 94.58% (73.45% +/- 20.32%). CONCLUSIONS: Bone regeneration was obtained in all cases; however, when planning alveolar bone distraction using the extraosseous distractor, greater distraction should be performed to compensate for the inclination of the distractor rod and possible bone loss. This adjustment should increase the efficacy of distraction osteogenesis.     

Longitudinal results of mandibular distraction osteogenesis in hemifacial microsomia

The aim of this study was to evaluate mandibular distraction therapy by three-dimensional (3-D) computed tomography (CT) imaging so as to be able to improve the treatment results. The study group consisted of eight children (3 male and 5 female) with hemifacial microsomia. For each child, CT scans of the head were available (Pro Speed S Fast Spiral scanner; General Electric). Longitudinal measurements of the mandible, bony and soft tissue 3-D reconstructions, and masticatory muscles were demonstrated. Three-dimensional CT scans provide important data concerning the results of mandibular distraction therapy and should be used in treatment evaluation. In some patients and for some muscles only, a small increase in the volume of the affected side of the masticatory muscles in comparison to the normal side was found 3 years after mandibular distraction. In around 50% of the cases, there seems to be a relapse occurring 1 year after distraction osteogenesis, and this relapse has a progressive character when seen 3 years after distraction osteogenesis in comparison to 15 weeks after distraction osteogenesis.     

Segmental distraction osteogenesis of the anterior alveolar process.

PURPOSE: This article describes a nonextraction therapy for patients with anterior tooth crowding in the mandible or with an unfavorable relation between the anterior dentoalveolar area and the skeletal base. The method involves the gradual repositioning of the dentate segment by use of distraction osteogenesis. PATIENTS AND METHODS: The method was applied in 25 patients. Indications comprised skeletal Class II patients with crowding, Class I patients with crowding, and Class III patients requiring decompensation before orthognathic surgery. A special hinge-joint bone plate was developed to allow the rotation of the anterior bone segment into the desired position. The gradual repositioning was achieved with orthodontic appliances. RESULTS: The procedure was successful in all patients. The typical advancement at the incisal edge was 2 to 5 mm. CONCLUSION: This method represents a new approach for nonextraction therapy in the mandible. It requires no soft or hard tissue grafting and results in favorable tissue conditions at the distraction site.     

Treatment of mandibular retrusion by distraction osteogenesis: a new technique

We treated the mandibular retrusion of a 20-year-old man by distraction osteogenesis. Our aim was to avoid any visible discontinuities in the soft tissue profile that may result from conventional "one-step" genioplasty. The result was excellent. In addition to a good aesthetic outcome, there was increased bone formation not only between the two surfaces of the osteotomy but also adjacent to the distraction zone, resulting in improved coverage of the roots of the lower incisors. Only a few patients have been treated so far, but the method seems to hold promise for the treatment of extreme retrognathism, as these patients often have insufficient buccal bone coverage.     

失感觉神经支配大鼠下颌骨牵张成骨动物模型的建立

目的：建立一个新的可行性和重复性俱佳的失感觉神经支配大鼠下颌骨牵张成骨模型。方法：24只大鼠随机分为2组,实验组大鼠先自下颌孔至颏孔切除下齿槽神经后,从升支前缘至下颌骨下缘行全层骨切开,用螺钉固定特制的钛牵张器,对照组为保留下齿槽神经的大鼠下颌骨牵张成骨,5d延迟期后,均进行单侧下颌骨牵张,速率：0．2mm／12h,牵张期为lOd,随后进入固定期。分别于固定期第14d、28d处死大鼠,进行大体标本观察和组织学检测。结果：实验过程被所有24只大鼠很好的耐受,切口感染率低,无牵张器脱落。大体标本观察表明,在牵张间隙形成了很好的骨痂组织,牵张间隙达到了预期的长度。感觉神经缺失对牵张成骨具有负面调节作用。结论：成功建立了一个新的可行性和重复性俱佳的失感觉神经支配大鼠下颌骨牵张成骨模型,该模型有助于感觉神经对牵张成骨影响的分子机制的进一步深入研究。     

The application of alveolar distraction osteogenesis following nonresorbable hydroxyapatite grafting in the anterior maxilla: a clinical report

Distraction osteogenesis is a method of increasing bone length through the application of slow, controlled force on bone segments where periosteum and medullary blood supply are maintained. Recently, the procedure has been adapted to alveolar augmentation prior to prosthodontic rehabilitation. This report describes the use of alveolar distraction in the anterior maxilla and presents, to the authors' knowledge, the first reported successful application of the technique following nonresorbable hydroxyapatite grafting.     

Complications in alveolar distraction osteogenesis: A clinical investigation.

PURPOSE: The purpose of this study was to evaluate distraction osteogenesis for reconstruction of vertically deficient alveolar ridges and to investigate the occurrence of complications during treatment and the effect of these complications on the final outcome. PATIENTS AND METHODS: The study included 23 patients who underwent a total of 29 distraction procedures. Two types of distractors were used: intraosseous and juxtaosseous. All of the patients were submitted to the same distraction protocol. The complications occurring during treatment were classified as 1) intraoperative, 2) postoperative, 3) during distraction and consolidation, and 4) postdistraction. RESULTS: The prevalence of cases with complications was 41.37% intraoperative, 24.13% postoperative, 65.51% during distraction and consolidation, and 58.62% postdistraction. Because many complications coincided in some patients, the overall prevalence throughout the treatment was 79.31% of cases; 3.44% of the complications jeopardized subsequent implant placement. CONCLUSIONS: Although a high frequency of complications was encountered, severe complications were rare. Most of the complications had simple solutions, and most did not jeopardize the final outcome. Distraction osteogenesis is a viable option for treating vertical alveolar bone defects.     

应用颌骨牵引成骨技术行下颌前部加宽术

目的 临床矫治上下颌骨宽度不调一下颌弓狭窄的病例时，既往采用的方法是正畸治疗调整下颌牙列内牙轴的方向。实际上这不是真正意义的下颌增宽，矫治后的效果已令人怀疑。运用颌骨牵引延长技术，使真正的下颌骨增宽成为可能。本文拟就运用颌骨牵引延长技术治疗下颌弓狭窄的手术程序、手术方法及手术效果、注意事项等作一探讨。方法 3例病人均为发育性下颌弓狭窄，同时伴有下颌后缩或上颌前凸畸形。手术分两个阶段：第一阶段行下颌骨前部加宽术，全麻下经口内入路行下颌正中截骨术，安置牵引器，按颌骨牵引成骨技术常规行牵引加力，并按常规拆除牵引器。第二阶段行正颌外科手术矫正主要的颌骨畸形。两阶段之间应用正畸技术调整牙轴方向、排齐牙列并去代偿。结果 第一阶段手术以后，下颌骨前部被延长7mm～10mm，新形成骨骨质良好，经正畸治疗和正颌外科手术治疗后病人面型及咬合关系良好，经复查效果稳定。结论 颌骨牵引成骨技术可用于下颌骨弓狭窄的病人的矫治，该技术效果肯定，手术并不复杂，术后反应不犬，宜于推广使用。     

Closure of vertical alveolar bone defects with guided horizontal distraction osteogenesis: an experimental study in pigs and first clinical results.

PURPOSE: To evaluate the option of treating alveolar clefts by guided distraction osteogenesis instead of applying osteoplasty with autologous bone grafts from iliac crest, rib or fibula. MATERIAL AND METHODS: At first, 30 land-bred pigs were operated upon. Treatment of each animal included creating bony defects measuring 2, 4 or 8 mm in the maxilla, anterior to the canine region and up to the nasal periosteum. In 15 of the 30 animals, a new horizontal segment distractor was tested. The device was placed in situ prior to creating an alveolar segment posterior to the defect. This segment was then transported gradually by distraction, thus crossing and closing the defect. At the end of the distraction and stabilization periods the newly formed bony tissue was examined. RESULTS: The critical size of defects was found to be larger than 4 mm. In five of six animals with a horizontal defect of 8 mm, complete ossification of the defect had occurred following distraction osteogenesis. This technique was then applied to five patients successfully. CONCLUSION: It was shown that distraction osteogenesis is a valid alternative for treating alveolar clefts.     

Surgical and prosthodontic treatment using alveolar distraction osteogenesis and implant placement for a patient with mandibular prognathism: a clinical report

A 49-year-old patient presented with an Angle Class III malocclusion with a partially edentulous mandible, as diagnosed by orofacial examination and radiographic and cephalometric analyses. The patient refused orthognathic surgery; therefore, the treatment plan included the preparation of all teeth and fabrication of provisional restorations to reestablish optimal occlusion. To allow for the placement of 3 implants, the edentulous posterior mandibular ridge was improved via alveolar distraction. The patient was recalled 3, 6, 12, and 24 months after prosthodontic treatment. The oral situation was stable and patient satisfaction was reported as high.     

Anterior maxillary alveolar distraction osteogenesis: a prospective 5-year clinical study

PURPOSE: Anterior maxillary alveolar vertical distractions were followed for a 5-year period of time. MATERIALS AND METHODS: A total of 30 vertical distractions were done in 28 patients. Two patients had both anterior maxilla and anterior mandibular distractions for a total of 30 distractions. Two distraction techniques were used: an implant device (3i) and an orthodontic screw device (Osteomed) for orthodontic attachment. Both devices enabled some horizontal as well as vertical movement. The average net vertical distraction was 6.5 mm, but the average anterior horizontal movement was less than 2 mm. RESULTS: Eighty-four implants were placed, but 8 implants failed to integrate. DISCUSSION: All failed implants had been placed in poor quality bone that needed bone grafting. The most common restoration was a fixed prosthesis supported by implants; the longest follow-up post loading was 4.4 years. CONCLUSION: This clinical study gives additional evidence in favor of the stability and utility of vertical distraction procedures in the maxillary esthetic alveolar zone.     

Bilateral sagittal split osteotomies versus mandibular distraction osteogenesis: a prospective clinical trial comparing inferior alveolar nerve function and complications

The aim of this study was to conduct a prospective clinical trial comparing the neurosensory function of the inferior alveolar nerve (IAN) after mandibular advancement surgery with either bilateral sagittal split osteotomies (BSSO) or mandibular distraction ostoegenesis (MDO). 23 Class II mandibular hypoplasia patients requiring mandibular advancement were randomized into two groups for either BSSO or MDO. Subjective and objective neurosensory evaluations were performed preoperatively and at the following postoperative times: 2 weeks (TBD1), 6 weeks (TBD2), 12 weeks (TBD3), 6 months (TBD4) and 12 months (TBD5). Subjective evaluation included the use of a visual analogue scale (VAS). Objective evaluation included the use of light touch (LT), two-point discrimination (2PD) and pain detection threshold (PD) tests. Intra-operative or postoperative complications were recorded. Using a mixed model, no significant differences were reported in subjective VAS scores and objective LT, 2PD and PD scores between the BSSO and MDO groups over 12 months (p > 0.05). Common postoperative complications included localized wound infection (BSSO = 2, MDO = 6) and condylar resorption (BSSO = 1, MDO = 1).     

应用钛镍记忆合金牵张成骨增高下颌牙槽嵴的初步研究

目的 探讨应用钛镍记忆合金牵张成骨增高下颌牙槽嵴的可行性。方法 选用成年杂种犬10只，拔除两侧下颌全部前磨牙和第1磨牙，实验组1个月后用完全埋置的钛镍记忆合金牵张器完成牵张手术。在牵张手术前及术后1、5、13周测量术区颌骨高度，拍X线片，分别在牵张完成后1、3个月处死动物，进行组织学研究。结果 牵张器就位后骨块即开始牵张升起，术后1周达7．5～11．5mm，其后无明显变化。X线片可见牵张完成后1个月牵张区骨密度增高，有新骨生成；3个月骨密度与周围牙槽骨接近。组织学观察牵张区早期有胶原束形成，随后钙化成骨。结论 用钛镍记忆合金牵张器可成功牵张增高犬下颌后牙区牙槽嵴，新骨以膜内成骨方式生成。     

Development of distraction osteogenesis model of the inferior mandibular border and alveolar bone

The aims of this study were to establish an experimental rat model for distraction osteogenesis of the mandible and alveolar bone for the investigation of histologic and radiographic analysis and to develop the device for various distraction models. For osteotomy location and distraction device design, micro-computed tomographic analysis of the structure of rat mandible was performed. Twenty mandibles of Sprawl-Dawley rats were osteotomized based on the analysis, and newly developed custom-made devices were applied with bone screws. After a 5-day latency period, a distraction of 0.2 mm at a single session, and a 4-week consolidation period, animals were killed for histologic samples. The rat distraction osteogenesis model for the inferior mandibular border and alveolar bone was successfully established based on the protocols used in this study. New bone formation occurred at both body and alveolar bones of the mandible by the combination of 2 modes: intramembranous ossification was predominant at the end of distraction period, whereas endochondral ossification was observed at the center of the distraction gap at the end of the 4-week consolidation period. This model can be applied to various conditions related to distraction osteogenesis and provide information for the development of improvements in clinical treatments using distraction osteogenesis.     

Bi-directional distraction osteogenesis of the alveolar bone using an extraosseous device

OBJECTIVES: In alveolar distraction, the bone segment tends to incline palatally or lingually, making rigid control of the segments difficult. The aim of this study was to evaluate the usefulness of a newly developed bi-directional extraosseous alveolar distractor (Medartis V2-Alveolar distractor) for pre- and perioperative vector management. MATERIAL AND METHODS: Seven patients with segmental alveolar atrophy following traumatic tooth loss were treated using the distraction device. The patients were followed up clinically and radiologically. Preoperatively, the initial vector for distraction was determined using CT by measuring the cross-section of the bone. The morphology of the alveolar bone was also analyzed in relation to the planned implant position. Postoperatively, the rate of osteogenesis was monitored with plane radiographs and CT scan. RESULTS: All cases had bone deficit at the anterior surface of the alveolar ridge, showing a typical inclination of the long axis of the bone. Using the distractor, vertical distraction and positioning of the segments with labial orientation was possible. After a consolidation period of 12 weeks on average, sufficient bone formation for implant installation was radiologically observable. Histologic and histomorphometric analysis of one bone biopsy showed very dense mineralized bone (area fraction=78%) with a multidirectional, complex architecture. Implant-supported prosthetic oral rehabilitation was successfully performed in all cases. CONCLUSION: All complications observed in this study were related to the bone deficiency at the anterior surface of the alveolar process. If the technique can be improved, this type of bi-directional distraction is a promising method for alveolar bone repair.