放射照射后牵张下颌骨成骨犬实验动物模型的建立

目的：建立放射照射后牵张下颌骨成骨犬实验动物模型。方法：选取成年中国犬12只,实验组10只以60 Co 颊舌向照射下颌骨后部标定区域,照射方法为22．8 Gy、5．7 Gy／次,共4次（生物等效剂量为50 Gy／25次）。对照组2只不照射。照射完成后3个月,在动物下颌第五和第六臼齿间行骨皮质切开术,植入骨牵张器,经过1周的延迟期,2次／d,每次0．5 mm 的速率连续牵张下颌骨10 d,然后固定8周。处死动物,以放射学,组织学和 SPECT 方法对牵张区新骨进行检查,对下牙槽神经进行组织学检查。结果：除实验组1只动物因麻醉意外死亡,其他动物都完成了实验。实验组和对照组新骨形成无明显差异。SPECT 显示实验组成骨活跃。观察到下牙槽神经修复性组织学变化。结论：放射照射后牵张犬下颌骨可形成新骨。     

牵张成骨延长山羊下颌骨后下齿槽神经的组织学变化

目的：研究下颌骨牵张成骨术后不同时间下齿槽神经的组织学改变。方法：对8只成年山羊行双侧下颌体骨皮质切开术,经口外安置自行研制的下颌牵张器,以每天1mm的速率向前牵引延长其中6只山羊的下颌骨10mm。于牵张结束后第2、4、8周各处死2只动物,取双侧下齿槽神经作组织学检查,另2只未牵张的山羊作对照。结果：下齿槽神经受牵张力作用发生了一定程的沃勒变性,主要表现为髓鞘肿胀、碎裂及轴索数目减少。但随着固定时间的延长,受损神经纤维逐渐得以再生。结论：下颌骨牵张成骨术后下齿槽神经发生了轻度的退行性变,但这种退行性变在适宜的速率牵张是可逆的。     

牵张成骨延长山羊下颌骨后下齿槽神经的组织学变化

目的 :研究下颌骨牵张成骨术后不同时间内下齿槽神经的组织学改变。方法 :对 8只成年山羊行双侧下颌体骨皮质切开术 ,经口外安置自行研制的下颌牵张器 ,以每天 1mm的速率向前牵引延长其中 6只山羊的下颌骨10mm。于牵张结束后第 2、4、8周各处死 2只动物 ,取双侧下齿槽神经作组织学检查 ,另 2只未牵张的山羊作对照。结果 :下齿槽神经受牵张力作用发生了一定程度的沃勒变性 ,主要表现为髓鞘肿胀、碎裂及轴索数目减少。但随着固定时间的延长 ,受损神经纤维逐渐得以再生。结论 :下颌骨牵张成骨术后下齿槽神经发生了轻度的退行性变 ,但这种退行性变在适宜的速率牵张下是可逆的     

兔下牙槽神经游离模型的建立

目的 建立兔下牙槽神经游离模型,为制作保留下牙槽神经的下颌骨骨折或骨缺损模型奠定基础.方法 选取大耳白兔15只,3只设为空白对照,12只为实验组,游离双侧下牙槽神经后,右侧保留,左侧切断,并于角前切迹前5mm处制作2mm×5mm骨折模型.术后3d、5d、7d、14d、2ld、28d行针刺试验.术后1w、2w、3w、4w各取3只制取骨标本行HE染色,取术后4周组及对照组双侧下牙槽神经行变色酸2R-亮绿染色.结果 下牙槽神经游离后功能保存良好,组织学观察显示神经游离侧骨愈合顺利,而神经切断侧骨折愈合延迟.外骨痴明显.变色酸2R-亮绿染色有髓神经纤维计数显示神经游离后四周与对照组之间无明显差异(P>O.05),而与神经离断侧差异有统计学意义(P相似文献   

兔下颌骨牵张成骨模型的建立

目的建立兔下颌骨牵张成骨动物模型。方法随机选取新西兰大白兔28只,施行双侧下颌骨切开术,安放牵张器,间歇1周后以0.4 mm/12 h的速度牵张,牵张7 d后固定,在不同时间随机处死动物2只,取下颌骨标本分别行影像学和组织学观察。结果实验动物均耐受手术,并基本获得预期牵张距离,影像学和组织学观察发现,裂隙内随时间延长渐有骨形成。结论以兔下颌骨建立牵张成骨模型经济、可重复性好。     

下颌骨缺损牵张成骨动物模型的建立

目的建立兔下颌骨缺损牵张成骨动物模型,为进一步研究牵张成骨奠定实验基础。方法25只健康成年兔随机分成6组,实验组5组,每组4只,对照组1组共5只。25只兔均行一侧下颌骨切开截骨术,实验组安置自行设计的下颌骨牵张器,经6 d间歇期后,以每天2次,每次0.4 mm的速度牵张8 d进入固定期,于牵张中期(牵张第4天)、牵张末期(牵张第8天),固定期第2、4、6周分别处死4只动物;对照组术后仅保持缺隙而不牵张,与实验组对应的每个时间点处死1只动物,取下颌骨观察骨愈合情况。结果牵张器牵张效率好,固位稳定,实验组动物的下颌骨被成功牵张,牵张区可见新骨形成。实验对照组表现为不同程度的骨不连及骨缺损。结论本研究建立的兔下颌骨缺损牵张成骨模型是较理想的动物模型。     

兔下颌骨骨膜牵张成骨的实验研究

目的 探讨骨膜牵张成骨术的新方法。方法 将自制骨膜牵张器固定于3只兔的双侧下颌骨表面,左侧行骨膜牵张,右侧不牵张,作为对照。牵张过程结束后处死所有动物,标本进行X线和组织学检查。结果 3只动物术后情况良好,无明显并发症。在大体标本和X线片上表现出新骨形成。组织学检查显示牵张区有成骨样细胞浸润和骨组织形成。结论 骨膜牵张成骨技术能够为骨缺损的修复提供一种新的方法。     

变速牵引成骨对兔下牙槽神经的影响

目的　研究变速牵引兔下颌骨15mm对下牙槽神经的影响。方法　5只新西兰白兔单侧下颌骨截开。延迟5d ,以每天1 5mm ,每天2次牵引9mm ,然后继续以每天1mm ,每天2次牵引6mm ,完成牵引后固定15周,分别行肉眼及组织学观察和电生理学检查。结果　下颌骨延长15mm ,新骨生成良好。下牙槽神经牵长2 1. 99% ,牵引结束时神经变性明显,感觉神经动作电位波幅下降为术前的9. 70 % ,潜伏期较术前有所延长,随后出现恢复趋势,到固定15周时,波幅恢复到术前的33. 85 % ,潜伏期基本恢复正常。结论　下颌骨变速牵引15mm后,下牙槽神经受到明显的影响,到15周时,下牙槽神经的功能有恢复的趋势,但恢复尚不完全。     

下颌骨骨压缩后下牙槽神经组织学变化的研究

目的观察下颌骨骨压缩前后下牙槽神经的组织学变化。方法北京本地犬8只，将其分成4组，每组2只。将钛合金骨压缩器植入实验犬右侧下颌骨体部，以1.0 mm/3 d的频率缩短骨压缩器，总共缩短5.0 mm。在实验后的第1天、第15天、第45天和第90天时分别处死4组动物，取压缩区域的下牙槽神经常规苏木精- 伊红染色，观察神经纤维的组织学变化。结果①骨压缩后第1天，神经纤维大量的退行性变，大量轴突肿胀，神经轴稀疏，连续性中断，较多神经纤维的髓鞘消失；②骨压缩后第15天、45天，神经纤维仍旧有脱髓鞘的现象，可以看到雪旺细胞，神经纤维的连续性逐渐恢复；③骨压缩后第90天，神经纤维均匀分布，神经纤维脱髓鞘的现象少见，轴突平行排列，密度均匀，神经束形态完整，与正常的神经结构类似。结论骨压缩可以对下牙槽神经的组织结构造成改变，但是这种损伤是暂时的、可逆的，随着时间的推移，损伤神经组织可以恢复接近正常。     

兔双侧下颌骨牵张成骨实验动物模型的建立

目的:建立兔双侧下颌骨牵张成骨实验动物模型。方法:选用16只成年雄性新西兰大白兔,随机分为4组,每组4只。在双侧下颌骨第一前磨牙前方无牙区行骨切开术,用自制牵张器固定。经过7d潜伏期,以每次0.5mm的速度牵张,每天2次,连续7d。分别在潜伏期末、牵张结束、固定期第14天、第28天处死动物,切取标本行X线和组织学观察。结果:全部动物的下颌骨被成功延长,牵张间隙逐渐被新生骨组织充填。结论:该方法建立的动物模型具有可行性和可重复性。     

Evaluation of inferior alveolar nerve function during distraction osteogenesis in the dog

Purpose: A series of electrophysiologic studies were performed in a canine model to evaluate inferior alveolar nerve (IAN) function during distraction osteogenesis of the mandible.Materials and Methods: Fourteen dogs, including two controls, were used in the study. Twelve dogs underwent a 10-mm bilateral mandibular lengthening with an intraoral bone-borne appliance and midbody osteotomy. By using sensory nerve action potentials, IAN function was assessed before and immediately after surgery, before and at the completion of distraction, and before necropsy after 4, 6, or 8 weeks of fixation.Results: Twelve of the 24 nerves showed a complete loss of evoked potential after surgery without recovery at any point throughout the study. Acute nerve injury caused by either the osteotomy or screw encroachment was identified at necropsy. The other 12 nerves showed reproducible responses after surgery. Eight of these nerves had significant amplitude attenuation of the evoked potentials, which was identified at necropsy as a result of acute injury. The remaining four nerves did not show significant evoked potential abnormalities and appeared to be grossly normal at necropsy. During distraction, the amplitude of evoked potentials in all 12 nerves remained at the postoperative level, whereas latency showed a significant delay. In 7 of these 12 nerves, various degrees of evoked potential recovery were identified at the completion of the study.Conclusions: The high incidence of acute IAN injury in the current study was primarily related to device construction and osteotomy technique. If acute nerve injury is avoided at surgery, distraction osteogenesis with 10 mm mandibular lengthening appears to produce minimal deleterious effect on IAN function.     

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。     

下颌骨牵引成骨术对兔下牙槽神经的影响

目的观察牵引成骨术的不同牵引速度和距离对下牙槽神经的影响。方法新西兰白兔16只,以不同的牵引速度和牵引距离组合,随机分成5组。通过肉眼观察、X线片及电生理检查、组织学观察等了解下颌骨成骨及下牙槽神经再生情况。结果以2.0mm/d速度牵引下颌骨会产生骨不连接,以1.5mm/d速度牵引颌骨15mm,虽可获得良好的成骨,但可造成下牙槽神经不可逆性的损伤。结论下颌骨牵引成骨术的速度宜控制在0.5～1.5mm/d范围内;当牵引距离较小时,可适当加大牵引速度以提高牵引效率,当牵引距离较大时,应调小牵引速度,以减小对下牙槽神经的损伤。     

Bilateral mandibular distraction in adult dogs with an epiperiosteal distractor

We tested the function and efficiency of a new intraoral, bone-borne distraction device for mandibular lengthening, and the effect of bilateral transsection of the inferior alveolar arteries on osteogenesis in adult dogs. Nine adult Beagles had bilateral complete mandibular osteotomies and epiperiosteal placement of the distractor. After 7 days, the mandibles were distracted at 1 x 1mm/day, 1 x 0.5 mm/day or 2 x 0.25 mm/day for 15 or 30 days, respectively. Hemimandibles were harvested after 1, 14, or 42 days consolidation and evaluated clinically, radiographically and histologically. The mean distraction achieved was 11 mm (range 4-16 mm). New bone formation and clinical stability increased with increasing consolidation time and was independent of the distraction protocol used. Osteogenesis at the distal and proximal mandibular fragments did not differ. In 10/18 distraction sites, wound dehiscences compromised osteogenesis. The new epiperiosteal distractor permitted successful distraction osteogenesis despite complete bilateral osteotomy with section of the medullary vessels in adult dogs.     

Changes in the inferior alveolar nerve after mandibular lengthening with different rates of distraction.

PURPOSE: This study investigated the changes in the inferior alveolar nerve after mandibular lengthening with different rates of distraction. MATERIALS AND METHODS: Bilateral mandibular corticotomies were performed in 8 goats. The mandibles in 6 goats were lengthened 10 mm using a custom-made distractor with 2 different rates of distraction (1 mm/d [n = 3] and 2 mm/d [n = 3]); the other 2 nondistracted mandibles served as a control. The goats with distracted mandibles were killed at 2 weeks after completion of distraction. The inferior alveolar nerve specimens from all animals were harvested and processed for histologic and ultrastructural evaluation. RESULTS: The mandibles were lengthened successfully in the distracted animals. Morphologic changes in the inferior alveolar nerves were observed when compared with the nondistracted controls. Moreover, signs of nerve degeneration, such as demyelination, axonal swelling, axoplasmic darking, and decrease in the number of axons, were more extensive and prominent in those nerves distracted at a rate of 2 mm/d. CONCLUSIONS: Degenerative changes in the inferior alveolar nerve occur after mandibular lengthening by distraction osteogenesis. The distraction rate of 1 mm/d appears to be tolerable and safe for the inferior alveolar nerve, but rapid distraction may cause serious degeneration.     

Expression of nerve growth factor and vascular endothelial growth factor in the inferior alveolar nerve after distraction osteogenesis

The objective of this study was to evaluate changes occurring in the inferior alveolar nerve (IAN) subsequent to mandibular distraction osteogenesis, with regard to the expression of nerve growth factor (NGF) and vascular endothelial growth factor (VEGF). Unilateral mandibular distractions (0.5mm each, twice per day for 10 days) were conducted on 8 mongrel dogs. Two animals were killed at 7, 14, 28 and 56 days after completion of distraction. The distracted IAN and contralateral control nerve were then harvested and analysed histologically and immunohistochemically. Signs of acute nerve injury, including demyelination, were observed in the distracted IAN on the 7th and 14th day after distraction. At 56 days, the histological features of the distracted IAN were similar to those of the control nerve. The levels of NGF and VEGF expression were significantly elevated on the 7th and 14th day after distraction. NGF was expressed in most of the distracted nerve tissues, but VEGF was primarily detected in Schwann cells and the neurovasorum. VEGF expression had returned to normal but NGF expression was still profoundly elevated 28 days after distraction. NGF expression returned to normal levels at 56 days after distraction. NGF and VEGF appeared to have been elicited from the Schwann cells and damaged nervous tissues, and they may play important roles in the initial healing of damaged nerves. VEGF expression returned to normal more quickly than did NGF expression. This may indicate that hypoxic conditions within the distracted nerve had recovered to normal during the early stages of consolidation. Micro-vessels in the distracted nerve may have recovered more rapidly than did the nerve tissue itself.     

Effect of distraction osteogenesis on the severely hypoplastic mandible and inferior alveolar nerve function.

PURPOSE: The purpose of this study was to examine the effect of distraction osteogenesis surgery on the inferior alveolar nerve (IAN) and on the stability of the occlusion in patients undergoing mandibular osteotomy and advancement for correction of severe retrognathia. MATERIALS AND METHODS: Five patients (4 women and 1 man) underwent vertical posterior body osteotomy or bilateral sagittal split ramus osteotomy with the application of a distraction device for advancement of the mandible of 10 to 14 mm. After a period of latency, each mandible was advanced 1 mm per day until the patient achieved a Class I occlusion. Distraction devices were removed after a suitable period of consolidation (4 to 11 months). IAN sensory function was evaluated by 2-point discrimination, response to painful stimulus, and moving brush stroke identification. Testing of the IAN was performed on all patients at 7 different time intervals: preoperative (T0), postsurgery and predistraction (T1), within 7 days after the end of distraction (T2), 3 months after T2 (T3), 6 months after T2 (T4), 9 months after T2 (T5), and 1 year after T2 (T6). The same surgeon performed all IAN testing. RESULTS: There were no instances of malunion or fibrous union. At the 1-year follow-up, all 5 patients showed no relapse of their advancement as assessed by their maintenance of a Class I occlusion. Radiographic analysis was not done to discern skeletal versus dental stability. All 10 IANs were intact after the initial surgery. As time progressed, all 10 nerves showed improvement of function as measured by 2-point discrimination, response to painful stimulus, and moving brush stroke identification. At 1 year postsurgery, all 10 nerves showed function consistent with or very near presurgery levels. CONCLUSION: Stable mandibular advancements of 10 mm and greater can be successfully accomplished by distraction osteogenesis without producing significant damage to the IAN.     

下颌骨牵引延长后下齿槽神经功能的评价

目的 采用三叉神经体感诱发电位（trigeminal somatosensory evoked potential,TSEP)检查恒河猴下颌骨牵引延长术对下齿槽神经功能的影响。方法 健康青年恒河猴7只，行下颌角部完全骨截开术，右侧或双侧安放牵引器。截骨间隙平均牵引距离为13．5mm。于术前、牵引完成时、牵引完成后4周分别进行下齿槽神经SEP检查。结果 术前下齿槽神经SEP各波的潜伏期测量值，两侧对比检验差异无显著性。牵引术完成时SEP各波的潜伏期较术前均有不同程度延长（P＜0．01，P＜0．001），波幅显著下降（P＜0．001）。术后4周各波潜伏期及波幅均有恢复，但多数差别仍有显著性。结论 TSEP检查提示下颌骨牵引延长术对下齿槽神经功能有一定影响，术后4周其功能有部分恢复。     

Response of Schwann cells in the inferior alveolar nerve to distraction osteogenesis: an ultrastructural and immunohistochemical study

The biological mechanisms of nerve adaptation to distraction osteogenesis have not yet been elucidated. This study observed response of Schwann cells in the inferior alveolar nerve (IAN) following mandibular lengthening by electron microscopy and immunohistochemistry of S-100 protein, a specific marker of Schwann cells. Unilateral mandibular distraction (10mm elongation) was performed in nine young adult goats. Three animals were sacrificed at 7, 14 and 28 days after completion of distraction, respectively. The distracted IAN specimens and control nerves (from the contralateral sides) were harvested and processed for histological, ultrastructural and immunohistochemical examinations. Wallerian degeneration was observed in the distracted IAN, and Signs of axonal regeneration, as well as many activated Schwann cells were seen in the lengthened nerves. The expression of S-100 protein increased significantly at early stage of distraction osteogenesis, but almost returned to the normal level at 28 days after distraction. This study suggests that Wallerian degeneration caused by mechanical stretching may stimulate Schwann cells to enter a proliferated and activated state. Schwann cells and S-100 protein appear to play crucial roles in axonal regeneration that contributes to nerve adaptation to gradual distraction. Therefore, the IAN injury caused by mandibular gradual distraction was not serious; it seems to recover totally through a complicated repair mechanism.