变速牵引与常速牵引成骨对下牙槽神经影响的比较研究

目的:通过比较变换速度和常规速度牵引成骨对下牙槽神经的影响,探讨较大距离牵引时提高牵引成骨效率的可能途径。方法:新西兰白兔9只,随机分成2组,单侧下颌骨截开。延迟5 d。变速组5只,以0.75mm×2/d,牵引9 mm,继续以0.5 mm×2/d,牵引6 mm,最长固定30周。常速组4只,以0.5 mm×2/d,牵引15mm,最长固定15周。分别行大体观察、电生理检查和组织学观察。结果:下颌骨延长15 mm,两组新骨都生长良好。牵引后两组下牙槽神经出现严重变性,感觉神经动作电位波幅明显下降,潜伏期延长,固定15周时,两组波幅都出现恢复趋势,潜伏期基本恢复,固定30周时,变速组神经结构和功能基本恢复正常。结论:变速牵引成骨可以在不增加下牙槽神经损伤的情况下,提高牵引成骨的效率。     

下颌骨牵引成骨术对下牙槽神经功能影响的实验研究

目的　研究下颌骨牵引成骨术对下牙槽神经功能的影响。方法　对青年恒河猴 16只 ,全麻下行下颌角部骨截开术及牵引器置入术 ,术后第 5天开始以 0 5mm× 2次 /d的速度牵引 ,共15d。采用八导肌电图仪 ,表面电极在颏孔处刺激 ,针电极在卵圆孔附近记录 ,分别在术前、牵引完成后 0、2、4、6、9、12周时行感觉神经动作电位测试。结果　牵引完成时潜伏期较术前增加 2 2 18% ,其后逐渐降低 ,至牵引完成后 12周时仍较术前高 10 70 %。牵引完成时波幅降至术前的 2 8 5 4% ,牵引后 12周时恢复至术前的 99 84%。结论　下颌骨牵引成骨术对下牙槽神经的功能会产生暂时性影响 ,随着神经髓鞘和轴突的再生 ,神经功能可逐渐恢复正常。     

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。     

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。     

下颌骨牵引成骨术对免下牙槽神经的影响

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。     

变速牵引提高牵引成骨效率的实验研究

目的:观察变换速度牵引兔下颌骨15mm后新骨生成的质量,探讨提高牵引成骨效率的方法。方法:新西兰白兔5只,单侧下颌骨截开。延迟5d后,以0.75mm/次、2次/d的速率牵引6d,共9mm;再以0.5mm/次、2次/d的速率牵引6d,共6mm;固定15周,新骨分别行大体、放射学和组织学观察。结果:牵引结束后新骨逐渐成熟,到固定15周时,牵引区新骨与正常骨接近。结论:变速牵引成骨能够保证新骨的良好生成,缩短牵引时间,提高应用效率。     

下颌骨牵张成骨对下牙槽神经影响的实验研究

目的　观察狗双侧下颌骨牵张成骨术中不同时间点的下牙槽神经的电生理功能及组织学结构的变化。方法　实验组 :12只狗行保留下牙槽神经的双侧下颌骨截断术 ,装上自制的口内牵张器 ,于术后第 8天开始牵张 ,1mm/d ,共 10d ,牵张长度约 10mm。分别在牵张中第 6天、牵张完毕后固定 2周及 8周时各处死 4只动物。分别在术前及术后的不同时期用电生理方法检测双侧下牙槽神经的传导功能 ,并于处死前取出双侧下牙槽神经进行组织病理学及超微结构组织学检查。对照组 :4只狗 ,其中 2只狗作为对照组 ,未行手术 ;另 2只狗为手术对照组 ,进行与实验组相同的骨切开截断术 ,上牵张器 ,但未行牵张和固定 ,于操作完毕时取出双侧下牙槽神经作为术后的组织学结构标本。结果　实验组动物的下牙槽神经在光镜下显示部分神经纤维稍肿胀变粗 ;电镜下显示部分神经纤维髓鞘的板层松解及脱髓鞘现象 ;电生理结果显示 ,神经传导的速度于截断术后的不同时期均低于术前 ,但仅术后第 8天 (即牵张前 )的传导速度与术前的传导速度差异有显著性 (P <0 .0 1)。结论　对狗的双侧下颌骨进行牵张成骨时 ,可一过性引起下牙槽神经损伤。其损伤的主要原因是手术过程所致。在适当的牵张速率、牵张长度和牢固的固定条件下 ,下颌骨的牵张成骨术对下牙槽 还原。     

Ⅰ型胶原在去下牙槽神经支配下颌骨骨折愈合中的表达

目的建立稳定性下牙槽神经损伤骨折模型,探讨下牙槽神经对下颌骨骨折骨痂中Ⅰ型胶原表达的影响。方法选用大耳白兔,游离双侧下牙槽神经,右侧保留,左侧切断,在此基础上制作2 mm×5 mm的骨折模型,应用苏木精-伊红、变色酸2R-亮绿染色、原位杂交染色检测下颌骨骨折愈合情况及愈合过程中Ⅰ型胶原的表达情况。结果正常下牙槽神经支配的下颌骨顺利完成骨折愈合,神经离断后骨折愈合延迟。Ⅰ型胶原原位杂交染色表明在第1、2周保留神经侧较神经离断侧Ⅰ型胶原mRNA明显,差异有统计学意义（P<0.05）;在第3、4周,两侧之间差异无统计学意义（P>0.05）。结论下牙槽神经对下颌骨愈合有调节作用,可影响Ⅰ型胶原mRNA的早期表达。     

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   

转移盘牵引成骨整复山羊下颌骨缺损体内实验

目的：观察自行研制的转移盘牵引成骨器（bifocal distraction osteogenesis）整复山羊下颌骨节段性缺损的治疗效果。方法：采用皮质骨切开术制备转移盘,修复下颌骨缺损15mm,延迟期7d,骨牵引每日1．0mm,每日2次,牵引完成后转移盘与对侧骨残端加压压迫3d,固定期X线观察及组织学研究。结果：转移盘为带有下牙槽动脉血供的骨块,骨牵引器固位良好,下颌骨在解剖关系状态下完成骨缺损修复,固定期2周放射影象可见新骨生成,4周可见骨样结构,2－3月骨质修复完成,结论：该牵引器设计合理,固位可靠,手术方法简单,治疗程序有效,可以完成下颌骨缺损的整复。     

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.     

Nerve growth factor injected systemically improves the recovery of the inferior alveolar nerve in a rabbit model of mandibular distraction osteogenesis

Our aim was to find out if nerve growth factor (NGF) injected systemically could improve the recovery of the inferior alveolar nerve in a rabbit model of mandibular distraction osteogenesis. We used 48 New Zealand white rabbits that were treated with bilateral distraction osteogenesis at a rate of 0.5 mm/12 h for 10 days. Immediately postoperatively, NGF or sodium chloride 0.6 μg/day was injected intramuscularly for 20 days. At the end of distraction and after consolidation times of 1, 2, and 4 weeks, the inferior alveolar nerves were evaluated histologically and histomorphometrically. Histologically, at 2 and 4 weeks there was less myelin debris, and more regenerating axons were present, in the NGF than the control groups. The density of myelinated axons was significantly greater in groups with NGF than controls at 2 and 4 weeks (p < 0.05). NGF given systemically can accelerate the recovery of the inferior alveolar nerve in rabbits after mandibular distraction osteogenesis, and is a promising treatment option for neurological complications of mandibular distraction osteogenesis.     

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.     

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。     

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.     

不同速率牵张下颌后下齿槽神经的组织学和超微结构改变

目的 研究不同速率牵张延长下颌骨后下齿槽神经的组织学和超微结构改变,为临床上确立合理而安全的牵张速率提供实验依据。方法 ８只山羊随机分为Ａ、Ｂ、Ｃ三组,Ａ、Ｂ组各３只,Ａ组１ｍｍ／ｄ,Ｂ组以２ｍｍ／ｄ牵张,Ｃ组２只动物为对照。牵张延长下颌骨１０ｍｍ,固定２ｗ处死。取下齿槽神经行组织学,透射电镜观察。结果 牵张动物的下齿槽神经均发生了Ｗａｌｌｅｒ变性,以２ ｍｍ／ｄ牵张组神经退行性病变严重而广泛。超微结构病变主要发生于粗大的有髓神经纤维,而细小的有髓神经及无髓神经纤维未见异常。结论 ２ｍｍ／ｄ牵张会对下齿槽神经造成严重损伤,而１ｍｍ／ｄ牵张速率为较适宜而安全的下颌牵张速率。