不同牵张速率对下颌骨延长后新骨生成的影响

目的：研究不同牵张速率延长下颌骨时对新骨生成的影响。方法：将12只山羊随机分为三组,行双侧下颌体骨皮质切开术后以三种不同牵张速率（0.5mm/d,1mm/d,2mm/d）向前延长下颌10mm。牵张完成后第2、4周各处死2只山羊,取双侧牵张间隙内新骨组织作X光片、组织学、扫描电镜和能谱仪分析。结果：以0．5mm/d和1mm/d牵张下颌骨后形成的新骨质量要好于2mm/d。结论：在牵张延长下颌骨时,1mm/d可能是最适宜的速率。     

不同牵张速率对山羊下颌骨牵张成骨中新骨形成的影响

目的:探讨山羊下颌骨牵张成骨中不同牵张速率对术后新骨形成的影响。方法:12只山羊随机分为3组,每组各4只,在对动物右下颌骨行骨皮质切开术后进行牵张,第1组动物以0.8mm/d的牵张速率进行牵张,第2组动物以1.6mm/d的牵张速率进行牵张,第3组动物以2.0mm/d的牵张速率进行牵张,随机选取实验组4只动物未手术侧正常下颌骨作为对照组。将各组新骨组织和对照组下颌骨组织分别进行骨密度检测和三点弯曲测试,对采用不同速率进行骨牵张后动物下颌骨新骨的生物力学强度和骨密度进行了对比观察。结果:0.8mm/d牵张组新骨骨密度值显著高于其余各牵张组,0.8mm/d牵张组新生骨三点弯曲实验指标均大于另2牵张组。结论:采用0.8mm/d的牵张速率进行牵张能最快促进新骨形成,提高成骨质量。     

不同速率牵张山羊下颌后下齿槽血管变化与血管生成的实验研究

目的:研究不同速率牵张延长山羊下颌骨后下齿槽动静脉的变化和新骨组织内血管生成情况。方法:8只成年山羊随机分为3组,A组(3只)以110 mm/d牵张,B组(3只)以210 mm/d牵张,C组(2只)为对照。A、B两组均牵张延长下颌10 mm,于牵张结束固定后第2周时处死动物,取牵张区下齿槽动静脉及新骨组织行组织学和定量组织学研究,观察下齿槽血管的管壁厚度和管径大小变化,以及新骨中微血管数量变化。结果:两种速率牵张后均未见下齿槽血管壁有病理性改变,但210 mm/d组的血管管径变小,管壁变薄,与对照组相比有显著差异(P<0105)。110 mm/d牵张后微血管密度较210 mm/d牵张后微血管密度高,且新生骨小梁更为成熟,其差异具有统计学意义(P< 0105)。结论:下颌骨牵张后下齿槽血管无明显变化,但快速牵张可能对牵张间隙内血管生成有不良影响。     

骨膜及下齿槽血管束对下颌骨牵张延长的作用

目的:确定下颌骨较差血运状态下进行牵张延长术的参数。方法:成年家兔16只,体质量2. 4~2. 6kg,随机等分为4组,每组4只;行双侧下颌骨骨切开术,采用内置式牵张器(西安中邦公司研制)对双侧下颌骨同时进行牵引;手术时破坏左侧下颌骨膜及下齿槽血管,而保护右侧。延迟期分别为1、7d;牵引速率分别为0. 5、1. 0mm/d, 2次/d;牵引距离均为10mm;保持期为4周。拍摄X线片,测量新骨抗弯强度,并脱钙组织切片观察。结果:骨膜及下齿槽血管破坏侧,延迟期7d组,牵张区新骨形成良好;延迟期1d组成骨质量较差或导致骨不连。结论:兔下颌骨骨膜及下齿槽血管破坏之后,也能进行牵张成骨修复,但要适当延长延迟期,对临床上早期应用牵张成骨技术修复创伤性下颌骨缺损有一定提示作用。     

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     

核素骨显像在局部应用rh-BMP/bFGF加速山羊下颌骨牵张成骨实验研究中的应用价值

目的:应用核素骨显像观察局部应用rh-BMP/bFGF加速山羊下颌骨牵张成骨的效果.方法:利用外置式牵张器进行山羊下颌骨牵张成骨.将10只实验用山羊随机分为5组,每组2只,在下颌第2和第3前磨牙之间行骨皮质切开,将含有rh-BMP15mg及bFGF 2000 UI的载体胶原膜置入左侧牵张骨折间隙,即刻牵开1 mm以利容纳置入的载体胶原膜.对照侧不加生长因子,牵引速度同实验侧.术后5 d开始牵引,3 mm/d,0.5 mm/次×6次/d,分别于牵张完成当日及第2、4、6、12周时将动物进行放射性核素骨扫描检查.结果:随着时间的延长,在不同周期,实验侧牵张间隙中央出现核素浓聚,强度明显较对照侧强.牵张完成12周:实验侧和对照侧核素浓聚变弱,基本上回复到周围正常骨组织密度水平,两者差异明显减少.结论:局部应用rh-BMP/bFGF后实验侧下颌牵张后新骨生成速度和数量优于对照侧,说明外源性生长因子能够加速下颌骨牵张延长区的骨愈合,核素骨扫描检查在观察牵张成骨的效果中具有较高的应用价值.     

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。     

用山羊建立下颌骨曲线牵张成骨实验动物模型

目的:探讨用山羊建立下颌骨曲线牵张成骨实验动物模型的可行性和优越性。方法:选用山羊4只,通过自行研制的下颌牵张器经口外途径建立2种下颌骨弧形缺损(下颌角及下颌骨正中联合部)牵张修复的动物模型。术后第6天开始牵引,速率1 mm/d,牵引25~34 d。结果:4只山羊的下颌骨弧形缺损成功地通过牵张成骨被修复,牵张间隙内新骨生成确切。结论:山羊是一种较理想而经济的进行牵张成骨基础研究的实验动物,所建动物模型具有很高的可行性和可重复性。     

下颌骨延长术后牵张器拆除时机的实验研究

目的 :研究家兔下颌骨延长术后新生骨回缩情况 ,确定牵张器的拆除时机。方法 :成年家兔 16只 ,体重 2 .4～ 2 .6kg ,随机等分为 4组 ,每组 4只 ;行双侧下颌骨骨切开术 ,采用内置式牵张器对双侧下颌骨同时进行牵引。延迟期 :7d ;牵张期 :10d ;牵引速率 0 .5mm/次 ,2次 /d ;保持期分别为 2周、4周、8周、12周。保持期后行第二次手术取出牵张器 ,并同时植入钛钉为参照 ,判断下颌骨改建后新成骨有无缩短 ,观察期为 8周。结果 :保持期为 2周、4周组的实验动物新生骨在 8周后明显回缩 ,分别为 2 .1± 1.2mm、1.4± 1.3mm ;而保持期 8周、12周组 ,8周后新生骨未见明显回缩。结论 :兔下颌骨牵张延长术后 ,牵张器应在保持期 8周拆除 ;拆除过早 ,新生骨区产生明显回缩。     

牵张成骨延长下颌骨过程中血管生成数量的定量检测

目的定量检测牵张成骨(DO)延长下颌骨过程中血管生成的数量,初步探讨DO过程中血管生成的时空模式。方法用自行研制的牵张器将12只成年雄性山羊双侧下颌骨以1 mm/d的速率延长10 mm,在牵张开始当天,牵张第5天,牵张结束当天,固定第102、0和30天分别处死2只动物,另选取2只山羊不实施手术作为正常对照组。获取牵张区骨组织标本并作相应的组织学处理后作JC70免疫组化染色,并用Chalkley血管计数法对血管生成数量进行定量检测。结果①在间隙期末已有大量血管生成,牵张至第5天时达到峰值,随后呈梯度递减的趋势。②牵张结束时,血管密度由骨小梁形成区带(MCF)向纤维区带(FIZ)递减;随着固定时间延长,各区带血管密度均呈梯度减弱;固定后期,MCF阳性染色基本消失,血管密度由FIZ向MCF递减。结论在牵张成骨延长下颌骨过程中,血管生成与新骨形成密切相关,两者具有空间联系性;牵张早期微血管的大量生成是向骨组织及周围软组织再生提供充足血供的组织结构基础。     

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.     

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。     

牵张成骨延长一侧下颌骨对颞下颌关节的影响

目的：研究牵张成骨（DO）延长一侧下颌骨对双侧颞下颌关节（TMJ）的影响。方法：用DO技术将8只山羊的一侧下颌骨延长10mm，在牵张完成后第8和16周分别处死4只动物，取双侧关节作组织学和扫描电镜研究。结果：下颌一侧DO术后双侧髁状突发生适应性改建，髁突表面超微结构正常。结论：在适当的牵张条件下延长一侧下颌骨不会对TMJ造成病理性损害。     

山羊下颌牵张成骨的超微结构观察及新骨钙磷元素测定

目的为进一步探索DO的成骨方式和新骨改建过程提供实验依据。方法标本取自6只山羊双侧下颌骨牵张成骨形成的新生骨组织及其邻近原骨组织,用扫描电镜观察骨组织断面的超微结构,同时用X线能谱仪测定新骨Ca/P原子个数比及其动态变化。结果牵张间隙超微结构观察显示大量新骨组织生成,其骨质密度和钙、磷元素含量随牵张后固定时间的延长而趋于正常骨组织。结论山羊下颌牵张成骨形成的新生骨段可逐渐改建为具有正常结构的骨组织。     

下颌牵张成骨过程中血管生成和血供重建的立体形态构筑

目的: 观察下颌牵张成骨过程中血管生成和血供重建的立体形态构筑。方法: 用自行研制的牵张器将12只成年雄性山羊双侧下颌骨以1mm/d的速率延长10mm,在牵张开始当天、牵张第5天、牵张结束当天、固定第10天、第20天和第30天分别处死2只动物,另选取2只山羊不实施手术作为正常对照组。采用树脂灌注微血管铸型技术,酸蚀后用扫描电镜观察牵张区血管的立体形态构筑。结果: 在牵张期,骨断端骨膜血管和骨髓内血管密度明显增加,以向牵张间隙中央增生为主,并开始相互连接形成血管网;在固定早期,在间隙中央仍可见少量血管增生,膨大的静脉窦排列方向与牵张方向趋于一致;随着固定时间的延长,牵张区的血管连接更加广泛,血管新生现象逐渐消失,血管系统变得更加成熟。结论:牵张区的血管新生与新骨的生成和矿化之间存在紧密的时空联系;牵张间隙的新骨组织同时接受来源于骨膜和骨髓的血供。     

Effect of icariin on bone formation during distraction osteogenesis in the rabbit mandible

The aim of this study was to evaluate the effect of icariin on bone formation during mandibular distraction. 40 Rabbits were randomly divided into experimental and control groups. Mandibular distraction was performed 5 days after unilateral mandibular osteotomy using a custom-made external distractor at a rate of 0.5 mm/12 h for 10 days. From the first day of distraction, icariin (2.5 mg/kg·day) was orally administered to the experimental group and placebo to the controls. 10 Rabbits were killed at the end of weeks 2 and 4 of the consolidation phase. The distracted hemimandible was harvested and newly formed bone was evaluated by soft radiography, histology and bone histomorphometry. Regenerated bone was evaluated for bone mineral density by dual-energy X-ray absorptiometry. The experimental group had fewer radiolucent areas on soft radiography. Bone mineral density of regenerated bone was higher in the experimental than in the control group at 2 and 4 weeks. At 4 weeks, the experimental group had greater volumes of new bone, higher trabecular number, and less trabecular separation than the controls. Oral administration of icariin could promote bone formation during mandibular distraction osteogenesis and might be a promising method for shortening the course of distraction osteogenesis.     

Correlation of immunohistochemical characteristics of the craniomandibular joint with the degree of mandibular lengthening in rabbits.

PURPOSE: This study examined immunohistochemical changes in the craniomandibular joints of rabbits after distraction osteogenesis following mandibular corticotomy. MATERIALS AND METHODS: The experimental animals (n = 8) were divided into 3 groups that underwent 2, 3.5, and 5 mm of unilateral distraction osteogenesis (groups 1, 2, and 3, respectively). After corticotomy of the left mandibular body and a 7-day healing period, a second operation was performed to expose the device. Distraction was then performed at the rate of 0.5 mm/d. A 14-day consolidation period was allowed after the distraction was complete. Changes in cartilage, osteoblast activity, and osteoclast activity were then examined. RESULTS: The differentiation and proliferation of cartilage increased in groups 1 and 2, were highest in group 2, and decreased in group 3. Group 2 also showed the greatest increase in the width of the hypertrophic chondrocyte layer. Relative to the control group, osteoclast activity was only somewhat higher in groups 1 and 2 but was significantly higher in group 3. Osteoblast activity was significantly higher in groups 1 and 2 than in the control group. However, the osteoblast activity in group 3 was slightly lower than that in group 2. At the time of unilateral mandibular distraction, no degenerative changes of the temporomandibular joint were observed in groups 1 or 2, but bone resorption was observed in group 3. CONCLUSIONS: The unilateral mandibular distraction of 2 or 3.5 mm was acceptable in that no degenerative changes of the temporomandibular joint were observed on either the distraction or the nondistraction sides. Five millimeters of distraction might be beyond physiologic limits.