【作者】 马文盛；

【导师】 董福生；

【作者基本信息】 河北医科大学 ， 外科学， 2009， 博士

【摘要】 目的:错牙合畸形严重影响患者的颅面发育、口腔功能、面部美观和心理健康,被世界卫生组织列为口腔三大疾病之一。据傅民魁等2000年统计公布的调查结果显示,错牙合畸形在我国的发病率替牙期为71.21%,恒牙期为72.92%。随着生活水平及口腔健康意识的不断提高,越来越多的错牙合畸形患者选择口腔正畸治疗。但目前常规的正畸牙齿移动速度一般为1mm/月,正畸疗程常需2年左右,对须拔牙正畸治疗患者疗程甚至更长。牙齿移动速度慢,正畸疗程长一直是困扰正畸医师和患者的一个十分严重的问题。探讨快速正畸牙齿移动,缩短正畸疗程是错牙合畸形矫治研究领域的一个重点和热点。牵张成骨(distraction osteogenesis, DO)技术是指在牵张力的作用下,在截开骨皮质的骨断面之间会产生持续缓慢的作用力,这种作用力(或称张力)会促使骨组织及其周围软组织的再生,从而在牵开的骨断面之间的间隙内形成新骨并导致骨周围软组织的同步生长。1992年McCarthy等将DO技术应用于颅颌面外科,治疗单侧颜面发育不全畸形并获得成功。近年来有学者将这一技术原理应用于正畸矫治以探索快速正畸牙齿移动的可能性。1998年,Liou和Huang等提出了“牙周膜牵张成骨(periodontal ligament distraction, PDLD)”快速移动牙齿的概念,Liou等对牙周膜牵张快速移动牙齿进行了临床试验,在拔除第一前磨牙并进行简单的牙槽隔减阻手术后,使用牙固位式的牵张装置远中移动尖牙,在3周内尖牙平均向第一前磨牙拔牙窝移动了6.5mm,且支抗牙没有明显前移。2002年Ki?ni?ci等提出“牙槽骨牵张(dentoalveolar distraction, DAD)”快速移动尖牙的技术。该技术在牙槽手术后牵引尖牙连同其周围的牙槽骨组织一同快速移动,其报道尖牙移动速度可达0.8mm/天,而支抗牙仅有微小的前移和伸长;而Sukurica等在另一项关于牙槽骨牵张的临床研究中发现尖牙到位后牙髓活力受损的问题。目前,牙周膜牵张和牙槽骨牵张这两种牵张成骨快速正畸牙齿移动的技术提出时间还很短,技术还不成熟,在手术方式、加力装置及速度、快速牙齿移动的成骨机理、牙周组织改建及对牙髓组织的影响等方面都有待深入研究。本研究通过建立牙槽隔减阻牙周膜牵张、牙槽骨牵张及拔牙固定矫治的实验动物模型,采用组织学观察方法、TRAP染色(抗酒石酸酸性磷酸酶染色)观察方法、免疫组化和原位杂交等技术对比研究牙槽隔减阻牙周膜牵张、牙槽骨牵张与拔牙固定矫治后移动牙的移动速度、移动牙与支抗牙牙周组织及牙髓组织的变化、破骨细胞在不同阶段的变化、新骨形成和牙周组织改建的特点,以探讨不同矫治方法牙齿移动方式、牙周膜改建、牙髓组织变化、骨形成的特点,为进一步研究及临床应用提供实验依据。在动物实验的基础上选择牙槽隔减阻牙周膜牵张快速移动牙齿进行临床应用研究,对牙槽隔减阻牙周膜牵张用牙固位式牵张装置进行研制,通过模型测量、X线观察、牙髓活力测试观察,探讨牙槽隔减阻手术方式、牙齿加力方式、牙齿移动速度、临床疗效及其安全性,为今后进行快速正畸牙齿移动提供临床依据。方法:一、牵张成骨快速正畸牙齿移动实验动物模型的建立1动物及分组:12只成年雄性Beagle犬,随机分为4组:A组(加力1周组)、B组(加力2周组)、C组(加力2周,保持2周组)和D组(加力2周,保持4周组)。每组3只动物,采取自身对照实验,选择其下颌第一前磨牙为移动牙,每组共6颗,随机分配为牙槽隔减阻牙周膜牵张快速正畸牙齿移动、牙槽骨牵张快速正畸牙齿移动和常规拔牙固定矫治各2颗移动牙。2动物模型建立过程:1)牙槽隔减阻牙周膜牵张动物模型的建立:拔除下颌第二前磨牙,用釉凿沿拔牙窝近中牙槽间隔与舌侧骨板交界处、与颊侧骨板交界处凿沟减阻,沟的深度到达第一前磨牙固有牙槽骨,同时在拔牙窝底斜向第一前磨牙根尖方向凿沟减阻,使拔牙窝近中的牙槽间隔半游离。粘接自制牵张装置。术后3天开始以每天两次,每次旋转螺旋90°的频率,加力2周后固定保持。2)牙槽骨牵张动物模型的建立:拔除下颌第二前磨牙,在第一前磨牙近中颊侧由牙槽嵴顶向下做黏骨膜瓣,暴露第一、第二前磨牙颊侧骨板。用骨凿去除第二前磨牙颊侧骨板及其拔牙窝但保留舌侧皮质骨;围绕第一前磨牙根尖下方及其近中做骨皮质切开,松解第一前磨牙舌侧松质骨与舌侧骨皮质的连接,形成一个有充分动度的包括第一前磨牙与周围骨组织的活动骨块,类似牵张成骨技术的输送盘。缝合伤口粘接自制牵张装置。术后3天开始以每天两次,每次旋转螺旋90°的频率,加力2周后固定保持。3)拔牙固定矫治实验动物模型的建立(常规对照实验动物模型):仅拔除下颌第二前磨牙。用0.25mm正畸结扎丝将150克力的镍钛螺旋弹簧固定在第一前磨牙近中和第三前磨牙远中,加力2周后固定保持。3检测指标:实验动物大体观察,移动牙移动距离测量、支抗牙移动距离测量,X线观察。二、牵张成骨快速正畸牙齿移动牙周组织改建的组织学观察1标本制取:A组动物于加力1周后处死,B组动物于加力2周后处死, C组动物于加力2周、保持2周后处死,D组动物于加力2周、保持4周后处死。切取含移动牙、支抗牙及其相邻组织的组织块,固定、EDTA脱钙、常规石蜡包埋。2 HE染色观察:石蜡包埋组织切片5μm,HE染色,光镜下观察移动牙张力侧牙周组织、压力侧牙周组织、牙髓组织和支抗牙牙周组织的变化。3 TRAP染色观察:石蜡包埋组织切片5μm,TRAP染色,光镜下进行TRAP染色阳性破骨细胞计数并对结果行单因素方差分析。三、牵张成骨快速正畸牙齿移动牙周组织中BMP-2蛋白及其mRNA的表达及意义1 BMP-2蛋白的免疫组织化学实验:石蜡包埋组织切片5μm,BMP-2抗体染色,图像分析系统做定量分析并对结果行单因素方差分析。2 BMP-2 mRNA的原位杂交实验:石蜡包埋组织切片5μm,BMP-2 mRNA原位杂交染色,图像分析系统做定量分析并对结果行单因素方差分析。四、牙槽隔减阻牙周膜牵张快速远中移动尖牙的应用研究1病例选择:选择11例减数正畸治疗患者,共20颗尖牙(上颌16颗,下颌4颗)。2制作牙固位式牵张器:制取石膏模型,在被牵张尖牙和同侧第一磨牙上制作带环,用螺旋扩弓器修改成牵张器的加力装置,扩弓器两端用1.2mm直径的钢丝分别与尖牙和第一磨牙带环焊接在一起,螺旋位于钢丝的龈方以使力线接近尖牙的抗力中心。3拔牙及牙槽隔减阻:在拔除第一前磨牙的同时行尖牙远中牙槽间隔减阻术:用超声骨刀沿拔牙窝近中牙槽间隔与舌(腭)侧骨板交界处、与颊侧骨板交界处、与牙槽窝底交界处,做“U”形沟,沟的深度以达到尖牙固有牙槽骨(骨硬板)但不损伤尖牙牙周膜为准,使拔牙窝近中的牙槽间隔半游离。4牵张器的安装及加力:术后粘固自制牵张器。术后3天开始加力,每日3次,每次0.1mm快速远中移动尖牙。尖牙到位后行常规矫治。5检测指标:分别于矫治前、尖牙到位后、矫治结束时取模型、拍摄曲面断层片和尖牙根尖片,检测尖牙牙髓电活力。结果:一、牵张成骨快速正畸牙齿移动实验动物模型的建立1移动牙移动距离:牙槽隔减阻牙周膜牵张:第1周1.47mm,第2周2.73mm,共3.98mm。牙槽骨牵张:第1周2.88mm,第2周1.25mm,共3.87mm。拔牙固定矫治:第1周0.47mm,第2周0.21mm,共0.68mm。统计结果:牙槽隔减阻牙周膜牵张与牙槽骨牵张的移动距离明显大于拔牙固定矫治(P<0.01);加力第2周,牙槽隔减阻牙周膜牵张移动距离大于牙槽骨牵张(P<0.05)。2支抗牙移动距离:加力2周,支抗牙的平均近中移动距离分别为:牙槽隔减阻牙周膜牵张0.52mm,牙槽骨牵张0.38mm,拔牙固定矫治0.65mm,三者间比较其差异无统计学意义。3移动牙牙齿倾斜度变化:加力2周移动牙的倾斜度变化分别为:牙槽隔减阻牙周膜牵张13.75°,牙槽骨牵张3.97°,拔牙固定矫治8.33°;两两比较,差异均有统计学意义(P<0.05)。4 X线观察:牙槽隔减阻牙周膜牵张:牵张加力期间,移动牙张力侧牙周膜迅速增宽,压力侧牙周膜轻度变窄,其远中牙槽间隔可见向拔牙窝弯曲变形并与移动牙一起进入拔牙窝。固定保持期间,张力侧变宽的牙周膜X线阻射密度逐渐增高,在移动牙近中形成新的骨硬板,牙周膜宽度逐渐缩窄直至接近正常。牙槽骨牵张:牵张加力期间,移动牙连同骨盘向远中移入骨缺损区域,同时移动牙张力侧牙周膜增宽,压力侧牙周膜缩窄。固定保持期间牵张间隙内有新骨生成,X线阻射密度逐渐增高,移动牙张力侧与压力侧牙周膜宽度逐渐接近正常牙周膜。拔牙固定矫治:加力期间,移动牙张力侧牙周膜略增宽,压力侧牙周膜略变窄。保持期间,其近远中牙周膜宽度逐渐趋于正常。X线片显示三种移动方式移动牙未见明显牙根尖吸收。二、牵张成骨快速正畸牙齿移动牙周组织改建的组织学观察1 HE染色观察结果:1)牙槽隔减阻牙周膜牵张:随加力时间的延长,移动牙张力侧牙周膜迅速增宽,牙周膜内成纤维细胞与成骨细胞大量增殖,由固有牙槽骨沿牵引方向迅速生成新生骨小梁;压力侧未见牙周膜受压坏死玻璃样变或明显牙骨质吸收,移动牙远中间隔骨被迅速压入牙槽窝,并逐渐改建。固定保持期间新骨逐渐成熟,牙周膜宽度恢复正常。2)牙槽骨牵张:牵张加力期间牵张区骨痂组织沿牵张方向形成新骨,同时移动牙牵张侧牙周膜增宽,细胞增殖,压力侧有牙周膜透明玻璃样变及牙骨质吸收现象。固定保持期间新骨逐渐成熟,牙周膜宽度恢复正常。3)拔牙固定矫治:随加力时间的延长,移动牙张力侧牙周膜增宽,牙周膜内成纤维细胞增殖,压力侧可见牙周膜透明玻璃样变及牙骨质吸收现象;其新生骨速度及程度均弱于牙槽隔减阻牙周膜牵张及牙槽骨牵张。在固定保持期间新骨逐渐成熟,牙周膜宽度恢复正常。4)三种牙齿移动方式加力期间牙髓组织表现为不同程度的充血及轻度水肿,保持期间牙髓组织逐渐恢复正常。2 TRAP染色观察结果:牙槽隔减阻牙周膜牵张与拔牙固定矫治加力第2周牙周组织破骨细胞数达到峰值,而牙槽骨牵张加力第1周牙周组织破骨细胞数达到峰值,且较长时间维持较高水平。三、牵张成骨快速正畸牙齿移动牙周组织中BMP-2蛋白及其mRNA的表达1在牙槽隔减阻牙周膜牵张、牙槽骨牵张及拔牙固定矫治牙周组织中, BMP-2蛋白的阳性表达主要位于牙周膜内的成骨细胞、成牙骨质细胞、成纤维细胞的胞浆及新生骨组织的骨基质中,而其mRNA的阳性表达主要位于成骨细胞、成牙骨质细胞、成纤维细胞及部分破骨细胞的胞浆中。2加力期间,三种方法BMP-2蛋白及其mRNA的阳性表达均不同程度增高,且均在加力两周时达到各自的峰值,牙槽隔减阻牙周膜牵张及牙槽骨牵张的阳性表达均大大强于拔牙固定矫治,但牙槽隔减阻牙周膜牵张与牙槽骨牵张二者之间差异无统计学意义。3牵张加力结束后的保持期,牙槽隔减阻牙周膜牵张与拔牙固定矫治BMP-2蛋白及其mRNA的阳性表达随时间延长明显回落,而牙槽骨牵张的阳性表达保持较强水平,高于同期的牙槽隔减阻牙周膜牵张和拔牙固定矫治,牙槽隔减阻牙周膜牵张与拔牙固定矫治间差异无统计学意义。四、牙槽隔减阻牙周膜牵张尖牙快速远中移动的临床研究1尖牙与支抗牙的移动距离:20颗尖牙在平均25.6天内向远中移动5.56mm(最小3.53mm,最大8.29mm)。支抗磨牙在平均25.6天内平均前移0.76mm(最小0mm,最大2.27mm)。2尖牙与支抗牙的倾斜与旋转:牵张结束时,尖牙平均有12.2°的远中倾斜和18.53°的近中颊向旋转。牵张结束时,支抗磨牙平均有1.95°的近中倾斜和1.15°的近中舌向旋转。3尖牙牙根吸收:被牵张的20颗尖牙中,有6颗在牵张结束时有?o根吸收(根尖变圆钝),其余14颗尖牙无根尖吸收现象,在矫治结束时,根尖片与曲面断层片显示被牵张尖牙根吸收情况与邻牙无明显差别。4尖牙牙髓活力变化:20颗被牵张尖牙的牙髓电活力测试值在牵张前平均为37.5,在牵张结束时平均为28.6,与牵张前相比有统计学意义(P<0.05﹚;在牵张结束后3个月时平均为38.5,与牵张前相比没有统计学意义(P>0.05)。结论:1成功建立了牙槽隔减阻牙周膜牵张与牙槽骨牵张两种牵张成骨快速正畸牙齿移动的动物模型。2牙槽隔减阻牙周膜牵张与牙槽骨牵张动物实验均实现了安全的快速正畸牙齿移动。3牙槽隔减阻牙周膜牵张快速正畸牙齿移动,主要是移动牙与压力侧牙周膜、牙槽隔的整体快速移动,张力侧牵张力增加,刺激新骨形成,牙周组织迅速改建所致。4牙槽骨牵张快速正畸牙齿移动,主要是由于牙槽骨骨盘截骨线两断端间在间歇性牵张力作用下牵张成骨,骨盘与移动牙整体移动所致。5牙槽隔减阻牙周膜牵张与牙槽骨牵张快速正畸牙齿移动过程中,均同时存在常规固定正畸牙齿移动牙周组织改建的方式。6牙槽隔减阻牙周膜牵张快速正畸牙齿移动比牙槽骨牵张快速正畸牙齿移动创伤小;采用牙固位式牵张装置,牙槽隔减阻牙周膜牵张比牙槽骨牵张对牙髓组织、牙周组织的不良影响更小,支抗控制更好。7建立了牙槽隔减阻的临床术式;研制了牙槽隔减阻牙周膜牵张用牙固位式牵张装置。8牙槽隔减阻牙周膜牵张快速正畸牙齿移动,牙槽隔颊舌(腭)侧及根尖下部有效的减阻是该技术的关键。9牙槽隔减阻牙周膜牵张快速正畸牙齿移动,牙齿创伤小;采用牙固位式牵张,操作简单;具有很好的临床疗效,可以广泛应用于临床。更多还原

【Abstract】 ObjectivesMalocclusion is one of the three major stomatological diseases confirmed by WHO (The World Health Organization), it affects craniofacial development, oral function, psysical and psychological health seriously. The prevalence of malocclusion is 71.21% in mixed dentition and 72.92% in permanent dentition in China (FU minkui, 2000). More and more malocclusion patients appealed to orthodontic treatment. Up to now, the traditional techniques showed the general velocity of orthodontic tooth movement (OTM) of 1mm/month, therefore, the process of orthodontic treatment usually lasted about 2 years or even longer. For that reason, scholars all over the world focused on how to accelerate the tooth movement and to shorten the duration of orthodontic treatment.Distraction osteogenesis (DO) is a method to induce new bone formation by applying mechanical strains on the preexisting bone. The formation of new bone is achieved through stretching of the callus in the osteotomy or corticotomy gap with distraction devices. It is suggested that the formation of the new bone in the osteotomy or corticotomy site with a width of approximately 1 mm per day can be achieved by this method. In 1992, DO was first applied to the human mandible by McCarthy et al, and since then it has been applied to all the bones of the craniofacial skeleton. Resently, DO has been used in orthodontics to achive rapid OTM. In 1998, Liou and Huang put forward the concept of periodontal ligament distraction(PDLD). They demonstrated the rapid distalization of 26 canines in human subjects using distraction of the periodontal ligament aided by alveolar surgery undermining the interseptal bone. They achieved an average 6.5 mm of distraction of the canines within 3 weeks without severe side effect. In 2002, Ki?ni?ci et al put forward the technique of dentoalveolar distraction(DAD), they made a corticotomy around the apex of the canine and a fracturing of the surrounding spongious bone around its root, so a fully mobilizing dentoalveolar segment that inclouded the canine is made, and then the canines ccould be distracted rapidly in a speed of 0.8mm/day, while the anchorage teeth could withstand the forces with minimal anchorage loss. But Sukurica et al reported that 14 out of 20 canines were negative to vitality test 6 months after the completion of DAD. Although a few researches on rapid tooth movement have been published, systemic research is scarce.This study will set up experimental animal models of PDLD and DAD firstly. The periodontium histological changes of moved tooth will be observed by light microscope to investigate the difference between the two new techniques and the traditional way. The number of TRAP positive cells were counted on the periodontium. Further more, the BMP-2 in the periodontium will be measured by using well- known immunohistochemistry and in situ hybridization techniques, so we can explore the BMP-2 change in protein and molecular level which help us understand deeply about periodontium remodeling and molecular biology mechanism of moved tooth. Based on study of experimental animal model, we choose PDLD technique to be used clinically,we will study the surgery procedure, mode of activation, speed of tooth movement, effectiveness and safety through model analysis, X-ray and vitality testing.Methods:1 To establish the experimental animal models of rapid orthodontic tooth movement through distraction osteogenesis by PDLD and DAD with Beagle dogs.Animal and grouping. Twelve male Beagle dogs were randomly devided into 4 groups: group A (1-week activating), group B(2-weeks activating), group C (2-weeks activating, 2-weeks retention) and group D(2-weeks activating, 4-weeks retention), with 3 dogs in each group. Of the 3 dogs in each group, the 2nd lower premolars were extracted, totally 6 lower 1st premolars were defined as moved teeth, and they were randomly devided into PDLD, DAD and routine fixed orthodontic tooth movement(routine control). The establishment of experimental animal models.The establishment of PDLD experimental animal model.After the 2nd lower premolar were extracted, grooves were made from the mesial of the extracted socket to the buccal and lingual cortical bone of the 1st lower premolar, and from bottom of the socket towards the apical proper alveolar of the 1st lower premolar by dental chisel. A costom-made, tooth borne distractor was bonded. The distractor was activated 90°, twice a day for 2 weeks and followed by retention period.The establishment of DAD experimental animal model. After the 2nd lower premolar were extracted, a mucoperiosteal flap was made along the buccal vestibule to expose the cortex of the 1st and 2nd premolar. The buccal wall of the extracted socket was removed and the socket was smoothed by dental chisel but the lingual cotex was retained. An corticotomy was made 5mm below the root apex and mesial of the 1st premolar, larger osteotomes were used to fully mobilize the alveolar segament by fructuring the surrounding spongious bone off the lingual cortex, which like an transport disc.A costom-made, tooth borne distractor was bonded right after stitching up the wound. After a latent period of 3 days, the distractor was activated 90°, twice a day for 2 weeks and followed by retention period.The establishment of routine orthodontic tooth movement experimental animal model.To extract the 2nd lower premolar, and nickel-titanium coin spring were bonded between the 1st and 3rd premolar with a force of 150g for 2 weeks and followed by retention period.Measurement indicators. The distances of movement of moved teeth and anchorage teeth were masured, and radiograph pictures were taken every week.2 Histological Study of periodontium remodeling of rapid orthodontic tooth movement through distraction osteogenesis. The dogs of group A were killed after activation for 1 week; group B after activation for 2 weeks; group C after activation for 2 weeks, retention for2 weeks; group D after activation for 2 weeks, retention for 4 weeks. Dentoalveolar segments including the 1st and 3rd premolars were then dissected out separately, fixed in 10% buffered formalin, and decalcified with EDTA. They were embedded in paraffin. Sections(5μm) were stained with hematoxylin and eosin . The number of osteoclasts in the periodontium of moved teeth were caculated by TRAP staining.3 The expressions of BMP- 2 protein and mRNA in periodontium of moved teeth of rapid orthodontic tooth movement through distraction osteogenesis.Making the sections on different period of time and processing by immunohistochemical and in situhybridization of BMP- 2 as well as analyzing diagram.4 An applied research of rapid canine distalization through PDLD after reducing interceptal bone resistance.20 canines in 11(8 male and 3 female, mean age 15.8 years) patients who required first premolar extractions. A tooth-borne, custom-made distractor was bonded right after the premolar was extracted and the interseptal bone distal to the canine was undermined. The distractor was activated 0.1mm, 3 times a day. Orthodontic models, panoramic radiographs, periapical radiographs, electrical vitality test were taken.Results:1 The establishment of the experimental animal models of rapid orthodontic tooth movement through distraction osteogenesis by ways of PDLD and DAD with Beagle dogs.After 2 weeks’activation, the average distal movements of moved teeth in PDLD and DAD were 3.98mm and 3.87mm separately compared with 0.68mm in routine control(P<0.01), and the average distal movements of moved teeth in PDLD was 2.73mm compared with 1.25mm in DAD in the 2nd week(P<0.05) . After 2 weeks activation, the average anchorage loss were 0.52mm in PDLD, 0.38mm in DAD and 0.65mm in routine control separately(P﹥0.05).The distal inclination of the moved teeth were 13.75°in PDLD, 3.97°in DAD and 8.33°in routine control separately (P<0.05).X-ray on PDLD: during the activating period, the PDL on tension side of the moved tooth widened rapidly and the PDL on pressure side compressed slightly, the interceptal bone bended into the distracted socket with the moved tooth. During the retention period, the density of the widened PDL on tenside increased, the width of PDL gradually regain normal and new proper alveolar formed.X-ray on DAD: during the activating period, bone disc moved into the bone defect area with moved tooth rapidly, and the PDL on tension side of the moved tooth widened simultaneously. During the retention period, the density of the distraction gap increased, the width of PDL gradually regain normal.X-ray on routine control: during the activating period, the PDL on tension side of the moved tooth widened and the PDL on pressure side compressed. During the retention period, the width of PDL gradually regain normal.There were no evidence of severe root resorption and alveolar bone loss in each modes.2 Histological study of periodontium remodeling of rapid orthodontic tooth movement through distraction osteogenesis.PDLD: along with the activation, the PDL on tension side widened significantly, fibroblasts enriched in PDL and new bone trabeculae formed actively with the same direction of distraction. No hyalinization zone of PDL or resorption of cementum were discovered on the pressure side, the interseptal bone was compressed into the extraction socket rapidly and remodeled gradually. During the retention period new trabeculae bone were mature gradually and the PDL in both sides reverted to normal.DAD: new trabeculae bone were seen along the direction of distraction in distraction area, at the same time the PDL on tension side widened gradually and cells accumulated, hyalinization zone and resorption of cementum were found occasionally on the pressure side. During the retention period new trabeculae bone were mature gradually and the PDL in both sides reverted to normal.Routine control: along with the activation, the PDL on tension side widened, hyalinization zone of PDL and resorption of cementum were discovered on the pressure side. The formation of new bone were weak compared with PDLD and DAD. During the retention period new trabeculae bone were mature gradually and the PDL in both sides reverted to normal.The pulp tissues showed mild hyperemia or edema during activate period and recovered during retention period.The osteoclasts activity significantly increased to peak in 2nd week on PDLD, while it increased to peak in 1st week on DAD and kept on a high level for relatively long period.3 The expressions of BMP- 2 protein and mRNA in periodontium of moved teeth of rapid orthodontic tooth movement through distraction osteogenesis.The expression of BMP-2 protein expressed mainly in osteoblasts near alveolar bone, cementoblasts near cementum, fibroblasts and new bone matrix, and its mRNA expressed mainly in osteoblasts, cementoblasts, fibroblasts and a few osteoclasts.The positive expression of BMP-2 protein and mRNA reached peak at 2nd week in PDLD, DAD and routine control, seperatedly, and the intensity of expression in PDLD and DAD are higher than routine control side, while there is no statistic significance between PDLD and DAD.During retention period, the intensity of expression reduced gradually in PDLD and routine control, while it kept on a high level for relatively long period in DAD.4 A clinical study of rapid canine distalization through PDLD after reducing interceptal bone resistance.The distraction procedure was completed in 18 to 35 days(mean 25.6±4.74 days). The distal displacement of the canines ranged from 0 to 2.27mm(mean 0.76±0.75 mm).The canines showed a mean of 12.2o distal tipping and a mean of 18.52o rotation.There was no significant root resorption and pulp vitality change after distraction.Conclusions:1 Two kinds of experimental animal model of rapid orthodontic tooth movement through distraction osteogenesis were established successfully by means of PDLD and DAD.2 Rapid orthodontic tooth movement were achived safely by means of PDLD (3.98mm in 2weeks)and DAD(3.87mm in 2weeks).3 The histological changes on moved tooth of rapid orthodontic tooth movement by means of PDLD are: after the resistance of interceptal bone was weaken, the moved tooth and the PDL on pressure side and the interceptal bone moved into the distract socket rapidly, while under the reinforced tension force, the PDL on tension side was distracted rapidly,new bone formation were activated and the periodontium rebuilded rapidly.4 The histological changes on moved tooth of rapid orthodontic tooth movement by means of DAD are: bone disc moved rapidly with moved tooth by interval force, and then regenerate bone formed in the distraction area.5 Mode of traditional orthodontic tooth movement was involved in both PDLD and DAD simultaneously.6 Rapid tooth movement through PDLD showed minor truma, root resorption and pulp symptom and better anchorage.7 We established a clinical procedure of reducing interseptal bone, and made a tooth-borne distractor for rapid canine distalization.8 The key technology of PDLD is the vertical osteotomies connected with an oblique osteotomy extending towards the base of the interseptal bone to weaken the resistance of ooth movement.9 Rapid orthodontic tooth movement through PDLD showed fewer truma and effective to shorten the duration of orthodontic treatment and to diminish the anchorage loss, it can be used in clinical extensively.更多还原