【作者】 张琳林；

【导师】 戴红卫；

【作者基本信息】 重庆医科大学 ， 口腔临床医学， 2010， 硕士

【摘要】 正畸导致的炎性牙根吸收是正畸治疗常见的并发症。正畸矫治过程中,牙周组织受力的作用发生牙槽骨的改建和牙周膜组织的更新,引起不同程度的牙根吸收。由于其高发性等特点,正畸牙移动导致的牙根吸收和修复成为目前正畸界研究的热点,但是正畸导致的牙根吸收后再修复的生物学过程及机制仍不清楚,吸收后的牙根是不是能恢复到正畸前?尚不十分清楚。目前,临床上对正畸引起的牙根吸收没有特别有效的预防方法,我们是不是可以通过干预牙根吸收后的修复过程,来达到正畸导致的吸收牙根更好的修复?因此,了解正畸性牙根吸收和吸收后的再修复机制非常重要。本研究建立正畸牙根吸收修复早期动物模型,结合扫描电镜、HE染色、TRAP染色和免疫组化技术,对正畸牙根吸收后的修复早期进行组织学研究,观察牙周组织中破牙骨质细胞、BMP-2和BSP的变化及规律,初步了解正畸导致的炎性根吸收修复早期过程的组织学变化过程,探讨BMP-2和BSP的表达与正畸导致的牙根吸收修复早期的相关性,阐明其作用机制,丰富正畸牙根吸收修复早期的理论基础和实践依据。方法建立正畸牙吸收修复早期动物模型,设置自身对照,对照组取对侧未加力侧。在SD大鼠上颌左侧第一磨牙与上切牙之间安置一0.012英寸闭隙镍钛拉簧,施加约50g的力,持续施力14d后拆除装置。在拆除装置后第0、1、3、5、7、10、14、28 d将大鼠麻醉,处死,固定,脱钙,制作大鼠第一磨牙及其周围牙槽骨石蜡切片,利用TRAP对破牙骨质细胞进行计数,电镜和HE染色观察牙周组织形态学变化,利用免疫组化方法检测BMP-2和BSP在牙周组织中的表达。结果1.成功建立了正畸牙根吸收修复早期动物模型。2. HE染色提示:实验组第一磨牙近中根可见:0天组牙槽骨及牙根可见显著的吸收现象,随着矫治器拆除时间延长,吸收逐渐停止,发生不同程度修复。3.TRAP染色提示:0天组可见细胞核在三个及其以上TRAP阳性染色破牙骨质细胞,主要排列在牙根表面吸收陷窝内,1天组可见破牙骨质细胞数量最多,实验第1天起,TRAP染色阳性多核破牙骨质细胞逐渐减少,实验第7天,TRAP染色阳性多核破牙骨质细胞数量已逐渐恢复至生理水平。4.扫描电镜结果提示:实验组随着矫治器拆除时间延长,牙根表面的吸收陷窝发生不同程度的修复。5.免疫组化提示:(1)BMP-2染色强度于第1天阳性表达达到峰值,与对照组比较有显著性差异,第3天起开始下降,第28天时呈弱阳性表达。(2)BSP染色强度于第3天阳性表达达到峰值,与对照组比较有显著性差异,第5天开始下降,第28天呈弱阳性表达。结论1. 50g正畸力会使大鼠牙根受力发生吸收,吸收部位多分布在牙根颈部、根分叉处和根尖1/3。2.在拆除矫治器后,吸收牙根可以发生不同程度的修复,发生在牙骨质区域的吸收较发生在牙本质区域的吸收修复更好,牙骨质与牙本质比较具有更强的修复能力。发生在根尖1/3区域的吸收比根颈部和根中部的吸收修复得更好。3.在拆除矫治器施力终止后,正畸牙牙根吸收并未停止,牙根吸收与牙根修复过程并存,7天后主要是修复现象存在。4.拆除矫治器后,牙周组织BMP-2和BSP表达变化具有一定规律性。推测BMP-2和BSP参与了正畸牙根吸收后修复过程的牙槽骨和牙骨质改建过程,在牙根吸收后的修复早期发挥了重要的作用。更多还原

【Abstract】 Background and ObjectiveInflammatory root resorption is a common side-effect during orthodontic tooth movement.During the process of orthodontic tooth movement, periodontal tissue were effected by mechanical strength, ocurred reconstruction of alveolar bone and updation of periodontal membrane,which caused varying degrees of root resorption.The root resorption caused by orthodontic tooth movement, due to its characteristics of high incidence of onset, many researches focus on root resorption and repair during orthodontic tooth movement. But the biological processes and mechanisms of root resorption and repair after orthodontic treatment are still unclear. Is resorption of the root can able to return to pre-orthodontic treatment? It is not clearly. At present, clinically, we have not particularly effective methods of prevention of root resorption during orthodontic treatment. Can we interfere with the repair process after root resorption, the root repair to achieve a better result? Therefore, it is very important to understand the nature of root resorption during orthodontic treatment and repair mechanism.In this study, we establish the early root resorption repair induced tooth resorption model, Combined with scanning electronic microscope(SEM), haematoxylin and eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemistry, and observed the histology changes and cementoclasts in periodontal tissue, the changes and expression of BMP-2 and BSP. Preliminary understand the histology changes of the early repair process after inflammatory root resorption caused by orthodontic treatment result. Discuss the relativity of the expression of BMP-2, BSP and early root repair after root resorption caused by orthodontic treatment, to clarify the mechanism, and rich the theoretical and practical basis of early root repair after root resorption caused by orthodontic treatment.MethodsWe established the early root repair after root resorption induced tooth resorption model in experiment group, control group include the opposite side without any force. An orthodontic appliance consist of a stretched closed coil spring (0.012 inch nickel–titanium wire) , ligated between the maxillary left first molar and the incisors of SD rats, moving the molar mesially with a force of 50g. After 14 days, the appliance was removed. Rats were anesthetized, sacrificed, fixed and decalcified, on 0, 1, 3, 5, 7, 10, 14, and 28 day after withdrawl appliance. Alveolar bone around the first molars were cut for paraffin histology and prepared sagittal paraffin sections, using TRAP to count on cementoclasts, and observed the morphological changes of periodontal tissue by SEM and HE staining, the expression BMP-2 and BSP in the periodontal tissues were detected by immunohistochemistry.Results1. Successfully established the early root repair after root resorption induced tooth resorption model.2. HE staining Tip: Appeared in the experimental group of first molar: 0 day group showed significant alveolar bone and root resorption, as time elapsed, with the appliance removal, resorption gradually stoped, occurred varying degrees repairment.3. TRAP staining results: 0 day group shows that the nucleus >3and TRAP positive cementoclasts, which was mainly arranged in the resorption of root surface, one day group showed the largest number of cementoclasts, experiment 1 day, TRAP staining of multinucleated cementoclasts were decreased, and on 7days, TRAP staining on the number of multinucleated cementoclasts had gradually returned to the physiological level.4. Scanning electronic microscope showed: In the experiment group, as time elapsed, with the appliance removal, resportion lacuna on the surface of root occurred varying degrees repairment. 5. Immunohistochemical staining showed:(1) BMP-2 staining intensity on day 1 expression reached its highest peak, Compared with control group, there were significant differences, day 3 begins to drop until day 28 weakly positive were observed.(2) BSP staining intensity on day 3 expression reached its highest peak, Compared with control group, there were significant differences, day 5 begins to drop until day 28 weakly positive were observed.Conclusion1. Under 50g of orthodontic force root absorption of rats happened, absorption site were distributed in the root neck, root furcation and apical 1 / 3.2. Some degree of root resorption during orthodontic tooth movement could be repaired after removed the appliances. The resorption occurred in cementum region repaired better than dentin region. As for the repair capacity, cementum was better than dentin. The resorption occurred in the apical 1 / 3 region repaired better than root neck and root central.3. After removal of appliance, force on the termination, root resorption during orthodontic tooth movement have not completely stopped, root resorption and root repair process co-exist, after 7 days the repair process continued mainly.4. Periodontal BMP-2 and BSP expression through the tooth root repair in rats after orthodontic tooth resorption the entire process and the changes had some regularity. We presumed BMP-2 and BSP participated in the repair process after orthodontic root resorption in alveolar bone and cementum remodeling.更多还原