【作者】 史瑞新；

【导师】 陈远萍；

【作者基本信息】 吉林大学 ， 口腔临床医学， 2005， 硕士

【摘要】 目的:正畸牙齿移动是伴有压力侧骨吸收和张力侧骨形成,从而使错位牙移动的一个骨改建过程,目前骨代谢研究认为转录因子NFKB 受体活化剂配体(receptor activator of NF-kB ligand /RANKL)是调节骨组织代谢参与骨改建过程的一个重要细胞因子。本实验的目的在于探讨实验性正畸牙齿移动过程中,牙周组织中RANKL 分布及其表达量的变化,进一步了解RANKL 与正畸牙齿移动时骨改建的关系,探索RANKL 参与骨改建的机制。方法:选取Wistar 大鼠42 只,雄性,体重225±25 克,随机分成正常对照组、实验组(1 天组、3 天组、5 天组、7 天组、14 天组、21 天组),共7 组,每组6 只。实验组以大鼠的上颌切牙为支抗牙,50g 力拉上颌第一磨牙向近中移动。于实验第1、3、5、7、14、21 天处死动物。取上颌第一磨牙及其牙周组织,制作以上颌第一磨牙为中心的、近远中方向的组织切片,行HE 染色及RANKL 免疫组化染色。分别检测第一磨牙近中、远中的牙槽骨表面和牙周膜中RANKL 的表达,结合正畸力作用时间将得到的组织切片进行半定量分析,在组织学观察及图像分析的基础上,对图像分析的灰度积分进行统计学处理。结果:在正常大鼠的牙周组织中,RANKL 呈弱阳性表达,主要表达于牙槽骨表面的成骨细胞和少量牙周膜成纤维细胞胞浆中,分布比较均匀。加力第1 天,张力区及压力区牙周组织未见明显变化,仅是牙周膜纤维排列略紊乱,RANKL 的染色略强于对照组的正常状态。加力第3 天,压力侧牙槽骨表面可见大量多核破骨细胞和骨吸收陷窝,RANKL 的表达显著增强,RANKL阳性细胞数量显著增多,主要分布于牙槽骨表面的成骨细胞和更多还原

【Abstract】 The growth and development of alveolar bone are influenced by biotic force. As Structural frames, the bone rebuild constantly in all the life of the people to form ideal structure to adapt mechanical environment. The biological mechanisms of tooth movement result from the cellular responses of periodontal connective tissues of exogenous mechanical forces.The orthodontic tooth movement is a bone remodeling process accompanied with the bone resorption on the compression side and the bone formation on the tension side .It was shown that receptor activator of NF-kB ligand (RANKL) has close relation with bone remodeling. The tumour-necrosis-factor-family molecule RANKL has been identified as a potential osteoclast differentiation factor. It is confirmed that RANKL can facilitate the bone resorption by osteoclast in vivo and induce the formation of osteoclast in vitro. RANKL is on the cell membrane of osteoblast. It is the key factor of signal transmission between osteoblast and osteoclast. RANK is the protein of the tumour necrosis factor receptor. RANK is on the osteoclast precursors and can be identified by RANKL.It is the only target signal receptor of facilitating osteoclast differentiation by RANKL. All kinds of factors of stimulating bone resorption act on the osteoblast and induce its membrane expressing RANKL. Then, RANKL combines with RANK which is on the precursors. Signal is introduced into precursors. This arose expanding reaction. Osteoclast is differentiated and mature. OPG combines with RANKL as the inducing fake receptor and restrains the formation and differentiation of osteoclast. So the OPG/RANKL/RANK cytokine system forms the key way of developing, mature and function of the osteoclast. RANKL is expressed in gingival, tooth follicle and periodontal ligament(PDL) fibroblasts.It plays an important role during the rebuilding of the periodontal tissues.It takes part in the tooth eruption, physiological root resorption of deciduous teeth and the orthodontic tooth movement. The purposes of our study are (1) to investigate the RANKL expression location and expression level changes in PDL during the experimental rat tooth movement process,(2)to explore the origination, mechanism of RANKL and the relation between RANKL and alveolar bone remodeling during the orthodontic tooth movement. Materials and methods:The male rats whose weights were almost 225±25 gram were chosen and they were divided into normal group and experimental( 1、3、5、7、14、21 day ) group randomly . Each group had 6 rats, and the total number was 42. A coil spring was deposited between the maxillary first molar and the maxillary central incisor, the first molar of rats was considered as the orthodontic tooth and the central incisor was the anchorage tooth. The first molar was moved to the mesial by 50g force.42 rats were sacrificed at 0 day,1 day, 3 day, 5 day, 7 day, 14 day and 21 day. All of tissue sections were processed, then proceeded with HE staining and RANKL immunohistochemical staining. Observing thehistological changes of periodontal tissue, the result was analyzed by the Computer Image Analyzing System and treated by statistics test. Results: There are RANKL expression in the compression and tension side of PDL in both non orthodontic treatment groups and orthodontic treatment groups. In the periodontal tissue of non orthodontic treatment groups, RANKL expressed lower. The localization of RANKL was marked in the cytoplasm of osteoblasts on the surface of alveolar bone and a few periodontal ligament fibroblasts., well-distributed. The expression of RANKL on the compression side is not lower than the tension side. In the 1 day group, no significant changes of RANKL expression was noted, except disturbing sequence of fibroblasts shapes. In the 3 days group, osteoclast activation was noted and strong RANKL expression exist in the compression side .The number of the cell which express RANKL increased . The localization of RANKL was marked in the cytoplasm of osteoblasts on the surface of alveolar bone and in the medullary cavity of bone and periodontal ligament fibroblasts near the alveolar bone. But in the periodontal ligament fibroblasts near the cementum RANKL expressed lower. In the 5 day group, the expression and distribution of RANKL were similar with the 3 day group. In the 7 day group, the osteoblasts on the surface of alveolar bone still express RANKL. The number of the cell which express RANKL near blood vessel decreased. In the 14 day group, the expression of RANKL became weaker. In 21 day group, RANKL expression level更多还原