Mechanisms involved in enhancement of osteoclast formation and function by periodontal cells obtained from sever orthodontic root resorption.

发生在正畸治疗期间和之后的牙根吸收的机制还不清楚。我们研究了正畸牙齿移动过程中牙髓和牙周韧带(PDL)中表达的P物质(SP)和压力(CF)刺激后炎症细胞因子的产生和破骨细胞的形成。从5例因正畸治疗而导致牙根吸收的患者的牙髓细胞中，加入SP(10^&lt；-4&gt；-10^&lt；-12&gt；mol/L)进行培养。同样，PDL细胞受到压力(0-3.0g/cm2)。24小时后检测前列腺素E_2(PGE_2)、白介素1β、白介素6、肿瘤坏死因子α水平。进一步将培养上清加入到培养的大鼠破骨细胞中，在形成吸收腔后观察到破骨细胞的形成。在牙髓细胞和牙髓细胞中，SP和CF刺激可使PGE2、IL-1β、IL-6和肿瘤坏死因子-α水平升高，但牙根吸收组升高幅度大于对照组，且呈时间和浓度依赖关系。在破骨细胞形成方面，牙根吸收组的吸收陷窝明显多于对照组。严重牙根吸收患者的牙髓和牙髓细胞在神经肽和机械刺激下产生大量炎性细胞因子。我们的结果提示，SP和CF可能在正畸治疗过程中牙髓和牙髓组织的炎症进展和牙根吸收的发生中起重要作用。

The mechanism of root resorption that occurs during and after orthodontic treatment has not been clarified. We investigated the production of inflammatory cytokines and osteoclast formation after stimulus with substance P(SP) and compression force(CF) that are expressed in dental pulp and periodontal ligament(PDL) during orthodontic tooth movement. Pulp cells were obtained from 5 patients with root resorption due to orthodontic treatment, and SP (10^<-4>-10^<-12> mol/L) was added and cultured. Similarly, PDL cells were exposed compression force (0-3.0 g/cm^2). The levels of prostaglandin E_2(PGE_2), interleukin(IL)-1β,IL-6, and tumor necrosis factor(TNF)-α were determined after 24 hours. Further, culture supernatants were added to cultured rat osteoclasts, and osteoclast formation was observed after formation of resorption cavities. SP and CF stimulus increased the levels of PGE_2, IL-1β, IL-6, and TNF-α though the increase was greater in the root resorption group than in the control group, in a time- and concentration- dependent manner in pulp cells and PDL cells. As for osteoclast formation, the resorptive pits were significantly increased in the root resorption group as compared to the control. Human pulp and PDL cells obtained from patients with severe root resorption produced large amounts of inflammatory cytokines following neuropeptide and mechanical stimulus. Our results suggest that SP and CF may be highly involved in the progress of inflammation in pulp and PDL tissue and the occurrence of root resorption during orthodontic treatment.