BACKGROUND: Cigarette smoking can seriously affect the periodontal tissues and root, and nicotine in tobacco can increase the progression of periodontal disease and influence bone remodeling thus leading to bone resorption. While intergrin αvβ3 participates in the root resorption induced by orthodontic tooth movement. OBJECTIVE: To investigate the effect of nicotine on root resorption induced by orthodontic tooth movement based on the indicators of intergrin αvβ3 expression in the odontoclasts. METHODS: A total of 110 Sprague-Dawley rats were randomly divided into the blank control group, normal saline group, 0.5 mg/kg nicotine group, 0.75 mg/kg nicotine group and 1 mg/kg nicotine group. In the last four groups, 50 g force was exposed on the maxil ary first molar, and intraperitoneal injection of nicotine tartrate solution or saline in a certain dose was performed daily. Then the histological changes and expression of intergrin αvβ3 were observed after exposed force on the maxil ary first molar for 1, 3, 5, 7 and 14 days using hematoxylin-eosin staining and immunohistochemical staining. RESULTS AND CONCLUSION: With the prolonging of time for exposing force, the periodontal ligament fibers around the root were distorted and lost normal shape, and inflammatory cel infiltration could be seen. Resorption lacuna and odontoclasts were found on the root surface in the pressure side and tension side as wel as the root bifurcation. The dose of nicotine injection, the number and depth of resorption lacuna on the root surface and the number of odontoclasts showed a dose-dependent manner. Immunohistochemical staining result showed that expression of intergrin αvβ3 could be seen in each group, except for the blank control group, and the expression intensity was increased with the prolonging of the time for force; the intergrin αvβ3 positive expression was strong after forced for 7 days, and decreased when forced for 14 days. The number of odontoclasts expressing intergrin αvβ3 was increased with the increasing of the nicotine dose. Nicotine may increase the root resorption in orthodontic tooth movement, and this effect may be in time- and dose-dependent manner.% 背景：吸烟严重影响牙周组织及牙根的健康，烟草中的尼古丁会加速牙周病患者牙周组织的破坏，影响骨改建，引起骨吸收。而整合素αvβ3参与正畸牙移动过程中的牙根吸收。目的：以整合素αvβ3在破牙骨质细胞的表达量为主要观察指标，初步探讨尼古丁对正畸牙移动牙根吸收的影响。方法：将110只实验SD大鼠随机分为空白对照组、生理盐水组以及0.5 mg/kg尼古丁组、0.75 mg/kg尼古丁组、1 mg/kg尼古丁组。后4组上颌第一磨牙施加50 g近中向拉力，同时每日向各组的大鼠腹腔注射一定剂量的尼古丁酒石酸溶液或生理盐水，运用苏木精-伊红染色和免疫组织化学染色，观察各组大鼠上颌第一磨牙加力1，3，5，7，14 d的组织变化情况和整合素αvβ3的表达量。结果与结论：随着加力时间的延长的，牙根周围的牙周膜纤维变形，排列紊乱，炎性细胞浸润，压力侧、张力侧以及根分叉处牙根表面开始出现吸收陷窝、破牙骨质细胞。尼古丁注射的剂量越大，牙根表面的吸收陷窝越多越深，破牙骨质细胞显著增加。免疫组化染色结果显示，除空白对照组外，整合素αvβ3在各个实验组的破牙骨质细胞中表达，并且随着加力时间的延长，其表达强度增强，加力7 d时呈现强阳性表达，加力达到14 d时，表达随之减弱。随着尼古丁注射剂量的增加，整合素αvβ3阳性表达的破牙骨质细胞逐渐增加。结果说明，尼古丁会加重正畸牙移动过程中的牙根吸收，并且可能具有时间依赖性以及剂量依赖性。
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