Effect Of Nicotine On Root Resorption Induced By Orthodontic Tooth Movement In Rats

Objective: To investigate the effect of nicotine on root resorption induced byorthodontic tooth movement.Method:110adult male Sprague-Dawley rats were randomly divided into experimentalcontrol group, negative control group, and nicotine injection0.5mg/kg group,0.75mg/kggroup and1mg/kg group. Nickel-titanium closed-coil springs were placed between themaxillary right first molars and first incisors, and exposed50g force. The specimen weresacrificed at1,3,5,7and14days after operation. One specimen from each group wasprepared for examination of the mesial root by scanning electron microscopy (SEM). Thenumber of intergrin αvβ3positive cells in periodontal tissues were determined byHematoxylin–eosin staining and immunohistochemical staining.Results: intergrin αvβ3was expressed in all groups,except for negative controlgroup.With the prolonged of time, the expression was increased, and on the7th day theexpression was the highest in all groups,but on the14th day it was decreased.Compared with other groups, intergrin αvβ3’s MOD index in the experimental controlgroup was low, besides MOD index was incresed with the increasing of the nicotinedose.Meanwhile, with the increasing of time of force,MOD index was increased,and onthe7thday was the highest in every group,but on the14thday it was decreased.In SEMpictures,the area and the deep of the resorption lacuna on the root surface were increasedwith the increasing of the nicotine dose.Conclusion: Intergrin αvβ3involved in root resorption induced by orthodontic tooth movement; nicotine may increased root resorption in orthodontic tooth movement, andthis effect may be time-dependent and dose-dependent.