Study on orthodontic root absorption and tooth movement discrepancy in rats

Objective To establish an animal model of orthodontic root absorption,study the effects of orthodontic force and duration on tooth movement and root absorption and investigate the relationship among the force,duration and orthodontic root absorption.Methods Sixty-six male SD rats weighed (300±20) g were included.Orthodontic tooth movements of the rats under different force durations(1,3,5,7,10,14 days) and different values of orthodontic force(40 g,60 g,80 g) were measured,and the orthodontic root absorption in each group was investigated with HE staining.Results The distance of tooth movement in each group was different.Root absorption was commonly observed in the middle part of the root,the extent of which depended on the force and duration applied.Conclusion ①The experimental animal model of orthodontic root absorption was successfully established.②In the distance of orthodontic tooth movement there existed a significant difference.③Some regularity was found in orthodontic root absorption.