[Histological study about the effect of orthodontic loading time and duration on the periodontal repair in autologous tooth transplantation].

Objective: The study established an animal model of autologous tooth transplantation in dogs and aimed to explore the effects of orthodontic loading time and duration on the periodontal repair in autologous tooth transplantation.

Methods: 12 Beagle dogs were selected and grouped randomly in this research. Four first premolar teeth in every dog were carried on autologous transplant operation. These teeth were exerted the orthodontic force after the operation in 2, 4, 8 and 12 weeks respectively. The loading duration was 1, 2 and 4 weeks respectively. We examined the dental and periodontal tissue samples in first premolar teeth by histological study, measured root absorption rate and analyzed reconstruction condition of periodontal tissue with statistical methods.

Results: Root absorption rates of the experimental group which was exerted the orthodontic force were lower than those of the control group. The difference between two groups had statistical significance (P < 0.05). Root absorption rates in different levels of orthodontic loading time (X) and the duration (Y) had no statistical significance (P > 0.05), but these two factors had interaction effect (P(X x Y) < 0.05).

Conclusion: Orthodontic force contributes to the improvement of root absorption and reconstruction of periodontal tissue in transplant teeth. The orthodontic loading time and the duration have no obvious effect on root absorption rate of transplant teeth. When X is two weeks and Y is four weeks, it is most beneficial for the reconstruction effect of periodontal tissues in transplant teeth.