Abstract: BACKGROUND: Bone remodeling is the biological basis of orthodontic tooth movement. Type 2 diabetes mellitus leads to metabolic changes in the jaw and alveolar bone, so it is hypothesized that tooth mobility characteristics may be altered in a high-sugar environment.
OBJECTIVE: To explore the impact of type 2 diabetes mellitus on orthodontic tooth movement in rats within one tooth movement cycle.
METHODS: Seventy-two Sprague-Dawley rats were selected. Forty rats were randomly chosen and fed with a high-fat diet to construct a type 2 diabetes mellitus model. Thirty-two rats that were successfully modeled were randomly divided into a type 2 diabetes mellitus group (n=16) and a diabetic orthodontic group (n=16). The remaining 32 rats were randomly divided into a control group (n=16) and an orthodontic group (n=16). The rats in the orthodontic group and the diabetic orthodontic group were equipped with nickel-titanium coil spring orthodontic force application devices to move the unilateral maxillary first molars mesially with a force of 50 g. The rats were anesthetized and sacrificed on the 3rd, 7th, 14th, and 21st days after orthodontic treatment, and Micro-CT was used to measure the mesial displacement of the first molars and detect the changes in the bone microstructure parameters on the tension side.
RESULTS AND CONCLUSION: There were significant differences in the tooth movement distances among the four groups of rats on the 3rd, 7th, 14th, and 21st days of orthodontic treatment (P < 0.05). There were significant differences in bone mineral density, bone volume fraction and trabecular bone separation on the tension side among the four groups on the 7th, 14th, and 21st days of orthodontic treatment (P < 0.05). There were differences in the trabecular thickness among the four groups on the 3rd and 14th days of orthodontic treatment (P < 0.05). The diabetic orthodontic group had the smallest tension-side alveolar bone mineral density, bone volume fraction, and trabecular thickness, and the largest tooth movement distance and trabecular separation on the 21st day of orthodontic treatment. The above results indicate that type 2 diabetes mellitus adversely affects bone microstructural parameters on the tension side in orthodontic tooth movement in rats, suggesting the occurrence of an osteoporotic state.

Key words: orthodontic tooth movement, type 2 diabetes mellitus, Sprague-Dawley rats, MicroCT, bone microstructure, engineered tissue construction