Effect of vitamin D on bone morphometry and stability of orthodontic tooth movement in rats

Vitamin D (VitD) maintains bone health and may influence orthodontic tooth movement (OTM). The objective was to evaluate the VitD effect on bone morphometry and the rate and stability of OTM.Thirty-two male Sprague Dawley rats were assigned into 2 experimental groups, treated with VitD by gavage (systemic) or injection (local), and 2 respective control groups treated with phosphate-buffered saline for 47 days. OTM was performed for 7 days with a nickel-titanium coil bonded between the maxillary first molar and incisors. Microcomputed tomography scanning was performed at 5 time points: before administration of VitD, the start of OTM, the end of OTM, 7 days post-OTM, and 30 days post-OTM. The rate and stability of OTM were assessed. Bone morphometry was analyzed by bone mineral density, bone volume/total volume, total porosity, trabecular pattern factor, structure model index, and connectivity density.The systemic VitD group showed a lower OTM rate and a lower relapse than the control (P <0.05). It also demonstrated increased bone mineral density, bone volume/total volume, and a decrease in total porosity (P <0.05). The bone structure appeared more fragmented and presented a lower connectivity density than the control (P <0.05). No statistical difference was found between VitD local administration and the other groups for the rate and stability of OTM or bone morphometry.The systemic administration of VitD caused a decrease in the OTM rate by generating more bone resistance but also contributed to a lower relapse with a higher bone mineral density.