Local injection of 1,25-dihydroxyvitamin D3 enhanced bone formation for tooth stabilization after experimental tooth movement in rats

The present investigation evaluated the effect of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) on alveolar bone formation during tooth movement in rats. Orthodontic elastics were inserted between the maxillary first and second molars on bilateral sides in male rats. 1,25(OH)₂D₃ was injected locally, at the concentration of 10^–10M, once every 3 days in the submucosal palatal area of the root bifurcation of the molar on the right side. Histomorphometric analysis revealed that tooth movement without application of 1,25(OH)₂D₃ decreased the mineral appositional rate (MAR) on the compression area at 7 days. Repeated injections of 1,25(OH)₂D₃ in the orthodontically treated animals distinctly stimulated alveolar bone formation on the mesial side at 14 days. There was a significant increase in MAR associated with elevated osteoblast surface (Ob.S/BS) value on the tension surface. These findings suggest that local application of 1,25(OH)₂D₃ enhances the reestablishment of supporting tissue, especially alveolar bone of teeth, after orthodontic treatment.