Effects of orthodontic tooth movement following ridge preservation using octacalcium phosphate collagen

Alveolar bone resorption following tooth extraction often poses challenges to orthodontic tooth movement. Conventional bone grafting materials used for alveolar ridge preservation (RP) are typically designed to achieve high bone strength; however, such properties may limit the dynamic bone remodeling required for efficient orthodontic tooth movement. This study investigated orthodontic tooth movement into RP sites treated with octacalcium phosphate collagen (OCP/Col) in a rat model. OCP/Col was applied to the extraction socket of first molars (n = 5 per group), followed by orthodontic movement of the second molars into the treated region. Tooth movement, root resorption, bone morphometric parameters (BMD and BV/TV), and angiogenesis were evaluated using micro-CT and histological analyses. The rate of tooth movement on Days 21-22 was significantly greater in the OCP/Col group than in the CTL group (0.0475 mm/day vs. 0.00375 mm/day, P < 0.05). Root resorption showed no statistically significant differences among groups (P = 0.62). Alveolar bone resorption in both width and height was significantly reduced in the OCP/Col group (P < 0.05), with lower resorption rates at Day 28 (width: 3.1% vs. 12.3%; height: 11.9% vs. 28.8%). Histological analysis demonstrated increased bone turnover and vascularization, with abundant Type H vessels being qualitatively observed on the tension side. These findings indicate that OCP/Col-based ridge preservation was associated with enhanced orthodontic tooth movement and reduced alveolar bone resorption without increased root resorption in this rat model. Further mechanistic and clinical studies are required to determine its translational relevance.