Orthodontic Tooth Movement Enhances Bone Healing of Surgical Bony Defects in Rats

Background: The question of whether the repair of an alveolar bony defect can be enhanced by orthodontic tooth movement was addressed. Methods: Alveolar bone defects were created in 52 Wistar male rats anterior to both maxillary first molars. After 1 week of healing, orthodontic protraction was applied for 2 weeks on the right side, resulting in mesial tipping and displacement movement. Subsequently, a retention appliance was inserted for 1 week. The left side served as the untreated (control) group. Vital bone staining (procion brilliant red H-8) was administered before and after orthodontic traction. Histomorphometric analysis was performed on 62 hemimaxillae using UV confocal microscopy and an imaging program. The total area of the bony defect was divided into 4 equal quadrants, and the area of bony apposition in each quadrant was measured. Results: The total area of bony apposition was 6.5-fold larger in the treated (26.41 x 10⁴ ± 28.92 x 10⁴ μm²) than in the control group (4.07 x 10⁴ ± 2.82 x 10⁴ μm²), approaching statistical significance (P = 0.065). The treated occlusal quadrants demonstrated highly significant (P = 0.010), greater bone apposition compared to the control group (13.8-fold) and to the treated apical quadrants (P = 0.04, 5-fold). Conclusions: This study confirms that orthodontic tooth movement is a stimulating factor of bone apposition. A conversion in the repair pattern of the bony defect from apico-occlusal in the control group (no tooth movement) to occluso-apical in the treated group (with tooth movement) further supports the linkage between tooth movement and enhanced bone deposition. Clinical implication suggests incorporation of orthodontic tooth movement in regenerative therapy.