Orthodontic tooth movement enhances bone healing of surgical bony defects in rats

Background: The question of whether the repair of an alveolar bony defect c an 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 protr action was applied for 2 weeks on the right side, resulting in mesial tippi ng and displacement movement. Subsequently, a retention appliance was inser ted for 1 week. The left side served as the untreated (control) group. Vita l bone staining (procion brilliant red H-8) was administered before and aft er orthodontic traction. Histomorphometric analysis was performed on 62 hem imaxillae using UV confocal microscopy and an imaging program. The total ar ea of the bony defect was divided into 4 equal quadrants, and the area of b ony apposition in each quadrant was measured. Results: The total area of bony apposition was 6.5-fold larger in the treat ed (26.41 x 10(4) +/- 28.92 x 10(4) mum(2)) than in the control group (4.07 x 10(4) +/- 2.82 x 10(4) mum(2)), 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 stimu lating factor of bone apposition. A conversion in the repair pattern of the bony defect from apicoocclusal in the control group (no tooth movement) to occlusoapical in the treated group (with tooth movement) further supports the linkage between tooth movement and enhanced bone deposition. Clinical i mplication suggests incorporation of orthodontic tooth movement in regenera tive therapy.