Factors influencing secondary alveolar bone grafting in cleft lip and palate patients: Prospective analysis using CT image analyzer

Objective: To examine the effect of migration of the germ of the lateral incisor into the bone for eruption factors on bone bridge resorption. Methods: Twenty-f ive subjects who underwent secondary alveolar bone graft were enrolled. The volume of the alveolar bone grafts immediately after the operation (V1), bone bridge formation 6 months postoperatively (V2), and tooth (teeth) migration into the bone bridge (Vt) were measured using a computed tomography (CT) image analyzer. Based upon these measurements, the following points were examined: (1) the correlation between the tooth-occupied ratio (Rt = VtlV2 x 100) and the ratio of bone bridge resorption (Rv = (V1 - V2)/ V1 x 100); and (2) comparison of the tooth-occupied ratio (Rt) and the ratio of bone bridge resorption (Rv) between the groups with and without the germ of the lateral incisor. Results: A significant negative correlation was found between Rv and Rt (p <.001). Comparison of Rv and Rt between the groups with and without a germ of the lateral incisor revealed that both indices were significantly higher in the former group than the latter one (p <.05). Conclusion: In cleft lip and palate patients with a germ of the lateral incisor, it is beneficial to carry out secondary bone grafting to the alveolar cleft at the age of 5 to 7 years, preceding eruption of the canine, in order to form a good bone bridge that will facilitate eruption of the lateral incisor and subsequent normal dentition and occlusion.