Preoperative 3D Morphological Predictors of Bone Bridge Formation in Secondary Alveolar Bone Grafting: A CBCT Analysis.
PURPOSE To identify independent preoperative three-dimensional (3D) morphological predictors for postoperative bone bridge formation in secondary alveolar bone grafting (SABG) using cone-beam computed tomography (CBCT), and to propose an optimal surgical strategy based on these quantitative indicators. MATERIALS AND METHODS This study evaluated 100 patients who underwent SABG. Preoperative and 6-month postoperative CBCT images were analysed. Patients were categorized into three surgical stages: lateral incisor eruption (Stage 1), canine eruption (Stage 2), and the multi-bracket treatment period (Stage 3). Preoperative cleft dimensions (volume, area and width) and postoperative outcomes (bone bridge thickness, height, and residual defect volume) were measured. Multiple linear regression analysis was performed to identify independent preoperative predictors of surgical success. RESULTS Multivariate analysis revealed that a larger preoperative cleft volume strongly predicted decreased postoperative bone bridge thickness at the mesial aspect (p < 0.001). Furthermore, a larger preoperative cleft area at the root apex was a significant independent predictor of decreased mesial bone bridge thickness (p = 0.019), and a wider preoperative cleft at the midportion strongly predicted decreased bone bridge height (p = 0.001). Volumetric analysis showed that patients in Stage 3 exhibited significantly larger preoperative cleft volumes. Consequently, while the absolute dimensions of the newly formed bone bridges did not differ significantly among the stages, Stage 3 patients were left with significantly larger postoperative residual bone defects. CONCLUSION The preoperative cleft volume, apical cleft area, and middle cleft width evaluated via CBCT are robust independent predictors of SABG outcomes. To minimize postoperative residual dead space and optimise bone filling, surgical intervention is strongly recommended during Stage 1 or 2, prior to the severe morphological expansion of the alveolar cleft.