Objective: To longitudinally evaluate the outcome of secondary bone grafting (SBG) using computed tomograms (CTs) and conventional dental radiographs.
Subjects: Nineteen alveolar clefts from 17 patients were used in this study.
Method: A two-dimensional evaluation of SBG was performed using dental radiographs at 1 year after SBG by assigning scores of 1 to 4 (from very good to poor) based on postoperative marginal bone level on the alveolar side. On the basis of postoperative marginal bone levels on the nasal side, clefts were also assigned to groups with the bony bridge on or above (group I) or below (group II) a horizontal reference line. Three-dimensional evaluation of the SBG was performed on horizontal CT slices with the residual cortical bone (RCB) ratio before SBG (T0) as well as 1.5 (T1), 3 (T2), 6 (T3), and 12 months (T4) after SBG.
Results: The RCB ratio at T4 in the group with scores 1 and 2 was significantly smaller than that of score 3. Furthermore, the mean RCB ratio at T4 in group I was significantly smaller than that in group II. Nineteen alveolar clefts were divided into two groups, A and B, based on a cluster analysis of the RCB ratios. Group A showed a continuous decrease in the RCB ratio from T0 to T2, but group B showed a significant decrease only in the period from T0 to T1.
Conclusion: These results suggested that the RCB ratio might be a useful parameter for evaluation of the bony bridge after SBG.