ObjectiveTo review the effectiveness of secondary alveolar bone grafting using iliac cancellous bone in patients with unilateral complete alveolar cleft and to investigate the factors influencing it.MethodsA retrospective study of 160 patients with unilateral complete alveolar clefts who underwent iliac cancellous bone graft repair at the Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, was conducted. Eighty patients in the young age group (6-12 years) and 80 in the old age group (≥13 years) were included. Bone bridge formation was determined using Mimics software, and the volume was measured to calculate the iliac implantation rate, residual bone filling rate, and resorption rate. The factors that affected bone grafting in both subgroups were investigated.ResultsUsing bone bridge formation as the clinical success criterion, the success rate for the entire population was 71.25%, with a significant difference of 78.75% and 63.75% for the young and old age groups, respectively (P=0.036). The gap volume in the latter was significantly larger than that in the former (P<0 .001). the factors that influenced bone grafting in the young group were the palatal bone wall (P=0.006) and history of cleft palate surgery (P=0.012), but only the palatal bone wall affected the outcome in the old age group (P=0.036).ConclusionThe results of alveolar bone grafting for the old age group were worse than those for the young age group. The palatal bone wall was an important factor that affected alveolar bone grafting, and alveolar bone grafting in the young patients was influenced by the history of cleft palate surgery.