Background: Although childhood obesity matters, the association between body mass index (BMI) and bone mineral density (BMD) progression in grafted tissue after secondary alveolar bone grafting (ABG) for children with cleft alveolus is scarcely studied. Accordingly, this study explored the influence of BMI on BMD progression after ABG.

Methods: Thirty-nine patients with cleft alveolus were enrolled receiving ABG at the mixed dentition stage. Patients were classified as underweight, normal weight, or overweight or obese according to age- and sex-adjusted BMI. BMD was measured in Hounsfield units (HU) from cone-beam computed tomography scans obtained 6 months (T1) and 2 years (T2) postoperatively. Adjusted BMD (HUgrafted tissue/HUpogonion¬, BMDa) was used for further analysis.

Results: For underweight, normal-weight, and overweight or obese patients, BMDaT1 values were 72.87%, 91.85%, and 92.89%, respectively (p = 0.727); BMDaT2 values were 111.49%, 112.57%, and 113.10% (p = 0.828); and density enhancement rates were 29.24%, 24.61%, and 22.14% (p = 0.936). No significant correlation was observed between BMI and BMDaT1, BMDaT2, or density enhancement rates (p = 0.223, 0.156, and 0.972, respectively). For patients with BMI < 17 and ≥ 17 kg/m2, BMDaT1 values were 89.80% and 92.89%, respectively (p = 0.496); BMDaT2 values were 111.49% and 113.10% (p = 0.216); and density enhancement rates were 23.06% and 26.39% (p = 0.573).

Conclusion: Patients with different BMI values had similar outcomes (BMDaT1, BMDaT2, or density enhancement rate) after our ABG procedure in the 2-year postoperative follow-up.