Age Thresholds and Gender Differences in Midpalatal Suture Maturation: A Cross-sectional Observational Study with CBCT for Maxillary Expansion Guidance.

OBJECTIVE: This study analyzed 3162 CBCT images to explore age and gender features in midpalatal suture (MPS) maturation staging, and identify the statistically significant age threshold for MPS ossification. METHODS: Axial CBCT sections of 3162 participants (1690 females, 1472 males, aged 3-90 years) were classified into six MPS maturation stages (A, B, C, D1, D2, E) based on Angelieri's criteria. The Youden index defined the diagnostic age threshold for MPS maturation; chi-squared tests assessed correlations between age, gender and stages. Kolmogorov-Smirnov, t-test and Wilcoxon test analyzed subgroup data distribution similarity, with statistical significance set at p < 0.05. RESULTS: The optimal age threshold for distinguishing MPS stages A, B, C and D was 11.2 years (males:11.2 years, females:10.75 years), with high diagnostic sensitivity and specificity. Age correlated significantly with MPS maturation (p < 2.2e-16). D2 stage, morphologically intermediate between D1 and E yet distinct, had a significantly different age distribution from both (p < 0.05), warranting independent staging. Adolescents (0-20 years) showed significant gender differences (p < 0.05), with females maturing earlier. CONCLUSION: The critical MPS ossification age threshold is 11.2 years, supporting reduced unnecessary radiological examinations in younger patients. MPS maturation advances with age and is earlier in females, especially in 0-20 years.