Factors influencing pterygomaxillary suture split after miniscrew-assisted rapid palatal expansion in late adolescents and young adults: A cone-beam computed tomography study.

Introduction: This study aimed to investigate the factors influencing the pterygomaxillary suture split (PMSS) after miniscrew-assisted rapid palatal expansion (MARPE) in late adolescents and young adults using cone-beam computed tomography.

Methods: Preexpansion (T0) and postexpansion (T1) cone-beam computed tomography images of 82 MARPE patients (mean age, 20.7 ± 3.7 years; range, 15.2-32.4 years) were analyzed. Vertical (SN-GoGn angle) and horizontal (ANB angle) skeletal relationships were assessed at T0. Associations between PMSS incidence and variables including age, sex, midpalatal suture maturation (MPSM) stage, palate length (PL), expansion magnitude, and midpalatal suture opening pattern were evaluated. Statistical analyses included Spearman's correlation test and the Wilcoxon signed rank test.

Results: PMSS was observed in half of the subjects after MARPE. Inferior PMSS demonstrated a moderate positive correlation with posterior palatal expansion (ρ = 0.561, P <0.001). Conversely, inferior PMSS showed significant negative correlations with MPSM stage (ρ = -0.555, P <0.001), age (ρ = -0.286, P <0.05), and the ANB angle (ρ = -0.316, P <0.05). No significant correlations were observed between PMSS and the posterior palatal expansion to anterior palatal expansion ratio, sex, PL, or SN-GoGn angle. The magnitude of inferior PMSS was significantly greater than that of superior PMSS (P <0.001), whereas left and right PMSS magnitudes were symmetrical (P >0.05).

Conclusions: Among late adolescents and young adults treated with MARPE, posttreatment PMSS magnitude showed a moderate positive correlation with posterior palatal expansion magnitude, a moderate negative correlation with MPSM stage, and weak negative correlations with both age and ANB angle. The bilateral PMSS magnitudes were symmetrical, with significantly greater magnitudes inferiorly than superiorly. Sex, PL, vertical skeletal pattern, and midpalatal suture opening pattern were not significantly associated with PMSS magnitude.