Orthodontic Sinus-Bone Dynamics: Biomechanical Insights

To investigate the dynamic relationship between sinus height (Δsh) and bone height (Δbh) changes in molar regions during orthodontic treatment. Pre- and post-orthodontic CT data from 20 patients were analyzed. Linear regression and Spearman’s correlation assessed Δsh6/Δsh7 and Δbh6/Δbh7 associations in first/second molars, with collinearity diagnostics ensuring validity. 1.First molar: Δsh6 and Δbh6 showed a significant negative correlation(Beta=-0.418,Rho=-0.472, p<0.01),explaining15.3%variance(adjustedR²=0.153).Second molar: Δsh7 and Δbh7 had no significant association (Beta=-0.244, Rho=-0.145, p>0.05; adjusted R²=0.035).Models exhibited no multicollinearity (VIF=1.0). First molar correlations likely stem from anatomical proximity, where direct force transmission accelerates sinus pneumatization and localized bone resorption. Second molar nonsignificance may reflect anatomical divergence, biomechanical dispersion, or limited power. Differential bone remodeling and occlusal load distribution may exacerbate regional disparities.First molar sinus expansion correlates with bone height reduction post-orthodontics, highlighting biomechanical monitoring needs. Second molar findings require validation via larger cohorts or 3D modeling. Future studies should integrate bone density and force dynamics to clarify mechanoregulatory pathways.