Anatomical Proximity of Posterior Maxillary Tooth Roots as an Independent Predictor of Maxillary Sinus Mucosal...

Objectives: This study aimed to evaluate the association of anatomical proximity between posterior maxillary tooth roots and the sinus floor with the presence and severity of maxillary sinus mucosal thickening (MT) using cone-beam computed tomography (CBCT). Materials and Methods: A retrospective CBCT-based analysis was performed on 300 patients (175 females, 125 males; mean age: 27.55 ± 8.74 years). Root-sinus anatomical relationships were classified into three proximity types based on increasing root-sinus closeness. Maxillary sinus mucosal thickness was measured in millimeters, and mucosal thickening was defined using both a binary threshold (>2 mm vs. ≤2 mm) and an ordinal severity classification (≤2 mm, 2-10 mm, >10 mm). Multivariable binary logistic regression models evaluated the presence of MT after adjustment for age, sex, diabetes, cardiovascular disease, and smoking. As the proportional odds assumption was not satisfied, MT severity was evaluated using multinomial logistic regression models adjusted for age and sex. Results: Mucosal thickening (>2 mm) was observed in 34.7% of patients on the right side and 34.7% on the left side, with bilateral involvement in 19.7%. Proximity type was significantly associated with mucosal thickening on the right and left sides (p < 0.01). In multivariable binary logistic regression, each one-unit increase in proximity type was associated with a 2.58-fold increase in the odds of mucosal thickening on the right side (OR = 2.58; 95% CI: 1.61-4.12; p < 0.001) and a 1.93-fold increase on the left side (OR = 1.93; 95% CI: 1.23-3.03; p = 0.004). In age- and sex-adjusted multinomial logistic regression, each one-unit increase in proximity type was associated with moderate mucosal thickening on both the right (OR = 2.60; 95% CI: 1.56-4.32; p < 0.001) and left sides (OR = 1.74; 95% CI: 1.06-2.87; p = 0.030), relative to normal mucosal thickness. Proximity type was also associated with severe mucosal thickening on the right (OR = 2.75; 95% CI: 1.26-6.04; p = 0.012) and left sides (OR = 2.79; 95% CI: 1.34-5.84; p = 0.006). Age showed a modest independent association in the binary models, whereas systemic factors, including diabetes, cardiovascular disease, and smoking, were not significantly associated with mucosal thickening. Sensitivity analyses using an alternative severity classification supported the association between proximity type and severe mucosal thickening on both sides, although the association with moderate left-side mucosal thickening was threshold-dependent. Conclusions: Anatomical proximity between posterior maxillary tooth roots and the sinus floor was independently associated with MT presence after adjustment for demographic and systemic factors and with MT severity after adjustment for age and sex. These findings support considering root-sinus proximity alongside odontogenic and sinonasal factors during CBCT-based assessment and treatment planning in the posterior maxilla.