Schneiderian membrane thickening and its association with apical periodontitis: a cone-beam computed tomography analysis.

To evaluate the presence of apical periodontitis (AP) and its association with characteristics of the Schneiderian membrane (SM) in cone-beam computed tomography images. The initial sample consisted of 516 tomographic scans comprising 1,032 maxillary sinuses (MS). After applying the eligibility criteria, 142 examinations and 197 MS images were included. Images were evaluated and measured using RadiAnt DICOM viewer software, and each MS was analyzed individually. Parameters assessed included the endodontic status of teeth (treated vs. non-treated), the presence of AP, the root location of the AP, cortical disruption, and SM thickness. Membrane thickness was categorized as normal (< 3 mm) or pathological (≥ 3 mm). Data were compiled in Microsoft Excel and subsequently exported to SPSS for analysis. Contingency tables were constructed for variables associated with membrane thickening, and either the Chi-square test for independence or Fisher's exact test was applied. The significance threshold was set at 5%. Schneiderian membrane thickening was observed in 43.1% of the 142 examinations. Thickening was more common on the left side (47.9%) and in cases involving a single endodontically treated tooth (44.4%). Prevalence was higher in males (47.8%) and in individuals aged 40-49 years. A significant and positive association was found between SM thickening and both endodontic treatment and the presence of AP (p = 0.014). Schneiderian membrane thickening is significantly associated with the presence of AP and with the combined presence of endodontic treatment and AP.