Background <p>The maxillary sinus is a pyramid-shaped cavity located within the facial skull. Comprehensive knowledge of its anatomy and anatomical variations is essential for surgical procedures in the posterior maxilla. Accurate radiological evaluation is therefore critical. This study aims to classify maxillary sinus floor morphology and assess the prevalence of maxillary sinus mucosal thickening in a Turkish subpopulation.</p> Methods <p>Cone-beam computed tomography (CBCT) images from 203 patients were analyzed. Sinus floor contours were classified as narrow, tapered, ovoid, square, or irregular based on the system described by Niu et al. The presence and degree of mucosal thickening were categorized according to Block’s classification as follows: &lt;2&#xa0;mm, 2–5&#xa0;mm, &gt; 5&#xa0;mm below the ostium, or soft-tissue density extending above the ostium. Chi-square tests were used for statistical analyses.</p> Results <p>A total of 180 patients met the inclusion criteria, and maxillary sinus morphology was evaluated at 1,080 tooth sites. No significant association was found between gender and mucosal thickening. Having at least two teeth adjacent to the sinus was significantly associated with mucosal thickening on both the right and left sides. No correlation was observed between age and mucosal thickening. Sinus morphology was also assessed based on the presence or absence of teeth or implants. Tooth loss influenced sinus morphology at multiple molar sites, whereas second premolar regions on both sides were unaffected.</p> Conclusions <p>Precise classification and evaluation of maxillary sinus floor morphology are essential for improving surgical planning and reducing complications in dental and maxillofacial procedures, particularly implant placement.</p>