Objective <p>This study aimed to characterize the morphology, orientation, and location of maxillary sinus septa in relation to posterior dentition status, and to evaluate the radiographically categorized (predicted) risk of Schneiderian membrane perforation using cone beam computed tomography (CBCT).</p> Methods <p>CBCT images from 300 individuals with adequate posterior maxillary visualization were retrospectively analyzed. Images with pathologic formations, prior sinus surgery, or fractures were excluded. The presence, orientation (mediolateral or anteroposterior), and location (premolar anterior, premolar–molar, molar posterior, or multiple) of maxillary sinus septa were recorded. Participants were grouped by posterior dentition status (&lt; 2 teeth or ≥ 2 teeth). Perforation risk was assessed radiographically using a modified seven-class system and categorized as low, moderate, or high. No intraoperative confirmation was performed.</p> Results <p>The mean age of participants was 43.5 ± 13.3 years; 54.7% were male. Septa were mostly mediolateral (91.7%) and located in the premolar region (40.0%). The most frequent predicted risk classes were Class I (33.0%) and Class III (32.7%). Moderate predicted perforation risk was higher in females (<i>p</i> = 0.011), and septum location was significantly associated with predicted perforation risk (<i>p</i> &lt; 0.001). No significant associations were observed between posterior dentition status, septum orientation, and predicted perforation risk.</p> Conclusions <p>Maxillary sinus septa exhibit variable morphological patterns and anatomical distributions that may be relevant for preoperative CBCT evaluation during sinus floor elevation. Although perforation risk was assessed radiographically and not confirmed intraoperatively, understanding septal morphology may enhance surgical awareness and inform individualized planning.</p>