Objective: Maxillary sinus augmentation is used when performing implant treatment in the maxillary molar region with inadequate bone height. Posterior superior alveolar artery (PSAA) is the branch of the maxillary artery that supplies the lateral sinus wall and sinus membrane. When performing an osteotomy via lateral approach, however, damage to the PSAA can occur, because it runs inside the lateral wall of the maxillary sinus, causing hemorrhage and hampering surgery. The objective of the present study was to compare the defect patterns with the distances from the alveolar crest and sinus floor to the PSAA. Method and Materials: 280 lateral regions in 235 patients with at least three missing consecutive posterior teeth were measured. Measurement locations were the 1st premolar (P1), the 2nd premolar (P2), the 1st molar (M1), and the 2nd molar (M2). Results: The detection rate was 29% to 59%, and the longest diameter was between 1.1 mm and 1.3 mm. The average distances between the PSAA and the alveolar crest were 24.1 mm, 21.3 mm, 15.4 mm, and 15.3 mm (P1-M2), with statistically significant differences in all locations except M1 and M2. The average distances between the PSAA and the maxillary sinus floor were 10.4 mm, 10.4 mm, 9.0 mm, and 8.5 mm (P1-M2), with no significant differences. There were no significant differences between different defect patterns in the distance between the PSAA and either the alveolar crest or the maxillary sinus floor. PSAA detection rate and the longest diameter were related to the spatial resolution of the computed tomography (CT) scan. Conclusion: Although the distance between the PSAA and the alveolar crest was significantly shorter in the molar region than in the premolar region, it did not affect the defect pattern. Keywords: defect pattern, dental implant, maxillary sinus augmentation, PSAA, x-ray computed tomography