Background: Pterygomaxillary separation is the most critical step of Le Fort I osteotomy. Nonideal separation of pterygomaxillary junction could be associated with many complications. The purpose of this study was to evaluate the anatomic basis of proper pterygoid osteotome in Le Fort I surgery. Materials and Methods: The cone beam computed tomography image of 177 patients were evaluated retrospectively. To design an ideal osteotomy, the angle and the length of the posterior curvature of the maxillary sinus wall were measured. For the classification of the posterior angle as low, medium, and high, the category was based on upper and lower groups consisting of 27%, where the measurement and representability are at the maximum level. Results: The mean posterior length of three angle groups was as follows: low group: 7.81 mm, medium group: 7.54 mm, and high group: 7.41 mm. The differences were not statistically significant (P 0.05). In addition, the posterior angle and length were evaluated according to the gender and the sides, and no statistically significant difference was found. (P 0.05). Conclusion: Ideal osteotomy technique for pterygomaxillary disjunction and the avoidance of related complications could be achieved by selecting patient-specific osteotome using radiographic assessment.