INTRODUCTION The aims of this study were to evaluate and compare skeletal, dentoalveolar, dental, and periodontal changes in surgically assisted rapid maxillary expansion (SARME) patients with and without pterygomaxillary disjunction. METHODS The records of 20 patients who underwent SARME in the clinics of the dental school at Marmara University in Turkey were collected and divided into 2 groups of 10 patients each, according to the surgical protocol followed. Cone-beam computed tomography images before the operation and 3 to 6 months after the end of active expansion were analyzed by 20 linear and 7 angular measurements. The reliability of the 3-dimensional analysis was investigated. RESULTS All transversal measurements in the dentoalveolar and dental levels increased after expansion in both the SARME with pterygomaxillary disjunction and the SARME without pterygomaxillary disjunction groups with no significant differences between them. In the SARME without pterygomaxillary disjunction group, more pronounced buccal alveolar bending and buccal tipping of the posterior teeth were found, but the difference did not reach statistical significance. SARME reduces buccal alveolar width in the premolar region significantly when pterygoid disjunction is not performed. CONCLUSIONS SARME with or without pterygomaxillary disjunction is an effective technique to treat maxillary transverse deficiency in adolescent and adult patients. Pterygomaxillary disjunction is advised in periodontally compromised patients. Cone-beam computed tomography scanning is a reliable method for studying the dentoskeletal effects of SARME.