Effect of pterygomaxillary disjunction on activation torque, intraoperative blood loss and operative time during surgically assisted rapid maxillary expansion

Surgically assisted rapid maxillary expansion (SARME) is a well-established procedure for treating transverse maxillary deficiency in skeletally mature patients. However, the necessity of pterygomaxillary disjunction (PMD) remains unclear. This study aimed to evaluate the effect of PMD on activation torque, an indirect clinical indicator of biomechanical resistance, intraoperative blood loss, and operative duration during SARME. This retrospective study included 51 patients who underwent SARME between 2022 and 2024 at our institution. Patients were classified according to whether PMD was performed (P1, n = 28) or not performed (P0, n = 23). Treatment allocation was non-random and reflected routine clinical decision-making processes. Activation torque data were available for 39 patients (P0, n = 17; P1, n = 22) and were analyzed across ten consecutive intraoperative activation turns using a nonparametric repeated-measures approach. Intraoperative blood loss, operative duration, and perioperative hemoglobin levels were also evaluated using the available data for each outcome. Activation torque increased significantly over ten activation turns (time effect, p < 0.001), with no significant group effect ( p = 0.758) or time × group interaction ( p = 0.725). No significant differences were observed between the groups in terms of intraoperative blood loss ( p =1.00 ), operative duration ( p = 0.87), or hemoglobin change ( p = 0.27). Hemoglobin levels decreased significantly postoperatively in both groups ( p < 0.001). PMD was not associated with statistically significant differences in activation torque, intraoperative blood loss, or operative duration during SARME. Mechanical resistance during expansion may reflect the combined contribution of multiple circummaxillary structures rather than solely the pterygomaxillary junction. Given the retrospective, non-randomized design and potential selection bias, these findings should not be interpreted as evidence of equivalence between the surgical approaches used. Under the investigated conditions, no measurable advantage of routine PMD was demonstrated.