RESUMO
OBJECTIVE: Surgical mandibular advancement procedures induce major adaptations of jaw-closing muscles. In this study, adaptation of antagonist muscles, the lateral pterygoid (LPM) and anterior digastric (DigA) muscles, was evaluated. STUDY DESIGN: Eighteen adult patients with mandibular retrognathia and individually varying vertical craniofacial dimensions were treated with bilateral sagittal split osteotomies (BSSO), in some cases combined with a Le Fort I osteotomy (LF Bimax). The sample was divided into 1 short-face (SF, n = 7) and 2 long-face groups (LF BSSO, n = 3; and LF Bimax, n = 8). Pre- and postoperative maximum cross-sectional areas (CSA) and volumes were compared in these groups. RESULTS: Postoperatively, CSA and volume of LPM increased in BSSO cases and decreased in bimaxillary cases. Inconsistent increases and decreases of CSA and volume of DigA were seen in all groups. CONCLUSIONS: The LPM became larger in SF and LF BSSO patients and smaller in LF Bimax patients. The DigA adapted unpredictably.
