[Technical note: Importance of primary reconstruction of orbicular muscle in modiolus defects: A clinical case report].

INTRODUCTION: The submental flap, first described by Martin and Baudet in 1990, was originally developed for the reconstruction of defects involving the lower two-thirds of the face. Owing to its reliable vascular pedicle and anatomical proximity, its indications have progressively expanded to include complex soft-tissue losses of the hemiface, particularly at the oral commissure, where both aesthetic and functional demands are high.

METHODS: We report the case of a 70-year-old patient presenting with a right cheek and labial commissure defect following an animal bite, associated with loss of the modiolus and orbicularis oris muscle sling. Reconstruction was performed in two stages: (1) restoration of the orbicularis continuity and coverage of the defect using an insular submental flap pedicled on the right submental artery, and (2) secondary commissuroplasty four months later to restore labial continence and facial symmetry.

RESULTS: The first stage achieved complete coverage of the composite defect and reestablishment of muscular continuity. Following commissuroplasty, the patient recovered satisfactory labial motility, oral opening, and functional continence. Subsequent staged debulking procedures refined the aesthetic outcome while maintaining flap trophicity and hair-bearing skin texture.

DISCUSSION: This case highlights the reliability and versatility of the submental flap in commissural reconstruction. Its favorable skin characteristics, robust vascularization, and wide arc of rotation make it an effective alternative to heterolabial flaps, allowing a "like-with-like" reconstruction that achieves both durable functional recovery and harmonious aesthetic integration.