[Hyperactivity of the muscles of the lip and chin and indications for surgery to reduce it].

Hyperactivity of the muscles controlling the lower lip and chin (muscles of the chin, buccinator, orbicularis, etc.) can be demonstrated at different levels of the muscular complex and may act as an elastic force against the mandibular alveolar process. Dysfunction in this region may lead to reduction of the alveolar bone quantity, reducing the tooth-bone equilibrium. If this balance is disturbed, periodontal lesions, a lower incisal crowding and a retrognathic mandibular process may result. Surgery to correct overactivity of the chin muscles is described here step by step. Resection of the muscles may be undertaken on a greater or lesser scale and striation of the muscle may also allow reduction of muscular strength. Reducing the muscular activity creates a better environment for the development of the mandible and its alveolar process. Depending on the clinical situation, these techniques can be associated with genioplasty, bone graft and/or mandibular orthognathic surgery.