Corticotomy-assisted implant-anchored molar intrusion for enhancement of orthognathic surgery results in patients with hemimandibular hyperplasia

Abstract

Objectives: Vertical skeletal facial asymmetries caused by hemimandibular overgrowth often result in compensatory dentoalveolar elongation on the affected side. Surgical leveling of dental arches during orthognathic surgery results in incomplete correction of the lower jaw asymmetry and necessitates further simultaneous surgical procedures, such as lower border ostectomy, inferior alveolar nerve lateralization, and grafting. Materials and methods: We present a novel technique for the vertical decompensation of dentoalveolar processes to improve orthognathic surgery outcomes. The technique consists of installing skeletal anchorage into the upper and lower jaws, corticotomies of the alveolar processes, and skeletally-anchored orthodontic molar intrusion by means of custom-made intrusion frameworks. The resultant unilateral posterior open bite enables larger rotation in the frontal plane during surgical repositioning of the lower jaw. Results: A 27-year-old woman with hemimandibular hyperplasia and compensatory elongation of the dentoalveolar processes was scheduled for orthodontic-orthognathic treatment. Four months of surgically-assisted intrusion resulted in a 7 mm unilateral posterior open bite. Two-piece Le Fort I osteotomy, bilateral sagittal split osteotomy (BSSO), condylectomy, genioplasty, and minimal lower border contouring were performed during a single-stage surgery. Conclusions: Surgically-assisted implant-anchored intrusion of the molars is a feasible technique for vertical pre-surgical decompensation in vertical skeletal asymmetries. The degree of unilateral posterior open bite achieved is essential for surgical planning since rotation of the mandible in the frontal plane reduces the degree of lower border ostectomy.