Long-term stability of basilar mandible osteotomy: Chin Wing

Abstract

The Chin Wing is a modified genioplasty extended along the basilar border and the angles of the mandible. This technique may be a better choice than standard genioplasty for correction of lip incompetence, retrogenia and high angle position associated with hyperdivergent cases. Our objective was to analyse the overall movement realized during surgery and the long-term stability of this procedure. Ten patients underwent a Chin Wing surgery from June 2018 to August 2019. All patients were operated on by the same surgeon. We performed a preoperative (PO), an immediate postoperative (POI), and an over 6 months postoperative (PO6) Cone Beam Computed Tomography (CBCT) for every patient. 3D reconstructions were performed for each CBCT with Proplan software. We were thus able to determine by subtractions acquired and resorbed bone volume. Some section plans were chosen in order to perform 2D measurements. The CBCT volume comparisons reveal a gain of 7.6cc between the PO and the POI, for a bone resorption of 2.5cc between POI and PO6 (33% of the volume gained). In 2D evaluation, we observe an average resorption of 1.7 mm corresponding to approximately 20% of the height gained, at the level of the mandibular angle. Given the low bone resorption we can consider Chin Wing stable over time. The important quantity of mobilized bone and the basilar rotational movement may explain over-standing aesthetic and functional outcome, compared to classical genioplasty