Stability of simultaneous maxillary and mandibular osteotomy for treatment of class III malocclusion: an analysis of three-dimensional cephalograms

Abstract

The current investigation was undertaken to study the three-dimensional (3-D) stability of simultaneous maxillary advancement and mandibular setback using rigid ®xation. The study also aimed to analyse the factors involved in postsurgical relapse by evaluation of changes in various parameters. Patients: Twenty-®ve cases were evaluated of simultaneous Le Fort I maxillary advancement and mandibular setback using rigid ®xation. Methods: Preoperative, immediate and 6-month postoperative skeletal and dental changes were analysed using 3-D cephalograms obtained from biplanar stereoradiography. Maxillary ®xation screws were used as landmarks to evaluate postoperative stability. Results: The mean maxillary advancement was 3.7 mm. Relapse in the sagittal, vertical, and transverse planes was not detectable in the maxilla ( p40.05). However, for an average mandibular setback of 5.7 mm, mean mandibular relapse was 1.1mm or 19.3% anteriorly ( p5 0.05). Surgical or postsurgical skeletal changes in the maxilla had no detectable in¯uence on mandibular relapse ( p4 0.05). Vertical alterations of the facial skeleton achieved surgically predicted the mandibular relapse (R2=0.27, p5 0.05). Conclusion: Maxillary advancement and vertical changes of +2mm did not in¯uence the postoperative stability of the mandible. Relapse of the mandible seems to be in¯uenced mainly by the amount and direction of the surgical alteration of mandibular position.