Increase in mandibular and chin projection with orthognathic surgery

Three groups of twelve patients, each of whom had a Class II, Division 1 malocclusion with a markedly convex facial profile and steep mandibular plane, were treated by orthodontic means and orthognathic surgery. One group had mandibular advancement, another had maxillary elevation, and the third had both surgical procedures combined, with genioplasties performed in some cases from each group. Changes were studied with the aid of lateral cephalometric headfilms taken just after surgery and from 5 to 105 months later. Horizontal changes in point B and pogonion after the follow-up period were 7.0 mm and 8.5 mm with mandibular surgery, 5.4 mm and 9.3 mm with maxillary surgery, and 10.7 mm and 16.4 mm with combined surgery. The amount of change is much larger than found with orthodontic or orthopedic treatment alone and makes possible the successful treatment of very difficult problems.