Positional changes after mandibular advancement by sagittal split osteotomies and wire osteosynthesis. Do combined orthodontics and the Dal Pont modification of the buccal osteotomy contribute to long-term stability?

Thirty-five cases of sagittal split ramus osteotomies with wire osteosynthesis as the exclusive procedure used to correct a dentoskeletal Class II deformity, were selected to form a homogeneous group for cephalometric evaluation of the short- and long-term, skeletal and dental changes. The group was statistically described as having severe micromandibulism, mild micromaxillism and mild dento-alveolar maxillary protrusion. The skeletal relapse within the first postoperative year was due to horizontal and dorsocranial rotational changes of the tooth-bearing segment. The joint-bearing segment rotated ventrocranially. As an overall result, the mandibular body was not lengthened but advanced. The relapse at the occlusal level was considerably less, partly due to the rotational component of the skeletal relapse mechanism, partly due to the compensating retroclination of the upper anterior teeth. With the condyles correctly repositioned at surgery, no relationship could be found between postoperative changes in condylar position and skeletal relapse. There was no difference in the average amount of skeletal relapse between the subgroup with the Dal Pont modification of the buccal osteotomy and the subgroup with the buccal osteotomy directed to the mandibular angle. The average skeletal relapse was greater in the combined surgical orthodontic cases, due to increased alveolar tooth mobility.