OPTION 3

The Hierarchy of Stability and Predictability

•            Stability after surgical repositioning of the jaws depends on the direction of movement, the type of fixation, and the surgical technique, largely in that order of importance.

•            The most stable orthognathic procedure is superior repositioning of the maxilla, closely followed by mandibular advancement in patients whose anterior facial height is maintained or increased. These procedures, the key ones in correcting severe Class II problems, can be considered to produce a highly stable result even without rigid fixation, and this remains true when they are combined in the treatment of patients with mandibular deficiency and a long face—but only if rigid fixation is used.

•            In the treatment of patients with Class III problems, with rigid fixation, the combination of maxillary advancement and mandibular setback is acceptably stable. In contrast, isolated mandibular setback often is unstable. So is downward movement of the maxilla that creates downward– backward rotation of the mandible. For this reason, almost all Class III patients now have maxillary advancement, either alone or (more frequently) combined with mandibular setback.

•            Surgical widening of the maxilla has the least stable result among the orthognathic surgical procedures. Widening the maxilla stretches the palatal mucosa, and its elastic rebound is the major cause of the relapse tendency.