Long-term stability of two-jaw surgery for treatment of mandibular deficiency and vertical maxillary excess.

Changes in cephalometric landmark positions and relationships were evaluated more than 5 years postsurgically in 26 patients whose long-face condition had been treated with a combination of superior repositioning of the maxilla and mandibular advancement. All the patients had a least 2-mm surgical intrusion of the maxilla and 2-mm lengthening of the mandible with wire osteosynthesis, maxillomandibular fixation, and skeletal suspension wires. On the average, a small amount of downward and backward rotation of the mandible occurred long term. The mean change in overjet was less than 1 mm. Most of the changes occurred in a minority of the patients: 20% of the group had 2 to 4-mm downward movement of menton, and the mandibular plane angle increased more than 2 degrees in 25% of the patients. On clinical evaluation, a tendency toward opening of the bite beyond 1 year postsurgery was noted in 5 of the 26 patients (19%), and one patient had a greater than 4-mm decrease in overbite. The condylion-pogonion distance decreased 2 to 4 mm in three patients, two of whom had shown greater than 4-mm shortening of this distance during the first postsurgical year. It appears that long-term shortening of the condylar process is not a highly prevalent problem, but changes of 2 to 4 mm in condylion-pogonion associated with modest clinical relapse may occur beyond 1 year postsurgery in 5 to 10% of these two-jaw surgery patients.