Purpose: When improving jaw deformity by two-jaw surgery, we are of the opinion from our clinical experience that a certain degree of undercorrection is occasionally beneficial from the perspective of stability. Functional deterioration is not always seen with undercorrection. We conducted this retrospective study to assess post-operative stability in patients with facial asymmetry, with the aim of both clarifying differences between the original three skeletal class patterns, and confirming the efficacy of surgery performed on the basis of our concept.
Patients and methods: All patients received optimal orthognathic treatment before and after surgery. Surgery was performed by our concept that undercorrection is not always bad. Nineteen patients were enrolled, and separated into three skeletal classes according to the ANB angle, because of the difference of the treatment modalities between them. Evaluations were performed by cephalometric measurements taken at least two-year post-operatively. Transverse occlusal cant, chin deviation, point A, point B, overjet and overbite were assessed.
Results: In all patients, transverse occlusal cant improved to <4°, which has been reported as the threshold for visual recognition of facial symmetry. Chin deviation was also improved to the degree at which soft tissue can sufficiently mask the asymmetry. The changes remained stable throughout follow-up and satisfaction was obtained from all patients.
Conclusions: Irrespective of original skeletal class patterns, post-operative stability of patients with facial asymmetry was achieved. Undercorrection is thus by no means problematic from the clinical perspective of stability and our concept of approach appears valid.
Keywords: Asymmetry; Stability; Two-jaw surgery; Undercorrection.