Article
Long-Term Stability of Surgical-Orthodontic Open-Bite Correction
Anterior open bites have, historically, been difficult to treat with fixed appliances and, before the advent of the Le Fort I osteotomy, attempts to correct this by mandibular surgery alone showed very high rates of relapse. With maxillary impaction surgery to reduce the posterior vertical dimension, success rates have now greatly improved.
However, the stability of such surgical correction has been reported to be variable. Few follow-up studies have examined surgically-treated patients beyond 5 years. This study examined 39 patients (17 male, 22 female) with a mean age of 20.8 years (range 13.6–43.4 years) who were recalled at an average time period of 8.2 years (range 2.0–18.9 years) after treatment. The original skeletal pattern was Class I in 3 patients, Class II in 20, and Class III in 16. Ten patients had a Le Fort I operation only, 9 had a mandibular operation only, and 20 had bimaxillary procedures. In 25 patients, fixation was by intraosseous wiring, while the remaining 14 had rigid fixation with miniplates and screws. Cephalometric radiographs were obtained at pretreatment, debond and at recall.
The mean anterior open bite was 4.25 mm (SD 2.03 mm) at the start of treatment, while the average overbite was 1.1 mm (SD 0.82 mm) at the end of treatment, with a mean open bite of 0.04 mm (SD 1.81 mm) at recall. Class II division 1 cases tended to have a slightly greater anterior open bite at recall (0.6 mm, SD 2.12 mm) and Class III cases maintained a positive overbite of 0.77 mm (SD 0.74 mm) at recall.
A positive overbite was found in 64.1% in the overall sample, with 47.8% of the Class II division 1 cases having a positive overbite at recall, compared with 87.5% of the Class III cases. One reason for this discrepancy may be due to the fact that the Class II division 1 samples had a higher mean Frankfort-Mandibular Plane Angle (35.4°) at the start of treatment compared with an average FMPA of 30.8° for the Class III cases.
Bivariate statistics with correlation coefficients were used in this paper. A larger sample and use of multivariable statistics would give a better insight into the factors influencing such long-term outcomes.