Factors associated with long-term vertical skeletal changes induced by facemask therapy in patients with Class III malocclusion.

OBJECTIVES: This study investigated the long-term vertical skeletal changes induced by facemask therapy in patients with Class III malocclusion and different vertical skeletal patterns.

MATERIALS AND METHODS: A total of 54 patients (20 boys and 34 girls; mean age, 7.7 ± 2.0 years) with Class III malocclusion who were successfully treated with facemask therapy were included in this study. Vertical skeletal changes (overbite depth indicator, angle between the Sella-Nasion (SN) plane and Gonion-Gnathion (GoGn) line, angle between the Frankfort horizontal (FH) plane and mandibular plane, gonial angle, and angle between the SN plane and palatal plane) were measured on lateral cephalograms from before treatment (T0) to after facemask therapy (T1) and from T0 to after retention (T2). Multivariate linear regression analysis was used to study the associations of the patients' skeletal patterns with the short-term (T0-T1) and long-term (T0-T2) vertical skeletal changes as a result of facemask therapy.

RESULTS: The mean treatment period of facemask therapy (T0-T1) was 1.4 ± 0.6 years, and the mean retention period (T1-T2) was 6.9 ± 2.6 years. Age at T0 was significantly correlated with vertical skeletal changes from T0 to T1. Differences in the treatment results between sexes were not significant. The angle between point A-point B line and mandibular plane to mandibular plane angle at T0 and the angle between the FH plane and mandibular plane at T0 were significant predictors for short-term and long-term changes. Changes in the Sella-Nasion-point A from T0 to T1 and from T1 to T2 significantly affected vertical changes in the short term and long term, respectively.

CONCLUSIONS: Vertical skeletal changes as a result of facemask therapy are significantly associated with severity of the skeletal Class III malocclusion and mandibular plane angulation before treatment and the amount of forward maxillary growth during the treatment and retention periods.