Long-term post-treatment stability of the Herbst appliance

The Herbst appliance is an adjunctive treatment for the correction of Class II malocclusions. Previous studies have indicated that the correction following the end of treatment frequently relapses. The purpose of this study was to assess the cephalometric changes during and following a treatment protocol of 12 months of Herbst appliance treatment followed by fixed appliance treatment, and 12 months of retention. The changes from the end of treatment to the retention recall were, on average, very small. The only statistically significant changes (Mixed linear model; P<0.05) observed were relapse in the ANB angle (-0.31°;sd=0.88), overjet (0.49mm;sd=0.94) and overbite (0.55mm;sd=0.98). These changes were considered not clinically significant. The Class II correction effected by this treatment protocol appears stable one year out of treatment.