Clinical complications during treatment with a modified Herbst appliance in combination with a lingual appliance

OBJECTIVE To assess the types and frequencies of clinical complications experienced when using a modified lingual Herbst appliance and to compare these with those associated with conventional Herbst appliances reported in the literature. METHODS Treatment records for 35 consecutive subjects treated during the observation period from October 2013 to August 2014 who received a combination of a lingual appliance and a modified Herbst appliance (WIN, DW LingualSystems) were assessed for complications linked to Herbst treatment phase. Complications were analyzed descriptively, and complication-free intervals were calculated using Kaplan-Meier plots. To enable a comparison with data reported in the literature, the cumulative treatment time for all subjects was divided by the total number of complications. RESULTS 71.4% of Herbst treatments were free from complications (n = 25). Complications were seen on 13 occasions (8 instances of Herbst attachment loosening, 5 L-Pin fractures). Most of these complications could be fixed chair side utilizing simple clinical measures. Considering all complications as identical statistical events, the percentage of treatments free from complications would be 88% for 100 days, 70% for 200 days and 56.8% for 300 days. For severe complications, the averaged complication-free treatment interval was found to be 27.8 months. CONCLUSION In terms of clinical sturdiness, and taking into consideration the step-wise mode of activation used here as well as the differences in the design of the various Herbst appliances, the WIN-Herbst appliance was found to be superior to comparable vestibular Herbst appliances, as well as the banded Herbst appliance belonging to the preceding generation of customized lingual systems. Success in treatment of non-compliant Angle Class II correction is considered to have better predictability using the modified anchorage strategy of the WIN-Herbst appliance.