Herbst treatment with mandibular cast splints—revisited

Abstract

The objective of this study was to reassess the dento-skeletal treatment effects and the amount of anchorage loss during reduced mandibular splint (RMS) Herbst treatment. One hundred consecutive Class II patients treated with a RMS-Herbst appliance were analyzed. The mean pretreatment age of the patients was 14.5 years, and the mean treatment time with the Herbst appliance was 8.1 months. Both before (T1) and after (T2) Herbst treatment a cephalometric measurement of lower incisor inclination, a sagittal occlusion analysis, and a dental cast analysis were performed. A comparison was performed with a historic Herbst control group treated with total mandibular cast splints (TMS). During treatment the lower incisors proclined markedly (12.9° ± 4.6°). The amount of incisor proclination in the RMS group was, on average, 3.6° larger (P < .001) than in the TMS group. The lower incisor proclination increased from 11.9° (prepeak) to 14.3° (young adult). The level of professional experience of the practitioners performing the treatment did not influence the amount of incisor proclination significantly. The total available space in the lower arch increased by an average of 1.8 mm, and a space opened between the lower second premolars and lower permanent first molars in 62% of the present RMS-Herbst (average of 0.4 mm per side). Treatment with RMS-Herbst appliances leads to higher proclination of the lower incisors than does treatment with TMS-Herbst appliances; it also leads to an overall larger amount of anchorage loss.