Herbst treatment with mandibular cast splints--revisited

Abstract

Objective: 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.

Materials and methods: 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).

Results: 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).

Conclusions: 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.

Figures

Figure 1

(A) TMS extending from first molars to canines. (B) Partial dislodgement of a lower TMS cast splint. (C) RMS extending from second premolars to canines.

Figure 2

Space opening between the lower second premolar and first permanent molar during RMS-Herbst treatment.

Figure 3

The SO analysis is performed on lateral head films in habitual occlusion. For all linear measurements, the occlusal line (OL) and the occlusal line perpendicular (OLp) from the first head film were used as a reference grid. The grid was transferred from the first tracing (T1) to the second tracing (T2) by superimposition of the tracings on the Nasion-Sella line (NSL) at Sella (S).

Figure 4

Individual treatment changes (T2-T1) for lower incisor inclination (IiL/ML) in 100 Class II patients treated with a RMS-Herbst appliance.

Figure 5

Individual treatment changes (T2-T1) for lower incisor inclination changes [IiL/ML(d)] in the prepeak (stages MP3 E-F or S 1-2), peak (stages MP3 FG-G or S 3-4), postpeak (stages MP3 H-I ) and young adults (stages R I-J) skeletal maturity groups.

Figure 6

SO analysis: Maxillary and mandibular skeletal and dental changes contributing to overjet correction and molar correction in 100 Class II patients treated with a RMS-Herbst appliance.

Figure 7

Individual treatment changes (T2-T1) in 100 Class II patients treated with a RMS-Herbst appliance. The values (mm) for the total available space and for the space between the second permanent premolar (P2) and the first permanent molar (M1) in the lower arch are given.

Figure 8

Intraoral photographs of a 12-year, 7-month-old girl with a Class II division 1 malocclusion and an aplasia of tooth 45. (A) Before treatment. (B) Space closure during RMS-Herbst treatment—note that in such a case it is useful to place an additional attachment in the area of the lower first premolar. (C) After Herbst treatment.