Comparison of 2 comprehensive Class II treatment protocols including the bonded Herbst and headgear appliances: a double-blind study of consecutively treated patients at puberty.Am J Orthod Dentofacial Orthop. 2009 Jun; 135(6):698.e1-10; discussion 698-9.AJ
The aim of this clinical trial was to compare the effects of 2 protocols for single-phase comprehensive treatment of Class II Division 1 malocclusion (bonded Herbst followed by fixed appliances [BH + FA] vs headgear followed by fixed appliances and Class II elastics [HG + FA]) at the pubertal growth spurt.
Fifty-six Class II patients were enrolled in the trial and allocated by personal choice to 2 practices, where they underwent 1 of 2 treatment protocols (28 patients were treated consecutively with BH + FA, and 28 patients were treated consecutively with HG + FA). All patients started treatment at puberty (cervical stage [CS] 3 or CS 4) and completed treatment after puberty (CS 5 or CS 6). Lateral cephalograms were taken before therapy and 6 months after the end of comprehensive therapy, with an average interval of 28 months. Longitudinal observations of a matched group of 28 subjects with untreated Class II malocclusions were compared with the 2 treated groups. Analysis of variance (ANOVA) with post-hoc tests was used for statistical comparisons. Discriminant analysis was applied to identify preferential candidates for the BH + FA protocol on the basis of profile changes (advancement of the soft tissues of the chin).
The success rate (full occlusal correction of the malocclusion after treatment) was 92.8% in both treatment groups. The BH + FA group showed a significant increase in mandibular protrusion. The increase in effective mandibular length (Co-Gn) was significantly greater in both treatment groups when compared with natural growth changes in the Class II controls. Significantly greater improvement in sagittal maxillomandibular relationships was found in the BH + FA group. Retrusion of maxillary incisors and mesial movement of mandibular molars were significant in the HG + FA group. The BH + FA group showed significantly greater forward movements of soft-tissue B-point and pogonion compared with both the HG + FA and the control groups. Two pretreatment variables were significant (F = 4.48; P <0.01) in predicting the posttreatment amount of mandibular soft-tissue improvement in the BH + FA group: Co-Go-Me and pogonion to nasion perpendicular.
Class II treatment with either protocol during the pubertal growth spurt induces significant favorable dentoskeletal and occlusal changes. Functional jaw orthopedics had a greater favorable impact on the advancement of the chin. The clinical indications for the preferential use of the Herbst appliance at puberty are a small mandibular angle and mandibular retrusion before treatment. When treated with the BH + FA protocol, these Class II patients have the greatest probability of achieving significant improvement in the profile by advancement of the soft tissues of the chin.