Three-dimensional treatment outcomes in Class II patients treated with the Herbst appliance: A pilot study

Introduction: The aims of this study were to analyze 3-dimensional skeletal changes in subjects with Class II malocclusion treated with the Herbst appliance and to compare these changes with treated Class II controls using 3-dimensional superimposition techniques. Methods: Seven consecutive Herbst patients and 7 Class II controls treated with Class II elastics who met the inclusion criteria had cone-beam computed tomographs taken before treatment, and either after Herbst removal or at posttreatment for the control subjects. Three-dimensional models were generated from the cone-beam computed tomography images, registered on the anterior cranial bases, and analyzed using color maps and point-to-point measurements. Results: The Herbst patients demonstrated anterior translation of the glenoid fossae and condyles (right anterior fossa, 1.69 +/- 0.62 mm; left anterior fossa, 1.43 +/- 0.71 mm; right anterior condyle, 1.20 +/- 0.41 mm; left anterior condyle, 1.29 +/- 0.57 mm), whereas posterior displacement predominated in the controls (right anterior fossa, -1.51 +/- 0.68 mm; left anterior fossa, 1.31 +/- 0.61 mm; right anterior condyle, 1.20 +/- 0.41 mm; left anterior condyle, 1.29 +/- 0.57 mm; P < 0.001). There was more anterior projection of B-point in the Herbst patients (2.62 +/- 1.08 mm vs 1.49 +/- 0.79 mm; P < 0.05). Anterior displacement of A-point was more predominant in the controls when compared with the Herbst patients (1.20 +/- 0.53 mm vs -1.22 +/- 0.43 mm; P < 0.001). Conclusions: Class II patients treated with the Herbst appliance demonstrated anterior displacement of the condyles and glenoid fossae along with maxillary restraint when compared with the treated Class II controls; this might result in more anterior mandibular projection.