Occlusal stability after Herbst treatment of patients with retrognathic and prognathic facial types : A pilot study.

OBJECTIVES

The purpose of this study was to assess and compare occlusal changes induced by Herbst treatment and the stability of these changes in patients with retrognathic and prognathic facial types.

PATIENTS AND METHODS

The sample comprised 11 retrognathic (SNA ≤76°, SNB ≤72°, ML/NSL ≥36°) and 10 prognathic (SNA ≥83°, SNB ≥80°, ML/NSL ≤32°) patients with Class II molar relationships of ≥0.5 cusp widths bilaterally or ≥1.0 cusp width unilaterally. Both groups involved similar distributions of skeletal maturity before treatment. Study parameters were assessed on casts reflecting the situations before treatment (T0), after Herbst treatment (T1), after multibracket treatment immediately following Herbst treatment (T2), and after a mean of 31.1 months of retention (T3).

RESULTS

Sagittal molar relationships improved by 0.8 cusp widths in the retrognathic and by 0.7 cusp widths in the prognathic group during active treatment (T0-T2). Insignificant changes of ≤0,2 cusp widths were seen in both groups during retention (T2-T3). Overjet decreased by 8.6 mm in the retrognathic and by 5.5 mm in the prognathic group during T0-T2, and both groups showed clinically irrelevant amounts of relapse by 0.7 mm during T2-T3. Overbite improved by 1.2 mm in the retrognathic and by 2.5 mm in the prognathic group during T0-T2, reaching mean values of 1.0 mm or 1.4 mm by T2, which was followed by 0.2 mm or 1.1 mm of relapse during T2-T3.

CONCLUSION

Treatment with a Herbst appliance seems to offer stable correction of the sagittal occlusal relationships in Class II patients with retrognathic or prognathic facial types, with the vertical changes being more pronounced in the prognathic cases.