Aim: To assess the skeletal and dental changes occurring during the retention period after adult Class II:1 Herbst treatment.
Material and Methods: 15 Class II:1 subjects (overjet > 6mm) with a minimum age of 18 years and completed growth according to pre-treatment hand wrist radiographs. All subjects were treated with a Herbst appliance (mean 9 months), followed by Multibracket (MB) treatment (mean 14 months). The retention period was at least 24 months. Lateral cephalograms (T1: before treatment, T2: after Herbst-MB treatment, T3: after retention) were analysed using the SO-analysis described by Pancherz and standard cephalometrics.
Results: During the entire observation period (T3-T1) the overjet was on average reduced by 5.2mm (12% skeletal changes, 88 % dental changes) and the molar relation improved by an average of 3.3mm (19% skeletal changes, 81 % dental changes). The amount of relapse (T3-T2) was small, amounting to 1mm for overjet and 0.25mm for molar relationship. Thus, during the retention period the relative contribution of skeletal changes to overjet and molar relation decreased by 6% and 12%, respectively compared to the active treatment period (T2-T1). Accordingly, the jaw base relationship (ANB +0.25°) deteriorated and the hard as well as soft tissue profile convexities (NAPg -0.37°/N’SsPg’ -0.65°) increased slightly during the retention period (T3-T2) despite an anterior rotation of the mandible (ML/NSL -0.15°).
Conclusion: Although Class II correction in adult Herbst-MB treatment is achieved by mainly dental changes, the treatment results showed good overall stability.