To investigate skeletal and dentoskeletal changes 20 years after bionator treatment.

Materials and Methods

Analog lateral cephalograms of 18 subjects treated with a bionator appliance during growth were digitized with a transmitted light scanner. Inclusion criteria were: increased overjet (≥4 mm), skeletal Class II, available lateral cephalograms before (T0), after (T1), and 20 years after (T2) treatment with only a Bionator. To assess standard cephalometric parameters, the software ivoris analyze was used. Data were analyzed using Friedman's two-way analysis of variance by ranks followed by Dunn's post hoc tests (P ≤ .05).


During therapy (T0–T1), ANB decreased significantly by 1.9° and remained unchanged long term. SNA slightly decreased (−0.6°) during treatment, SNB and SNPg increased (+1.4°, +1.7°). All three parameters showed a significant increase at T2 (+1.2°, +1.6°, +1.6°). Vertical measurements (ML-NL, ML-NSL, NL-NSL) remained almost unchanged during therapy. NL-NSL also was unchanged during the long-term interval; ML-NSL and ML-NL decreased significantly (−3.4°, −4.9°). During treatment, the maxillary incisors retroclined (OK1-NL: −1.6°, OK1-NA: −0.6°), the mandibular incisors proclined (UK1-ML: +3.5°, UK1-NB: +4.9°), neither significantly. Long term, there was a nonsignificant tendency toward proclination of upper (OK1-NL: +0.1°, OK1-NA: +0.7°) and retroclination of lower incisors (UK1-ML: −1.5°, UK1-NB: −5°).


Changes of ANB after bionator treatment without additional fixed appliances remained stable after 20 years. The observed long-term changes are probably consequences of well-known physiological and age-related processes.

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Author notes


Junior Researcher, Department of Orthodontics, University Medical Centre Regensburg, Regensburg, Germany.


Associate Professor, Department of Orthodontics, Justus-Liebig-University Giessen, Giessen, Germany.


Junior Researcher, Department of Prosthetic Dentistry, University Medical Centre Regensburg, Regensburg, Germany.


Chairman, Department of Orthodontics, University Medical Centre Regensburg, Regensburg, Germany.


Professor Emeritus, Faculty of Medicine, LMU University of Munich, Munich, Germany.