Twenty-year follow-up of functional treatment with a bionator appliance (part 2): a retrospective cephalometric analysis of skeletal and dentoskeletal changes

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

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.