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

Objectives: 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). Results: During therapy (T0-T1), ANB decreased significantly by 1.9 degrees and remained unchanged long term. SNA slightly decreased (-0.6 degrees) during treatment, SNB and SNPg increased (+1.4 degrees, +1.7 degrees). All three parameters showed a significant increase at T2 (+1.2 degrees, +1.6 degrees, +1.6 degrees). 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 degrees,-4.9 degrees). During treatment, the maxillary incisors retroclined (OK1-NL:-1.6 degrees, OK1-NA:-0.6 degrees), the mandibular incisors proclined (UK1-ML: +3.5 degrees, UK1-NB: +4.9 degrees), neither significantly. Long term, there was a nonsignificant tendency toward proclination of upper (OK1-NL: +0.1 degrees, OK1-NA: +0.7 degrees) and retroclination of lower incisors (UK1-ML:-1.5 degrees, UK1-NB:-5 degrees). Conclusions: 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. (Angle Orthod. 2023;93:269-274.)