Introduction: This study was designed to evaluate the effectiveness of the open-bite bionator in growing subjects with increased vertical dimensions.
Methods: The records of 20 subjects with high-angle skeletal relationships (MPA > or =25 degrees) were examined. Cephalometric measurements were compared with those obtained from 23 sets of records of an untreated group matched according to age, sex, vertical skeletal relationships, and time intervals between records. Lateral cephalograms were analyzed before the start of treatment (mean age; 8.3 years) and after therapy and retention, with a mean period of observation of 2.5 years.
Results: The treated group had a significantly smaller palatal plane-mandibular plane angle (-1.9 degrees) and a greater overbite (+1.5 mm) associated with a significantly smaller overjet when compared with the control group.
Conclusions: Based on the analysis of this sample, early treatment of skeletal open bite with the open-bite bionator appears to produce a modest effect that mainly consists of significant improvement in intermaxillary divergence. No favorable effects on the extrusion of posterior teeth were found.