RESUMEN
AIM: The aim of the present prospective study was to evaluate if the treatment performed using high-pull traction on a Stephenson plate had real orthopaedic outcomes in subjects with severe Class II Division 1 malocclusion due to maxillary protrusion. MATERIALS AND METHODS: Twenty-three growing patients showing Class II Division 1 malocclusion (Stephenson plate group, SPG) were treated and compared with an untreated Class II control group (CG - 21 subjects selected from the database of Bolton-Brush Growth Study). Lateral cephalograms at T0 and T1 for both groups were analysed using cephalometric tracing by Jarabak, Pancherz and Ghosh-Nanda. RESULTS: Orthopaedic forces were applied in SPG. SPG group showed significantly greater decrease than CG group of SNA° (-1.4° vs +0.7°), ANB° (-1.3° vs +0°), WITS (-1° vs 0.6°), overjet (-4.1 mm vs +0.3 mm), molar relationships (-6.1° mm vs -0.1 mm) and upper incisors proclination (1/SpP, -10.3° vs -1°). The maxilla substantially maintained its position (A/OLp +0.3 mm, SNA° -1.4°) while the mandible slightly grew (Pg/OLp +1.7 mm; SNB° + 0.7°). Facial pattern and AFA/AFP ratio did not change. CONCLUSION: The high-pull traction on the Stephenson plate produced more dental than skeletal outcomes in growing subjects, despite of the application of orthopaedic forces.