Comparison of arch dimension changes in 1-phase vs 2-phase treatment of Class II malocclusion.

Introduction: We compared arch dimension changes in 1-phase and 2-phase treatment of Class II malocclusion. This was a prospective randomized clinical trial conducted in the Department of Orthodontics at the University of Florida between 1990 and 2003.

Methods: During phase 1 treatment, 86 subjects were treated with a bionator, 93 were treated with headgear/biteplane, and 81 served as the observation group. For phase 2, all subjects were then treated with full orthodontic appliances. Arch dimensions were followed; maxillary and mandibular alginate impressions were taken at baseline, end of early Class II treatment or observation, beginning of fixed appliance treatment, end of orthodontic treatment, and approximately 3 years posttreatment. Alginate impressions were taken of each dental arch at each data collection point. These were poured in orthodontic stone, trimmed, and photocopied from the occlusal aspect. These images were then scanned and measured.

Results: Although differences between the treatment groups were found in both the maxillary and mandibular arches after phase 1, these differences were no longer evident by the end of full orthodontic treatment or after posttreatment retention.

Conclusions: There were no differences in arch dimensions after 1-phase or 2-phase treatment of Class II malocclusion.