| Summary: | The purpose of this study was to evaluate the treatment and post-treatment changes in a sample of patients with a Class II division 1 malocclusion (n = 50) who received orthodontic treatment and who were out of retention a minimum of 3 years. The entire sample was evaluated at three time periods (T1 = pre-treatment, T2 = post-treatment and T3 = post-retention). They w re examined as a total sample and then broken down by treatment received, gender, arch and zone (molar, canine or incisor region). The following dental cast variables were measured to an accuracy of 0.01mm: (1) intermolar width; (2) intercanine width; (3) incisor alignment. For the purpose of this study, relapse is defined as any change in tooth position within the arch in the transverse dimension. The results of both aspects of the investigation identified, the following trends: (1) arch changes were independent of the type of orthodontic treatment; (2) arch form changed following the completion of all forms of active orthodontic treatment; (3) this "relapse" in orthodontic treatment appeared to be a function of the degree of orthodontic tooth movement. Although these findings relate to only one sub-category of Angle's Class II patients, they indicated that retainers were mandatory to maintain the changes subsequent to active orthodontic treatment. It was also apparent that the assessment of relapse, defined by changes in tooth position following orthodontic treatment, is an inappropriate assay of orthodontic quality assurance. (Abstract shortened by UMI.)
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