Predictors of relapse in orthodontically-treated Class III malocclusions

This study aimed to investigate the possibility of predicting relapse from the pretreatment records of children with orthodontically treatable Class III malocclusions. Sixty-four patients were studied: 31 individuals had been treated by a non-extraction technique, the remaining 33 with mid-arch extractions. Cephalometric and model data taken at the start of treatment and at least 2 years after all treatment and retention had ceased were examined. An individual diagnosis of relapse or stability was made from the post-retention records and the start of treatment records analysed in relation to this information. The capacity for predicting the observed outcome of therapy was assessed in three ways: correlation coefficients, the number of cephalometric measurements exceeding two standard deviations from a control group mean, and discriminant analysis. Only the latter proved an effective indicator of relapse, with a separate discriminant model being necessary for each sub-group.