Discrepancy index relative to age, sex, and the probability of completing treatment by one resident in a 2-year graduate orthodontics program.

INTRODUCTION: The American Board of Orthodontics' discrepancy index (DI) was designed to objectively quantify the complexity of a malocclusion before orthodontic treatment. In this study, we assessed the influence of age and sex on the DI distribution of a large mixed sample of patients. An additional objective was to ascertain the effectiveness of the DI for predicting the probability that 1 resident can complete the treatment of the malocclusion in a 24-month residency.
METHODS: A group of 6 calibrated investigators independently determined the DI scores for 716 consecutive patients in the permanent dentition from the patient pool of Indiana University's graduate orthodontics program over 7 years. The DI was scored and compared with the patient's sex and age, and it was noted whether the patient was transferred to a second resident when the first one graduated.
RESULTS: The DI is not significantly related to sex or age, but it was a significant predictor for patients who required transfer to a second resident for completion of treatment.
CONCLUSIONS: The DI was a relatively stable index for measuring malocclusion complexity. It is independent of sex or age but is a consistent indicator of the greater time and effort required to complete treatment, because of the significant correlation to the necessity to transfer patient care to a second resident. Copyright Â