Introduction: The American Board of Orthodontics (ABO) discrepancy index (DI) quantifies the severity of a malocclusion. The ABO objective grading system (OGS) assesses the quality of orthodontic finishing. Indiana University's comprehensive clinical assessment (CCA) supplements the OGS to provide an instrument to determine clinical outcomes. The purposes of this article were to (1) determine whether treatment outcome is related to the type of malocclusion as defined by the ABO classification, (2) determine the fraction of finished orthodontic cases in the graduate orthodontics clinic that are within the ABO standards for passing the phase III clinical examination, (3) evaluate the contribution of each component of the OGS and the CCA to the total OGS and CCA scores, (4) determine the percentage of finished cases that meet the ABO case category specifications, and (5) identify problem areas to improve the quality of treatment for challenging malocclusions.
Methods: Three hundred eighty-two cases that satisfied requirements for 8 of the ABO's malocclusion categories were selected from 989 consecutively finished cases from 1998 through 2003. They were evaluated by using the OGS, the CCA, and the DI.
Results: The average OGS score was 32.64, the average CCA score was 5.62, and the average DI score was 20.94. There was no significant difference in the OGS and the CCA scores among the categories. Categories 2, 5, 7, and 8 had a DI score that was significantly higher than the average for the entire sample. The OGS and CCA scores were positively correlated with the DI score, meaning that complex malocclusions are challenging to finish well. The most points lost for the OGS and the CCA were for occlusal contacts and treatment efficiency (length of treatment relative to the result), respectively. The fewest points lost were for interproximal contacts and vertical control, respectively. Furthermore, prematurely terminated cases (early debonds) had longer treatment times and higher (worse) OGS and CCA scores.
Conclusions: This study demonstrates problems in treating complex malocclusions in a graduate orthodontics program and suggests methods for increasing the quality of clinical outcomes.