Treatment complexity index for assessing the relationship of treatment duration and outcomes in a graduate orthodontics clinic

Introduction: Clinical cases completed by the Indiana University School of Dentistry (IUSD) graduating orthodontic classes of 2004, 2005, and 2006 were assessed to determine factors that affect orthodontic treatment duration. Methods: The sample consisted of 455 consecutively finished patients who received comprehensive treatment in the full permanent dentition. They included optimally finished and prematurely terminated (early debond) patients. The American Board of Orthodontics (ABO) discrepancy index (DI) was used to evaluate the severity of the pretreatment malocclusion. A specifically designed treatment complexity index (TCI) was used to evaluate complexity based on treatment modalities. The ABO objective grading system (OGS) and the IUSD comprehensive clinical assessment (CCA) were used to evaluate the clinical outcome for all patients. Results: The average treatment duration was 29 months. The mean DI, OGS, and CCA scores were 15.30, 23.34, and 4.48, respectively. Increased treatment length was associated with 0.022-in slot size brackets, percent of treatment spent in nickel-titanium wires, Class II malocclusion, increased DI score, and increased TCI score. In evaluating outcomes for 2004 through 2006, there was no significant relationship between treatment duration and clinical outcome as measured by the OGS and CCA scores. Conclusions: The DI and TCI are sensitive prospective indicators of treatment duration. After the introduction of a rigorous clinical protocol for controlling poor outcomes, because of patients exceeding predicted treatment times, the clinical results for this sample are independent of treatment duration.