American board of orthodontics- discrepancy index (ABO-DI) as prognostic factor for the duration of orthodontic treatment: A cross-sectional retrospective study

Abstract

To evaluate American Board of Orthodontics-Discrepancy Index (ABO-DI) as a prognostic factor in predicting the duration of orthodontic treatment.This cross-sectional retrospective study was conducted on the pre-treatment and post-treatment records of 151 consecutively de-bonded cases, who were treated between January 2016 and September 2013 with comprehensive orthodontic therapy. The ABO-DI was used to assess the pretreatment severity of malocclusion. The sample was divided into three groups based upon the discrepancy score calculated from pretreatment study model and lateral cephalogram; Group-1 (DI score <16; n= 65), Group-2 (DI score 16-25; n= 49) and Group-3 (DI score> 25; n=37). The duration of orthodontic treatment was calculated as total treatment time (in months) from the date of placement of initial brackets and archwires to the date when orthodontic appliances were removed. Spearman’s correlation test and One way ANOVA analysis followed by Post-Hoc tests for multiple comparisons were used to assess the association between the ABO-DI scores and duration of orthodontic treatment.The mean duration of treatment for Group-1, Group-2 and Group-3 was found to be 25.83±8.42, 28.16±10.55 and 28.84±9.61 months respectively, but there was no statistically significant relationship between the severity of malocclusion on the duration of comprehensive orthodontic treatment (P>0.05). An insignificant correlation (P=0.102, r= -0.134) between different groups of severity of DI scores and treatment duration was revealed with Spearman test.The duration of orthodontic treatment increased with increase in severity of malocclusion, however, it is not a reliable tool for predicting the treatment duration.