Relationship between Discrepancy Index and the Objective Grading System in Thai board of orthodontics Patients

Objective Using the American Board of Orthodontics system (ABO), this study determined whether there was any relationship between the Discrepancy Index (DI) and Objective Grading System (OGS) scores. Second objective was to determine the correlation between the objective scores by ABO system and subjective scores judged by candidates. Materials and methods 200 records from 25 candidates for Thai board of orthodontics were evaluated using (1) DI and (2) OGS. Candidates were asked to evaluate their own cases on 2 parameters: (1) difficulty level and (2) Satisfaction visual analog scale (VAS). Spearman correlation coefficients were computed to assess the relationship among these 4 variables. In addition, 3 subgroups of DI scores (low, medium, high) were tested if there were any association with 3 subgroups of OGS (passing, undetermined, failing), using Chi-square test. Results Mean DI was 23.48 (SD 15.39), OGS was 26.39 (SD 9.77), Satisfaction VAS was 62.81 (SD 8.04) and median of difficulty level was 2.15. There were no correlation between DI and OGS, OGS and Satisfaction VAS, DI and Satisfaction VAS. However, difficulty level was, at low level, significantly correlated with DI and Satisfaction VAS (p-value <.05). Percentage distribution of DI; low was 10%, medium was 42% and high was 48.0%, and of OGS; passing 26%, undetermined 45% and failing 29%. There were no association among 3 subgroups of DI with 3 subgroups of OGS. Conclusions DI could not be used as a weighted factor for OGS in determining if the case would pass or fail in ThBO cases.