Relationship between the Dental Aesthetic Index and Discrepancy Index

Abstract

Objective: To establish the association between malocclusion severity and orthodontic case complexity as assessed by the Dental Aesthetic Index (DAI) and the American Board of Orthodontics Discrepancy Index (ABO-DI), respectively. Design: Cross-sectional study. Setting: Pre-treatment dental casts and radiographs from 500 individuals (294 women and 206 men; mean age = 26.06 ± 11.58 years) were randomly selected from the orthodontics department of a private university. Methods: Malocclusion severity was assessed using DAI and case complexity was evaluated with ABO-DI. Three previously calibrated operators performed the measurements. Spearman’s correlation analysis, Mann–Whitney U test, Kruskal–Wallis test and a linear generalised model were used for statistical evaluation ( P < 0.05 was considered significant). Results: Although the correlation (r = 0.45; P < 0.0001) between malocclusion severity and case complexity was moderate, strong evidence of an association ( P < 0.001) between dichotomised DAI and ABO-DI total scores was observed. The linear generalised model showed that for each point of increase in DAI score, the ABO-DI score increased an average of 0.3624 points ( P < 0.0001). Conclusion: An association between malocclusion severity and case complexity is suggested. A linear generalised model could be used to predict the complexity of the case from the malocclusion severity (DAI score).