Relationship between the Dental Aesthetic Index and Discrepancy Index

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.

Cross-sectional study.

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.

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).

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).

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).