Accuracy of Digital American Board of Orthodontics Discrepancy Index

The objective of the this study was to compare accuracy and reliability of the American Board of Orthodontics Discrepancy Index obtained manually on plaster casts (the gold standard) with scores obtained using their digital models in OrthoCad software and Motion View’s Ortho Insight 3D software. Plaster models were obtained from 45 previous patients with varying degrees of malocclusion. Measurements were completed manually with a periodontal probe as necessary. The same casts were scanned and analyzed using Ortho Insight 3D (Motion View Software, Hixson, TN). Alginate impressions were made of the original plaster casts and sent to OrthoCad (Cadent, Carlstadt, NJ) for digital model fabrication and analysis. Total DI score and its target disorders were computed manually on plaster casts and digitally using the respective software. Intra-rater and inter-rater reliability was assessed for 15 subjects using Spearman’s Rho correlation test. Accuracy DI scores and its target disorders were assessed for all 45 subjects using Wilcoxon signed ranks test to determine differences in digital calculation compared to manual calculation. Intra-rater and inter-rater reliability was high for total DI score and most target disorders (r>0.8). No significant difference was found between total DI score when measured with OrthoCad compared to manual calculation. Total DI score calculated by Ortho Insight 3D was found to be significantly larger than manual calculation by 2.71 points.