الفهرس 
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Abstract
Aim: To assess the accuracy of digital study models versus plaster models in a mixed dentition stage through the Tanaka and Johnston prediction equation.
Design: This study included impressions for 16 participants. Plaster models were produced, scanned, and digitized with a 3shape scanner (R700), measurements were performed by 1st and 2nd examiners on plaster models with a digital caliper (0-150 mm/6 –fraction/metric Vernier measuring Caliper-China), and on digital models by 3shape Ortho-analyzer software (v.2017-1; 3shape-Copenhagen). Required space for each case was then calculated by both methods (manual and digital) through Tanaka and Johnston’s prediction equation.
Results: A statistically significant difference was found between (3D models) and (2D models) with a mean difference =0.29 [95% CI (0.13-0.44)] for the maxillary arch, and 0.32 [95% CI (0.15-0.5)] for the mandibular one where (p=0.001). The majority of these disparities, however, were not deemed clinically significant. Based on the inter-examiner performance, a firm agreement was found between the readings of the two examiners with ICC = 0.964 for 3D models and 0.948 for 2D models in the maxillary arch and ICC=0.964 for 3D models and 0.948 for 2D models in the mandibular arch.
Conclusions: Digital models are considerably accurate and have a clinically acceptable accuracy compared to measurements made with a digital caliper on plaster models.