Evaluation of the Accuracy of Digital Impression Techniques Based on an Integrated ADA Model

Abstract

ObjectiveThe purpose of this in vitro study was to assess and compare the accuracy of three digital impression techniques based on an innovative integrated model.Materials and MethodsThe integrated model was created by incorporating crown, inlay, and long-distance specimens from the American Dental Association (ADA) Standard No. 132. Digitized files of the model were acquired using three distinct impression techniques: intraoral scanner (IOS), extraoral scanner with negative cast (EOS_N), and extraoral scanner with positive cast (EOS_P). A coordinate measuring machine (CMM) was employed to establish the gold standard. The digital files of the model obtained via the extraoral scanner were designated the reference set for 3D fitting. Statistical analysis was performed using a one-way analysis of variance and Tukey's posthoc test.ResultsFor the crown specimen, the relative error of EOS_N for indices d1 and d2 was higher than that of IOS and EOS_P. For the inlay specimen, IOS showed the highest trueness for d3 and h2. For the long-distance specimen, IOS exhibited superior trueness for indices l1 and l3. EOS_N displayed the lowest trueness for l2. For l4, IOS had the largest relative error. No significant differences were observed among the three groups for l5 and l6. Notable deviations were evident in the 3D fitting maps at various locations in three experimental groups.ConclusionsThe three digital impression techniques exhibited varying capacities for capturing features of the integrated ADA model. For crown preparations, IOS and EOS_P are recommended, while for inlay preparations, no technology meets the standard requirements. IOS is recommended for partial impressions, while both EOS_N and EOS_P are suited for full-arch impressions.