Accuracy of four different intraoral scanners according to different preparation geometries

To evaluate the accuracy (trueness and precision) achievable with four intraoral scanners (IOSs) and different preparation geometries.

A model of a maxillary arch with different preparation geometries (onlay, inlay, veneer, full-crown) served as the reference master model (RMM). The RMM was scanned 10 times using four commonly used IOSs (Trios 2 [TR], 3Shape; Omnicam [OC], Dentsply Sirona; True-Definition [TD], 3M ESPE; and Primescan [PS], Dentsply Sirona). Scans were matched using a 3D measurement software (Inspect 2019, GOM) and a best-fit algorithm, and the accuracy (trueness and precision) of the preparation types of the scanning data was evaluated for positive and negative deviations separately. All data were subjected to univariate analysis of variance using SPSS version 24 (IBM).

Mean (± SD) positive deviations ranged from 4.6 ± 0.7 μm (TR, veneer) to 25.9 ± 2.4μm (OC, full crown). Mean negative deviations ranged from -7.2 ± 0.6 μm (TR, veneer) to -26.4 ± 3.8 μm (OC, full crown). There were significant differences (P < .05) in terms of trueness and precision among the different IOSs and preparation geometries.

The transfer accuracy of simple geometries was significantly more accurate than those of the more complex prosthetic geometries. Overall, however, the IOSs used in this study yielded results that were clinically useful for the investigated preparation types, and the mean positive and negative deviations were in clinically acceptable ranges.