Background:
There is an increasing amount of research on digital dental solutions. The influence of depth and shape of the preparation on trueness,precision of IOS was analyzed.

Aim of the study:
This in vitro study was performed to compare the accuracy of full-arch scans from different scanners, depending on depth and shape of the preparation. Scans were compared with the reference scanner.

Material and methods:
A 3D-printed fully dentate mandible printed model with six standardized preparations of varying depth and outline has been scanned with 8 intraoral scanners and 1 laboratory scanner. Printed model was then scanned with a highly precise benchmark scanner (Comet 6, ZEISS). Preparations were divided into three outline forms: circle, rectangle, square and two depth groups of 3.0 and 6.0 mm. All scans were compared for a best-fit accuracy with the reference scan.

Results:
Results obtained for Emerald (0-880.0 µm) and iTero (10-180.0 µm) scanners were characterized by the worst trueness parameter and high dispersion of data. Other scanners did not differ from the reference level (0) by more than 100.0 µm and neither the depth nor the shape of the preparation played a significant role in accuracy. The best accuracy was observed for TRIOS4 (0-50.0 µm) Omnicam (0-40.0 µm) The laboratory scanner (Series7, Dental Wings) achieved trueness level of 12.5-70.0 µm.

Conclusions:
Most scanners compared in this study were able to perform well in typical clinical situations. Outlier measurements obtained for Emerald and iTero may result from software or technical issues. Intraoral scanners showed similar accuracy to the laboratory scanner compared in this study.