Comparison of the accuracy between full-arch digital scans and scannable impression materials: an in vitro study.

Background: In some clinical cases, full-arch impression could be difficult to take correctly with the digital way. Patients with high flow salivary rate or with difficulties in mouth opening can still benefit from a conventional impression with elastomer materials that can be directly or indirectly digitized. The aim of this study was to compare the accuracy and precision of two different intraoral scanners (IOSs) and an impression material with scannable properties, by means of three-dimensional analysis of a complete dental arch.

Methods: An anatomical model of complete upper arch, modified with a Scan body placed in the retroincisive area, was used. It was firstly scanned by a desktop scanner to create a digital reference model. Then, 3 groups were created, each constituted by 5 samples. In the first group, 5 impressions were taken from the same master model with the scannable PVS material (Hydrorise Implant), 5 scans were taken using Trios4 (3Shape) and other 5 scans with iTero Element 5D (iTero). STL files obtained from IOSs, and scanned impressions were three-dimensionally superimposed on the STL file of the reference model using the Scan body geometry.

Results: The ANOVA Test (P<0.005) did not show any statistically significant difference between the accuracy and precision values of the groups. Each group shows clinically acceptable deviations from the reference model.

Conclusions: Scannable polyvinylsiloxane impression materials are equally accurate and precise as the two IOSs tested in full-arch dentate impressions.