Effect of CAD-CAM restorative materials and scanning aid conditions on the accuracy and time efficiency of intraoral scans.

Abstract

This in vitro study aimed to evaluate the effects of restorative materials and scanning aid conditions on the accuracy and time efficiency of intraoral scans. Identical anatomic contour crowns were fabricated using the following materials: hybrid ceramic, 3 mol% yttria-stabilized tetragonal zirconia, 4 mol% yttria-partially stabilized zirconia, 5 mol% yttria-partially stabilized zirconia, cobalt-chromium (Co-Cr), resin, lithium disilicate, and feldspathic ceramic. The models were digitized and analyzed for accuracy (n = 10) under three scanning aid conditions (powder-based, liquid-based, and none). Additionally, the effect of metal restorations on the scan accuracy of other crowns was investigated. The scan time for complete arches was also recorded. One-way analysis of variance, Welch analysis of variance, and post-hoc comparison or independent t-tests were used for trueness analysis, and the F-test was used to examine precision (α = 0.05). Significant differences were observed in the trueness of the different restorative materials under the no-scanning aid condition (P < 0.05). In contrast, no statistically significant difference among the groups was observed with the powder- or liquid-based scanning aid. For each restorative material, the no-scanning aid condition showed significantly lower trueness than that with powder- or liquid-based scanning aids. The presence of a Co-Cr crown did not affect the trueness of other restorations in the arch. The scan time efficiency significantly increased on applying a powder- or liquid-based scanning aid. Using a scanning aid was effective to improve the scan accuracy of the tested restorative materials and scan time efficiency. Applying scanning aids to existing intraoral restorations can help improve prosthesis quality and reduce the need for clinical adjustment at the occlusal or proximal contacts.