Influence of crown shade, translucency, and scan powder application on the trueness of intraoral scanners.

Objectives: Natural teeth and dental restorations present with various shades and levels of translucency. This study aimed to determine whether these variations in ceramic crowns and scan powder application affect the trueness of intraoral scanners.

Methods: Eight identical premade resin typodonts, each prepared for a crown on the maxillary right second molar, were used. Eight lithium disilicate crowns, distinguished by two levels of translucency (high and low) and four shades (BL1, A2, A3, and A4), were fabricated to an identical design and cemented onto each typodont, providing eight distinct experimental groups (2 levels of translucency × 4 shades). Reference scans were acquired using a desktop scanner. Test scans were performed ten times for each experimental group using two different intraoral scanners (Medit i700 and CEREC Primescan AC), with and without the application of scan powder (n = 10). Three-dimensional metrology software was used to assess the trueness of the intraoral scan datasets. Statistical analysis involved the Kruskal-Wallis H test, Mann-Whitney U test, and independent t-test (α=0.05).

Results: For powder-free intraoral scan datasets, the crown shade did not significantly affect trueness within each translucency group (P = 1.000). For both intraoral scanners, compared with low translucency groups, higher marked deviations were exhibited by high translucency groups (P<.001). Scan powder use largely mitigated these differences (P>.05) and enhanced the trueness of the intraoral scan (P<.01).

Conclusions: Shade did not significantly influence the trueness of intraoral scans. High-translucency crowns were scanned with less accuracy than were low-translucency crowns.

Clinical Significance: Unlike tooth shade, translucency significantly affected the accuracy of intraoral scans. Therefore, considering the use of scan powder when scanning objects with high translucency may be beneficial.