Quantitative analysis of color accuracy and bias in 4 dental CAD-CAM monolithic restorative materials with different thicknesses: An in vitro study

Statement of problem. Computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic restorative materials have become a popular option because of advantages such as convenience and efficiency. However, studies that quantitatively analyzed their color accuracy and bias are lacking. Purpose. The purpose of this in vitro study was to evaluate the color accuracy and bias of 4 CAD-CAM monolithic restorative materials with different thicknesses by using the CIELab color space. Material and methods. Four types of dental CAD-CAM monolithic restorative materials in shade A2, lithium disilicate glass-ceramic (IPS e.max CAD), infiltrated ceramic (VITA Enamic), resin-nano ceramic (LAVA Ultimate), and polymethyl methacrylate (Telio CAD), were prepared as 12x12-mm specimens of 10 different thicknesses (from 0.5 to 5.0 mm) (N=200, n=5). After polishing with SiC P1500-grit, CIELab color coordinate parameters of the specimens were measured with a spectrophotometer (VITA Easyshade V). The color accuracy and bias were described by DE00, Delta L*, Delta a*, and Delta b* in the CIELab color space, and the data were analyzed by using a 2-way ANOVA, post hoc Tukey-Kramer test, and the t test (alpha=.05). Results. The DE00, Delta L*, Delta a*, and Delta b* were significantly influenced by material type and thickness (P<.001). Specimens at a thickness of 0.5 mm represented the maximum Delta E-00. The minimum Delta E-00 was observed at a thickness of 2.0 mm for LAVA Ultimate, 1.5 mm for VITA Enamic and Telio CAD, and 4.0 mm for IPS e.max CAD. The Delta E-00 of all specimens significantly exceeded the 50:50% acceptability threshold (1.8 unit) (P<.001). LU exhibited higher Delta E-00, Delta a*, and Delta b* than the other 3 materials in all thickness expect for 0.5 mm. For color bias, the Delta E-00 was more influenced by Delta b* and Delta L* than Delta a*. Conclusions. The color accuracy and bias were significantly affected by material type and thickness. The color inaccuracy of the tested materials was statistically significant and clinically perceptible. Improved clinical outcomes may be expected from the 1.5-mm- to 2.0-mm-thick restorations.

Automated summary

This study aimed to evaluate the color accuracy and bias of 4 CAD-CAM monolithic restorative materials with different thicknesses using the CIELab color space. Results showed that material type and thickness significantly affected color accuracy and bias, with restorations at thicknesses of 1.5 mm to 2.0 mm potentially leading to improved clinical outcomes.