Research Findings on CAD-CAM Materials

Researchers from the Prosthodontics Department at Samsun, Turkey recently observed that the long-term use of alcohol‐containing mouth rinse may alter the optical properties of tested CAD‐CAM materials in tested laminate veneer thickness. Also, for the color stability with the long-term use of tested mouth rinses, lithium disilicate may be preferred for both types of restorations, as published in the Journal of Esthetic and Restorative Dentistry.

"The color change of ZH zirconia with LI mouth rinse in laminate veneer thickness was high," explained Rafat Sasany, the lead author of the study.

For both zirconia ceramics, translucency decreased, and the color was less stable in laminate veneer thickness after immersed in LI compared to the crown thickness, he further revealed.

Sasany and colleagues conducted this study to investigate the effect of mouth rinses on the color and translucency of three computer‐aided design and computer‐aided manufacturing (CAD‐CAM) restorative materials in laminate veneer and crown thicknesses.

Specimens from two different 5Y‐TZP zirconia (InCoris TZI (IT), and Zirkonzahn (ZH)) and lithium disilicate (IPS e.max CAD [IC]) in two different thicknesses (0.7 mm for laminate veneer, and 1.5 mm for crown) were sectioned. All specimens were colored with an A2‐shade liquid, and the baseline color values were recorded according to the CIELab system with a spectrophotometer.

Each group was divided into two subgroups (n = 15) according to the immersion solution: two different mouth rinses, KL (Klorhex), and LI (Listerine, cool mint) for 180 hours. The color coordinates (L*, a*, b*) of the specimens were measured before and after immersion in a mouth rinse, and TP and ΔE00 color differences were calculated by using the CIEDE2000 color difference formula. A 3‐way ANOVA, Bonferroni test, and 1‐sample t-tests were used to analyze the data (α = 0.05).

Findings

• A significant interaction of material, thickness, and mouth rinse for translucency parameter and color difference (ΔE00) data (p < 0.001) was found.
• TP decreased for both zirconia materials in laminate veneer thickness when immersed in LI mouth rinse (p < 0.05).
• No difference was found among the TP mean values of three materials in crown thickness after immersed in mouth rinses (p > 0.826).
• Both zirconia materials immersed in LI showed greater discoloration than after immersed in KL (p < 0.05).
• A significant difference was found in color change values among three materials for the laminate veneer thickness after immersed in LI (p < 0.001).
• However, all color difference values were within the clinical acceptability threshold, except for when ZH in laminate veneer thickness was immersed in LI.

Hence, the authors concluded that "The color change of ZH zirconia with LI mouth rinse in laminate veneer thickness was high. For both zirconia ceramics, translucency decreased and the color was less stable in laminate veneer thickness after immersed in LI compared to the crown thickness."