Color change of CAD-CAM materials and composite resin cements after thermocycling

Abstract Statement of problem The color of resin cements and computer-aided-design and computer-aided-manufacturing (CAD-CAM) restorations may change with aging. Purpose The purpose of this in vitro study was to analyze the influence of thermocycling on the color of CAD-CAM materials with underlying resin cement. Material and methods Seven different CAD-CAM materials, composite resins and glass-ceramics were cut into 0.7-mm and 1.2-mm thicknesses (n=10) and cemented with a dual-polymerizing resin cement, a light-polymerizing resin cement, and a preheated composite resin (N=420). Color values were measured by using spectrophotometry. Specimens were subjected to thermocycling (5°C and 55°C; 5000 cycles). The measured color difference (ΔE) data were analyzed by using descriptive statistics. Normality of data distribution was tested by using the Kolmogorov-Smirnov test. Three-way and 1-way ANOVA followed by the Scheffe post-hoc test and unpaired 2-sample Student t test were computed to determine the significant differences among the tested parameters (α=.05). Results ΔE values were significantly influenced by the CAD-CAM material (η p 2 =0.85, P P 2 =0.03, P =.003) but were not influenced by thickness ( P =.179). Significant interactions were present among thickness, cement, and CAD-CAM materials ( P P P =.003). Conclusions Restoration materials and composite resin cement types used for cementation influence the amount of color change due to aging.