Assessment of Color Stainability of Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) Ceramic Materials After Hot and Cold Coffee Immersion at Different Time Intervals.

BACKGROUND This spectrophotometric study assessed the color stability of CAD/CAM restorative materials with different exposed surfaces following staining by hot Arabic Qahwa and cold coffee. MATERIAL AND METHODS Ninety-six specimens were fabricated from 3 different CAD/CAM ceramic materials: Vita Suprinity (Vita-S), Vita Enamic (Vita-E), and Vitablocs Mark II (Vitablocs-MII). We divided 32 specimens for each group into glazed or polished surfaces, with 16 specimens in each group, then subdivided them according to staining materials: Arabic Qahwa and Frappuccino Cold Coffee. Color of specimens was measured during immersion in staining materials (BEFORE) as baseline with (Vita classic) and (L, a, b), for average color changes (ΔE00), then remeasured after 2, 4, and 12 weeks, and described as 1st, 2nd, and 3rd measurements for VITAPAN Classic shade and T1, T2, and T3 for ΔE00 values using the CIE L*a*b* equation. We performed ANOVA and then post hoc testing. RESULTS We found significant differences in ΔE00 values during immersing in hot Arabic Qahwa and cold coffee for tested materials in glazed or polished specimens. Polished specimens of Vita-S and Vita-E had the highest color changing and staining compared to glazed surfaces. Vitablocs-MII had the best color stability through immersion periods. Moreover, there were changes in relation to VITAPAN Classic shade guide for both Vita-S and Vita-E specimens during different immersion periods. CONCLUSIONS Coffee caused staining and contamination of ceramic material. Values of ΔE00 for tested ceramic materials were significantly different but were within the clinically acceptable range. Polished specimens showed higher staining; therefore, we highly recommend re-glazing of ceramic restorations to maintain color stability.

Assessment of perceptibility and acceptability of color difference of denture teeth.

OBJECTIVES: To assess the color difference values that represent the perceptibility and acceptability thresholds of denture teeth. METHODS: Eighteen interchangeable right upper central incisors denture teeth were selected to have color difference values from representative left upper central incisor denture tooth in a range of 0.4-11.4 ΔE* units measured with a spectrophotometer (CM 2600d, Minolta Konica, Japan). These teeth were placed in an artificial dental arch in a phantom head. Under controlled conditions, a total of 80 observers divided into 4 groups (technicians, nurses, dentists and researchers) were asked to report the perceptibility and acceptability of each of the color difference values. The findings was then analysed using logistic regression for determining the perceptible and acceptable thresholds of dental color differences. RESULTS: The determined color difference values at which 50% of all observers could detect a color difference (50:50 probability) was 1.9 ΔE* units with a 95% confidence interval and ranged from 1.7 ΔE* units to 2.1 ΔE* units. The determined color difference value at which 50% of all observes preferred to replace the tooth because of unacceptable color difference (50:50 probability) was 4.2 with a 95% confidence interval that ranged from 3.9 ΔE* units to 4.7 ΔE* units. CONCLUSIONS: Within the limitation of this study, the following conclusions were made: 1. The mean color perceptibility threshold was significantly lower than the mean color acceptability threshold. 2. Significant differences between different observers groups were noticed in determination of perceptibility and acceptability of color differences. The technicians groups displayed lower perceptibility and acceptability limits than the dental nurses and non-dental observers. CLINICAL SIGNIFICANCE: When shade matching artificial denture teeth to natural teeth, 50:50 perceptibility (1.9 ΔE* units) and acceptability (4.2 ΔE* units) thresholds are used to compare color difference values. The technicians group displayed lower perceptibility and acceptability limits than other observers.