Evaluating the color stability of two esthetic ceramic materials after different surface treatments and accelerated aging procedures

Abstract

Aim: Observing and evaluating the long/short-term discoloration tendency of the esthetic prosthetic materials of lithium disilicate-based glass-ceramics (IPS e.max CAD LT) and leucite-based feldspathic glass-ceramics (VITA Mark II) materials, which are esthetically very close to each other at first glance.

Methodology: 80 samples of A2 colored lithium disilicate and feldspathic blocks samples were overglazed and polished separately to evaluate the surface treatment procedures according to CIELAB color coordinates. For accelerated aging purposes, half of the examples were treated to red wine, and the other half were treated to coffee. Color changes were calculated using the ΔE formula. The results were put into record as ΔE-1, ΔE-2, and ΔE-3. Records of the results were evaluated using IBM SPSS Statistics Standard Concurrent User V 25 statistics package program. Data distribution regarding numerical variety and changes were evaluated using the Shapiro Wilk normality test and Q-Q graphics. 

Results: The data was evaluated using O'Brien clinical color tolerance scales. None of the samples has shown a perfect (ΔE=0-0.5) color match after 4 weeks of accelerated aging. Every group has shown results of significant statistical changes at various rates and percentages and divided into 4 subgroups as excellent, good, clinically acceptable and incompatible categories.

Conclusion: Since aging procedures affect ceramic systems' ΔE values in a variety of ways, the aging protocol utilizing in vitro aging techniques for color changing should be evaluated alongside ceramic type and surface finishing procedures.