Effect of ceramic material and resin cement systems on the color stability of laminate veneers after accelerated aging.

STATEMENT OF PROBLEM

Laminate veneers are susceptible to color change during clinical service. Studies that compare the effects of different ceramic and resin cement systems on color stability are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the color stability of laminate veneers after accelerated aging using different ceramic and resin cement systems.

MATERIAL AND METHODS

Ceramic specimens (N=168; shade A1; thickness, 0.50 ±0.05 mm; diameter, 10.00 ±0.10 mm) were prepared using nanofluorapatite and lithium disilicate (high translucency [HT] to low translucency [LT]) ceramics. Light-polymerizing (LP) cements were classified by brightness (high or low). Dual-polymerizing cements were classified by composition (base-only [DB] or base-catalyst [DC]) for comparison of color stability on the basis of polymerization type. DB cement was light-polymerizing, whereas DC cement was dual-polymerizing. They were further classified by shade (transparent, white, or yellow [n=7, each]). Color difference (ΔE) values were obtained by spectrophotometric quantification of L* (lightness), a* (green-red), and b* (blue-yellow) values before and after aging. The Kruskal-Wallis, Mann-Whitney U, Wilcoxon signed rank, and Bonferroni post hoc tests were used for statistical analysis.

RESULTS

After specimens were subjected to accelerated aging, HT ceramic specimens luted with yellow-shade DC cement exhibited the greatest color change (ΔE=2.11), whereas HT and LT ceramic specimens luted with low-brightness LP cement exhibited the least color change (ΔE=1.37). In HT ceramic specimens, which exhibited the greatest color change of the 3 ceramic types, transparent shade cement exhibited significantly lower ΔE values than the other shades with DB (P<.001) and DC cements (P=.010). High-brightness cement exhibited significantly higher ΔE values than low-brightness cement when used with NF (P=.017), HT (P<.001), and LT (P<.001) ceramics. The ΔE values of DB cement were not always lower than those of DC cement. For all specimens, the aging of laminate veneers decreased the L* values and increased the a* and b* values.

CONCLUSIONS

Ceramic and resin-cement systems affected the color stability of laminate veneers. Relative to other ceramics, HT lithium disilicate ceramics exhibited greater color changes upon aging. For HT ceramics, the use of transparent shade resin cement is recommended. The lower the brightness of resin cement, the higher the color stability of veneers. For luting of 0.5-mm-thick laminate veneers with dual-polymerizing cement, light polymerization did not yield better color stability than dual polymerization over time.