Color stability of ceramic veneers as a function of resin cement curing mode and shade: 3-year follow-up

by Janes Francio Pissaia, Brunna Katyuscia de Almeida Guanaes, Cibele Cândida de Almeida Kintopp, Gisele Maria Correr, Leonardo Fernandes da Cunha, Carla Castiglia Gonzaga

The influence of curing mode and shade of resin cements on the color stability of minimum-thickness ceramic veneers after a three-year storage time in distilled water was evaluated in this study. Ninety-six 0.5-mm-thick feldspathic ceramic veneers (Mark II) were luted onto resin composite substrates (Filtek Z350 XT, shade A2E) with two light-cured (NX3 Light-cure and AllCem Veneer) and dual-cured resin cements (NX3 dual-cure and AllCem) in various shades. The specimens were stored in distilled water at 37°C. Color measurements were performed with a spectrophotometer at the following times: 1h and 24h; 7, 30, and 180 days; and 1, 2, and 3 years. Data for color difference (ΔE_ab) light-cured and dual-cured resin cements were analyzed by two-way ANOVA with repeated measures and Tukey’s test (α = 0.05). For the light-cured cements, the ΔE_ab values were as follows: NX3-Yellow (2.37±1.35) = ACV-A1 (2.40±1.21) = ACV-Trans (2.52±1.46) = ACV-E-Bleach M (2.56±1.42) = NX3-White (2.69±1.49) = NX3-Clear (2.98±1.68). The lowest ΔE values were found for 1 h (0.61±0.36)^a, followed by 24 h (1.15±0.55)^b and 30 days (2.48±1.11)^c. One year, 180 days, and 2 and 3 years presented higher ΔE_ab values (3.34±0.94, 3.52±1.04, 3.52±0.95 and 3.55±1.14, respectively)^d. For the dual-cured cements, the ΔE_ab values varied as follows: NX3-Clear (2.32±1.24)^a = NX3-Yellow (2.37±1.32)^a = NX3-White (2.76±1.43)^a < AC-Trans (3.77±1.91)^b = AC-A3 (4.13±2.11)^b < AC-A1 (5.38±2.92)^c. Considering time, the lowest ΔE_ab values were found for 1 h (0.48±0.25)^a, followed by 24 h (2.13 ±0.83)^b, 30 days (3.54±1.31)^c, and 180 days (3,70±1.73)^c. The follow-up times of 1 (4.43±2.15)^d, 2 (5.02±1.74)^e, and 3 years (4.90±2.12)^e presented higher ΔE_ab values. This study demonstrated that light-cured resin cements were less susceptible to color change than dual-cured cements. After 2 years of follow-up, all cements presented ΔE_ab values above the acceptability threshold.