Abstract
This study investigates the color correspondence of resin cements and try-in pastes, and the color stability of bonded lithium disilicate ceramic disks. Resin composite disks were fabricated (n = 36) to serve as the background for lithium disilicate disks prepared in two thicknesses (0.5 and 1.0 mm, n = 18 each). Two brands were used for try-in and cement procedures: Variolink Veneer and AllCem Veneer. For baseline, water was applied between the ceramic disks and their respective backgrounds to achieve the control group. This set was subjected to color measurement using an intraoral measurement device (T0). The try-in was inserted between background and ceramic, and this set was subjected to color measurement (T1). After adhesive procedures, the ceramic disk was placed under cement, and color measurement was performed with uncured cement (T2) and 24 h after light-curing (T3). Each set was immersed in distilled water and thermal-cycled, with color measurement being performed after 10,000 (T4) and 20,000 (T5) cycles. Color differences were calculated by CIELab (rEab) and CIEDE2000 (rE00). Data were analyzed by two-way ANOVA for repeated measurements and Tukey's test (α=5%). There was color correspondence of try-in and resin cement for the Variolink system, regardless of the ceramic thickness (p > 0.05). For the AllCem system, the thickness significantly influenced the color measurement (p < 0.001). The Variolink system also demonstrated color stability after 20,000 thermal cycles with rEab < 3.46 and rE00 < 2.25. It was concluded that the color correspondence between a try-in and its respective cement may vary according to resin cement composition.
Highlights
MethodsResin background disk fabrication Disk-shaped resin composites (Llis; FGM, Joinville, Brazil) in shade A2 served as the background colors to mimic the prepared enamel substrates (n = 36)
The results of rEab and rE00 measurements on ceramic disks with thicknesses of 0.5 mm or 1.0 mm are presented in Tables 1 and 2, respectively
Considering the possibility of a thin air layer occupying the interspace of ceramic and resin disks, which would dramatically increase the difference of the color measurements, a refractive liquid was applied into the interspace to maintain an optical connection,[6,10] and the color coordinates of the refractive liquid applied complexes were set as a baseline
Summary
Resin background disk fabrication Disk-shaped resin composites (Llis; FGM, Joinville, Brazil) in shade A2 served as the background colors to mimic the prepared enamel substrates (n = 36). The resin composite was light-cured for 40 s with an LED light-curing unit (LED 3MESPE, St Paul, MN), with a mean light intensity of 1400 mW/cm[2]. The mean of three measurements for each disk was calculated, and the surface roughness was standardized at 0.88 ± 0.07 μm. After these measurements, the disks were ultrasonically cleaned in purified water for 20 min, and stored in distilled water at 37 °C for 24 h
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