Opacity of four resin cements to their try-in pastes

Objective: The purpose of this study was to evaluate the opacity match of four resin cements to their corresponding try-in pastes. The following materials were evaluated: 3M Experimental Resin Veneer (Cement 6 shades, 3M/ESPE), Nexus II (4 shades, Kerr), Variolink II (6 shades, Ivoclar/Vivadent) and Calibra (5 shades, L.D.Caulk/Dentsply). Methods: Using two glass slides and mylar shim stocks, cement specimens were made at the following thickness: 30, 50, 75, 100, 200, 350 and 500 micrometers. The resin cements were then light cured according to the manufacturer's instructions. Five specimens were made for each group. The same technique was used when making the try-in paste specimens, except that the specimens were not light polymerized. Five measurements of each specimen were made for each shade, averaged and used to calculate the difference (Delta E) between each pair of resin and try-in paste. Opacity of the samples was calculated by obtaining the contrast ratio of the specimen. Using the previously made specimens for the color measurements, the opacity was measured with a portable transmission Densitometer 331. Results: Opacity results for the 3M resin cement indicated a very close match between resin and try-in paste for all of the shades evaluated. When the White Opaque (range from 0.035 to 0.45) was compared to the White Opaques from Nexus II (range 0.29 to 0.72) and Variolink II, (range 0.31 to 0.75), this shade might not have enough opacity to mask a severely discolored tooth. The opacity for Calibra, Nexus II and Variolink II resin cements was also consistent. Variolink II had the most opaque shades. Conclusions: (1) The opacities of all the resin cements were within range of their try-in pastes. (2) The 3M experimental resin cements had the most translucent shades. (3) Nexus II and Variolink II had the most opaque shades.