Effects of resin cements on the color of all ceramic core substructure

Technological advances have allowed the accomplishment of esthetically successful treatments specifically in the anterior region. Due to the fact that metal-ceramics which have been in use for many years may cause gingival discolorations and esthetic disadvantages of metals such as lack of translucency, full ceramic restorations have started to gain more popularity in recent years. With the improvements in full ceramic systems as well as resin cements used with ceramics, it is possible to obtain restorations having very similar optical properties with the natural tooth. The purpose of our study is to assess the influence of resin cements used with full ceramic systems on the full ceramic substructure. IPS e.max Press (Ivoclar Vivadent, Schaan, Liechtenstein) with high esthetic properties was used as the ceramic substructure. 3 different shades of Panavia F 2.0 (Kuraray Co Inc, Kurashiki, Japan), Rely X U100 (3M ESPE, St.Paul, Minneapolis, USA) and Variolink 2 (Ivoclar Vivadent, Schaan, Liechtenstein) were applied on the ceramic substructure and the shade differences caused by resin cements were examined spectrophotometrically.In the present study, 180 IPS e.max Press ceramic substructure discs having 15 mm diameter and 1± 0.05 mm thickness were used. The surface finishing and polishing procedures were completed in the grinder-polisher device using 320-, 600-, 800-, 1000- and 1200- grit grinding paper for 15 minutes under water. Before resin cement application, the color values of the discs were measured in the spectrophotometer device and recorded. Numbers were assigned on these discs and Light,White and Opaque colors of Panavia F 2.0, Trancent,A2 and A3 of Rely X U100 and Translucent, A1 , A3 colors of Variolink 2 were used by a metal model and 0.7 mm. cement thickness was obtained. The first spectrophotometric measurement was made after the application of the resin cements :then a second measurement was performed in the same order. The obtained values were recorded according to the CIE L*a*b* color system. The color change values were converted into NBS units and the clinical color differences were evaluated. Two way Anova was used in the comparison of colors and materials and non-parametric Mann Whitney-U test in the comparison of samples with and without cements taking the number of samples into consideration. Paired t-test was used in the comparison of the color changes in A1 and A3 substructures.The results were evaluated at the 95% significance range and p< 0.05 significance level. The results indicated that the application of Panavia White, Panavia Opak and Rely X A3 resin cements on A1 and A3 colored substructure discs caused a ?marked change? according to the NBS criteria. On the other hand, all the other resin cements caused an ?extremely marked change? on all the substructure discs. Panavia Light was detected as the least effective cement in color change among the translucent colors of resin cements applied on A1 and A3 colored discs. The cement that caused the highest level of color change among the A3 colors of cements was determined to be Variolink A3. Within the resin cements, Panavia Opak was the cement causing the least color change whereas A3 within the RelyX 100 colors. Within the colors of Variolink 2, A1 had the least color change among A1 discs and Translucent on the A3 discs. All the color changes between cements were statistically significant.