Effect of different high-palladium metal-ceramic alloys on the color of opaque and dentin porcelain

Statement of problem. The color of dental porcelain depends on the type of metal substrate. Little research has been done to document the effects of different types of high-palladium alloys on the color of dental porcelain. Purpose. The purpose of this in vitro study was to evaluate the effects of different high-palladium alloys on the resulting color of dentin porcelain, as well as on that of opaque porcelain after simulated dentin and glazing firing cycles. Material and methods. Three Pd-Cu-Ga alloys, Spartan Plus (S), Liberty (13), and Freedom Plus (F), and 5 Pd-Ga alloys, Legacy (L), IS 85 (1), Protocol (P), Legacy XT (X), and Jelenko No. 1 (N), were examined. A Pd-Ag alloy, Super Star (T), was included for comparison to the high-palladium alloys, and the Au-Pd alloy, Olympia (0), served as the control. Six cast discs (16 X I mm) were prepared from each of the alloys. Shade B I opaque porcelain (Vita-Omega) was applied at a final thickness of 0.1 mm. After 2 opaque porcelain firing cycles, the surfaces were airborne-particle abraded, and the specimens were divided into 2 groups. In the first group, 0.9 mm of B1 dentin porcelain was applied. The other group of specimens with only opaque porcelain underwent the same dentin porcelain and glazing firing cycles. Color differences (DeltaE) were determined with a colorimeter between the control and each experimental group, after the second opaque porcelain, second dentin porcelain, and glazing firing cycles. One-way analysis of variance and Dunnett’s multiple range test were performed on the DeltaE data (alpha=.05). Results. After the application of dentin porcelain, the 3 Pd-Cu-Ga alloys showed significantly different (P<.05) Delta E values (S = 2.3 +/- 0.5, B = 1.4 +/- 0.3, and F = 1.3 +/- 0.7) than the control group. After the glazing cycle of this group, the 3 Pd-Cu-Ga alloys and the Pd-Ag alloy exhibited significantly different (P<.05) DeltaE values (S = 2.8 +/- 0.8, B = 2.2 +/- 0.3, F = 1.9 +/- 1.0, and T = 1.4 0.5) than the control group. After the simulated dentin porcelain firing cycles, the specimens with only opaque porcelain exhibited significantly different (P<.05) Delta E values (S = 5.2 +/- 1.4, B = 5.4 +/- 0.6, and F = 3.9 +/- 0.2) than the control group. The color difference between the 3 Pd-Cu-Ga alloys with only opaque porcelain and the control group increased more after the simulated glazing cycle (S = 6.6 +/- 1.5, B = 6.3 +/- 0.5, and F = 4.6 +/- 0.1). The observed color differences between the Pd-Ga alloys and the control group were not statistically significant at any point. Conclusions. The Pd-Cu-Ga alloys with only opaque porcelain, after the simulated dentin porcelain and glazing firing cycles, exhibited clinically unacceptable color differences. The application of dentin porcelain to the Pd-Cu-Ga alloys resulted in clinically acceptable color differences. The application of dentin porcelain to the Pd-Ag alloy, after the glazing firing cycle, resulted in clinically acceptable color differences (approximately 2.8 to 3.7 Delta E CIELAB units). The Pd-Ag alloy specimens with only opaque porcelain did not exhibit significant color differences from the control group, whereas significant color differences from the control group after the dentin porcelain and glazing firing cycles were still clinically acceptable

Polymerization Shrinkage and Flexural Modulus of Flowable Dental Composites

Linear polymerization shrinkage (LPS), flexural strength (FS) and modulus of elasticity (ME) of low-viscosity resin composites (Admira Flow™, Grandio Flow™/VOCO; Filtek Z350 Flow™/3M ESPE; Tetric Flow™/Ivoclar-Vivadent) was evaluated using a well-established conventional micro-hybrid composite as a standard (Filtek Z250™/3M ESPE). For the measurement of LPS, composites were applied to a cylindrical metallic mould and polymerized (n = 8). The gap formed at the resin/mould interface was observed using SEM (1500×). For FS and ME, specimens were prepared according to the ISO 4049 specifications (n = 10). Statistical analysis of the data was performed with one-way ANOVA and the Tukey test. The conventional resin presented significantly lower LPS associated with high FS and ME, but only the ME values of the conventional resin differed significantly from the low-viscosity composites. The relationship between ME and LPS of low-viscosity resin composites when used as restorative material is a critical factor in contraction stress relief and marginal leakage

In vitro evaluation of marginal and internal adaptation of class II CAD/CAM ceramic restorations with different resinous bases and interface treatments

This in vitro study evaluated the influence of different composite bases and surface treatments on marginal and internal adaptation of class II CEREC CAD/CAM ceramic inlays, before and after simulated occlusal loading