Efeito do número de queimas e da pigmentação extrínseca nas propriedades de uma cerâmica a base de silicato de lítio reforçada por zircônia

Abstract

The objective of this research was to evaluate the effect of extrinsic pigmentation and multiple fires on the mechanical, physical and surface properties of a zirconia-reinforced lithium silicate ceramic (ZLS). ZLS (VITA Suprinity) ceramic blocks were rounded and sliced to obtain 90 discs with 12 mm in diameter and 1.2 mm in thickness, distributed in 6 groups (n = 15) according to the surface treatment (CO: Control - without pigmentation; DF - “Double Firing”: crystallization and pigmentation performed in separate steps; SF - “Single Firing”: crystallization and pigmentation in a single step;) and number of firings (II - 2 fires; IV - 4 fires) : COII, COIV, SFII, SFIV, DFII and DFIV. The samples were then subjected to color and translucency analysis (colorimetric spectrophotometry), roughness (profileometry), xray diffraction (XRD) and resistance (biaxial flexion; 1mm / s; 1000KgF). The data obtained were submitted to statistical analysis of variance (ANOVA), Tukey's test and t-test (α = 5%). The results revealed that the type of treatment performed for pigmentation modified the ceramic physically (p <0.01), mechanically (p <0.01) and even its roughness (p <0.01). The type of technique used and the number of burns did not significantly influence the color difference in any group of the tested samples. However, the number of burns influenced translucency (DFII: 7.10; DFIV: 6.35; p = 0.02) and roughness (DFII: 122 μm; DFIV: 77 μm; p <0.01) only in the DF groups , the resistance changed only in the SF groups (SFII: 271 MPa; SFIV: 325 MPa; p <0.01). The XRD showed differences in amorphous content between the groups, but the number of burns did not change the composition of these samples. The samples submitted to the DF technique, therefore, showed a better performance due to color stability and translucency, lower values of roughness when compared to another technique and greater resistance, mainly, by increasing the number of burns.