Avaliação da rugosidade de uma cerâmica de silicato de lítio reforçada com zircônia: efeitos da caracterização extrínseca e do número de queimas

Abstract

This study investigated the effects of extrinsic characterization and the number of firings on the surface roughness of a zirconia-reinforced lithium silicate glass-ceramic (ZLS). The methodology involved the production of 30 ZLS discs (12 mm in diameter and 1.2 mm in thickness), distributed into three groups, with the following characterization protocols: Co (control) underwent two firings, one for crystallization and the other performed after manual glaze application; St (pigmented) was subjected to three firings, one for crystallization, another for pigment application, and the last after glaze; St+Fi (pigmented with correction firing) followed the same process as the St group, with the addition of an extra firing to simulate pigmentation correction, totaling four firings in total. After the application of heat treatments and pigmentation according to the manufacturer's protocol, the roughness (Ra) was measured by a roughness meter (0.25 mm cutoff; 0.5 mm\s). The results indicated that the mean surface roughness (Ra) values showed statistically significant differences between the analyzed groups (p < 0.01). The control group (Co) presented lower roughness (0.19 ± 0.02 μm), which differed from the extrinsic characterization groups. The St group exhibited a mean value of 0.22 ± 0.02 μm, and the St+Fi group presented 0.23 ± 0.01 μm, with no significant difference between the latter two groups. These results suggest that the main influence on roughness was the presence of pigmentation, not the number of firings performed. We conclude that extrinsic characterization has a direct impact on the surface roughness of ZLS ceramics, while the variation in the number of firings did not demonstrate a significant influence on this characteristic.