Efeito da caracterização extrínseca e quantidades de queimas no comportamento mecânico e superficial de uma cerâmica de silicato de lítio reforçada com zircônia

Abstract

This study evaluated the roughness, biaxial flexural strength and hardness of zirconiareinforced lithium silicate (ZLS) ceramics after the application of pigment for extrinsic characterization and the respective firing processes. Thirty ZLS discs were manufactured, according to ISO 6872, and distributed into three groups (n=10) with different characterization protocols: control (Co), in which only one crystallization firing and one firing after manual glaze application were performed (totaling two firings); pigmented (St), subjected to crystallization firings, pigment application and glaze (totaling three firings); and pigmented with correction firing (St+Fi), in which, in addition to the firings performed for the St Group, an additional firing was performed to simulate pigmentation correction (totaling four firings). Roughness (Ra) was measured at the center of each sample with a roughness tester (0.25 mm cutoff; 0.5 mm/s), biaxial flexural strength was measured in a universal testing machine (1000 kgf, 1 mm/min), and hardness was determined by Vickers indentation (10 s, 50 g, HV 0.050/490.4 mN). The results showed that extrinsic characterization significantly increased surface roughness in the pigmented groups compared to the control (p < 0.01), although the number of firing cycles did not influence this property. No statistically significant differences were found in biaxial flexural strength (p = 0.57) and Vickers hardness (p = 0.06) between the groups. It is concluded that ZLS ceramics present mechanical stability, even after the application of pigments and additional firings, being suitable for aesthetic corrections without compromising their functionality or durability.