Extrinsic Characterization Sustainability in Zirconia Reinforced Lithium Silicate Ceramics

Abstract

ABSTRACT OBJECTIVE. To investigate the effect of aging on the surface roughness and the color sustainability of externally characterized zirconia reinforced lithium silicate glass-ceramics treated with different surface protocols. METHODS. Sixty blocks (12-mm X 14-mm; 1.5-mm) of pre-crystalized zirconia reinforced-lithium silicate glass-ceramic (Vita Suprinity, Vita Zahnfabrick, Germany) CAD/CAM were crystalized and treated with different surface protocols, as extrinsic characterization (EC), mechanical polishing (MP), glaze layer (GL), surface adjustment (SA) and no treatment – control group (CG). Experimental groups (n=10) were divided as follow: CG; EC-MP-GZ; EC-GZ; EC-MP; EC-GZ-SA-GZ; EC-GZ-SA-MP and submitted to thermocycling (5,000 cycles, 5-55C) and toothbrushing simulation (5,000 cycles). Surface roughness (Ra and Rq), color change (CIED2000) and biofilm growth were evaluated. Statistical analysis was performed with a two-sided 5% significance level for all tests. RESULTS. For the parameter RaX, the control differed from EC-GZ and EC-MP (p = 0.04). For the parameter RqX, EC-GZ presented higher surface roughness compared than EC-MP-GZ and the group EC-GZ-SA-MP (p=0.02). EC-MP (p<0.01) and the EC-GZ-SA-MP (p<0.01) showed higher color change E00 after aging, while CG and EC-MP-GZ the least. For the biofilm growth, no significant group effect on bacteria counts was found (p=0.089). CONCLUSION. The aging protocol affected the surface roughness, and color of externally characterized zirconia reinforced lithium silicate glass-ceramics submitted to different surface treatment protocols. In the present study, when the mechanical polishing was performed before glaze application, the slightest color change and surface roughness were observed compared to the other surface treatments. Bacteria were not able to grow in the material surface, under the conditions tested in the present study.