EFFECT OF DIFFERENT FINISHING/POLISHING PROTOCOLS ON FATIGUE RESISTANCE AND WEIBULL MODULE OF DIFFERENT TYPES OF ZIRCONIA
Dental prosthesis; Ceramic; CAD/CAM; Adhesion
Objective: To evaluate the effect of different finishing/polishing protocols on the fatigue strength of new generations of zirconia. Materials and Methods: Ninety (N=90) ceramic discs (Ø:12mm; 1.5mm-ISO 6872) were made, 45 of ultra-translucent zirconia (UT-VITA, Vita Zahnfabrik) and 45 of a 3Y-3Y hybrid zirconia ceramic 3Y-TZP and 5Y-PSZ with translucency gradient (GT-e.max Zircad prime GT, Ivoclar). After the ceramic discs sintering, they were divided into 6 groups (n=15), according to the factors “ceramic (UT and GT)” and “Finishing and polishing protocol” (Diamond burs + Rubbers; Rubbers and Control). The discs were subjected to the fatigue resistance test by the stepwise stress method (5Hz for 10,000 cycles) with a step increment of 50N starting at 100N and continuing until failure. Complementary analyzes of X-ray Diffraction (XRD) and surface roughness were also carried out. Results were statistically evaluated using 2-way ANOVA, Tukey test (5%) and Weibull analysis. Results: The fatigue strength and life cycle number of the two ceramics was influenced by the type of finishing and polishing protocol. The hybrid ceramic showed higher values of resistance to fatigue, as well as a higher rate of survival to fatigue cycles. Conclusion: The finishing and polishing protocol influences the fatigue behavior of the new generations of dental zirconia, with the use of burs revealing the lowest resistance values.