Efeitos de diferentes concentrações de ácido fluorídrico e do tempo de condicionamento na resistência de união à zircônia glazeada

Abstract

The objective of the present study was to evaluate the influence of the conditioning time with 5% and 10% hydrofluoric acid on the bond strength between a vitrified Y-TZP ceramic and a resin cement. Pre-sintered ceramic blocks Y-TZP (IPS e.max® ZirCAD - Ivoclar Vivadent) were cut to obtain 70 blocks, with each insert received two samples. Prior to sintering, the blocks were regularized with grit silicon carbide papers #180, #600 and #1200. They were then divided randomly into seven groups, one being the control group in which the silicatization was performed with Rocatec Soft and a group in which the blocks received a layer of Vita Akzent Plus glaze spray, and were conditioned with hydrofluoric acid (Condac Porcelana) at a concentration of 5% and 10% for 5, 10 or 20 seconds on the adhesion surface. For cementation, Relyx Ceramic Primer and a dual resin cement (Relyx ARC) were used. In each block two cement columns were obtained, totaling 20 samples per group. After 5000 cycles of thermocycling, the shear test was performed (EMIC, DL 2000), bond strength was recorded and used to calculate the adhesive strength. In addition, failure analysis was also performed on all samples with a stereomicroscope (Stemi 2000-C), revealing 100% adhesive failures. In order to evaluate the influence of the surface treatment on the bond strength, the data obtained in this study were submitted to the statistical analysis of variance (Kruskal-Wallis test), after considering the distribution of residues, it was determined that the original data did not provide an adequate adjustment because the data did not fit a normal probability distribution. The Kruskal-Wallis test revealed that there was significant interaction effect, indicating that there was change in bond strength due to surface treatment (p value = 0.001).