Polishing resulted in the lowest values for surface roughness and higher SFE values. Polished ceramics showed less C albicans adherence while the adherence of Streptococci was greater than C albicans in all conditions.

This study evaluated the influence of zirconia surface finishes on the wear of an enamel analogue. 40 zirconia discs were divided into four groups: control (without finish); glazed; polished; polished and glazed. All samples were subjected to wear against steatite antagonists. The specimens underwent roughness, topographic, scanning electron microscopy (SEM) and wettability analyses. Quantitative wear measurements were performed on both steatites and discs. To measure wear of steatites the weight before and after the test and the diameter after the test were used. Profilometer measurements were performed to determine the wear on discs. Roughness, volumetric wear and mass loss were analyzed using the Kruskal-Wallis and Dunn tests (5%), while contact angle values were analyzed with One-way ANOVA and Tukey tests (5%). The polished group had the lowest roughness means, being statistically different from the other groups (p-value=0.0001). The glazed group presented the lowest steatite volumetric wear (p-value=0.0001), but not statistically different from the polished and glazed group, whereas these groups presented the highest zirconia volumetric wear, with statistically different (p-value=0.0002) compared to the others. SEM showed irregularities on the control groups surface, grooves on the polished group, and a homogeneous surface for the glazed group with a few pores. All groups presented contact angles lower than 90 degrees, characterizing hydrophilic surfaces. It can be concluded that just glazed zirconia caused less wear on the antagonist when compared to no finish and polished zirconia.

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PurposeThis study evaluated the fatigue failure load (FFL) and the number of cycles for fatigue failure (CFF) of traditional (porcelain layer up) and reversed (zirconia layer up) designs of porcelain‐veneered zirconia samples prepared with heat‐pressing or file‐splitting techniques.Materials and MethodsZirconia discs were prepared and veneered with heat‐pressed or machined feldspathic ceramic. The bilayer discs were bonded onto a dentin‐analog according to the bilayer technique and sample design: traditional heat‐pressing (T‐HP), reversed heat‐pressing (R‐HP), traditional file‐splitting with fusion ceramic (T‐FC), reversed file‐splitting with fusion ceramic R‐FC), traditional file‐splitting with resin cement (T‐RC), and reversed file‐splitting with resin cement (R‐RC). The fatigue tests were performed using the stepwise approach at 20 Hz, 10,000 cycles/step, step‐size of 200 N starting at 600 N, and proceeding until failure detection or up to 2600 N if enduring. The failure modes (from radial and/or cone cracks) were analyzed in a stereomicroscope.ResultsThe reversed design decreased the FFL and CFF of bilayers prepared with heat‐pressing and file‐splitting with fusion ceramic. The T‐HP and T‐FC reached the highest results, which were statistically similar between them. The bilayers prepared by the file‐splitting with resin cement (T‐RC and R‐RC) were similar to the R‐FC and R‐HP groups regarding FFL and CFF. Almost all reverse layering samples failed by radial cracks.ConclusionsThe reverse layering design did not improve the fatigue behavior of porcelain veneered zirconia samples. The three bilayer techniques behaved similarly when used in the reversed design.