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Purpose: To evaluate the effect of simulated gastric acid solution (SGAS) and resin cement composition on the shear bond strength (SBS) of zirconia-based materials with different levels of translucency to composite resin. Materials and Methods: A total of 40 medium-opacity (MO; 3Y-TZP) and 40 medium-translucency (MT; 4Y-PSZ) zirconia slabs were distributed into four groups according to the composition of the resin luting system (MDP free or with MDP [primer + Panavia V5]) and storage method (distilled water or SGAS [5% hydrochloric acid]). Composite resin cylinders were cemented on the zirconia surface and stored for 91 hours. SBS, failure mode, and surface characterization analyses via scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were performed. SBS data were analyzed using three-way ANOVA and Tukey tests, and failure mode was assessed using one-way ANOVA (P < .05). Results: Storage media (P = .180), resin cement (P = .110), zirconia (P = .404), and their interactions did not affect SBS values. Bond strength ranged from 21.41 to 26.11 MPa. SEM images showed that SGAS modified the surface topography of zirconia and resin cement. The presence of chlorine and silicon (wt%) were higher after SGAS storage than after water storage in both cements used, while barium was higher only for the MDP cement. There was a prevalence of mixed failures for most of the groups. Conclusions: The SBS between both types of zirconia and resin cement was not affected by SGAS, although changes in zirconia topography were observed after SGAS exposure. The presence of MDP in the cement layer had no effect on the SBS challenged by SGAS. [ABSTRACT FROM AUTHOR]

Titanium-based dental prostheses are essential for prosthodontics and can now be 3D printed using powder bed fusion (PBF) technology with different densities by controlling the process parameters. This study aimed to assess the surface topography and bonding strength of dental resins made of 3D-printed titanium alloys with varying densities and growth directions. Three groups of titanium alloy (Ti6Al4V) specimens differentiated by density (low, medium, and high) were produced using laser-melting 3D printing technology (N = 8). Each group included specimen surfaces with vertical and horizontal growths. Vickers microhardness, surface profilometry, wettability, and shear bond strength (SBS) of the titanium samples were measured for all groups. Scanning electron microscopy (SEM) was performed. Statistical analyses were conducted using a two-way ANOVA and Fisher's multiple test. Higher-density specimens exhibited greater microhardness (p < 0.05), and those with horizontal growth directions were harder (p < 0.05) than their vertical counterparts within the same density category. Additionally, low-density specimens in both growth directions had the highest surface roughness values (p < 0.05) compared to the other groups. The wettability values were similar (p > 0.05) among the groups in the vertical direction, but not in the horizontal direction (p < 0.05). However, the density type did not significantly (p > 0.05) influence the bonding strength of 3D-printed titanium. This study revealed significant variations in surface roughness, contact angle, and microhardness based on density and growth direction. [ABSTRACT FROM AUTHOR]

This laboratory study aimed to evaluate the effect of different surface patterns using femtosecond laser treatment on the enclosed mold shear bond strength (EM-SBS) of resin composite to zirconia (ZrO2) surfaces and to contrast it with the widely used tribochemical silica coating (TBC) surface conditioning method. A set of fifteen rectangular ZrO2 blocks were randomly divided into five groups according to surface pretreatment: Control G0—no treatment; G1—TBC with silane application; G2—femtosecond laser irradiation with horizontal lines 30 µm apart; G3—femtosecond laser irradiation with horizontal lines 15 µm apart; and G4—femtosecond laser irradiation with cross lines 30 µm apart. The pretreated surfaces were characterized by a surface profilometer, tensiometer and scanning electron microscope. The EM-SBS of resin composite stubs to ZrO2 was measured followed by fractographic analysis. The surface roughness and water contact angle were observed to be statistically higher among the femtosecond laser groups compared to the TBC and control groups. The G4 group exhibited the highest EM-SBS among all the groups, irrespective of the ageing conditions used. At the end of 5000 thermocycles, G4 exhibited EM-SBS of 14.05 ± 4.21 MPa compared to 13.80 ± 3.01 MPa in G1 and 5.47 ± 0.97 MPa in G0. The two-way ANOVA revealed a significant effect of both study groups and ageing conditions on the EM-SBS (p < 0.001). Utilization of femtosecond laser technology holds promise as a potential and alternative mechanical retention approach for enhancing the bonding strength of the resin composite to ZrO2. [ABSTRACT FROM AUTHOR]

PURPOSE. The aim of this study was to evaluate the effect of occlusal adjustments on the surface roughness of yttria-tetragonal zirconia polycrystal (Y-TZP) and wear of opposing artificial enamel. MATERIALS AND METHODS. Twenty-five Y-TZP slabs from each brand (Lava, 3M and Bruxzir, Glidewell Laboratories) with different surface conditions (Control polished - CPZ; Polished/ground - GRZ; Polished/ground/repolished - RPZ; Glazed - GZ; Porcelain-veneered - PVZ; n=5) were abraded (500,000 cycles, 80 N) against artificial enamel (6 mm diameter steatite). Y-TZP roughness (in µm) before and after chewing simulation (CS) and antagonist steatite volume loss (in mm3) were evaluated using a contact surface profilometer. Y-TZP roughness was analyzed by three-way analysis of variance (ANOVA) and steatite wear by two-way ANOVA and Tukey Honest Difference (HSD) (P=.05). RESULTS. There was no effect of Y-TZP brand on surface roughness (P=.216) and steatite loss (P=.064). A significant interaction effect (P<.001) between surface condition and CS on Y-TZP roughness was observed. GZ specimens showed higher roughness after CS (before CS - 3.7 ± 1.8 µm; after CS - 13.54 ± 3.11 µm), with partial removal of the glaze layer. Indenters abraded against CPZ (0.09 ± 0.03 mm3) were worn more than those abraded against PVZ (0.02 ± 0.01 mm3) and GZ (0.02 ± 0.01 mm3). Higher wear caused by direct abrasion against zirconia was confirmed by SEM. CONCLUSION. Polishing with an intraoral polishing system did not reduce the roughness of zirconia. Wear of the opposing artificial enamel was affected by the material on the surface rather than the finishing technique applied, indicating that polished zirconia is more deleterious to artificial enamel than are glazed and porcelain-veneered restorations. [ABSTRACT FROM AUTHOR]