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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]

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]

This study aimed to systematically review the literature related to the impact of low temperature degradation (LTD) on the crystalline structures and optical properties of different types of dental monolithic zirconia materials. The systemic review was performed based on the PRISMA statement. In vitro studies investigating the effect of accelerated aging in autoclave (2 bar pressure 134°C – ISO standard 13356-2008) on the crystalline structure and/or optical properties of Yttria-partially stabilized zirconia (Y-PSZ) were included. Specific search terms were used for peer-reviewed articles published in PubMed, Ovid MEDLINE, and EMBASE databases. From 286 eligible articles, 51 articles were selected for full-text analysis, 10 failed to meet the inclusion criteria, and 41 articles were included in this review. Autoclave aging (30 min – 300 h) results in an increase in monoclinic phase (m) content up to 80% for tetragonal zirconia and reaching saturation after 35 h of autoclave aging. All included articles reported less than 1% of monoclinic phase for cubic zirconia after autoclave aging. Translucency parameter was reported between 2.34 and 19.7 after autoclave aging (4–100 h). For same aging time, contrast ratio ranged between 0.48 and 0.95. An increase in monoclinic phase was reported for tetragonal zirconia, while cubic zirconia demonstrates resistance to LTD. The optical properties for all zirconia materials investigated seem more compromised with increasing aging time. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia (Y-SZ) has become a reliable material option to restore severely compromised teeth. Y-SZ materials are prone to low-temperature degradation (LTD), which generates a tetragonal-to-monoclinic (t-m) transformed, porous layer. We suggest that room-temperature atomic layer deposition (RT-ALD) could be used for the infiltration and deposition of nanoscale SiO 2 film over this layer, creating a protective hybrid surface against further degradation by LTD. This study investigated the potential of developing a Y-SZ transformed layer under controlled conditions for the infiltration of silica using RT-ALD, aiming to develop a hybrid zirconia-silica interface, and to investigate the effect of silica deposition/infiltration via RT-ALD on the surface roughness and wettability of zirconia-based materials. Sintered specimens (14 mm × 4 mm x 2 mm) were prepared from four different Y-SZ materials (n = 40): low translucency 3 mol % Y-SZ (3Y-LT; Ceramill ZI, Amann Girrbach); high translucency 4 mol % Y-SZ (4Y-HT; Ceramill Zolid); and two high translucency 5 mol % Y-SZ (5Y-HT – Lava Esthetic, 3M; 5Y-SHT – Ceramill Zolid, FX white). Specimens were exposed to hydrothermal treatment (HTT) to develop similar depths of crystalline changes. RT-ALD was used to deposit a thin film of silica (SiO 2). Surface roughness and wettability analyses were performed to investigate the effect of treatment (HTT and RT-ALD) and material on Y-SZ surface properties, and data was analyzed by two-way ANOVA and Tukey HSD (p < 0.05). RT-ALD and HTT-RT-ALD treated specimens of 3Y-LT and 5Y-HT materials were exposed to further hydrothermal aging (HA) and the surface was characterized by time-of-flight secondary ion mass spectrometry (ToF-SIMS). There was a significant interaction effect of material and treatment (HTT and RT-ALD) on roughness (p = 0.02), and surface wettability (p < 0.001). Silica deposition via RT-ALD resulted in a significant increase in surface roughness of all materials tested, while surface wettability was either improved or not changed based on the material type and HTT exposure. Nanofilms of SiO 2 were successfully deposited on Y-SZ materials and infiltrated 3Y-LT zirconia. [ABSTRACT FROM AUTHOR]