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Purpose: To compare the interfacial fracture toughness (IFT) of two MDP-based composite cements and a resin-modified glass-ionomer cement (RMGIC) with third-generation zirconia CAD-CAM restorations using two different airborne-particle abrasion (AB) pressures., Methods: Blocks were cut into prisms (n=60), split and sintered to the desired equilateral half prisms. Half-prisms were divided into two groups for AB at 0.5 or 2.5 bar with 50 µm Al 2 O 3 particles. Each group was then further divided into 3 subgroups, and half-prisms were bonded to their counterparts with Panavia V5 (V5), Panavia Self Adhesive Cement Plus (SA), or RMGIC Fuji Plus (n=10/group). The IFT was determined using the Notchless Triangular Prism test in a water bath at 36°C after thermocycling (10,000 cycles). Surface roughness and SEM analyses were performed for representative zirconia samples after AB, and composite cements were tested for flexural strength and wettability., Results: SA (2.5 bar) showed a significantly higher IFT. The 3 other groups with SA and V5 showed no significant difference in their IFT values regardless of the AB pressure (1-way ANOVA). Weibull analysis of SA was higher than V5. All RMGIC samples debonded while thermocycling, and were, therefore, not included in the statistical analysis. Surface roughness increased with increasing AB pressure, and both cements showed similar flexural strength values and good wettability., Conclusion: Contrary to RMGIC, composite cements show high performance with zirconia after AB. Increasing AB pressure enhances the micromechanical retention of composite cement. Future perspectives should include study of the effect of AB pressure on zirconia surface properties.

Objectives: To evaluate silane influence on the interfacial fracture toughness (IFT) of composite cement, with the two sub-classes of CAD-CAM composites, polymer-infiltrated ceramic networks (PICN) and dispersed fillers (DF), after hydrofluoric acid etching (HF) or airborne-particle abrasion (AB). A secondary objective was to correlate results with developed interfacial area ratio (Sdr) and surface wettability., Methods: Experimental PICN and DF blocks were cut into equilateral half-prisms, which were treated with HF or AB, then treated with an experimental silane or not and bonded to their counterparts with an experimental light-cure resin cement. After thermocycling, samples (n=30 per group) were tested for IFT using the notchless triangular prism test in a water bath at 36°C. Moreover, profilometry and contact angle measurement were performed on rectangular samples of each group. Finally, bonding interface was analysed by SEM., Results: PICN-HF treated with silane showed the highest IFT significantly. Three-way ANOVA revealed the influence of silane, material class and surface pre-treatment (HF or AB) on IFT (p<0.05). When silane was used, IFT was correlated with Sdr, while surface wettability was increased. Silane application significantly increased IFT for PICN but not for DF, while PICN performed better with HF and DF with AB., Significance: Silane increases IFT of composite cement with PICNs, but not with DF materials. Results suggest that silane increases the micromechanical bond by promoting resin cement spreading and penetration in surface roughness. This roughness is significantly higher for pre-treated PICNs than for DF due to their specific honeycomb microstructure when etched, which explains their better bonding properties., (Copyright © 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to evaluate the interfacial fracture toughness (IFT) of composite cement with dispersed filler (DF) versus polymer-infiltrated ceramic network (PICN) computer-aided design and computer-aided manufacturing (CAD-CAM) composite blocks after 2 different surface pretreatments using the notchless triangular prism (NTP) test. Two DFs (Cerasmart [CRT] and Lava Ultimate [LVA]), 2 PICNs (Enamic [ENA] and experimental PICN [EXP]), and e.max CAD lithium disilicate glass-ceramic (EMX, control) prism samples were bonded to their counterparts with Variolink Esthetic DC composite cement after either hydrofluoric acid etching (HF) or gritblasting (GR). Both procedures were followed by silanization. All samples ( n = 30 per group) were thermocycled (10,000 cycles) and tested for their IFT in a water bath at 36°C. Moreover, representative samples from each group were subjected to a developed interfacial area ratio (Sdr) measurement by profilometry and scanning electron microscopy (SEM) characterization. EXP-HF gave the highest IFT (1.85 ± 0.39 MPa·m 1/2 ), followed by EMX-HF and ENA-HF, while CRT-HF gave the lowest (0.15 ± 0.22 MPa·m 1/2 ). PICNs gave significantly better results with HF, and DF showed better results with GR. A 2-way analysis of variance indicated that there were significantly higher IFT and Sdr for PICNs than for DF. A positive correlation ( r² = 0.872) was found between IFT and Sdr. SEM characterization showed the specific microstructure of the surface of etched PICNs, indicating the presence of a retentive polymer-based honeycomb structure. Etching of the typical double-network microstructure of PICNs causes an important increase in the Sdr and IFT, while DF should be gritblasted. DF exhibited significantly lower Sdr and IFT values than PICNs. The present results show the important influence of the material class and surface texture, and consequently the micromechanical bond, on the adhesive interface performance of CAD-CAM composites.

Aim: The aim of this study was to evaluate the effect of water storage on the flexural strength (σf) of four self-etching adhesive resin cements (SEARC) and on the dentin-titanium shear bond strength (SBS) mediated by them., Materials and Methods: The selected SEARC were Rely X Unicem, G-Cem, Maxcem, and SmartCem2. For each material, 50 bars (2×2×25 mm) were made and stored in water at 37°C for 1 hour, 1 day, 7 days, 30 days, and 60 days before σf was determined via a three-point bend test. Titanium cylinders were bonded to freshly exposed human dentin surfaces using the selected cements. Fifty samples were obtained for each SEARC and were stored in water at 37°C for 1 hour, 1 day, 7 days, 30 days, and 60 days before SBS was determined. The results were statistically analyzed using two-way analysis of variance followed by Scheffé multiple means comparisons (α=0.05). Pearson's correlation coefficient between σf and SBS was determined., Results: Significantly different σf and SBS values were obtained for the four cements. With regards to the effect of water storage, the σf of all materials increased during the first 7 days, was not significantly different between materials by 30 days, and then remained relatively constant or decreased for SmartCem2; SBS was not affected by water storage, with the exception of Maxcem, where a significant drop in SBS was detected after 1 day and no deterioration thereafter. No correlation was found between σf and SBS., Conclusions: Under the experimental conditions of this study, 60 days of water storage negatively affected the σf of SmartCem2 but did not negatively affect the SEARC-mediated dentin-titanium SBS (Maxcem showed a significant drop in SBS after 1 day but no deterioration thereafter). The dentin-titanium adherence afforded by Rely X and G-Cem was significantly higher than that of Maxcem and SmartCem2.

Objectives: The purpose of the work reported here was to develop a surface treatment of an alumina-based ceramic (In Ceram) that would make reliable bonding to a resin-based luting agent possible., Methods: The surface treatment studied was the application of a suspension of a fine-grained, refractory powder, which after drying was sintered to the surface at 960 degrees C. The adherence potential of the surface was determined by measurement of bond energy., Results: It was found that the surface treatment, in conjunction with a heat-treated, silane coupling agent, resulted in mean bond energies of 47 (+/- 19), 56 (+/- 22), and 525 (+/- 116) J/m2 for the three resin cements studied., Significance: It was concluded that the new surface treatment makes reliable bonding possible, which may allow new indications for this material.

Indirect composites have been undergoing an impressive evolution over the last few years. Specifically, recent developments in computer-aided design-computer-aided manufacturing (CAD-CAM) blocks have been associated with new polymerization modes, innovative microstructures, and different compositions. All these recent breakthroughs have introduced important gaps among the properties of the different materials. This critical state-of-the-art review analyzes the strengths and weaknesses of the different varieties of CAD-CAM composite materials, especially as compared with direct and artisanal indirect composites. Indeed, new polymerization modes used for CAD-CAM blocks-especially high temperature (HT) and, most of all, high temperature-high pressure (HT-HP)-are shown to significantly increase the degree of conversion in comparison with light-cured composites. Industrial processes also allow for the augmentation of the filler content and for the realization of more homogeneous structures with fewer flaws. In addition, due to their increased degree of conversion and their different monomer composition, some CAD-CAM blocks are more advantageous in terms of toxicity and monomer release. Finally, materials with a polymer-infiltrated ceramic network (PICN) microstructure exhibit higher flexural strength and a more favorable elasticity modulus than materials with a dispersed filler microstructure. Consequently, some high-performance composite CAD-CAM blocks-particularly experimental PICNs-can now rival glass-ceramics, such as lithium-disilicate glass-ceramics, for use as bonded partial restorations and crowns on natural teeth and implants. Being able to be manufactured in very low thicknesses, they offer the possibility of developing innovative minimally invasive treatment strategies, such as "no prep" treatment of worn dentition. Current issues are related to the study of bonding and wear properties of the different varieties of CAD-CAM composites. There is also a crucial need to conduct clinical studies. Last, manufacturers should provide more complete information regarding their product polymerization process, microstructure, and composition, which significantly influence CAD-CAM material properties. [ABSTRACT FROM AUTHOR]