This study investigated the flexural properties, shear bond strength (SBS) and interface to dentin of three recently developed selfadhesive bulk-fill materials. Methods: Bars of Surefil One (SO), Cention N (CN), Activa BioActive Restorative (AB) and EQUIA Forte HT Fil (EQUIA) were tested for flexural strength and flexural modulus in self-curing and light-curing modes. In addition, SBS to dentin was tested in specimens without pretreatment and after application of universal adhesive (Scotchbond Universal). EQUIA was used as the control material. Results: The flexural properties were significantly better in light-curing mode for all materials except CN. CN had the highest SBS values after universal adhesive application (33.8 MPa), and SO had the highest SBS without pretreatment (20.9 MPa). Conclusion: The mechanical and adhesive properties of these new materials varied widely.

This study aims to compare the shear bond strength (SBS) of a direct resin composite to CAD-CAM resin composite blocks treated with different surface treatments: micromechanical, chemical or a combination of both. Eight CAD-CAM resin composite blocks, namely Brilliant Crios, Cerasmart 270, Vita Enamic, Grandio block, Katana Avencia, Lava Ultimate, Tetric CAD and Shofu Block HC were chosen. The micromechanical surface treatment protocols tested were hydrofluoric acid, polyacrylic acid or sandblasting, and the chemical one was a universal primer. These treated CAD-CAM blocks were tested to determine the SBS of a light-curing composite resin Z100 bonded to their surface. Two-way ANOVA followed by Tukey’s post hoc test was used to investigate the difference in SBS. Failures were analyzed by Fisher’s exact test. Bonding interfaces were examined by scanning electron microscopy. The micromechanical surface treatments give the highest SBS values: sandblasting appears to be the most efficient procedure for dispersed filler composite blocks, while hydrofluoric acid etching is preferable for polymer-infiltrated ceramic network (PICN) blocks. The use of universal primer does not improve SBS values on dispersed filler composite blocks. For PICN blocks, the use of universal primer significantly increases SBS values when combined with hydrofluoric acid etching.

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In this work, the very weak exothermic formation reaction of MgAl2O4 spinel is successfully conducted in a self-sustaining manner with the advantages of energy savings, high reaction rate and highly porous product. The energy and Al2O3 required for this reaction are obtained from the combustion reaction of TiO2-B2O3-Al while MgO is added to the reactive mixture. Ignition of the reaction mixture is carried out at room temperature despite the dilution effect of MgO (19 vol%). Reduced aluminium grain size and preheating the reactant before ignition were found to be very effective to complete the formation reaction of MgAl2O4 spinel. Thermodynamic calculations of adiabatic combustion temperatures and spinel molten fractions at different initial temperatures were carried out. Oxidation resistance study of this new composite shows that it can safely work up to 600°C in open atmosphere and that 700°C is considered to be its threshold oxidation temperature.