This study investigated the effect of saliva contamination on chemical changes of ceramic surface as well as the influence of saliva cleaning methods on ceramic-resin bond strength. Saliva was used to contaminate leucite (LGC) and lithium disilicate (LDGC) glass ceramic surfaces. The following cleaning methods were tested: water spray, cleaning with orthophosphoric acid, universal cleaning paste, ultrasonic cleaning with water, re-etching with hydrofluoric acid. Non-contaminated ceramic sample served as control. Chemical analysis of ceramic surfaces was performed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Shear bond strength (SBS) of ceramics to resin material was tested after 24-hour water storage and after thermocycling. The most effective cleaning method of saliva-contaminated ceramic surface was cleaning LGC surface with orthophosphoric acid or re-etching the LDGC surface with hydrofluoric acid. The application of the following methods resulted in obtaining reliable bond strength.

Commercially available polymer surfaces for in vitro applications are characterized to different extents in terms of hydrophobicity, binding preferences, and immunoglobulin capacity. We compared five, well or poorly defined polystyrene plates, used as standard hydrophobic surfaces for studying biological interactions. Antibody binding (ELISA) and platelet adhesion (release of alkaline phosphatase from adhered platelets) were contrasted with total protein adsorption (alkaline phosphatase assay and bicinchoninic acid assay). In the assays, we utilized four plasma proteins: human serum albumin (HSA), C-reactive protein (CRP), fibronectin, and fibrinogen. At 0.5 μg antigen/well, all antibodies bound to their antigens most effectively on Nunc (MaxiSorp and MediSorp, Waltham, Massachusetts, USA) microplates, as compared to Sarstedt (Nümbrecht, Germany) and Corning microplates (Tewksbury, Massachusetts, USA). The significant differences between Nunc and Corning were seen in the binding of anti-HSA (P ≤ 0.01) and anti-fibronectin (P ≤ 0.0002). Similar patterns were shown in experiments of ADP-induced platelet adhesion to fibrinogen immobilized at 200 μg/well. Platelet adhesion noted on Corning microplates was roughly three times lower compared to those observed on MaxiSorp (P < 0.01), MediSorp (P < 0.02), and Sarstedt (P < 0.05). In a parallel study, we have also shown the superiority of tissue culture-Sarstedt surface over micro test Sarstedt plate. Furthermore, the antibody binding, but not platelet adhesion, was positively correlated with total protein adsorption. Our findings indicate that of five polystyrene surfaces, Nunc microplates are optimal for studies of protein adsorption, as they had the highest binding capacity and relatively the least affected protein structure, pointing to the role of surface chemistry in protein adsorption and adsorption-induced conformational changes in a protein structure.

Background. Biodentine ® is a bioactive calcium silicate-based material, with better strength parameters, an easier application method and a shorter setting time than mineral trioxide aggregate (MTA). The bond strength between Biodentine and the composite material is essential for the durability of the layered restoration.Objectives. The objective of this study was to evaluate the bond strength of Biodentine to a resin-based composite at various acid etching times and with different adhesive strategies. Material and methods.In the 1 st part of the experiment, the specimens were divided into 2 groups: the adhesive was applied in the total-etch (TE) and self-etch (SE) techniques. In the TE group, 37% orthophosphoric acid was applied after 30 s (TE 30) and 240 s (TE 240). In the SE group, the SE system was applied for 30 s (SE 30) and 240 s (SE 240). In the 2 nd part, the SE systems Clearfil ® SE Bond and Clearfil S3 Bond Plus were evaluated (the CSE and CS3 groups, respectively). In each group, the adhesive system was applied in 1 (the CSE 1 and CS3 1 subgroups) or 2 layers (the CSE 2 and CS3 2 subgroups). The specimens were subjected to a shear bond strength (SBS) test in a universal testing machine.Results. Shear bond strength was higher after a prolonged etching procedure in the TE (TE 30: 2.51 MPa, TE 240: 9.39 MPa) and SE techniques (SE 30: 5.92 MPa, SE 240: 7.89 MPa). A statistically significant influence was detected in relation to 30 s of surface preparation time for Clearfil S3 Bond Plus (p < 0.001). Greater bond strength was revealed after the application of 1 layer of the Clearfil S3 Bond Plus single-bottle system (CS3 1: 6.42 MPa). Conclusions.The SBS of Biodentine to the composite depends on both the etching time and the mode of application of the adhesive systems. Higher bond strength was obtained for the SE adhesive in a shorter application time.

This paper describes morphological differences and associated functional properties of dental composites based on dimethacrylate resins reinforced by nanoparticulate silica filler modified according to different silanization procedures. Surface morphology of the materials was evaluated by means of AFM, while nanohardness and elasticity modulus of the surface layer - by nanoindentation and abrasion - gravimetrically. The effects of silane treatment of nanoparticulate silica surface on possible filler loading, mechanical properties and abrasion resistance of the composites were discussed. The influence of the amount and kind of silane coupling agent on the example of 3 -methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane were presented. The modification of nanoparticulate silica with 3 -methacryloxypropyltrimethoxysilane enabled the introduction of 15% more filler than modification with vinyltrimethoxysilane. The abrasion resistance depended strongly on the composite morphology and the micromechanical parameters of the surface layer. The composite modified with vinyltrimethoxysilane, containing the highest percentage of filler particles smaller than 1 μm in diameter, exhibited the lowest abrasion (0.3 vol.%). Abrasive wear seemed to be a linear function of nanoindentation hardness with the correlation coefficient of R2 = 0.96. The highest hardness of the surface layer of commercial composite (130 MPa) resulted in the highest abrasive wear (7.7 vol.%). The type and the quantity of silane coupling agent used for silica modification strongly influence the morphology and mechanical and tribological properties of the dental composites. The application of more than the calculated, optimal amount of silane to nanosilica modification enables higher filler loading, but the composites exhibit inferior mechanical characteristics. Nanoindentation hardness of surface layer showed to be the most useful parameter in estimation of material susceptibility to abrasion.