For experimental groups, the effect of saliva on the polar component and the total surface free energy varied depending on type of coating, with this effect being more significant for rough surfaces. As observed for the non-coated specimens, significant differences were also found mainly for the polar component of rough surfaces treated with S and HP coatings. However, for the S coating, saliva decreased the polar component, and the values became similar to the polar component

of the control group; for the HP coating, an increase in the polar component was observed after incubation with saliva. Thus, the effect of saliva on the surface free energy varied depending on substrate characteristics, particularly the chemical Selleck ERK inhibitor composition and surface roughness. These findings suggest that the nature of

the surface-exposed chemical groups after coating applications may influence the formation of the salivary pellicle (adsorbed salivary proteins). Other authors have also reported that small differences in the chemical composition of acrylic resins changed the adsorption of salivary proteins and, consequently the nature of the adsorbed salivary pellicle.47 and 48 In this study, this phenomenon was particularly evident for rough surfaces due to a larger surface area and more exposed chemical groups available to interact with saliva. In the present investigation, XTT assay results showed that, for the specimens fabricated in contact with the stone, the adhesion of C. albicans in S30, S35 and HP30 groups was lower as compared with the control.

One factor that might have contributed to these TCL findings would find protocol be the hydrophilicity of the coated surfaces. 21, 27 and 28 As mentioned before, the rough surfaces coated with S30, S35 and HP30 exhibited significantly higher mean surface free energy values as compared with the control group, suggesting a decreased hydrophobic character. Hence, in this study, the decrease in C. albicans adhesion in the S30, S35 and HP30 groups may be partially related to the hydrophilicity of the rough surfaces treated with these coatings. Changes in chemical compositions of the coated acrylic surfaces may also have contributed to the findings as demonstrated by the XPS analysis. There were changes in the carbon and oxygen content with special relevance for S and HP coatings. In addition, surfaces modified with the S coating also exhibited an additional peak for the presence of sulphur. The S coating contains sulfobetaine, a member of the zwitterionic betaine family of compounds, 5, 10, 11, 13, 14, 15, 16, 18, 21 and 49 which have a mixture of anionic and cationic terminal groups with an overall neutral charge. Surfaces with zwitterionic groups resist non-specific interaction with plasma proteins and cells via a bound hydration layer from solvation of the charged terminal groups in addition to hydrogen bonding.