Biodeterioration of dental materials: Influence of bacterial adherence

The aim of this work was to carry out a comparative study of microbial adhesion on dental alloys and glass ionomers that release fluoride. The action of NaF on the early stages of biofilm development and on the corrosion of the metallic dental materials was analysed. Open circuit potential measurements and potentiostatic electrochemical techniques with different perturbation programs as well as SEM observations, and optical and epifluorescence microscopy were employed. A notable effect of topography and the nature of the substratum on bacterial distribution was observed. In addition, changes in the density and thickness of microbial colonies were noticed when fluoride was present. The results show that the antimicrobial effect of fluoride was significant against planktonic but not against sessile microorganisms. Fluoride released by glass ionomers did not impede bacterial adhesion to the surface. With respect to corrosion, fluoride did not alter significantly the passivity of the dental metallic biomaterials assayed, except for Cu‐Al alloy. Titanium dissolution could occur at high fluoride concentrations (8gl^‐1) during oxide layer formation. Consequently, bacterial adherence was influenced by the nature and topography of the substratum and by the presence of fluoride which could also affect the electrochemical behaviour of some metallic substrata.