Adhesion of Streptococcus mutans to different restorative materials.

Adherence of oral bacteria to the surface of dental restorative materials is considered an important step in the development of secondary caries and periodontal disease. The aim of this study was to investigate and compare the adherence of different restorative materials to Streptococcus mutans strain (CCUG35176) in order to ascertain possible differences. The materials tested ranged across different classes including: flowable composites (Gradia Direct LoFlo; Filtek Supreme XT Flowable), anterior composites (Gradia Direct Anterior), universal composites (Filtek Supreme XT), packable composites (Filtek Silorane; Filtek P60), glass-ionomers (Fuji IX Gp Extra; Equia) and a control reference material (Thermanox plastic coverlips). Bacterial suspension was deposited onto each material and the adhesion was evaluated trough the colony forming units (CFUs) determination. Packable silorane-based composite was found to be less adhesive than posterior packable composite P60, flowable composites and glass ionomers. The fluoride of glass ionomers did not prevent the attachment of S. mutans; furthermore, after roughness analysis and SEM investigations, the hypothesis that the difference in bacterial adhesion can be determined by the particular surface chemistry of the material itself as well as by different electrostatic forces between bacteria and restorative surfaces must be given serious consideration.