Abstract

The cariogenic potential of dietary carbohydrates can be evaluated using biofilm models and a S. mutans biofilm has been used to evaluate the cariogenic potential of lactose, but to evaluate the cariogenicity of starchy products a more complex biofilm should be developed. Thus, the aim of this study was to develop a biofilm model composed of A. naeslundii (ATCC12104), S. gordonii (ATCC35105) and S. mutans (UA159), bacteria that respectively metabolize starch, express amylase-binding protein and use starchy hydrolysates. At present, data of this biofilm grown under sucrose exposure are shown. Biofilms of each species and of the three species were formed on saliva-coated bovine enamel slabs in ultrafiltered tryptone-yeast extract broth at 37°C, 10% CO2, during 4 days. Eight times a day, the biofilms were exposed to 10% sucrose. The pH of the media (indicator of biofilm acidogenicity) was determined 2×/day. At 5th day the biofilms were collected for: (a) biofilm biomass determination (bacterial viability, wet weight), (b) extracellular soluble and insoluble polysaccharide concentration, (c) intracellular polysaccharide concentration. On the dental blocks were measured the percentage of change in surface microhardness (%SMC). Also, the structure of the biofilms formed was evaluated by SEM and confocal laser microscopy. S. mutans biofilm was the most acidogenic (pH 82 h: 4.41 ± 0.10; n = 3), presented greater concentration of insoluble extracellular polysaccharide (15.8 ± 6.1; n = 3) and provoked higher enamel %SMC (45.3 ± 4.8; n = 3) than the other mono-species biofilms. The three species grew up together in the biofilm formed, which showed unique properties if compared with the mono-species biofilms. The findings show that it is possible to grow a complex biofilm formed by A. naeslundii, S. gordonii and S. mutans, which may be a more appropriate method to evaluate the cariogenic potential of starchy products.