Background: Adherence of bacteria to teeth surface is considered an important step in the development of caries and the use of fissure sealants is crucial for the prevention of caries in occlusal surfaces of molars and premolars. The aim of this study was to investigate and compare the adherence of Streptococcus mutans to different fissure sealants, after acidic drink exposure. Material and Methods: The tested materials were Fissurit, Fissurit FX, Grandio Seal, Fuji Triage, Constic. Bacterial suspension was deposited onto each material and the adhesion was evaluated trough the colony forming units (CFUs) determination with or without acidic drink exposure. Results: The tested materials showed different behaviors with significant differences. Bacterial adherence values of the untreated materials were very dissimilar: Fuji Triage and Constic materials showed the better results ( P <0.05). Conclusions: Surface alteration after acidic drink exposure, changed the bacterial adhesion (except for Grandio Seal): Fissurit, Fissurit FX and Fuji Triage decreased their susceptibility to be colonized by S. mutans ( P <0.05); on the contrary, Constic increased up to ~4 times the bacterial adhesiveness respected to the untreated control ( P <0.05)