Abstract: In the conventional methods for suppressing dental caries using antibacterial agents, enzyme inhibitors or antibiotics, exocellular polysaccharides in oral biofilm prevent the permeation of antibacterial agents, enzyme inhibitors, antibiotics, or the like, and it is thus difficult to render intended suppressive effects on dental caries. Further, use of antibacterial agents or the like involves a high risk of resistant bacteria emergence, and thus it is not preferable. Thus, there remains a need for the development of a safer and more effective method for suppressing dental caries by regulating biofilm formation caused by dental caries causative bacteria instead of controlling the dental caries causative bacteria. A composition which regulates a quorum sensing according to the present invention can provide the inhibition of the tooth decay biofilm formation.