Oral biofilm‐associated diseases, such as caries and periodontitis, represent global public health challenges. The diseases develop as a result of dysbiosis of the oral microbiome. There is a long tradition in medicine for treating bacterial infections by the use of antibiotics. Unfortunately, biofilm bacteria are significantly less sensitive to antibacterial agents than are their planktonic counterparts. This property of biofilm challenges us in our daily work as dentists, and might explain why many oral prophylactic agents predicted to be efficacious in vitro, only show marginal effect in vivo.

Commercial resin-based composites are mainly composed of dimethacrylate-based monomers, such as triethyleneglycol dimethacrylate (TEGDMA), inorganic fillers and a coupling agent. Cured resinbased composites have no antibacterial effect against oral bacteria and half of all fillings replaced are because of new caries . Chitosan is a natural carbohydrate polymer derived from the deacetylation of chitin. Chitosan has been shown to have an inhibitor effect on the adherence of oral bacteria onto human tooth surfaces.