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.

Methacrylate monomers that are found to leach from cured resin-based dental materials induce biological effects in vitro. The underlying mechanisms have not been fully elucidated although involvement of increased cellular reactive oxygen species (ROS) and DNA-damage has been suggested