What are the antibacterial effects of native and methacrylate modified chitosan?

This summary is based on the research done by the Nordic Institute of Dental Materials (NIOM) and published in the European Cells and Materials: Antibacterial effects of native and methacrylate modified chitosan (2013)

IS Dragland, T Knarvang, and HM Kopperud

Context

Commercial resin-based composites are mainly composed of dimethacrylate-based monomers, such as triethyleneglycol dimethacrylate (TEGDMA), inorganic fillers and a coupling agent. Cured resin-based composites have no antibacterial effect against oral bacteria (1) and half of all fillings replaced are because of new caries (2).

Chitosan is a natural carbohydrate polymer derived from the deacetylation of chitin and has been shown to have an inhibitor effect on the adherence of oral bacteria onto human tooth surfaces (3). Chitosan has a polycationic carbohydrate structure with three reactive functional groups. The positive charged amino groups are suggested to be the cause of chitosan’s antimicrobial activity.

Functionalization of chitosan with methacrylate groups allows for copolymerization with the resin in dental materials which means that chitosan can be incorporated in resin-based composites in order to produce material with antibacterial activity.

Purpose of the Study

To study the antibacterial effects of modified chitosan, adding functional methacrylate groups.

Key Findings

• Chitosan was demonstrated to inhibit planktonic growth and biofilm formation depending on the concentration of chitosan in the medium.
• The results of the two test models suggest that chitosan has a higher antibacterial activity against S. epidermidis than against E. coli.
• Chitosan could be modified with a methacrylate functionality, but the modified chitosan had poor solubility and had low antibacterial effect compared to natural chitosan.

References

1. S. Imazato (2003) Antibacterial properties of resin composites and dentin bonding systems. Dent Mater 19:449-57.
2. V Deligeorgi, IA Mjør, NH Wilson (2001) An overview of reasons for the placement and replacement of restorations. Prim Dent Care 8:5-11.
3. H Sano, K Shibasaki, T Matsukubo et al. (2001) Comparison of the activity of four chitosan derivatives in reducing initial adherence of oral bacteria onto tooth surfaces. Bull Tokyo Dental College 42:243-9.

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