Chitosan, a natural, carbohydrate polymer derived from the deacetylation of chitin, is the second most common polymer found in nature after cellulose. Chitosan is produced commercially from crab and shrimp shell wastes with different degrees of deacetylation and molecular masses. Because of chitosan’s promising biological activities, including non-toxicity and antimicrobial activity, it is used for a variety of purposes in food production, medicine, agriculture, cosmetics, and biotechnology. The mechanism behind chitosan’s antimicrobial activity is still somewhat uncertain. The main theory is that positively charged amino groups of chitosan participate in an electrostatic interaction with negatively charged groups in the cell surface of bacteria, resulting in damage to the cell wall, influencing the permeability or barrier properties. Resin composites are now the most used dental restoration material in the Nordic countries. Annual failure rate for composite fillings seems to be 1-3 %, but individual studies have reported higher numbers. The main reason for the replacement of composite fillings is the development of secondary caries. To prevent such a development, experiments with antimicrobial agents incorporated in resin composites are carried out. Chitosan has shown an antimicrobial effect against oral bacteria and is tested for the use as an  antimicrobial agent in composites and other dental materials and oral hygiene products.

Chitosan – antibakteriell bruk i dentale materialer
Dragland IS, Kopperud HM.
Holmstrup P (ed.), Odontologi 2015
Aktuel Nordisk Odontologi, København, Munksgaard, 2015; pages 97–109.