Chitosan and Enamel De-Remineralization

A study that evaluated the in vitro effect of chitosan treatment, in terms of concentration and time of action, on enamel de-remineralization behavior upon a pH cycling assay was recently published in the Journal of Dentistry. Hu­man tooth samples were ex­posed to de-remineralizing solutions of controlled pH using a random experimental design. Micro­hard­ness and phosphorus chemical analysis were employed to evaluate the loss of phosphorus from the samples. Optical coherence tomography (OCT) im­ages were obtained for selected specimens in order to evaluate the degree of penetration of chitosan into enamel. The study found that Vickers microhardness re­sults were higher for samples treated with chitosan for concentration between 2.5 mg/mL and 5.0 mg/mL and time of action between 60 and 90 seconds. Maximum inhibition of mineral loss obtained was 81%. Chemical analysis indicated lower net phosphorus loss for samples treated with chitosan. Chi­tosan had little effect on the remin­eralization process. OCT re­sults indicated a correlation of chitosan penetration with chitosan concentration. For chitosan concentrations of 2.5 g/mL and 5.0 g/mL the penetration was up to the dentin-enamel junction.
     The study concluded that chitosan interferes with the process of demineralization of the tooth enamel, inhibiting the release of phosphorus. Demineral­ization is influenced by the concentration and exposure time of the bio­polymer to the enamel. Mi­crohardness measurements may be used as an indication of mineral loss from tooth enamel. Addition­ally, OCT im­ages support the idea that chitosan may act as a barrier against acid penetration, contributing to its demineralization inhibition.