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.
(Source: Journal of Dentistry, November 2010, Volume 38, Issue 11)
