Statement of problemCandida adherence to the denture base is an important cause of denture stomatitis. In addition, infections with drug-resistant Candida have become more prevalent, especially among elderly and immunocompromised patients. Thus, alternative safe antifungal agents for oral applications are needed. PurposeThe purpose of this in vitro study was to investigate the activity of chitosan, a natural biopolymer, against common oral Candida species and its efficacy in inhibiting C albicans adherence to denture-base acrylic resin. Material and methodsThe minimum fungicidal concentrations (MFCs) of 5 types of chitosan against 6 species of Candida and 10 C albicans clinical isolates were determined by broth and agar dilution, respectively. N-succinyl chitosan (NSC), low- and high-molecular-weight water-soluble chitosan (LMWC and HMWC), and oligomer and polymer shrimp-chitosan were examined. NSC and HMWC, as pure gel and as a mixture with carboxymethylcellulose (CMC), were applied to acrylic resin disks, incubated with C albicans for 24 hours, and washed, and adherent cells were collected for colony count. The effects of HMWC on human gingival fibroblasts after 1 and 24 hours of treatment were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The retention force of HMWC gel was measured by using a universal testing machine. The Kruskal-Wallis and Mann-Whitney U tests were used to compare the antiadherence activity (α=.05). ResultsHMWC had the highest antifungal activity against most Candida species tested and C albicans clinical isolates. HMWC gel completely inhibited C albicans adherence to denture base acrylic resin (P<.001). CMC denture adhesive significantly increased C albicans adherence (P<.001), but adding 2×MFC HMWC into CMC reduced the adherence, although this was not statistically significant (P=.06). HMWC at 1×MFC and 2×MFC showed no toxic effect on gingival fibroblast viability and proliferation. Moreover, the retention force provided by HMWC gel was sufficient for use as a denture adhesive (>5000 Pa). ConclusionsHigh-molecular-weight, water-soluble chitosan is a biocompatible biopolymer that could inhibit C albicans adherence and that showed properties suitable for development into an antifungal denture adhesive.
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