Application of chitosan as a novel antimicrobial dental material —Effects of form, molecular weight, and deacetylation degree on its antimicrobial activity against <i>Candida albicans</i>

Oral candidiasis is a significant health concern, especially for elderly individuals. The present study examined chitosan as a potential antimicrobial dental material for Candida albicans treatment. Four types of chitosan products purified from Chionoecetes opilio and Decapodiformes, with varying weight average molecular weight and degree of deacetylation (DAC) were used. Antimicrobial activity was assessed with fungal viability assays, culture turbidity measurements, and live/dead cell staining, while mechanism of action was determined by examining extracellular adenosine triphosphate (ATP) level, reactive oxygen species (ROS) production, and gene expression changes. All examined products exhibited antimicrobial activity, with Decapodiformes-derived chitosan showing better efficacy. Greater molecular weight was correlated with immediate effects and higher DAC with sustained activity. Chitosan treatment increased extracellular ATP and ROS levels, and suppression of genes involved in mitochondrial biosynthesis and drug resistance. These findings suggest potential use of chitosan as an antimicrobial agent in dental materials for oral candidiasis prevention and treatment.