Inhibitory effects of xylitol and sorbitol on Streptococcus mutans and Candida albicans biofilms are repressed by the presence of sucrose.

Objective: Among the preventive and therapeutic options available for dental caries, sugar alcohols (xylitol and sorbitol) have been widely promoted as oral healthcare products due to its perceived anticariogenic effect. However, the therapeutic efficacy of these sugar alcohols against Streptococcus mutans and Candida albicans in a sucrose supplemented environment, as found in disease-prone conditions in the oral cavity, has not been adequately investigated.

Methods: Single and mixed-species biofilm formation was evaluated in medium with different concentrations of xylitol, sorbitol with or without sucrose supplementation. Biofilm quantification methods such as crystal violet assay, XTT assay, CFU counting complemented with confocal and electron microscopic techniques were used.

Results: Under sucrose-free conditions, xylitol and sorbitol demonstrated a significant dose-dependent inhibitory effect on S. mutans biofilms, whereas inhibitory effect on C. albicans biofilm was weak. The presence of 1 % sucrose in the environment diminished the inhibitory effect of both xylitol and sorbitol on S. mutans and C. albicans mono-species biofilms. Sucrose supplementation on pre-formed S. mutans biofilms also reduced the inhibitory effect of xylitol. Xylitol and sorbitol presence reduced mixed-species biofilm formation and altered the biofilm architecture and glucan production. However, sucrose supplementation reduced the inhibitory effect of sugar alcohols and enhanced the mixed-species biofilm formation.

Conclusions: Xylitol and sorbitol exerts an inhibitory effect on S. mutans and C. albicans biofilm formation and this inhibitory effect is repressed by the presence of sucrose.