Low-cariogenicity of trehalose as a substrate

Objectives: The effects of trehalose on cariogenesis by mutans streptococci were investigated. Methods: Inhibited effect of trehalose on water-insoluble glucan (WIG) synthesis from sucrose by glucosyltransferase (GTase) of mutans streptococci was assayed. The acid fermentability of trehalose by mutans streptococci was determined by the measurements of pH, and amounts of lactic acid production. Plaque pH was determined by the measurements of collected plaque from volunteers after sugar mouth-rinse. Rat experimental caries was investigated by feeding a sucrose and/or trehalose diet. Results: Trehalose was not utilized as a substrate for GTase. In addition, trehalose inhibited synthesis of WIG by GTase in the presence of sucrose. Trehalose showed weaker and slower acid fermentation than sucrose by mutans streptococci. The levels of lactic acid production from trehalose by Streptococcus mutans and Streptococcus sobrinus were 24.2 and 59.8% of those from sucrose, respectively. The minimum plaque pH after sucrose mouth-rinse was lower than those after trehalose mouth-rinse in all subjects. Plaque pH after trehalose mouth-rinse never reached critical pH. The substitution of trehalose for sucrose in the rat diet significantly reduced caries scores. Furthermore, rats fed diets containing sucrose and trehalose had significantly lower caries scores than those fed a sucrose diet. Conclusions: These results suggested that trehalose might be not only lowly cariogenic but also anti-cariogenic, and is promising as a sugar substitute.