RESEARCH ARTICLE l

[3], and cancer prevention in the human intestine [4]. A number of studies using lactic acid bacteria for the prevention of oral diseases have been reported [5-10]. Probiotic bacteria in the human oral cavity include Bifidobacterium species and Lactobacillus species [11]. Oral administration of Lactobacillus salivarius WB21-containing tablets and oil reduced plaque accumulation, experiments [12], and a clinical trial indicated that the number of P. gingivalis in subgingival plaque was reduced by oral administration of L. salivarius TI 2711-containing tablets but recovered following cessation of tablet ad-ministration [13]. However, there have been no reports regarding caries prevention and control by L. salivarius. Lactobacillus species are microbial markers of dental caries risk [14]. Some species of lactobacilli have bee