Early childhood caries（ECC） is an extremely destructive form of caries involving maxillary primary anterior teeth. Preventing ECC is an important work on caries prevention in worldwide by the World Health Organization. Cariogenic bacteria are considered the major etiologic agent in the development of ECC. Streptococcus mutans is the important cariogenic bacteria of ECC, the recent researches are on its colonization, transmission and genotypes. Actinomyces and Lactobacillus are the dominant microorganisms in the oral cavities of children with ECC. The colonization of Candida albicans and Bifidobacterium is associated with ECC. With the development of molecular biology techniques, studies are to the plaque microflora. This review presented the recent researches on the above aspects.
