Development of the Oral Microbiota

The fetal oral cavity is generally considered sterile, yet oral microbes like Streptococcus and Fusobacterium found in amniotic fluid indicate early exposure.

The delivery mode significantly influences the initial oral microbiome.

Vaginal birth introduces vaginal microbiota, while cesarean birth exposes the oral cavity of the newborn to skin microbiota.

Oral microbial colonization begins within the first day after birth, as microbes from the surrounding environment, caregivers, and breast milk enter the oral cavity.

Streptococcus salivarius is one of the pioneer species that colonize the oral mucosa.

As the infant grows, other bacteria like Lactobacillus, Actinomyces, Neisseria, and Veillonella begin to colonize the infant’s mouth.

Tooth eruption introduces new nonshedding surfaces that support microbial colonization of additional species, like Streptococcus mutans.

The formation of gingival crevices enables colonization by periodontal microbes, increasing microbial diversity.

These microbes adhere to the surfaces of teeth and to one another, forming biofilms that can develop into dental plaque.