1.2 Infectious Disease

Specific acidogenic organisms in dental plaque, notably the Mutans streptococci (MS) (i.e., Streptococcus mutans, Streptococcus sobrinus) bacterial group and some strains of Lactobacillus species, are those bacteria most often implicated in dental caries.1–4

Initial Infection and Transmission

The initial infection usually presents after an infant’s teeth have erupted, and the particular genetic signatures of the bacteria in the infant’s mouth frequently match those in the mother’s mouth.5–9 MS are usually acquired somewhere between ages 6 and 31 months, although these bacteria have been found living on the dorsum of the tongue in infants as young as 3 months.10 Transmission occurs through normal social contact such as kissing and sharing food and utensils.

Tooth Demineralization

Acidogenic bacteria require sugar or the breakdown of carbohydrates into sugars to thrive. In an oral environment rich in sugars, these bacteria produce acid byproducts that demineralize the tooth surface. This is a dynamic process that is affected by other factors such as frequency of sugar ingestion, salivary buffering, and the presence or absence of arginolytic (alkali-producing) bacteria in the dental plaque biofilm.4,11

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