Early childhood caries (ECC) is reported as the most prevalent chronic condition in children, with over 1.8 billion new cases identified annually worldwide. According to American Academy of Pediatric Dentistry (AAPD), ECC is the presence of 1 or more decayed (noncavitated or cavitated lesions), missing (due to caries), or filled tooth surfaces in any primary tooth in a child 71 months of age or younger. In children younger than 3 years of age, any sign of smooth-surface caries is indicative of severe early childhood caries (S-ECC). From ages 3 through 5, 1 or more cavitated, missing (due to caries), or filled smooth surfaces in primary maxillary anterior teeth or a decayed, missing, or filled score of more than or equal to 4 (age 3), more than or equal to 5 (age 4), or more than or equal to 6 (age 5) surfaces constitutes S-ECC. 

Complex, multispecies communities of microflora live in the oral cavity in a homeostatic environment. These native microflorae are important in protecting the host from invasions by different foreign infections, but dental caries may develop if this homeostasis is upset. Dental caries is thought to be caused by a combination of biological and environmental variables, including dental plaque, saliva, fluoride consumption, oral hygiene, and food. Streptococcus mutans and Lactobacillus casei are two of the many bacteria that contribute to the development of dental caries.  However, it was shown that the cariogenic bacteria S. mutans and S. sobrinus, which belong to the Mutans Streptococci family, are mostly linked to tooth caries. Nevertheless, it has also been documented that other oral streptococcus bacteria, such as S. sanguinis, S. oralis, S. gordonii, and S. salivarius, influence cariogenicity by modifying the biofilm community and interacting with MS during the caries process.

Streptococcus mutans is the oral microbial flora that is mostly implicated with ECC. It is a facultative anaerobic, Gram-positive bacterium that typically survives as a normal part of the oral bacterial population. However, when fermentable carbohydrates are present, these acid-producing organisms destroy teeth by dissolving their structure. A common tooth colonizer, Streptococcus sanguinis is a Gram-positive facultative anaerobic bacterium whose presence is linked to the presence of healthy biofilms and the lack of dental caries. Therefore, knowing how oral streptococci contribute to dental caries may become more crucial for disease prevention.   

In order to determine the function of streptococcal species in S-ECC, prior studies examined tooth plaque. It was asserted, meanwhile, that dental plaque did not accurately represent the incidence of oral bacteria and MS. Colonization of MS over the entire dentition is best observed in saliva, hence it was recommended as a substitute for plaque. It was discovered that MS remained in saliva due to its surface antigen proteins.

This illness is associated with a number of risk factors: Due to certain characteristics of the bacterium and predisposing factors associated with the host’s oral cavity, Streptococcus mutans can easily and quickly colonize a child’s oral cavity. For example, structural characteristics of the enamel and dentin in the primary dentition can predispose to decay; poor oral hygiene, which results in the deposit of plaque, can affect Streptococcus mutans colonization; poor dietary habits and low socioeconomic status can contribute to the onset of decay. 

A higher risk of dental caries has been linked to the consumption of sugar and sugar-sweetened beverages (SSB) in the form of sodas, energy drinks, fruit-flavoured drinks, and, to a lesser extent, 100% juice. Two-thirds of children between the ages of two and nineteen consumed at least one sugar-sweetened beverage (SSB) on any given day, according to an analysis of the National Health and Nutrition Examination Survey (NHANES) 2011 to 2014. Children who consumed SSB also experienced significantly higher levels of untreated dental caries than children who consumed other beverage types.