Although ECC was known to be a significant problem in preschool populations at the time of the Surgeon General’s Report in 2000, comprehensive understanding of its epidemiology has been limited due to the lack of a case definition, complexity in accessing this age group for data collection, and the difficulty in examining these young children. In the United States most studies of caries prevalence in preschool populations are derived from convenience samples of Head Start and WIC populations that may be at higher caries risk than the general population. An overview of studies from 3-5-year-old Head Start children in the last ten years shows that dental caries ranges from 1.34 dmft (decayed, missing and filled teeth) in a Mississippi study to 8.33 dmft in a Native American Arizonian population.

A better understanding of the epidemiology of caries in preschool children can be derived from the National Health and Nutrition Examination Survey (NHANES III) conducted between 1988-1994 (see above) and the Continuous National Health and Nutrition Examination Survey, that compared caries prevalence among children in 1988-1994 to 1999-2004. National studies are more reliable than other surveys because they are large representative samples with careful standardization of examiners. Furthermore, because the surveys include data on socioeconomic factors, insights can be derived regarding the prevalence of dental caries and its treatment in U.S. preschool children at various income levels.

The NHANES data collected between 1988-1994 shows that the number of decayed or filled teeth (dft) is high in U.S. preschool children. Poor and near poor two-year olds have an average of half a dft per child. The prevalence of lesions is greater in subsequent age groups, with the poor and near poor five-year-old children having 2.7 dft. In contrast, the non-poor five-year-olds’ mean dft is less than 1. Separate analysis of children with caries experience demonstrates the severity of disease among these children. For instance, irrespective of economic status, two-year-old children with caries have more than 3 lesions per child. Differences in dft between economic levels are also less evident in three- and five-year-olds. Thus, on average, non-poor children have fewer lesions but experience disease severity similar to that of poor and near poor children.

NHANES data also show the percentage of preschool children with caries experience and untreated decay by poverty status. More than 10% of poor and near poor two-year-olds have caries; more than half of the poor and near poor five-year-olds have caries. The disease is essentially untreated among these children, as shown by the percentage of untreated decay. Therefore, data from NHANES III clearly indicate that: 1. Caries is highly prevalent in poor and near poor U.S. preschool children; 2. in contrast to declining prevalence of dental caries among children in older age groups, the prevalence of dental caries in U.S. poor children under the age of five is increasing; 3. those children with caries experience, irrespective of income status, have high numbers of teeth affected; and 4. dental caries in U.S. preschool children is largely untreated.