Untreated dental decay is defined as the presence of untreated caries. Caries is the disease that causes tooth decay and can lead to cavities in teeth. This indicator is tracked using the Oral Health Examination component of the Continuous National Health and Nutrition Examination Survey, collected since 1999. The measurement protocol has been described. Data on missing primary teeth are not captured by NHANES. Indicators of caries in primary teeth omit missing teeth to avoid potential misclassification of teeth lost to natural exfoliation as missing due to caries.