The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States, and to assess changes over time. The survey is unique in that it combines interviews, physical examinations, and laboratory analysis of biological specimens. Laboratory data are obtained by analysis of blood and urine samples collected from survey participants at NHANES Mobile Examination Centers. Health status is assessed by physical examination. Demographic and other survey data regarding health status, nutrition, and health-related behaviors are collected by in-person interviews. NHANES findings are used to determine the prevalence of diseases, risk factors for diseases, and health disparities. The NHANES sample is designed to be nationally representative, so that NHANES findings can be used as the basis for national standards for height, weight, blood pressure, and children?s growth charts. In addition, NHANES data are used in epidemiological studies, for development of public health policy, to design health programs, and to guide future research. Data are released in two-year cycles and are publicly available on the NCHS website. The oral health component of NHANES is supported jointly by CDC Division of Oral Health and NIDCR. During various two-year data-gathering cycles it may include a caries and tooth loss examination, periodontal disease assessment, and fluorosis examination; as well as a set of interview questions regarding oral health quality of life measures. Examinations are performed by dentist-examiners who have been trained in standardized methods to ensure validity, and calibrated against a standard examiner for consistency.