: During this period, major studies like the National Health and Nutrition Examination Survey (NHANES) were releasing data on the prevalence of dental caries in the United States, which researchers often use as a benchmark "index" for that era. 3. "Index of" (Web Directory Context)

For children, the 2007 index used letters A through T. (A: Upper right second molar; J: Upper left second molar; K: Lower left second molar; T: Lower right second molar).