The traditional criteria (the “Dean Index“) for diagnosing dental fluorosis was developed in the first half of the 20th century by H. Trendley Dean. While the Dean Index is still widely used in surveys of fluorosis — including the CDC’s national surveys of fluorosis in the United States — dental researchers have developed more finely tuned diagnostic scales. These include the “Thylstrup-Fejerskov Index (“TF Index”) and the “Tooth Surface Index of Fluorosis” (“TSIF“). Whereas the Dean Index identifies five types of fluorosis (questionable, very mild, mild, moderate, and severe), the TF Index identifies nine.