Believe it or not, according to the National Institute of Dental and Craniofacial Research (NIDCR), 92% of American adults aged 20 to 64 have had cavities in their permanent teeth, and 26% of them currently have untreated dental decay. But not all cavities are the same, and dental professionals use a specific classification system to assess them. In fact, there are six classes of cavities based on the tooth type and the location of the decay, as well as four classifications t