The document defines the Decayed, Missing, and Filled Tooth (DMFT) index, developed in 1938 to measure the prevalence of coronal caries in permanent teeth, detailing its components and the examination procedure. It also outlines the limitations of the DMFT, particularly its inapplicability to certain populations and conditions. Additionally, it describes the Decayed, Missing, and Filled Surfaces (DMFS) index, emphasizing its sensitivity and clinical application in assessing caries on tooth surfaces.