Black's Classification of Caries Lesions

Class I Caries affecting pits and fissures on occlusal third of molars and premolars, occlusal two thirds of molars and premolars, and Lingual part of anterior teeth.

Class II Caries affecting proximal surfaces of molars and premolars.

Class III Caries affecting proximal surfaces of central incisors, lateral incisors, and cuspids.

Class IV Caries affecting proximal including incisal edges of anterior teeth.

Class V Caries affecting gingival 1/3 of facial or lingual surfaces of anterior or posterior teeth.

Class VI (never described by Black, added later by others) Caries affecting cusp tips of molars, premolars, and cuspids.