Which areas can carious lesions occur?

A) Gingival margin
B) Periodontal dentin ligament
C) Pit and fissures
D) Gingival sulcus

C
Explanation: C) Carious lesions occur in four general areas, based on tooth anatomy as categorized below. (1 ) Pit-and-fissure caries are found on the occlusal surfaces of posterior teeth; in lingual pits of the maxillary incisors; and in buccal pits located on the surfaces of lower molars. Incomplete fusion or hypoplasia of the enamel in these pits (or grooves) during tooth development increases caries susceptibility. Resin sealants can be bonded to the surface of pits and fissures soon after tooth eruption to reduce the risk of caries in these areas. (2 ) Smooth-surface caries arise on intact smooth enamel surfaces other than at the location of the pits and fissures. Smooth-surface caries can be further divided into (1 ) caries that affect the buccal and lingual tooth surfaces, and (2 ) interproximal caries, which affect the contact area of adjoining tooth surfaces (i.e., mesial or distal surfaces). (3 ) Root-surface caries might involve any surface of the root. Unlike coronal caries which be-gin in enamel, these lesions are initiated in dentin on root surfaces exposed to the oral environment. Thus, the risk of these lesions increases as gingival recession occurs in adults. (4 ) Secondary/recurrent caries occur on the tooth surface adjacent to an existing restoration.