舌侧中空而平滑的下颌切牙是成人牙齿中最小的。
Narrow and flat in the labial-lingual dimension, the mandibular incisors are the smallest human adult teeth. Visible radiographically from only one plane, they often appear more accessible than they really are. The narrow lingual crown offers a limited area for access. Smaller fissure burs and no. 2 round burs cause less mutilation of coronal dentition. The access cavity should be ovoid, with attention given to a lingual approach. Frequently the mandibular incisors have two canals. One study reported that 41.4% of mandibular incisors studied had two separate canals; of these, only 1.3% had two separate foramina. The clinician should search for the second canal immediately upon completing the access cavity. Endodontic failures in mandibular incisors usually arise from uncleaned canals, most commonly toward the lingual. Access may be extended incisally when indicated to permit maximum labiallingual freedom. Although labial perforations are common, they may be avoided if the clinician remembers that it is nearly&nbs
