关键词: 上颌第一磨牙, 根管变异, 腭侧双根管

Abstract: Maxillary first molar with two palatal canals is rare. Clinicians should be aware of the normal anatomy of root canal system and vigilant about the possible existence of canal variation. A patient with acute episode of chronic pulpitis of 26, as presented by the case report, was examined to have four canals, which were the mesial buccal canal, the distal buccal canal, the mesial palatal canal and the distal palatal canal. When suspecting the existence of canal variation, clinicians should carefully explore the pulpal floor, further by changing the X-ray projection angle to confirm the existence of variation and prevent the missed canals, all of which are necessary for a successful root canal therapy.

Key words: Maxillary first molar, Canals variation, Two palatal canals