In the permanent maxillary central incisor, root canal treatment can be effective. There frequently are three pulp horns in this tooth.[16] In nearly all maxillary central incisors, there is one canal with one apex.[21] During root canal therapy, access into the pulp is frequently located centrally on the lingual surface between the incisal edge and the cingulum. At the level of the cervical line, the shape of the canal is triangular but becomes circular at the middle level of the root.[21] Although the root is generally straight, the most common points of curvature is near the apex, and their direction is more common toward the distal and lingual.