Maxillary Central Incisor

The maxillary central incisor always has one root and Type I canal configuration. The root is bulky, with a slight distal axial inclination but rarely has a dilaceration. A labio-lingual section of the tooth shows that the pulp cavity comes to a point near the incisal edge, becomes wider as it approaches the cervical line, then narrows to the apex. The apical foramen frequently exists short of the apex, to

the labial direction.

The mesio-distal section reveals that the pulp cavity is wider towards the incisal area and then tapers to the apex.

A cross section of the tooth in the cervical area shows that the canal has a slightly triangular shape, with the apex toward the lingual surface and the base to the labial. For this reason, the outline form of the access cavity for maxillary central incisors is round but slightly triangular to give direct access to the entire canal.

The access cavity preparation is begun by using a round-point tapered fissure bur in the exact center of the lingual surface (entrance is always gained through the lingual surface). The bur could be directed parallel to the long axis of the crown or at right angle to the tooth. If the access is begun at a right angle to the long axis, there might be a possibility of penetration too far labially, or for completely missing the pulp canal on a tooth with considerable dentinal sclerosis.

Once the canal is found, a safe-tipped tapered fissure bur is used to remove any dentin overhangs that would trap debris, sealer or other materials, which might cause crown discoloration or prevent direct access to the apex. The resulting cavity should be smooth and continuous.

The maxillary central and lateral incisor and the canine roots, and therefore, their canals have a distal axial inclination. This means that in penetrating along the long axis of the tooth, the bur must be slightly angled toward the distal surface. Failure to provide for this situation may lead to penetration of the mesial portion of the root.

Lingual view of maxillary central incisor