Anatomy of a Tooth

The Labial Aspect

• The mesial outline of the crown is convex from the cervical line to the crest of curvature, located at the junction of the incisal and middle thirds.
• The distal outline of the crown is slightly concave from the cervical line to the crest of curvature, located at the center of the middle third.
• The tip of the cusp is in line with the center of the root.
• The distal slope of the cusp is longer than the mesial slope.
• The cervical line is convex toward the root.
• The labial surface has a shallow depression mesially and distally, dividing the three lobes, with the middle one being more developed, producing the labial ridge.
• The root is long and conical, with the apex curved distally.

The Lingual Aspect

• The tooth is narrower lingually than labially.
• The cingulum in the maxillary canine is larger than that in the maxillary central and lateral incisors.
• There is a well-developed lingual ridge confluent with the cusp tip, dividing the lingual fossa into two fossae.
• There is a developmental depression mesially and distally extending for most of the root length.

The Mesial Aspect

• The labial and lingual outlines of the crown are more convex than those in the maxillary central and lateral incisors.
• The crest of curvature is located at the cervical thirds.
• The curvature of the cervical line is 2.5 mm towards the cusp.
• A line bisecting the cusp is labial to a line bisecting the root.
• There is a developmental depression extending on part of the root.

The Distal Aspect

• The curvature of the cervical line is less distally than mesially.
• The developmental depression of the root is more pronounced mesially.

The Incisal Aspect

• The labio-lingual dimension is greater than the mesio-distal dimension.
• The ridge of the labial lobe is very noticeable labially, with its greatest convexity at the cervical third.
• The cingulum is well developed and makes a small arch when compared with the labial outline, which makes a large arc.

The Permanent Mandibular Canine

Principal Identifying Features

• The mandibular canine is narrower mesio-distally and labio-lingually than the maxillary canine.
• The lingual surface of the crown of the mandibular canine is shorter than that of the maxillary canine.
• The cingulum is less developed and less prominent marginal ridges.
• The cusp of the mandibular canine is not as well-developed as that of the maxillary canine.
• The tip of the cusp is not in a line with the center of the root.

MCB

• The mesial slope of the cusp is shorter than the distal slope.
• The distal outline of the crown is more rounded than the mesial outline.
• The mesial surface of the crown is nearly straight with the mesial surface of the root, with the contact area being near the mesio-incisal angle.
• The distal contact area is located more incisally than the maxillary canine.