Permanent Mandibular Canine is the third tooth
from the midline. Its tooth number in FDI system is 43 and 33, in Universal system it is 27 and
22 and in Zsygmondy Palmar system it is 3 with appropriate quadrant brackets. The word Canine
is derived from the Latin word 'Canis' moreover it is also called Corner Tooth and Cuspid.
The function of mandibular canine is tearing. The tooth develops from four developmental lobes-
mesial, labial, distal and lingual. Together with maxillary canine it helps in guiding the jaw to
close in correct position called Canine Guidance. In the jaw it is the 'last tooth standing' as it
fights two main diseases of teeth- caries, by its self cleansing property and loss of anchorage, by
having a long root. The chronology of the tooth, age of eruption of mandibular canine is
9 to 10 years. Coming to its dimensions, the cervico-incisal length of the crown is 11
millimeters and root length is 16 millimeters. The mesio-distal diameter of the crown is 7
millimeters and at cervix it is 5.5 millimeters. The labiolingual diameter of the crown is 7.5
millimeters and at cervix it is 7 millimeters. The curvature of cervical line on mesial side is 2.5
millimeters and on distal side it is 1 millimeter. The morphology of the crown is studied under
5 aspects let us start with the labial aspect. The outline form of the crown is trapezoidal with
its longer side towards the cusp and the shorter side towards the cervical line. The cusp tip lies
on the midline axis of the tooth. Among the two cuspal slopes running from the cusp, the distal
cuspal slope is longer than the mesial cuspal slope. Coming to the contact areas- the mesial
contact area is in the incisal third and the distal contact area is in the middle third. The
cervical line is convex with its convexity towards the root. The labial surface shows a labial ridge
running from the cusp tip to the cervical line. A single root is present
which is smooth and conical. Coming to the lingual aspect. As the lingual
aspect is narrower than the labial aspect all the features of the outline form from the labial
aspect are same in the lingual aspect as well, although, the crown surface is very different. Two
cuspal ridges- mesial cuspal ridge running from the cusp tip to the mesial contact area and distal
cuspal ridge running from the cusp to the distal contact area. Mesial marginal ridge running from
the mesial contact area to the cingulum and distal marginal rate running from the distal contact area
to the cingulum. A lingual ridge running from the cusp trip to the cingulum. The cingulum is the
circular convexity present in the cervical third. Between these ridges and cingulum are two shallow
concavities called the lingual fossae. The root is smooth and conical. Next, the mesial aspect. The
outline form of the crown is triangular or wedge shaped with its base in the cervix. The cusp tip
lies lingual to the midline axis of the tooth. The labial surface of the crown is convex with its
crest of curvature at the level of the cingulum. On the other hand the lingual outline is convex
in the cervical third, concave in the middle third and convex in the incisal third. The cervical line
is convex and the convexity is towards the crown. The root is smooth and tapering. A depression runs
along the root length called mesial developmental depression. Next the distal aspect. All
the features of the tooth from the mesial aspect are same in the distal aspect as
well, though, the distal developmental depression present on the root is deeper
than the mesial developmental depression. Finally, the incisal aspect. As with all permanent
teeth, no part of the root is visible from the incisal aspect. The labial outline is convex and
the lingual outline shows lingual convergence. The cusp tip lies slightly lingual to the center.