Summary
Highlights
From the incisal aspect, no part of the root is visible. The labiolingual dimension is greater than the mesiodistal dimension, an adaptation to labial forces. The labial outline is convex due to the labial ridge. The lingual aspect is narrower than the labial due to lingual convergence, characteristic of anterior teeth. The cusp tip is positioned slightly labial and mesial to the center of the tooth.
The maxillary canine is the third tooth from the midline. Its numbering varies across systems: FDI (13, 23), Universal (6, 11), and Zsygmondy Palmar (3 with quadrant brackets). The name 'canine' comes from the Latin 'Canis' (dog), highlighting its prominence, and it's also known as cuspid, corner tooth, or eye tooth. Its primary function is tearing.
Canines facilitate 'canine guidance' by aligning the jaw into correct occlusion. They are often the last teeth in the mouth due to their long, stable roots and self-cleansing, convex crowns, which makes them less prone to caries. Canines are crucial for aesthetics, supporting the corners of the mouth; their absence can cause lip drooping and an aged appearance. The root's thickness forms the 'canine eminence' on the alveolar ridge, with a 'canine fossa' just behind it. Maxillary canines are the second most common impacted teeth after third molars due to potential space issues during eruption.
Canines develop from four lobes: mesial, labial, distal, and lingual. The labial lobe is most developed, forming the cusp, while the lingual lobe forms the cingulum. Maxillary canines typically erupt between 11-12 years of age. Key measurements include a crown length of 10mm, root length of 17mm, mesio-distal crown width of 7.5mm (at contact area) and 5.5mm (at cervix), and labio-lingual diameter of 8mm (at cingulum) and 7mm (at cervix). The cervical line curvature is 2.5mm mesially and 1.5mm distally.
From the labial aspect, the crown is trapezoidal. The cusp tip is centered, with two cuspal slopes: a shorter mesial slope and a longer distal slope. The mesial contact area is at the junction of the incisal and middle third, while the distal contact area is entirely within the middle third. The distal outline is slightly more concave than the mesial outline, and the cervical line is convex towards the root. The labial surface is prominently convex with a labial ridge, often showing slight concavities mesially and distally indicating developmental lobes. The root is smooth, convex, and tapers towards the apex.
The palatal side is narrower than the labial, maintaining the same overall outline but with distinct surface features. Five ridges are visible: mesial and distal cuspal ridges, mesial and distal marginal ridges, and one lingual ridge running from the cusp to the cingulum. The large cingulum is in the cervical third, flanked by two shallow concavities: the mesial lingual fossa and distal lingual fossa.
From the mesial aspect, the crown has a triangular or wedge shape, with the cusp tip slightly labial to the midline. The labial outline is convex due to the labial ridge, with maximum convexity at the cingulum. The lingual outline is complex, convex incisally, then concave in the middle, and convex cervically. The cervical line is convex towards the crown. The root is smooth, convex, and tapers, featuring a mesial developmental depression in the middle third. The distal aspect is similar to the mesial, but the distal developmental depression on the root is typically deeper.