Canine Anatomy for Dental Hygiene Students

Developmental origin
- Formed from 4 lobes: 3 facial lobes + 1 lingual lobe (cingulum)
- Clinical importance: lobes create morphological landmarks (labial ridge, cingulum) used for instrumentation and restorations.
Morphologic role in the dentition
- Nicknamed the “cornerstones” of the mouth; located at curvature changes of the dental arch ⇒ aid in guiding lateral mandibular movements (canine guidance).
- Only anterior teeth with a well-developed cusp; cusp used for tearing food, protecting posterior teeth during excursions.
General crown & root traits
- Single cusp visible from both labial and lingual views.
- Longest overall tooth in each arch: combines longest crown + longest root → offers greatest periodontal support.
- Roots
- Wider labiolingually than mesiodistally.
- Taper to the lingual, producing an ovoid cervical cross-section.
- Developmental (longitudinal) root depressions on both sides, typically deeper on distal.
- Lingual anatomy
- Pronounced lingual ridge running from cusp tip to cingulum; splits the lingual surface into a mesial and distal fossa.
- Proximal contacts: distal contact positioned more cervically than mesial (helps identify left vs. right).

Mesial cusp ridge shorter than distal → diagnostic of right vs. left.
Subtle but detectable labial ridge (remnant of middle facial lobe).
Distal crown outline more convex; crown subtly tapers toward cervical line.
Overall facial outline ≈ pentagon.
Root
- Significantly longer than the crown (≈ 16-17\,\text{mm}).
- May deflect slightly to distal in apical third.

Crown profile is wedge-shaped.
Extremely prominent cingulum causes cervical bulge—important when placing sub-gingival instruments.
Developmental concavity/depression on cervical third of crown & root; deepest on distal → plaque retention risk.
Labiolingual dimension is the greatest of any anterior tooth; offers strong anchorage for prosthetics.
CEJ curvature: greater on mesial than distal (≈ 2-2.5\,\text{mm}).

Facio-lingual width > mesio-distal width.
Marginal ridges taper toward the cingulum, making the lingual half narrower.
Lingual surface more convex than labial.
Cingulum centered facio-lingually.
Distal facial & lingual surfaces may appear “pinched.”
Functional wear pattern: diamond-shaped facet on cusp tip and lingual slope due to occlusal contacts.

Mesial crown outline almost straight, forming a nearly continuous line with root → easier to identify vs. maxillary.
Mesial cusp ridge nearly horizontal; still shorter than distal ridge.
Crown appears longer incisocervically but narrower mesiodistally compared with maxillary.
Root is generally straight; distal curvature less common.

Cingulum less developed and often distally displaced when viewed incisally.
Less pronounced marginal ridges & lingual ridge → lingual surface smoother, shallower fossae.
Incisal edge positioned lingual to root’s long axis (contrasts with maxillary, which is labial).

Pronounced mesial & distal root depressions; distal is deeper.
Roots are broad labiolingually in cervical half, creating strong support.
Common anomaly: bifurcated root (≈ 6 %) in apical third → one facial & one lingual canal.
Pulp anatomy: normally one canal, but bifurcated roots contain two separate canals.

Crown bulk: maxillary > mandibular.
Cingulum prominence: maxillary > mandibular.
Mesial crown outline: convex (max) vs. straight (mand).
Root curvature: distal tip common (max) vs. usually straight (mand).
Incisal edge position: facial to long-axis (max) vs. lingual (mand).
Labiolingual dimension: both wide, but maxillary shows greater cervical prominence.

Occlusion: canines guide lateral movements, protecting posterior teeth (canine guidance).
Periodontal consideration: longest root offers excellent support for overdentures and abutments.
Restorative landmark: labial ridge used to contour composite/ceramic restorations accurately.
Endodontic implication: normally 1 canal; be vigilant for rare bifurcation in mandibular.
Instrumentation: deep distal root depression can harbor calculus; adapt curette blades appropriately.
Esthetics: canine eminence influences lip fullness; over-reduction may flatten facial profile.

Mandibular canine bifurcated root
- Faces: separate facial & lingual roots.
- Radiographic detection: look for “double-barrel” appearance.
- Clinical impact: complicates extraction, endodontic access, and implant planning.

Cats (and many carnivores) possess markedly elongated canines used primarily for piercing and holding prey—demonstrates evolutionary conservation of the tearing function in human canines.

When probing, watch for deeper sulcus readings on distal of canines due to concavity.
During scaling, roll instrument into distal root depression to avoid burnishing calculus.
For patient education, explain why canine wear facets can indicate bruxism; consider night-guard referral.
Recognize diamond-shaped wear on maxillary canines as indicator of functional intercuspation pattern.