Permanent Canines Notes

Permanent Canines: General Features

• Permanent canines are the four anterior teeth located at the corners of each quadrant in each dental arch.

• They are the third tooth from the midline in each quadrant, distal to the incisors and mesial to the posteriors.

• Permanent canines are succedaneous, replacing the primary canines of the same type.

• Function:

  • Due to their tapered shape and prominent cusp, canines pierce or tear food during mastication.

  • They serve as a major support for facial muscles, maintaining the vertical dimension of the face.

  • Anatomists consider them the cornerstones of the dental arch because of their position, form, and function.

  • Without intact canines, facial contours cannot be maintained, and a loss of height occurs in the lower third of the vertical dimension.

  • They support incisors and premolars in mastication and speech.

  • They act as guideposts during occlusal movement, serving as a protective functional device during lateral deviation of the mandible.

  • Canines help relieve excessive horizontal forces on posterior teeth.

• Stability:

  • Canines are the most stable teeth in the dentition due to their long root length, which provides increased periodontal tissue support.

  • Proximal root concavities also increase periodontal anchorage.

  • They have a significantly reduced risk of loss from periodontal disease or traumatic injury.

  • Often, they are the last teeth present in a failing dentition.

• The canines (or their roots) often serve as stabilizing anchors for replacements of lost teeth in prosthetic procedures, such as partial fixed or removable dentures and permanent bridges.

• Maxillary and mandibular canines resemble each other.

  • The crown of each is about the same size.

  • Viewed proximally, the crown appears triangular, like all anterior teeth.

  • Viewed labially or lingually, the crown outline appears pentagonal.

  • Canines are wider labial-lingually than incisors, even wider than maxillary central incisors.

• Each canine has an incisal ridge on its masticatory surface, like other anteriors.

  • Unlike incisors, it has a cusp tip that is in line with the long axis of the root when first erupted.

  • The incisal ridge is divided into two cusp slopes, or ridges, due to the cusp tip.

• Canines have a vertical and centrally placed labial ridge.

• Each canine has a cingulum and marginal ridges on its lingual surface, similar to incisors.

  • They also have a centrally placed vertical lingual ridge extending from the cusp tip to the cingulum.

• The lingual ridge creates two separate and shallow lingual fossae between it and the bordering marginal ridges.

  • These lingual fossae are more pronounced on maxillary canines than on mandibular canines.

• Permanent canines are the longest teeth in the dentition.

  • Each has a particularly long, thick root, usually between 1 and 1½ times the length of the crown.

  • The long and large root is externally manifested by the vertically oriented and labially placed bony ridge called the canine eminence of the alveolar process, especially on the maxillary arch.

• With attrition, the lengths of the cusp slopes are often altered due to tooth-to-tooth contact.

  • The overall narrower incisal ridges become wider incisal edges, similar to worn incisors.

Permanent Maxillary Canines #6 and #11 (#13 and #23)

• Erupt between 11 and 12 years of age, with root completion between 13 and 15 years.

• Usually erupt after the mandibular canines, after the maxillary incisors, and possibly after the maxillary premolars.

• The crown is similar in length, or even shorter than that of a maxillary central incisor.

• The crown is considerably wider labiolingually than that of a central incisor but noticeably narrower mesiodistally.

• Somewhat resembles a mandibular canine.

  • The cusp is more developed and larger, and the cusp tip is sharper.

  • The entire lingual surface features are more prominent, including the lingual ridge and marginal ridges.

• As long as a mandibular canine, but the crown is as long as, or slightly shorter than that of a mandibular canine.

• The long root is single and has a blunt apex; it is the longest root in the maxillary arch.

• The pulp cavity consists of a single pulp canal and a large pulp chamber.

  • The pulp chamber usually has only one pulp horn.

Labial View Features

• The mesial half of the crown resembles part of an incisor, and the distal half resembles part of a premolar, showing the transition from the incisors to the premolars in the maxillary arch.

• Usually, both imbrication lines and perikymata are present in the cervical third of the surface, especially in newly erupted teeth.

• The distal outline is shorter than the mesial outline and usually has a depression between the distal contact area and the CEJ, which helps to distinguish the right from the left.

• From the labial view, the mesial and distal contacts are on two different levels of the tooth, which helps to distinguish the right from the left.

• The single cusp is round, and the mesial cusp slope is shorter than the distal cusp slope when first erupted, which helps to distinguish the right from the left.

Lingual View Features

• The mesial, distal, and incisal lingual outlines are similar to those on the labial view of the tooth.

• The lingual surface also has a prominent mesial marginal ridge and distal marginal ridge.

• A centrally placed vertical lingual ridge is also present from the cingulum to the cusp tip, separating two lingual fossae—the shallow but visible mesiolingual fossa and distolingual fossa.

Proximal View Features: Mesial and Distal

• The mesial and distal aspects present a triangular outline.

• They resemble the maxillary incisors but are stronger looking, especially in the cingulum region.

Mesial

• The CEJ curves higher incisally on the mesial than on the distal surface, which helps to distinguish the right from the left.

• The cusp tip is toward the labial.

Distal

• The distal view of the tooth is similar to the mesial view, but the CEJ curvature is less on the distal than on the mesial surface.

Incisal View Features

• The labiolingual width is large in comparison with that of any other anterior tooth, making it an extremely strong tooth during mastication.

• The crown outline is asymmetrical; the mesial part of the crown has greater labiolingual bulk.

• The distal part of the crown appears thinner than the mesial and gives the impression of being stretched to make contact with the first premolar.

• More specifically, the mesial half of the labial outline is quite rounded, and the distal half is frequently concave.

• The distal half of the lingual outline is also frequently concave because the distal fossa is deeper and thus more pronounced.

Clinical Considerations with Permanent Maxillary Canines

• Impaction: They may erupt labially or lingually to the surrounding teeth.

• The maxillary canines may also fail to erupt fully, remaining impacted within the alveolar process.

• Dentigerous Cyst: Developmental cyst formation may occur within the dental tissue of an impacted crown of a maxillary canine, resulting in a dentigerous cyst.

• Dilaceration: The root of maxillary canines may also undergo distorted angulations or dilaceration, and there may be several curvatures along its length.

Permanent Mandibular Canines #22 and #27 (#33 and #43)

• Erupt between 9 and 10 years of age with root completion between 12 and 14 years.

• Thus, these teeth usually erupt before the maxillary canines and after most of the incisors have erupted.

• It closely resembles a maxillary canine.

• Although the entire tooth is usually as long, it is narrower labiolingually and mesiodistally than a maxillary canine.

• The single cusp is not as well developed in size, and the two cusp slopes are thinner labiolingually than those of a maxillary canine.

• The lingual surface of the crown is smoother than that of a maxillary canine, having a less developed cingulum and two marginal ridges.

• The single root may be as long as that of a maxillary canine but is usually somewhat shorter, although it still has the longest mandibular root.

• The mesial developmental depression on the root is more pronounced and often deeper compared with that of a maxillary canine.

  • A distal developmental depression similar to the mesial one is also apparent.

  • These proximal concavities may extend the full length of the root.

  • The developmental depressions may be extremely pronounced, to the point of creating a facial and lingual component in the apical third and giving the tooth a double-rooted appearance.

• The pulp cavity resembles that of a maxillary canine in that both usually have one pulp canal and a large pulp chamber.

  • There is also only one pulp horn.

Labial View Features

• The labial surface is not as rounded as that on a maxillary canine, especially in the incisal two-thirds of the tooth. In contrast, however, it is generally rounder than a mandibular incisor.

• The distal outline is shorter and rounder than the mesial outline, similar to that of a maxillary canine, which helps to distinguish the right from the left.

• Similar to a maxillary canine, the mesial and distal contacts are on different levels of the tooth, which helps to distinguish the right from the left.

• The cusp slopes are different.

  • The mesial cusp slope is shorter than the distal cusp slope when first erupted, which helps to distinguish the right from the left.

Lingual View Features

• The lingual surface is less pronounced, except for the faintly demarcated features of a lingual ridge, mesial marginal ridge, distal marginal ridge, and two lingual fossae, the distolingual fossa and the mesiolingual fossa.

Proximal View Features: Mesial

• It is again similar to a maxillary canine from a mesial view with a similar triangular shape and pointed cusp on the crown.

• The CEJ curve is more toward the incisal on the mesial surface than the distal, which helps to distinguish the right from the left.

Incisal View Features

• From this view, it is similar to a maxillary canine, but it is slightly more symmetrical compared with the maxillary tooth.

Clinical Considerations with Permanent Mandibular Canines

• A disturbance that may occur is an accessory root or bifurcated root in the apical third with labial and lingual root branches.

• This tooth is the anterior tooth most likely to have a bifurcated root, although this is still rare.