Canines

Permanent Canines: General Features

• Definition and Positioning

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

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

  • Permanent canines are succedaneous, meaning they replace primary canines of the same type.

TABLE 16.2: Permanent Canines

• Identification Codes

  • Universal Numbering System:

  • Maxillary Canine: #6 and #11

  • Mandibular Canine: #22 and #27

  • International Numbering System:

  • Maxillary Canine: #13 and #23

  • Mandibular Canine: #33 and #43

• Crown Features

  • Single cusp with tip and slopes, labial ridge, cingulum, lingual ridge, marginal ridges, and lingual fossae.

  • Longest tooth in the dental arch with characteristics as follows:

  • Maxillary Canine:

    • Prominent lingual surface with a sharp cusp tip.

  • Mandibular Canine:

    • Less pronounced lingual surface and less sharp cusp tip.

  • Height of contour:

    • Labial: Cervical third

    • Lingual: Middle third

    • Incisal third

• Contact Areas

  • Mesial contact

  • Distal contact

  • Distinguishing right from left:

    • Maxillary canine has a shorter mesial cusp slope with more pronounced mesial CEJ (Cementoenamel Junction) curvature.

    • Mandibular canine shows more cervical contact on the distal, with a shorter distal outline viewed from the labial side.

• Root Features

  • Junction between the incisal third and middle thirds is a key feature for distinguishing canines from other teeth.

  • For maxillary canines:

  • Long, thick single root, oval on cervical cross-section.

  • Proximal root concavities provide increased periodontal anchorage.

  • Blunt root apex.

  • For mandibular canines:

  • Oval on cervical cross-section but with developmental depressions creating a double-rooted appearance.

  • Pointed apex.

TABLE 15.2: Approximate Eruption and Root Completion Ages for Permanent Teeth

• Maxillary Teeth

  • Central incisor: Erupts at 7 to 8 years, root completion at 10 years.

  • Lateral incisor: Erupts at 8 to 9 years, root completion at 11 years.

  • Canine: Erupts at 11 to 12 years, root completion at 13 to 15 years.

  • First premolar: Erupts at 10 to 11 years, root completion at 12 to 13 years.

  • Second premolar: Erupts at 10 to 12 years, root completion at 12 to 14 years.

  • First molar: Erupts at 6 to 7 years, root completion at 9 to 10 years.

  • Second molar: Erupts at 12 to 13 years, root completion at 14 to 16 years.

  • Third molar: Erupts between 17 to 21 years, root completion at 18 to 25 years.

• Mandibular Teeth

  • Central incisor: Erupts at 6 to 7 years, root completion at 9 years.

  • Lateral incisor: Erupts at 7 to 8 years, root completion at 10 years.

  • Canine: Erupts at 9 to 10 years, root completion at 12 to 14 years.

  • First premolar: Erupts at 10 to 12 years, root completion at 12 to 13 years.

  • Second premolar: Erupts at 11 to 12 years, root completion at 13 to 14 years.

  • First molar: Erupts at 6 to 7 years, root completion at 9 to 10 years.

  • Second molar: Erupts at 11 to 13 years, root completion at 14 to 15 years.

  • Third molar: Erupts between 17 to 21 years, root completion at 18 to 25 years.

References: Data from Nelson S. Wheeler's "Dental Anatomy, Physiology and Occlusions," 10th ed. Philadelphia: Elsevier; 2015.

Importance of Permanent Canines

• Functionality

  • Patients often refer to canines as their eyetooth; historically, they have been known as cuspids.

  • Their tapered shape and prominent cusp enable them to pierce or tear food during mastication.

  • Positioned in the dental arch, canines provide major support for facial muscles, maintaining the overall vertical dimension of the face and preventing collapse in the lower third.

• Arch Support

  • Canines act as support for incisors and premolars during chewing and speaking.

  • They function as guideposts during occlusal movements and protect against excessive horizontal forces on posterior teeth.

Stability and Longevity of Permanent Canines

• Canines are the most stable teeth in the dentition due to:

  • Long root length that offers significant periodontal tissue support.

  • Proximal root concavities contribute to enhanced periodontal anchorage, reducing the risk of loss from periodontal disease or trauma, hence often being the last teeth to remain in a failing dentition.

  • They rarely suffer from dental caries, with a crown shape that encourages self-cleansing and minimal retention of biofilm.

  • Canines frequently serve as anchoring points for lost tooth replacements in prosthetic dental procedures, including partial fixed/removable dentures and permanent bridges.

Aesthetic Role of Permanent Canines

• Each canine contributes to esthetics by holding the skin of the labial commissure in position, reducing the visibility of deep lip lines or wrinkles that may develop with age.

Comparison Between Maxillary and Mandibular Canines

• General Comparison

  • Both maxillary and mandibular canines share similarities but also have several distinctive features.

  • The crowns are similar in size; from a proximal view, they appear triangular, consistent with all anterior teeth.

  • Labial/lingual views show pentagonal crown outlines, width across the labiolingual dimension being greater than that of incisors.

• Unique Features of Maxillary Canines

  • Each maxillary canine has an incisal ridge similar to other anterior teeth but is distinguished by their cusp tip, dividing the incisal ridge into two cusp slopes.

  • The mesial cusp slope is typically shorter than the distal cusp slope, with the maxillary canine's mesial cusp slope occluding with the distal cusp slope of a mandibular canine.

  • The length of cusp slopes and the position of cusp tips can change due to attrition, varying in height over time.

  • Canines uniquely feature a centrally placed vertical labial ridge.

• Lingual Features of Maxillary Canines

  • Each maxillary canine possesses a cingulum and marginal ridges similar to incisors.

  • The crown is narrower on the lingual side compared to the labial, possessing a centrally placed vertical lingual ridge that extends from the cusp tip to the cingulum, creating two separate, shallow lingual fossae which are more pronounced on the maxillary canines than on the mandibular.

• Length and Root Features of Maxillary Canines

  • Permanent canines are the longest teeth in the entire dentition.

  • They possess a long, thick root that is generally between 1 and 1.5 times the length of the crown.

  • Externally, the length and size of roots manifest as a vertically oriented bony ridge in the canine eminence particularly noted in the maxillary arch.

Specific Features of Maxillary Canines

• Eruption and Root Completion

  • Erupt between ages 11 and 12 years, root completion typically occurs between ages 13 and 15 years.

  • Erupts after all incisors and possibly after maxillary premolars.

• Crown Characteristics

  • The crown length is similar to or even shorter than maxillary central incisors but wider labiolingually.

  • Canine crowns are noticeably narrower mesiodistally compared to central incisors.

  • The lingual surface's cingulum is more developed, adding strength during mastication, and the cusp is larger and sharper compared to the mandibular canine.

• Lingual Surface Features

  • All lingual surface features are more pronounced on maxillary canines compared to other types.

  • Although equal in length to a mandibular canine, the maxillary canine crown might be slightly shorter.

  • Contains a long single root with a blunt apex, distinguishing it as the longest root within the maxillary arch.

  • Developmental depressions on the root are more pronounced on the distal compared to the mesial, leading to a more prominent crown at CEJ on the distal side.

  • Consists of one single pulp canal and a large pulp chamber with one pulp horn.