Mandibular canine: FDI 33 and 43

The numbers on both sides

In FDI the first digit is the quadrant and the second is the position counted from the midline. 33 is quadrant 3, position 3: the lower left canine. 43 is the same position in quadrant 4, on the lower right. Universal numbers adult teeth from 1 at the upper right third molar around to 32 at the lower right third molar, which makes this tooth 22 on the lower left and 27 on the lower right. Palmer writes the position inside a bracket that shows the quadrant. In plain text that gives LL3 and LR3.

Crown surfaces: mesial, distal, labial (facial), lingual and incisal.

The ADA chart also uses the older name cuspid.

Development and eruption

Calcification starts at 4 to 5 months and the crown is finished at 6 to 7 years. The tooth erupts at 9 to 10 years and the root is done at 12 to 14 years, about a year ahead of the upper canine.

Read on 24 October 2026. Sources: Human tooth development, tables citing Ash and Nelson, Wheeler's Dental Anatomy, Physiology and Occlusion (Wikipedia); American Dental Association, Tooth development charts (primary and permanent). Figures are usual values, and teeth vary from person to person.

Crown

The labial outline is pentagonal. The crown is less than 1 mm narrower than the maxillary canine but 0.5 to 1 mm longer. The cusp has a thinner ridge from front to back, and its tip usually lines up with the center of the root, though it can sit toward the tongue.

The lingual surface is smoother because the cingulum and the lingual ridges are less defined than on the upper canine.

To orient an extracted canine, look at the labial view: the side with the shorter cusp slope is the mesial side. In the Wheeler description the mesial contact lies in the incisal third, near the mesioincisal angle, and the distal contact lies lower, at the junction of the incisal and middle thirds. The shape of the contact does not identify the side reliably.

Read on 24 October 2026. Sources: Craciunescu and others, Dental Anatomy and Morphology of Permanent Teeth, in Human Teeth, From Function to Esthetics (IntechOpen, 2023); MolarPath note Permanent tooth morphology (built on Wheeler's Dental Anatomy, 11th ed., and Sturdevant's Operative Dentistry, 8th ed.). Figures are usual values, and teeth vary from person to person.

Roots and canals

The root is long, a little shorter than the maxillary canine's root. Ingle's Endodontics tabulates one root and one canal. The Chilean CBCT sample of 336 mandibular canines found 98.5 percent single rooted and 9.2 percent with two canals. An Indian sample of 250 found Vertucci type I in 79.6 percent and type III in 13.6 percent. A Saudi review reports 95.8 percent type I.

Read on 24 October 2026. Sources: Number of roots and canals, from Ingle's Endodontics (animated-teeth.com); Betancourt and others, CBCT assessment of root and canal morphology in mandibular anterior teeth in a Chilean subpopulation, BMC Oral Health 2026; Amardeep and others, Root Canal Morphology of Permanent Maxillary and Mandibular Canines in Indian Population Using CBCT, Anatomy Research International 2014; Asiri and others, Root Morphology and Canal Configuration of Permanent Canines Among Saudi Population, Int J Gen Med 2022. Figures are usual values, and teeth vary from person to person.

Neighbors and the baby tooth before it

The mandibular canine comes in before the premolars in the lower arch, at 9 to 10 years, while the maxillary canine arrives last in its arch. The primary mandibular canine has the same shape as the maxillary one, only smaller.

The AAPD notes that taking out the lower primary canines to relieve crowding costs up to 2.7 mm of arch length. If the primary canines are taken out, a passive lingual arch has been suggested to save the leeway space.

Read on 24 October 2026. Sources: American Dental Association, Tooth development charts (primary and permanent); Chussid, Anatomy of Primary Teeth, Columbia University College of Dental Medicine lecture; American Academy of Pediatric Dentistry, Management of the Developing Dentition and Occlusion in Pediatric Dentistry (2024 revision); MolarPath note Eruption sequence and chronology (built on McDonald and Avery, 11th ed., and Proffit's Contemporary Orthodontics, 7th ed.). Figures are usual values, and teeth vary from person to person.

Local anesthesia

The canine lies in front of the mental foramen, so an incisive nerve block gives pulpal anesthesia and leaves the tongue alone. A conventional inferior alveolar block also works.

In adults the dense bone makes infiltration unreliable at the molars but workable at teeth in front of them. The mental foramen sits most often under the second premolar.

Read on 24 October 2026. Sources: MolarPath note Mandibular techniques, local anesthesia (built on Malamed's Handbook of Local Anesthesia, 7th ed.). Figures are usual values, and teeth vary from person to person.

Clinical and exam points

The space between the lateral incisor and the first premolar is small, so a lower canine easily erupts out of line, a pattern the dental anatomy chapter links to limited space.

The AAPD records that premature loss of a mandibular primary canine can lead to an immediate midline shift, but a review of the Iowa and Toronto growth studies found that the lower midline did not change significantly after loss of one primary canine.

Timing differs a little between boys and girls. Girls generally reach dental maturity and erupt teeth somewhat earlier than boys, a small but consistent difference, so a delay is judged on the whole pattern of teeth and not on a single canine.

Read on 24 October 2026. Sources: Craciunescu and others, Dental Anatomy and Morphology of Permanent Teeth, in Human Teeth, From Function to Esthetics (IntechOpen, 2023); American Academy of Pediatric Dentistry, Management of the Developing Dentition and Occlusion in Pediatric Dentistry (2024 revision). Figures are usual values, and teeth vary from person to person.

Questions and answers

Read on 24 October 2026. Sources: American Dental Association, Tooth development charts (primary and permanent); Betancourt and others, CBCT assessment of root and canal morphology in mandibular anterior teeth in a Chilean subpopulation, BMC Oral Health 2026; MolarPath note Permanent tooth morphology (built on Wheeler's Dental Anatomy, 11th ed., and Sturdevant's Operative Dentistry, 8th ed.). Figures are usual values, and teeth vary from person to person.