Primary mandibular canine: FDI 73 and 83
The lower baby canine: the smaller twin of the upper canine, with the lower primate space just behind it.
Quick answer
- FDI 73 and 83, Universal M and R, Palmer LLC and LRC.
- Primary mandibular canine erupts at 17 to 23 months.
The numbers on both sides
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Lower left canine | 73 | M | LLC |
| Lower right canine | 83 | R | LRC |
In FDI the first digit is the quadrant and the second is the position counted from the midline. 73 is quadrant 7, position 3: the lower left primary canine. 83 is the same position in quadrant 8, on the lower right. Universal gives baby teeth the letters A to T, from the upper right second molar around to the lower right second molar, which makes this tooth M on the lower left and R on the lower right. Palmer writes the letter for the position inside a bracket that shows the quadrant. In plain text that gives LLC and LRC.
Crown surfaces: mesial, distal, labial (facial), lingual and incisal.
Development and eruption
| Stage | Age |
|---|---|
| Calcification begins | 17 weeks in utero |
| Crown completed | 9 months |
| Erupts | 17 to 23 months |
| Root completed | 3.25 years |
| Shed | 9 to 12 years |
Calcification starts at about 17 weeks in utero and the crown is complete at 9 months. The tooth erupts at 17 to 23 months, the root is complete at 3.25 years and the tooth is shed at 9 to 12 years.
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 cusp is pointed and the enamel is thin. The crown is narrower than the maxillary primary canine and narrows at the neck. The distal cusp slope is the longer one, the reverse of the upper primary canine.
Space around it matters. In most children the lower primate space lies behind the canine, between the canine and the first primary molar. There is no primate space distal to the primary second molars.
Read on 24 October 2026. Sources: Chussid, Anatomy of Primary Teeth, Columbia University College of Dental Medicine lecture; MolarPath note Primary tooth morphology (built on McDonald and Avery's Dentistry for the Child and Adolescent, 11th ed.). Figures are usual values, and teeth vary from person to person.
Roots and canals
The root is conical, narrow from side to side and long for the size of the crown, as for other anterior primary teeth. The checked sources give no canal count for the canine.
Read on 24 October 2026. Sources: Chussid, Anatomy of Primary Teeth, Columbia University College of Dental Medicine lecture. Figures are usual values, and teeth vary from person to person.
Neighbors and the tooth that replaces it
The permanent mandibular canine replaces it and erupts at 9 to 10 years, before the premolars in the lower arch. Resorption of the primary canine starts on the lingual root surface, and the canine is part of the leeway space with the two primary molars.
Proffit puts the leeway surplus at about 2.5 mm per side in the lower arch, against about 1.5 mm per side in the upper arch, so the lower arch gains more room as the molars drift forward.
The AAPD notes that a space analysis can evaluate arch length at the time the incisors erupt. It adds that extracting primary or permanent teeth to relieve crowding should not be done without a comprehensive space analysis and a short-term and long-term orthodontic plan.
Read on 24 October 2026. Sources: MolarPath note Primary tooth morphology (built on McDonald and Avery's Dentistry for the Child and Adolescent, 11th ed.); American Dental Association, Tooth development charts (primary and permanent); 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
A child's lower canine can be reached by infiltration. The mandibular foramen sits low in young children, at or below the occlusal plane, and rises with growth, so an inferior alveolar block goes lower than in an adult.
The canine lies in front of the mental foramen, and an incisive block gives pulpal anesthesia there without numbing the tongue.
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 AAPD discusses taking out lower primary canines to give the permanent incisors more room. The decrease in incisor irregularity is statistically significant, but it comes with a loss of arch length of up to 2.7 mm, and the guideline suggests weighing the two before removal.
Premature loss of a mandibular primary canine has been reported to cause an immediate midline shift, although a review of the Iowa and Toronto growth studies found the lower midline did not change significantly after loss of one primary canine. If the canines are removed, a passive lingual arch has been suggested to hold the leeway space.
Read on 24 October 2026. Sources: 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
What are the numbers for the primary mandibular canine?
FDI 73 and 83, Universal M and R, Palmer LLC and LRC.
When does it erupt and when is it shed?
The ADA chart gives 17 to 23 months for eruption and 9 to 12 years for shedding.
What happens if a lower primary canine is lost early?
The AAPD reports a possible midline shift and a loss of arch length of up to 2.7 mm when the canines are removed for crowding.
Where is the lower primate space?
Between the primary canine and the first primary molar.
Read on 24 October 2026. Sources: American Dental Association, Tooth development charts (primary and permanent); American Academy of Pediatric Dentistry, Management of the Developing Dentition and Occlusion in Pediatric Dentistry (2024 revision); MolarPath note Primary tooth morphology (built on McDonald and Avery's Dentistry for the Child and Adolescent, 11th ed.). Figures are usual values, and teeth vary from person to person.
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