The four quadrants
Right and left are the animal's own. Quadrants run clockwise as you face the patient: 100 right maxilla, 200 left maxilla, 300 left mandible, 400 right mandible. The deciduous quadrants are 500, 600, 700 and 800 in the same order, so a retained deciduous canine in the right upper jaw is 504, beside the permanent 104. The number is said as the quadrant then the position: one oh four, three oh nine, one ten, four eleven.
The rule of 4 and 9
Because dogs and cats lose premolars differently, counting positions from the incisors would give the same tooth a different number in different species. Triadan fixes two landmarks instead. The canine is always position 04 and the first molar is always 09. From those you count: 01 to 03 are incisors, 05 to 08 are premolars, 09 to 11 are molars. When a species lacks a tooth, its number is simply left out. The upper fourth premolar (108, 208) and the lower first molar (309, 409) are the carnassial teeth in both species.
Chart: which positions each species has
The right side of each jaw, positions 01 to 11. The left side mirrors it in quadrants 2 and 3. "None" means the species has no tooth at that position.
| Position | Dog, upper (1xx) | Dog, lower (4xx) | Cat, upper (1xx) | Cat, lower (4xx) |
|---|---|---|---|---|
| 01 | first incisor | first incisor | first incisor | first incisor |
| 02 | second incisor | second incisor | second incisor | second incisor |
| 03 | third incisor | third incisor | third incisor | third incisor |
| 04 | canine | canine | canine | canine |
| 05 | first premolar | first premolar | none | none |
| 06 | second premolar | second premolar | second premolar | none |
| 07 | third premolar | third premolar | third premolar | third premolar |
| 08 | fourth premolar | fourth premolar | fourth premolar | fourth premolar |
| 09 | first molar | first molar | first molar | first molar |
| 10 | second molar | second molar | none | none |
| 11 | none | third molar | none | none |
The adult dog's dental formula is I 3/3, C 1/1, P 4/4, M 2/3 per side, 42 teeth. The adult cat's is I 3/3, C 1/1, P 3/2, M 1/1, 30 teeth. That is why a cat has no 105, 305 or 306, and no second molars at all. Every tooth for all four dentitions, adult and deciduous, is listed in the Triadan tables in the glossary.
Worked example: charting a COHAT callout
During a dental procedure on a dog the veterinarian says "three oh nine, furcation two". Quadrant 3 is the left mandible. Position 09 is, by the rule, the first molar, so this is the left mandibular first molar, a carnassial tooth with two roots, which is why furcation can be graded on it. Next comes "one oh eight, fractured, pulp exposed": quadrant 1, right maxilla, position 08, the upper fourth premolar, with a complicated crown fracture. In a cat the same callout could not be 105; if you hear it, ask, because the tooth does not exist.
Common mistakes
- Swapping left and right. Quadrant 1 is the animal's right upper jaw, which is on your left as you face it.
- Counting a cat's premolars from 05. The cat's first upper premolar is 106 and its lower premolars are 307 and 308.
- Charting a retained baby tooth on the permanent number. A persistent deciduous canine is 504, not 104.
- Hearing one ten as one hundred and ten. The quadrant is said first, then the two digit position.
- Grading furcation on a single rooted tooth. Incisors and canines have one root and no furcation.
ChartCall has canine and feline odontograms in modified Triadan, with callouts spoken the way a veterinarian dictates them. Switch the chart to dog or cat at the top of the daily charting drill. For the abbreviations that go with the numbers, see dental charting abbreviations and symbols.
Sources
Checked against these sources on 26 September 2026. Conventions differ between schools, offices and clinics; where yours differ, follow your program.
- The modified Triadan system: nomenclature for veterinary dentistry, Journal of Veterinary Dentistry, 1991. The paper that adapted the original 1972 Triadan system for animals and set out the rule of 4 and 9.
- American Veterinary Dental College, veterinary dental nomenclature. The nomenclature and abbreviation lists that clinics and veterinary technology programs commonly follow.