The Modified Triadan System provides a universal numbering scheme for veterinary dental charting. Each tooth receives a three-digit number: the first digit indicates the quadrant, the second and third digits identify the specific tooth within that quadrant. Use the Dental Anatomy Tool for an interactive reference.
| Quadrant | First Digit | Anatomy |
|---|---|---|
| Right maxilla | 1 | Upper right |
| Left maxilla | 2 | Upper left |
| Left mandible | 3 | Lower left |
| Right mandible | 4 | Lower right |
For deciduous teeth, add 5 to the quadrant number: 5 (right maxilla), 6 (left maxilla), 7 (left mandible), 8 (right mandible).
Teeth are numbered from midline (01) to caudal (11 in dogs, 09 in cats). The canine is always 04, the first premolar is 05, and so on. The formula for dogs is 2(I3/3 C1/1 P4/4 M2/3) = 42.
Common Triadan numbers to memorize: 104 and 204 are the upper canines; 404 and 304 are the lower canines. The carnassial teeth (largest chewing teeth) are 108/208 (maxillary fourth premolar) and 409/309 (mandibular first molar).
Deciduous teeth erupt at 3–6 weeks in puppies and 2–4 weeks in kittens. Permanent teeth erupt at 3–5 months (dogs) and 3–4 months (cats). Retained deciduous teeth—particularly canines—require extraction to prevent malocclusion and periodontal disease. Never leave a deciduous tooth when its permanent successor has erupted.
| Tooth Type | Dog Eruption | Cat Eruption |
|---|---|---|
| Incisors | 3–5 months | 3–4 months |
| Canines | 4–6 months | 4–5 months |
| Premolars | 4–6 months | 4–6 months |
| Molars | 5–7 months | 4–5 months |
Canines (04): Fractures from trauma, tooth resorption in cats. Lower canines may cause palatal trauma in malocclusions.
Carnassials (108, 208, 409, 309): Most commonly affected by periodontal disease due to deep roots and complex anatomy. Fractured carnassials often have endodontic involvement.
Incisors: Dental calculus accumulation, tooth resorption (cats), trauma from cage biting.
First molars (109, 209, 410, 310): Periodontal disease, especially in small breeds where crowding occurs. Use Dental AI to analyze dental photos for educational staging.
Dental radiographs are essential for complete assessment—50% of tooth structure is below the gumline. Upload dental photos to the Dentistry Specialist for AI-assisted educational analysis.
Recommend dental evaluation for retained deciduous teeth, fractured teeth, oral masses, halitosis, or difficulty eating. Annual dental exams are part of preventive care.
- First digit = quadrant (1–4 permanent; 5–8 deciduous).
- Dogs: 42 teeth; cats: 30 teeth. Canine is always 04.
- Carnassials: 108/208 and 409/309—most affected by periodontal disease.
- Extract retained deciduous teeth when permanent successor has erupted.
- 50% of tooth structure is below gumline—radiographs are essential.