Modified Triadan System
Introduction
The modified Triadan system provides a consistent method of numbering teeth across different animal species.
The system is based on the permanent dentition of the pig, which has 11 teeth in each quadrant - three incisors, one canine, four premolars and three molars. The grand total is 44 teeth.
Quadrant
The first digit of the Triadan numbering system refers to the quadrant: right maxilla, left maxilla, left mandible, right mandible.
The quadrants are numbered 1-4 starting with the right maxilla and ending with the right mandible in a clockwise direction as viewed from the front of the animal.
For deciduous dentition, numbers 5-9 are used in the same way.
Tooth position
The second and third digits refer to the tooth position within the quadrant, with the sequence always starting at the midline.
Certain rules should be followed in species that have fewer teeth, such as cats, rabbits and horses.
The central incisor is always 01 and the following incisors are 02 and 03.
The canines are always 04.
The premolars are 05 to 08 and the last premolar is always 08.
The first molar is always 09 and the following molars are 10 and 11.
The carnassials of carnivores can be used as landmarks to help number the teeth, as the upper carnassials are always the last premolars (108 and 208) and the lower carnassials are always the first molars (309 and 409).
The numbers of the other teeth can then be determined from there.
| Modified Triadan System Learning Resources | |
|---|---|
 Test your knowledge using flashcard type questions |
Veterinary Dentistry Q&A 03 |
References
Tutt, C. (2006) Small animal dentistry: a manual of techniques Wiley-Blackwell
Johnston, N. Veterinary Dentistry interactive programme