THE TRIADAN SYSTEM OF LABELING TEETH
cases with other general practitioners and specialists without confusion about which tooth is being discussed. An organized labeling system makes medical records clear and understandable, avoiding self-defined, confusing shorthand and abbreviations that would not make sense to someone outside the practice.
Before we begin discussing dentistry in earnest, it is important to have a working understanding of common dental vocabulary. Knowledge of the Triadan system is key to developing a working vocabulary in veterinary dentistry. A standardized method for labeling all teeth in an organized way is necessary for accurate documentation, communication, and education. This allows you to discuss Dental formulas First, it is important to note the canine and feline dental formulas. They are often written in this format: ● Canine Adult: 2 x (I 3/3, C 1/1, P 4/4, M 2/3) = 42 teeth total ● Deciduous : 2 x (I 3/3, C 1/1, P 3/3) = 28 teeth total ● Feline Adult : 2 x (I 3/3, C 1/1, P 3/2, M 1/1) = 30 teeth total ● Deciduous : 2 x (I 3/3, C 1/1, P 3/2) = 26 teeth total The phrase “2 x” accounts for the symmetry of the left and the right sides. This same dental formula is true for two sides of the mouth, hence 2 x. The letters I (incisor), C (canine), P (premolar), and M (molar) represent the different types of teeth in the mouth. The numbers after each type of tooth represent the number of maxillary/mandibular teeth. The Triadan system While the dental formula represents the number of teeth that should be present in the mouth, the Triadan system is used to identify specific, individual teeth. This system, which is used globally in veterinary medicine, gives each tooth its own three-digit number. For organizational purposes, the mouth is divided into four quadrants: upper right, upper left, lower left, and lower right. Each quadrant is assigned a number, and all the teeth within the same quadrant will start with the same number. The order starts at right maxillary (upper right) teeth and clockwise from there (from the veterinarian’s perspective). Figure 1: Triadan System
and increase as you go distally. The number scheme starts with _01 in every quadrant. The most rostral and medial tooth in each quadrant (the first
incisor) is numbered as follows: ● Upper right quadrant: 101 ● Upper left quadrant: 201 ● Lower left quadrant: 301 ● Lower right quadrant: 401
When noting deciduous teeth, the sequence begins with 500 (starting at the right maxillary quadrant) and goes clockwise as before: ● Right maxillary first deciduous incisor: 501 ● Left maxillary first deciduous incisor: 601 ● Left mandibular first deciduous incisor: 701 ● Right mandibular first deciduous incisor: 801 From there, every sequential tooth within the quadrant is assigned a number. These numbers increase as you move caudally within the quadrant. Within the right maxillary quadrant, the three incisors are labeled 101 through 103. The canine tooth is just caudal to the incisors, so it is labelled 104. The first three premolars are labeled 105 through 107, and the fourth premolar (carnassial tooth) is 108. The molars are labeled 109 and 110. This pattern repeats itself in the left maxillary quadrant, where the teeth are labeled 201 to 210. The mandibular teeth are labeled in a similar fashion, except there are three molars in the mandibular arcade. Therefore, the caudal molars on the mandibular arcade are labeled 311 and 411. Figure 2: Canine Dental Chart
Note . From Royal Veterinary College, 2002. Note that teeth in the upper right (right maxillary) quadrant are numbered as the 100s. Proceed clockwise to the upper left (left maxillary) quadrant, where teeth are in the 200s. Next, the lower left (left mandibular) teeth are in the 300s, and the lower right (right mandibular) teeth are in the 400s. Within each quadrant, each tooth has an individual number. These numbers begin with _01 at the rostral (front) midline
Note . From Royal Veterinary College, 2002.
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Book Code: VFL1526
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