The dental formula is a shorthand notation used to represent the number and type of teeth in each quadrant of the mouth. It describes the arrangement of teeth, including incisors, canines, premolars, and molars.
Understanding the Dental Formula
The dental formula uses a numerical representation to specify the number of each tooth type in one half of the jaw. Because of the bilateral symmetry of the dentition (mirrored on both sides), this provides the complete picture. The formula is expressed as two numbers separated by a slash (/).
- The numerator represents the number of teeth in the upper jaw (maxilla).
- The denominator represents the number of teeth in the lower jaw (mandible).
Within each number, the teeth are represented in this order:
- Incisors (I): Teeth at the front used for cutting.
- Canines (C): Pointed teeth next to the incisors, used for tearing.
- Premolars (P): Teeth behind the canines, used for grinding.
- Molars (M): Teeth at the back of the jaw, used for crushing.
Example: Permanent Dentition Formula
The permanent dentition dental formula is typically written as 2123/2123. Let's break it down:
- 2: Two incisors in each quadrant of the upper jaw (maxilla).
- 1: One canine in each quadrant of the upper jaw (maxilla).
- 2: Two premolars in each quadrant of the upper jaw (maxilla).
- 3: Three molars in each quadrant of the upper jaw (maxilla).
- 2: Two incisors in each quadrant of the lower jaw (mandible).
- 1: One canine in each quadrant of the lower jaw (mandible).
- 2: Two premolars in each quadrant of the lower jaw (mandible).
- 3: Three molars in each quadrant of the lower jaw (mandible).
This means a full set of permanent teeth totals 32 teeth (2 x (2+1+2+3) = 32).
Different Dental Formulae
It's important to note that dental formulae can vary slightly depending on species and even individual variations. The provided example (2123/2123) represents the typical human permanent dentition. Deciduous (baby) teeth have a different formula.
