Basic Dental Anatomy

Different Teeth

The oral cavity is split up into top and bottom jaws. The top jaw is known as the maxilla. The bottom jaw is known as the mandible.

The jaw can be separated into four quadrants. Each quadrant can be separated into:

  • Central and lateral incisors
  • A canine (cuspid)
  • Two premolars (bicuspids)
  • Three molars (first molar, second molar, and wisdom tooth)

teeth

Identifying Teeth

In the United States, teeth are numbered from 1 through 32 in order to describe which tooth a clinician is referring to. This is known as the Universal Numbering System.

This numbering system begins in the top right quadrant with the very back tooth (the wisdom tooth), and proceeds in a clockwise fashion.

Universal Numbering

 

Tooth Surfaces

Each tooth has five surfaces on it:

  • Occlusal / incisal surface – the biting surface
  • Mesial surface – surface towards the midline of the mouth
  • Distal surface – surface away from the midline of the mouth
  • Buccal / vestibular / facial surface – surface facing the outside (cheek) of the mouth
  • Lingual / palatal surface – surface facing the inside (tongue / palate) of the mouth

Incisal Occlusal MesialDistal

Buccal Lingual


Test Your Knowledge

Pretend the red shading is caries – identify which teeth and surfaces are involved:

Quiz 1

Image adapted from source: Wikipedia

This is the first molar in the first quadrant, and therefore is tooth number 3.  Note, the wisdom teeth are not visible in the mouth, but most still be accounted for in the numbering system. The wisdom tooth in this quadrant of the jaw would be tooth 1, the second molar would be tooth 2, and the tooth we are looking at is tooth three. The ‘caries’ goes from the mesial of the tooth, to the occlusal of the tooth, to the buccal of the tooth. Therefore, the caries here would be tooth 3, MOB (mesial – occlusal – buccal).

Quiz 2

Image adapted from source: Wikipedia

This is the canine in the second quadrant, and therefore is tooth number 11. The ‘caries’ is on the incisal portion. Therefore, the caries here would be tooth 11, I (incisal).

Quiz 3

Image adapted from source: Wikipedia

This is the first premolar in the second quadrant, and therefore is tooth 12. The ‘caries’ in on the mesial and occlusal portion. Therefore, the caries here would be tooth 12, MO (mesial occlusal).


Other Tooth Numbering Systems

While the United States uses the Universal Numbering System, other countries such as Canada use the FDI or ISO tooth numbering system.

Here, teeth in each quadrant are numbered 1 through 8:

  • Central incisor = 1
  • Lateral incisor = 2
  • Canine / cuspid = 3
  • Premolar / bicuspid = 4 and 4
  • Molars = 6, 7 and 8

Then, each quadrant is assigned a number:

  • The top right quadrant = 1
  • The top left quadrant = 2
  • The bottom left quadrant = 3
  • The bottom right quadrant = 4

FDI system

geniusDental Anatomy