Dental Anatomy: Tooth Numbering Systems

Study Notes

There are three tooth numbering systems: Palmer, Universal, and International
These systems are used to document patient treatment and record dental information accurately
Each system has its own unique notation and method of identifying teeth

Most frequently used among orthodontists and practitioners in the United Kingdom
Divides the upper and lower arch into four quadrants
Uses simple brackets to represent the four quadrants of dentition
In deciduous teeth, uppercase alphabetic letters represent the primary teeth in each quadrant
In permanent teeth, numbers 1-8 are used in each quadrant, starting from the midline

Adopted by the American Dental Association in 1975
Uses numbers 1-32 to identify the 32 teeth in the permanent dentition
Maxillary teeth are numbered from 1-16, starting from the maxillary right third molar
Mandibular teeth are numbered from 17-32, starting from the mandibular left third molar
In primary dentition, uppercase letters A-T are used to identify the 20 teeth

Uses two digits to identify teeth, with the first digit indicating the dentition, arch, and side, and the second digit indicating the tooth position
For permanent dentition, the first digit is 1-4, and the second digit is 1-8, starting from the midline
For deciduous dentition, the first digit is 5-8, and the second digit is 1-5, starting from the midline

The facial surface of the tooth is towards the face or lip
The lingual surface of the tooth is towards the tongue or palate
The occlusal surface is the surface of premolars and molars that come in contact with opposing jaw during closure
The proximal surfaces are the sides of the tooth next to an adjacent tooth, with mesial surfaces facing towards the midline and distal surfaces facing away from the midline### Line Angles and Point Angles
Line angle is formed by the junction of two surfaces and is named after both surfaces.
Point angle is formed by the junction of three surfaces and is named after these three surfaces.

Anterior teeth have 4 point angles:
- Distolinguo incisal point angle
- Distolabio incisal point angle
- Mesiolinguo incisal point angle
- Mesiolabio incisal point angle
Posterior teeth have 4 point angles:
- Distolinguo occlusal point angle
- Distobucco occlusal point angle
- Mesiolinguo occlusal point angle
- Mesiobucco occlusal point angle

The crown and roots can be divided into thirds for descriptive purposes.
The crown is divided into:
- Occlusal or incisal third
- Middle third
- Cervical third
The root is divided into:
- Cervical third
- Middle third
- Apical third
The crown can be divided in three directions:
- Inciso- or occlusocervically
- Mesiodistally (into mesial third, middle third, and distal third)
- Labio- or buccolingually (into labial or buccal third, middle third, and lingual third)