Tooth Numbering

Table of Contents
History of Tooth Numbering
Teeth Numbering Systems
Names of Teeth
Parts of the Tooth

by John Baker


Dentists have a specialized notation systems for when they discuss and write about specific teeth. Each tooth is assigned a number and is therefore more convenient to reference. Over the years, over 20 different teeth numbering systems have been developed. Today, general dentists use one of the three major dental tooth numbering systems for the numbering of human teeth. 

The three most common systems used are the FDI World Dental Federation notation, Universal numbering system (dental), and Palmer notation method. The FDI system is used throughout the world, however in the Unites States dentist predominantly use the Universal Numbering System

History of Tooth Numbering

In 1947 the American Dental Association or ADA recommended the use of the Palmer notation method. Because this method required the use of symbols it was very difficult when typing on a keyboard. Therefore, in 1968 the Association officially supported the Universal system. The World Health Organization and the Fédération Dentaire Internationale officially uses the two-digit numbering system of the FDI system.

Tooth Charts

Teeth Numbering Systems

FDI World Dental Federation Notation

The FDI World Dental Federation notation is used internationally by dentists around the world. Its function is to associate information to a specific tooth. The FDI system uses a two-digit numbering system in which the first number represents a tooth's quadrant and the second number represents the number of the tooth from the midline of the face.
The notation is relatively simple, the human teeth are symmetrically arranged in the mouth. Each quadrant of the mouth has 8 different teeth that are mirrored horizontally and vertically to the other quadrants. 
In the FDI World Dental Federation notation each one of these 8 teeth is assigned a number from 1 to 8, starting from the center front tooth (central incisor) and moving backwards up to the third molar (number 8). Each quadrant is also assigned a number, from 1 to 4 for the adult (permanent) teeth or 5 to 8 for the baby (primary or deciduous) teeth.

The Universal Numbering System

The Universal numbering system is a dental notation system commonly used throughout the United States. It is designed to be a notation for associating information to a specific tooth. It assigns numbered values and letters to each tooth, making it more convenient to reference when needed.

The Universal Numbering System, assigns a specific, unique number to each of thirty-two teeth that adults have. If you have had your wisdom teeth removed or have lost natural teeth because of trauma or decay, the numbers for those spots still exist and would be skipped when counting. Having your wisdom teeth removed is very common.

The numbering begins in the upper right of your mouth, starting with the upper right wisdom tooth. The numbers then moves across your upper row of teeth until reaching the wisdom tooth on the upper left of your mouth, which is number 16. You then continue counting at the lower left and continue in the opposite direction, moving from the lower left of your mouth to the lower right. You will finally end at number 32, your lower right wisdom tooth.

The four teeth on the top and bottom rows of your mouth (7, 8, 9, 10, 23, 24, 25, and 26) are commonly referred to as incisors. You use them to grip and cut your food.

The next set of teeth appears behind the incisors, and are referred to as canines or cuspids (6, 11, 22, and 27). These teeth are longer and sharper than your other teeth, and are used to hold food in place. 

Even further back in your mouth are bicuspids (4, 5, 12, 13, 20, 21, 28, and 29), that can perform the same duties as canines or molars.They help to move food from the canine teeth to the molars.

The last set of teeth are  referred to as molars (2, 3, 14, 15, 18, 19, 30, 31). Since many adults have their wisdom teeth removed, those teeth are not officially included in the count. However, if you still have them, they are also classified as molars. These teeth are there simply to grind and crush the food that the bicuspids have carried back through the mouth.

In the original system, children's 20 primary teeth or baby teeth are numbered in the same order (from 1 to 20), except that a small letter "d" follows each number to indicate deciduous (primary or adult) teeth. 
However, many dentists today use a modified version of the Universal Numbering System for children, with letters instead of teeth numbers. The primary teeth are designated by upper case letters A through T, with A being the patient's upper right second primary molar and T being the lower right second primary molar

Palmer Notation Method

The Palmer Notation Method is a system used by dentists to associate information to a specific tooth. It  continues to be the preferred method used by dental students and dentists throughout the United Kingdom.  It was originally termed the "Zsigmondy system" after the Hungarian dentist Adolf Zsigmondy who first developed the concept in 1861.

In the United States the Palmer notation was first suggested as the method used by dentists. However after consideration they switched to the Universal Numbering System, which was more conducive to typing because it does nott involve the use of symbols.

The Palmer notation consists of a symbol (┘└ ┐┌) designating in which quadrant the tooth is located and a number indicating the position from the midline. Adult teeth are numbered 1 to 8, with deciduous (baby) teeth indicated by a letter A to E. .

The Palmer Notation Method used by some orthodontists, pedodontists and oral surgeons.


Dental Notation Systems

Names of teeth

Tooth Identification

A standard adult has 32 teeth which have erupted by the age of 13. This is excluding the wisdom teeth. In both the maxillary and mandibular arches there are similar teeth.  There are four types of teeth in both arches.  These include the incisors, the canines, the premolars and the molars.  Each of these teeth are located in a different region of the mouth and serve unique purposes.

  • Incisors – The four front teeth in the mouth are known as incisors.  They are located in both the maxillary and mandibular arches.  The two center teeth are known as central incisors and the teeth on either side of them are known as lateral incisors.  All of these teeth are responsible for cutting or biting food. 
  • Canines –  These teeth form the corners of the mouth.  There are 2 canines in the maxillary arch and 2 canines in the mandibular arch.  These teeth are responsible for tearing food particles when chewing.
  • Premolars – There are 4 premolars in each arch and two are located behind each canine in the arch.  These teeth are smaller than the molars and are responsible for crushing food in the chewing process.  These teeth are also only present in the permanent dentition.  The primary dentition only consists of incisors, canines and molars.
  • Molars – There are normally 6 molars in each arch; three on the left and three on the right side.  They are referred to as first, second and third molars.  Some people never develop third molars and often these are the molars that are so far back in the mouth that they have difficulty coming in and may have to be taken out.  The role of the molars in chewing is to grind the food.

Introduction to Dental Anatomy

Parts of the tooth

The Five parts of the Tooth

Each tooth contains five different parts that serve different functions. The teeth are the hardest substances in the human body and are essential for chewing as well as play an important role in speech. The teeth are made up of two major sections:  the crown and the root.  The crown of the tooth is what is visible in the mouth, the surface level of the teeth.  The root of the tooth is the portion which is normally not visible in the mouth and is anchored within the bone. Within each tooth, there are 5 different parts that are present; the enamel, the dentin, the pulp, the cementum and the periodontal ligament.

  1. Enamel – Makes up the protective outer surface of the crown of the tooth.
  2. Dentin – Makes up the majority of the inner surface of the tooth. It cannot normally be seen except on x-rays. It underlies the enamel and is made up of living cells which secrete a hard mineral substance.
  3. Pulp – This is the area inside the tooth that holds the nerves and blood vessels of the tooth. It is in the center of the tooth and is in both the crown and the root of the tooth. It is the softer living inner structure of teeth.
  4. Cementum – Makes up the outer surface of the root of the tooth. It is much softer than enamel. Cementum is a layer of connective tissue that binds the roots of the teeth to the gums and jawbone.
  5. Periodontal Ligament - Tissue which helps hold the teeth tightly against the jaw. 

Additional information