Understanding Dental Lingo - Teeth Numbers & Mouth Quadrants

Understanding Dental Lingo - Teeth Numbers & Mouth Quadrants
profile picture of Dr. Jay Khorsandi, DDS
Understanding Dental Lingo - Teeth Numbers & Mouth QuadrantsClinical Content Reviewed by Dr. Jay Khorsandi, DDS
Last Modified:

Clinical content featured by Byte is reviewed and fact-checked by a licensed dentist or orthodontist to help ensure clinical accuracy.

We follow strict sourcing guidelines and each page contains a full list of sources for complete transparency.

Table of Contents

  1. Mouth Quadrants
  2. How Are Teeth Numbered?
  3. Gum Numbering
  4. Other Common Lingo
  5. References

Dentistry lingo is an excellent way for oral healthcare professionals to quickly and accurately identify spots inside your mouth. For instance, a dentist can simply instruct “cavity at 17,” which is far less confusing than if they called out “cavity at the left mandibular third molar.”

This is essential as it makes it easy to note down and identify teeth, mouth partitions, dental gum scores, and numbering for your gums.

Like any other profession, dentists have their own jargon. You’ve no doubt heard some of it when you were having your teeth cleaned or going through another dental procedure.

But the likelihood is that most of these words are foreign to you. For instance, to you, the word arch might mean a particular shape or a curved structure used to support a weight in a building, but to dentists it means upper or lower denture.

Dental jargon is extensive as it includes naming sections inside your mouth and numbering of teeth and gums.

Mouth Quadrants

Another familiar word you might hear is quadrant. It also has nothing to do with an x and y-axis on graphs but rather sections in your mouth. To make identification easier, dentists divide your mouth into four different sections they call quadrants.

In short, dentists will name the quadrants with the nose at the top and the chin bottom. They will start documenting the quadrants from the top of the mouth. Quadrant 1 will be to the patient’s right, while Quadrant 2 will be to the left.

On the bottom, the naming will flip because instead of Quadrant 3 being on the patient’s right, it will be on the patient’s left, though Quadrant 4 will be on the right, just below Quadrant 1.

Dentists do this deliberately because they go through the quadrants in a clockwise motion during an exam. They typically start examining your mouth from the right before moving to Quadrant 2 on the left.

The purpose of compartmentalizing your mouth in this way is to make it easier to specify and pin down problem spots in your mouth.

How Are Teeth Numbered?

There are three primary methods dentists use to number teeth.

  • Palmer notification method
  • ISO notation system
  • Universal system

Each has its own system for numbering milk teeth (also called deciduous or baby teeth) and permanent teeth:

1. Palmer Notation Method

Introduced in 1861, this is the oldest method. It came to prominence after a recommendation by the American Dental Association (ADA) in 1947. The method relies heavily on quadrants.

Permanent teeth numbering is from 1-8, with the incisors numbered 1. Proceed from the center to the end in either direction of each quadrant, ending with the molars designated tooth No. 8. Baby teeth get the same treatment but use letters A through E.

It uses the plus symbol (+) to denote a tooth on the upper right, a “+” for the upper left, a “+” for the lower right, and “?” for the lower left.

2. FDI World Dental Federation ISO notation system

The ISO notation is the most widely used system around the world. It is a two number notation system.

It utilizes quadrants to number teeth, with each quadrant providing the first number. Numbering starts from the incisors (Tooth 1) in the middle, running to the molars (Tooth 8) at the back.

For permanent teeth, the numbering starts from Quadrant 1, so the first tooth will be 11, followed by 12. And the last will be 18.

Next, shift to the second quadrant, with the teeth numbered from 21, 22, all the way to 28. This goes on until the fourth and final quarter, where the first tooth will be 41 and the last 48.

For example, when you see the number 37, the three means it’s in the third quadrant, tooth number seven.

Primary teeth also get the same treatment, but the numbering proceeds as follows–52-55, 61-65, 71-75, and finally, 81-85.

3. Universal System

Although its name is universal, it’s only widely used in the United States. The numbering commences at A and proceeds to T for the milk teeth, while the permanent teeth classification starts from 1 through 32.

For permanent teeth, start numbering from the first quadrant on the upper far right at the wisdom tooth (maxillary right third molar), and proceed sequentially along the upper arch to the upper left wisdom tooth (maxillary left third molar), which you designate number 16.

Switch to the lower left, starting at the third quadrant with the left wisdom tooth (mandibular left third molar) acquiring number 17, and move to the furthest end of the fourth quadrant (mandibular right third molar), which you label 32.

Milk teeth follow the same pattern, with the furthest tooth at the upper right acquiring the designation A, and the last tooth to the left titled J. The lower teeth start at the left (K) and end with T at the far right. Alternatively, the first letter could be 1D, with the last tooth designated 20D.

Gum Numbering

Another confusing numbering system occurs when the dentist starts poking around your gums.

What they are doing is measuring the gap between the teeth and gums, providing the measurements in millimeters. This is what they mean:

  • 1-3 mm: healthy gums
  • 3-5 mm but no bleeding: you possibly have gum disease
  • 3-5 mm with bleeding: high likelihood you have gum disease in its early stages
  • 5-7 mm with bleeding: you almost certainly have gum disease, tissue damage, and bone loss
  • 7 mm or more with bleeding: gum disease at an advanced stage that requires surgery to resolve

Other Common Lingo Dentists Use

Jargon provides a pain-free way for dentists to find their way around your mouth. One common lingo you may hear is the word calculus. It has nothing to do with mathematics but refers to mineral material deposits stuck to your teeth or roots of teeth.

Similarly, you may hear a dentist call out a random number after examining your teeth. That is probably the dental score rating of your gums. If they yell 0, that’s not failure – it means your gums passed with flying colors. They are in perfect condition.

A 1 means you have some mild bleeding and plaque at the edges of your teeth. 2 means dead plaque hardened around your teeth, requiring gentle cleaning, while 3 means you might have gum disease.

A score of 4 means you have gum disease that will need treatment.


Common Dental Terms. Smile, California.

Standardization of the tooth numbering systems. (September 1989). National Library of Medicine.

Types of Teeth, Structures, Location and Functions. Proctor & Gamble.

Disclaimer: This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to serve as dental or other professional health advice and is not intended to be used for diagnosis or treatment of any condition or symptom. You should consult a dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.