Dentists in the United States number adult teeth 1 through 32, starting at the upper right wisdom tooth and ending at the lower right wisdom tooth. The numbering follows a specific path around your mouth, and once you understand the pattern, you can identify any tooth by its number. Two main systems exist worldwide: the Universal system used in the U.S. and the FDI system used internationally.
How the Universal Numbering System Works
The Universal Numbering System, adopted by the American Dental Association, assigns each of the 32 permanent adult teeth a number from 1 to 32. The count begins at your upper right wisdom tooth (tooth #1), moves along the entire upper arch to your upper left wisdom tooth (#16), then drops down to the lower left wisdom tooth (#17) and continues across to the lower right wisdom tooth (#32). Think of it as a big U-shape: across the top from right to left, then across the bottom from left to right.
Your mouth is divided into four quadrants, split by the midline (the imaginary vertical line between your two front teeth) and separated into upper and lower jaws. Each quadrant contains eight teeth in a full adult set. Here’s the complete breakdown:
Upper Right (Teeth 1 to 8)
- 1: Third molar (wisdom tooth)
- 2: Second molar
- 3: First molar
- 4: Second premolar
- 5: First premolar
- 6: Canine (eye tooth)
- 7: Lateral incisor
- 8: Central incisor (front tooth)
Upper Left (Teeth 9 to 16)
- 9: Central incisor (front tooth)
- 10: Lateral incisor
- 11: Canine
- 12: First premolar
- 13: Second premolar
- 14: First molar
- 15: Second molar
- 16: Third molar (wisdom tooth)
Lower Left (Teeth 17 to 24)
- 17: Third molar (wisdom tooth)
- 18: Second molar
- 19: First molar
- 20: Second premolar
- 21: First premolar
- 22: Canine
- 23: Lateral incisor
- 24: Central incisor (front tooth)
Lower Right (Teeth 25 to 32)
- 25: Central incisor (front tooth)
- 26: Lateral incisor
- 27: Canine
- 28: First premolar
- 29: Second premolar
- 30: First molar
- 31: Second molar
- 32: Third molar (wisdom tooth)
A quick way to orient yourself: the numbers are always from the patient’s perspective, not the dentist’s. “Right” means your right side. Teeth 8 and 9 are your two upper front teeth, and 24 and 25 are your two lower front teeth.
Which Numbers Are Your Wisdom Teeth?
Wisdom teeth are the four third molars at the very back of each quadrant. In the Universal system, they are teeth 1 (upper right), 16 (upper left), 17 (lower left), and 32 (lower right). If your dentist says “we need to extract number 17,” that’s the lower left wisdom tooth. Because these four teeth bookend the numbering sequence, they’re easy to remember: 1 and 32 are on the right side, 16 and 17 on the left.
How Baby Teeth Are Labeled
Children have 20 primary (baby) teeth instead of 32, and the Universal system uses letters instead of numbers for them. The letters run from A through T, following the same path as the adult numbering: upper right to upper left (A through J), then lower left to lower right (K through T).
Baby teeth don’t include premolars or third molars, so each quadrant has only five teeth: a central incisor, lateral incisor, canine, first molar, and second molar. Letter A is the upper right second molar, E is the upper right central incisor, F is the upper left central incisor, and J is the upper left second molar. The pattern then drops to K (lower left second molar) and continues to T (lower right second molar). Using letters makes it impossible to confuse a baby tooth with an adult tooth on dental records.
The FDI International System
Outside the United States, most countries use the FDI (Fédération Dentaire Internationale) system, which assigns each tooth a two-digit code. The first digit identifies the quadrant, and the second digit identifies the tooth’s position within that quadrant.
For adult teeth, the quadrant numbers are:
- 1: Upper right
- 2: Upper left
- 3: Lower left
- 4: Lower right
The second digit runs 1 through 8, from the central incisor (1) to the third molar (8). So tooth “11” (pronounced “one-one,” not “eleven”) is the upper right central incisor. Tooth “36” is the lower left first molar. The upper left wisdom tooth is “28,” and the lower right wisdom tooth is “48.”
For baby teeth, the quadrants use digits 5 through 8 instead (upper right is 5, upper left is 6, lower left is 7, lower right is 8), and the second digit runs 1 through 5 because children only have five teeth per quadrant. A child’s upper right canine would be “53.”
The FDI system has one practical advantage: the first digit always tells you which quadrant you’re in, so you can immediately narrow down the location without memorizing a 1-to-32 sequence. The Universal system, by contrast, requires you to know that tooth 19 is the lower left first molar, which isn’t intuitive unless you’ve counted through the sequence.
How to Figure Out Your Own Tooth Number
If your dentist mentions a number and you want to locate it, start by narrowing down the quadrant. In the Universal system, teeth 1 through 8 are upper right, 9 through 16 are upper left, 17 through 24 are lower left, and 25 through 32 are lower right. Once you know the quadrant, the pattern within it is always the same: it starts at the wisdom tooth (the farthest back) and moves toward the front teeth at the midline.
The most commonly referenced teeth tend to be the first molars (teeth 3, 14, 19, and 30), because these are the large chewing teeth that often need fillings or crowns. Tooth 30, the lower right first molar, is one of the most frequently treated teeth in adults. Your canines (6, 11, 22, and 27) are the pointed teeth next to your front teeth, and the premolars (4, 5, 12, 13, 20, 21, 28, 29) sit between the canines and molars.
If you’ve had wisdom teeth removed, those numbers still exist in the system. Your dentist’s chart will simply note that teeth 1, 16, 17, or 32 are missing. The remaining teeth keep their original numbers regardless of how many teeth are actually present.