Teeth numbers are a standardized system dentists use to identify each tooth in your mouth. Adults have up to 32 permanent teeth, numbered 1 through 32 in the Universal Numbering System used across the United States. The count starts at your upper right wisdom tooth, moves across the top to your upper left wisdom tooth, drops down to the lower left, and sweeps back across to end at your lower right wisdom tooth.
How the Numbering Sequence Works
The numbering follows a specific path shaped like a backwards “C.” It begins with tooth #1 at the back right of your upper jaw and counts forward toward your front teeth. When it reaches tooth #8 (your upper right front tooth), it continues to #9 (upper left front tooth) and keeps going back to #16 at the far left of your upper jaw. From there, it drops down to #17 at the far left of your lower jaw and counts forward again, passing through the lower front teeth and ending at #32, your lower right wisdom tooth.
Think of it as starting in the upper right corner, sweeping left across the top, then sweeping right across the bottom. Once you understand this path, any tooth number immediately tells you roughly where it sits in your mouth.
Upper Teeth: Numbers 1 Through 16
Your upper jaw (the maxilla) holds teeth 1 through 16. Here’s the full breakdown:
- #1: Upper right wisdom tooth (third molar)
- #2: Upper right second molar
- #3: Upper right first molar
- #4: Upper right second premolar
- #5: Upper right first premolar
- #6: Upper right canine
- #7: Upper right lateral incisor
- #8: Upper right central incisor
- #9: Upper left central incisor
- #10: Upper left lateral incisor
- #11: Upper left canine
- #12: Upper left first premolar
- #13: Upper left second premolar
- #14: Upper left first molar
- #15: Upper left second molar
- #16: Upper left wisdom tooth (third molar)
Lower Teeth: Numbers 17 Through 32
Your lower jaw (the mandible) holds teeth 17 through 32. Notice that the sequence picks up on the left side of the lower jaw, directly below where it ended on the upper jaw:
- #17: Lower left wisdom tooth (third molar)
- #18: Lower left second molar
- #19: Lower left first molar
- #20: Lower left second premolar
- #21: Lower left first premolar
- #22: Lower left canine
- #23: Lower left lateral incisor
- #24: Lower left central incisor
- #25: Lower right central incisor
- #26: Lower right lateral incisor
- #27: Lower right canine
- #28: Lower right first premolar
- #29: Lower right second premolar
- #30: Lower right first molar
- #31: Lower right second molar
- #32: Lower right wisdom tooth (third molar)
Common Teeth You’ll Hear Referenced
Certain tooth numbers come up more often than others in dental offices. Your wisdom teeth are #1, #16, #17, and #32, the four corners of your mouth. If a dentist recommends wisdom tooth extraction, they’ll specify which of these four need to come out.
Your front teeth, the ones visible when you smile, are #6 through #11 on top and #22 through #27 on the bottom. Teeth #8 and #9 are your two upper front teeth (central incisors), the ones most people picture first when they think of a smile. Teeth #3, #14, #19, and #30 are your first molars, the large chewing teeth that often get fillings because of their deep grooves.
What Each Tooth Type Does
The numbering system maps onto four distinct types of teeth, each with a different job. Your eight incisors (#7–#10 on top, #23–#26 on the bottom) are the flat front teeth with narrow edges built for cutting into food. The four canines (#6, #11, #22, #27) are the pointed teeth next to the incisors, designed for tearing tougher foods like meat and raw vegetables.
Behind the canines sit eight premolars (#4–#5, #12–#13, #20–#21, #28–#29). These have a flatter biting surface and handle tearing, crushing, and grinding. The twelve molars fill in the rest (#1–#3, #14–#16, #17–#19, #30–#32), including the wisdom teeth. Molars are your primary chewing teeth, with broad surfaces designed for crushing and grinding food before you swallow.
How Baby Teeth Are Numbered
Children’s primary teeth use letters instead of numbers. The 20 baby teeth are labeled A through T, following the same path as the adult system: starting at the upper right, sweeping across the top, dropping to the lower left, and ending at the lower right. Letter A is the upper right second molar, and T is the lower right second molar. Children don’t have premolars or wisdom teeth, which is why they have only 20 teeth instead of 32.
Dental Quadrants
Dentists also divide the mouth into four quadrants, split by an imaginary vertical line between your two front teeth and a horizontal line between your upper and lower jaws. These quadrants are coded for insurance and dental records: 10 for the upper right, 20 for the upper left, 30 for the lower right, and 40 for the lower left. When your dentist says a procedure involves a specific quadrant, they mean one of these four sections.
Tooth Surface Codes
Along with the tooth number, your dental records often include letters that identify which surface of the tooth is affected. If you see something like “19-MO” on a treatment plan, that means tooth #19 (lower left first molar) with work needed on two specific surfaces. The surface codes are:
- M (Mesial): The side facing toward the front of your mouth
- D (Distal): The side facing toward the back of your mouth
- O (Occlusal): The chewing surface on top of molars and premolars
- B (Buccal): The side facing your cheek
- L (Lingual): The side facing your tongue
- F (Facial): The front-facing surface, used for front teeth
- I (Incisal): The biting edge of front teeth
So “MOD” on a molar means the filling or damage involves the front-facing side, the chewing surface, and the back-facing side of that tooth. More surfaces typically means a larger restoration.
Other Numbering Systems
The Universal Numbering System (1–32) is the standard in the United States, adopted by the American Dental Association. Outside the U.S., dentists commonly use the FDI (Fédération Dentaire Internationale) system, also called the ISO system. It uses a two-digit code where the first digit indicates the quadrant (1–4 for adults, 5–8 for children) and the second digit identifies the tooth’s position, counted from the center. For example, tooth #18 in the FDI system is the upper right wisdom tooth, which corresponds to #1 in the Universal system.
If you’re reading dental records from another country or an international dental school, this difference in systems is worth knowing. The teeth are the same; only the labels change.