How to read the FDI system: quadrant first, then position
Dentists in India and most of the world use the FDI two-digit system. Picture the patient facing you. The first digit tells you the quarter: 1 is the upper right, 2 is the upper left, 3 is the lower left, and 4 is the lower right. Right and left are the patient's, not yours.
The second digit counts back from the middle of the face: 1 is the central incisor, 2 the lateral incisor, 3 the canine, 4 and 5 the premolars, and 6, 7 and 8 the molars (8 being the wisdom tooth). The numbers are said one digit at a time, "three six", never "thirty-six".
| Quarter | Numbers (middle to back) | Which teeth |
|---|---|---|
| Upper right | 11, 12, 13, 14, 15, 16, 17, 18 | Central incisor to third molar |
| Upper left | 21, 22, 23, 24, 25, 26, 27, 28 | Central incisor to third molar |
| Lower left | 31, 32, 33, 34, 35, 36, 37, 38 | Central incisor to third molar |
| Lower right | 41, 42, 43, 44, 45, 46, 47, 48 | Central incisor to third molar |
FDI numbering for adult teeth: general information on how dentists label teeth.
How to read 36, 16 and 46 on a dental report
Tooth 36 is read as quarter 3 (lower left), position 6 (first molar): the lower left first molar. The same logic gives 16 for the upper right first molar, 26 for the upper left, and 46 for the lower right. First molars are the teeth most often named on reports, because they are the first permanent molars and decay early.
A wisdom tooth is always an 8: 18, 28, 38 or 48. A report that says "38 pericoronitis" is describing gum inflammation around the lower left wisdom tooth. The teeth themselves are described in our guides to molar teeth and premolar teeth.
Milk teeth numbering: quadrants 5 to 8
Milk teeth use the same two-digit idea, with quadrants 5, 6, 7 and 8 for the upper right, upper left, lower left and lower right. Because a child has five teeth per quarter, the second digit runs only from 1 to 5: central incisor, lateral incisor, canine, first molar, second molar. So 74 is the lower left first milk molar. Our guide to primary teeth describes the set.
| Quarter | Numbers (middle to back) | Which teeth |
|---|---|---|
| Upper right | 51, 52, 53, 54, 55 | Central incisor to second milk molar |
| Upper left | 61, 62, 63, 64, 65 | Central incisor to second milk molar |
| Lower left | 71, 72, 73, 74, 75 | Central incisor to second milk molar |
| Lower right | 81, 82, 83, 84, 85 | Central incisor to second milk molar |
FDI numbering for milk teeth: general information.
Universal and Palmer systems
The Universal system, common in the United States, numbers adult teeth 1 to 32 in one run, starting at the upper right wisdom tooth, crossing to the upper left (16 is the upper left wisdom tooth), then continuing from the lower left wisdom tooth (17) round to the lower right wisdom tooth (32). Milk teeth use the letters A to T.
The Palmer system draws a small bracket symbol to show the quarter and uses the numbers 1 to 8 within it, with letters A to E for milk teeth. It is clear on paper but awkward to type, so computers favour FDI. The same tooth therefore has three names: the upper right first molar is 16 in FDI, 3 in Universal, and a 6 inside a bracket in Palmer. If a foreign report uses a different system, ask the dentist to confirm which tooth it means. For the tooth names behind the numbers see our guide to the types of teeth.
Common questions
Which tooth numbering system is used in India?
The FDI two-digit system is the standard in India and in most countries. Some dental textbooks and foreign reports use the Universal or Palmer system, so it is worth checking which one a report is using.
What is tooth 46 in the FDI system?
Tooth 46 is the lower right first molar: quarter 4 is the lower right, and position 6 is the first molar. It is one of the most commonly filled teeth, since it is among the earliest permanent teeth to come through.
Why are the numbers not 1 to 32?
The two-digit system lets a number carry two facts at once, the quarter and the tooth type, so a dentist can tell where and what the tooth is without a chart. The 1 to 32 run belongs to the Universal system.
Do missing teeth change the numbers?
No. A number always refers to a position, not to the tooth that happens to be there. If tooth 36 is removed, the space is still called 36, and 37 stays 37.
About this page
This page is general information, not a diagnosis or a quotation. Prices are prevailing Lucknow market ranges. Your own treatment and cost are determined after an examination. For questions about your own case, call +91 83036 12717.