DentaXTooth Numbering Systems Explained: FDI, Universal and Palmer (with Conversion Chart)
Dentists around the world chart teeth in three different ways, and the same tooth can have a completely different number depending on the system. This guide explains FDI, Universal and Palmer notation and gives you a chart to convert any tooth between them.
FDI two-digit notation (ISO 3950)
The FDI system, also called ISO 3950 notation, is used in most countries and is the international standard. Each tooth gets two digits: the first is the quadrant (1 upper right, 2 upper left, 3 lower left, 4 lower right for permanent teeth, and 5 to 8 for the same quadrants of primary teeth) and the second is the position counted from the midline, from 1 for the central incisor to 8 for the third molar. Tooth 36, for example, is the lower left first molar and is read as three-six, not thirty-six.
Universal numbering (1 to 32, A to T)
The Universal system is used mainly in the United States. Permanent teeth are numbered 1 to 32, starting at the upper right third molar (1), running across the upper arch to the upper left third molar (16), then dropping to the lower left third molar (17) and ending at the lower right third molar (32). Primary teeth use the letters A to T in the same order.
Palmer notation and how to convert
Palmer notation labels teeth 1 to 8 (permanent) or A to E (primary) counted from the midline, and adds a bracket-style symbol to show the quadrant. To convert between systems, first identify the quadrant and the position from the midline, then read the matching row in the charts below. The most common mistake is mixing up left and right: charts show the patient's right side, not the viewer's.
Permanent teeth conversion chart
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 11 | 8 | 1 |
| Lateral incisor | 12 | 7 | 2 |
| Canine | 13 | 6 | 3 |
| First premolar | 14 | 5 | 4 |
| Second premolar | 15 | 4 | 5 |
| First molar | 16 | 3 | 6 |
| Second molar | 17 | 2 | 7 |
| Third molar (wisdom tooth) | 18 | 1 | 8 |
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 21 | 9 | 1 |
| Lateral incisor | 22 | 10 | 2 |
| Canine | 23 | 11 | 3 |
| First premolar | 24 | 12 | 4 |
| Second premolar | 25 | 13 | 5 |
| First molar | 26 | 14 | 6 |
| Second molar | 27 | 15 | 7 |
| Third molar (wisdom tooth) | 28 | 16 | 8 |
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 31 | 24 | 1 |
| Lateral incisor | 32 | 23 | 2 |
| Canine | 33 | 22 | 3 |
| First premolar | 34 | 21 | 4 |
| Second premolar | 35 | 20 | 5 |
| First molar | 36 | 19 | 6 |
| Second molar | 37 | 18 | 7 |
| Third molar (wisdom tooth) | 38 | 17 | 8 |
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 41 | 25 | 1 |
| Lateral incisor | 42 | 26 | 2 |
| Canine | 43 | 27 | 3 |
| First premolar | 44 | 28 | 4 |
| Second premolar | 45 | 29 | 5 |
| First molar | 46 | 30 | 6 |
| Second molar | 47 | 31 | 7 |
| Third molar (wisdom tooth) | 48 | 32 | 8 |
Primary (baby) teeth conversion chart
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 51 | E | A |
| Lateral incisor | 52 | D | B |
| Canine | 53 | C | C |
| First molar | 54 | B | D |
| Second molar | 55 | A | E |
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 61 | F | A |
| Lateral incisor | 62 | G | B |
| Canine | 63 | H | C |
| First molar | 64 | I | D |
| Second molar | 65 | J | E |
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 71 | O | A |
| Lateral incisor | 72 | N | B |
| Canine | 73 | M | C |
| First molar | 74 | L | D |
| Second molar | 75 | K | E |
| Tooth | FDI | Universal | Palmer |
|---|---|---|---|
| Central incisor | 81 | P | A |
| Lateral incisor | 82 | Q | B |
| Canine | 83 | R | C |
| First molar | 84 | S | D |
| Second molar | 85 | T | E |
Quadrants are named from the patient's point of view.
Frequently asked questions
Which tooth numbering system is the international standard?
The FDI two-digit system (ISO 3950) is the international standard and is used in most countries. The Universal system is mainly American, and Palmer notation is traditionally used in parts of the UK and in orthodontics.
What is FDI tooth 36 in the Universal system?
FDI 36 is the lower left first molar, which is number 19 in the Universal system.
How are primary teeth numbered in the FDI system?
Primary teeth use quadrants 5 to 8 and positions 1 to 5, so 51 is the upper right primary central incisor and 85 is the lower right primary second molar.
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