# Tooth 1: Upper Right Third Molar

> In the Universal Numbering System, tooth 1 is the upper right third molar (maxillary right third molar). Its FDI (ISO 3950) designation is 18 and its Palmer designation is 8 in the upper right quadrant. It is a molar in the upper arch with typically 3 roots.

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Last verified: 2026-07-08

Neutral tooth-designation reference only; not clinical, diagnostic, or treatment advice. Root counts describe typical permanent-tooth morphology and vary between individuals.

## Direct answer

- Which tooth is number 1? In the Universal Numbering System, tooth 1 is the upper right third molar (maxillary right third molar). Its FDI (ISO 3950) designation is 18 and its Palmer designation is 8 in the upper right quadrant. It is a molar in the upper arch with typically 3 roots.
- Universal number: 1
- FDI / ISO 3950 designation: 18
- Palmer designation: 8 UR
- Plain-language name: Upper Right Third Molar
- Anatomical name: Maxillary Right Third Molar
- Quadrant: Upper Right
- Arch and side: upper, right
- Type: molar
- Typical roots: 3

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | 1 |
| FDI / ISO 3950 | 18 |
| Palmer notation | 8 UR |
| Tooth name | Upper Right Third Molar |

## Note

Commonly called the wisdom tooth.

## Search terms

- which tooth is number 1?
- tooth 1
- tooth number 1
- universal tooth 1
- adult tooth 1
- upper right third molar
- maxillary right third molar
- fdi 18
- palmer 8
- upper right tooth 8
- upper right molar

## Sources

- `TOOTH-1` American Dental Association — Universal Numbering System. <https://www.ada.org/publications/ada-news/2020/november/how-to-count-teeth-numbering-systems>
- `TOOTH-2` ISO 3950:2016 — Dentistry, designation system for teeth and areas of the oral cavity (FDI two-digit). <https://www.iso.org/standard/68292.html>
- `TOOTH-3` FDI World Dental Federation — two-digit notation. <https://www.fdiworlddental.org/>

## Related

- [Full tooth numbering chart](https://dentovio.com/tools/tooth-numbering-chart/index.html.md)
- [FDI to Universal converter](https://dentovio.com/tools/fdi-to-universal-converter/index.html.md)
- [Palmer notation converter](https://dentovio.com/tools/palmer-notation-converter/index.html.md)
- [Next tooth: Tooth 2: Upper Right Second Molar](https://dentovio.com/tools/tooth-numbering-chart/tooth-2/index.html.md)