# Tooth 12: Upper Left First Premolar

> In the Universal Numbering System, tooth 12 is the upper left first premolar (maxillary left first premolar). Its FDI (ISO 3950) designation is 24 and its Palmer designation is 4 in the upper left quadrant. It is a premolar in the upper arch with typically 2 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 12? In the Universal Numbering System, tooth 12 is the upper left first premolar (maxillary left first premolar). Its FDI (ISO 3950) designation is 24 and its Palmer designation is 4 in the upper left quadrant. It is a premolar in the upper arch with typically 2 roots.
- Universal number: 12
- FDI / ISO 3950 designation: 24
- Palmer designation: 4 UL
- Plain-language name: Upper Left First Premolar
- Anatomical name: Maxillary Left First Premolar
- Quadrant: Upper Left
- Arch and side: upper, left
- Type: premolar
- Typical roots: 2

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | 12 |
| FDI / ISO 3950 | 24 |
| Palmer notation | 4 UL |
| Tooth name | Upper Left First Premolar |

## Search terms

- which tooth is number 12?
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- fdi 24
- palmer 4
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- upper left premolar

## 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)
- [Previous tooth: Tooth 11: Upper Left Canine](https://dentovio.com/tools/tooth-numbering-chart/tooth-11/index.html.md)
- [Next tooth: Tooth 13: Upper Left Second Premolar](https://dentovio.com/tools/tooth-numbering-chart/tooth-13/index.html.md)