# Tooth 13: Upper Left Second Premolar

> In the Universal Numbering System, tooth 13 is the upper left second premolar (maxillary left second premolar). Its FDI (ISO 3950) designation is 25 and its Palmer designation is 5 in the upper left quadrant. It is a premolar in the upper arch with typically 1 root.

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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 13? In the Universal Numbering System, tooth 13 is the upper left second premolar (maxillary left second premolar). Its FDI (ISO 3950) designation is 25 and its Palmer designation is 5 in the upper left quadrant. It is a premolar in the upper arch with typically 1 root.
- Universal number: 13
- FDI / ISO 3950 designation: 25
- Palmer designation: 5 UL
- Plain-language name: Upper Left Second Premolar
- Anatomical name: Maxillary Left Second Premolar
- Quadrant: Upper Left
- Arch and side: upper, left
- Type: premolar
- Typical roots: 1

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | 13 |
| FDI / ISO 3950 | 25 |
| Palmer notation | 5 UL |
| Tooth name | Upper Left Second Premolar |

## Search terms

- which tooth is number 13?
- tooth 13
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- maxillary left second premolar
- fdi 25
- palmer 5
- upper left tooth 5
- 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 12: Upper Left First Premolar](https://dentovio.com/tools/tooth-numbering-chart/tooth-12/index.html.md)
- [Next tooth: Tooth 14: Upper Left First Molar](https://dentovio.com/tools/tooth-numbering-chart/tooth-14/index.html.md)