# Which tooth is number 13?

Answer: 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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Answer intent ID: `tooth-number-13`
Cluster: Tooth numbering reference
Last verified: 2026-07-08
Reviewer: see source page

## Direct answer

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.

## Query patterns

- Which tooth is number 13?
- Tooth 13: Upper Left Second Premolar
- Which tooth is 13?
- What is tooth number 13 in FDI and Palmer notation?
- Which tooth is FDI 25?
- What is FDI 25 in Universal numbering?
- FDI 25 to Universal tooth number
- ISO 3950 tooth 25
- Which tooth is Palmer 5 Upper Left?
- Palmer 5 Upper Left to Universal
- Upper Left Palmer 5 tooth
- UL Palmer 5 permanent tooth
- Upper Left Second Premolar tooth number
- Universal 13 FDI 25 Palmer 5
- which tooth is number 13?
- tooth 13
- tooth number 13
- universal tooth 13
- adult tooth 13
- upper left second premolar
- maxillary left second premolar
- fdi 25

Source citations:
- `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/>

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## Supporting public URLs

- [/tools/tooth-numbering-chart](https://dentovio.com/tools/tooth-numbering-chart)
- [/tools/fdi-to-universal-converter](https://dentovio.com/tools/fdi-to-universal-converter)
- [/tools/palmer-notation-converter](https://dentovio.com/tools/palmer-notation-converter)
- [/tools/tooth-numbering-chart/tooth-13](https://dentovio.com/tools/tooth-numbering-chart/tooth-13)

## Related answers

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- [Palmer notation converter](https://dentovio.com/answers/palmer-notation-to-universal-converter)
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- [Which tooth is number 2?](https://dentovio.com/answers/tooth-number-2)