# Tooth 4: Upper Right Second Premolar

> In the Universal Numbering System, tooth 4 is the upper right second premolar (maxillary right second premolar). Its FDI (ISO 3950) designation is 15 and its Palmer designation is 5 in the upper right 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 4? In the Universal Numbering System, tooth 4 is the upper right second premolar (maxillary right second premolar). Its FDI (ISO 3950) designation is 15 and its Palmer designation is 5 in the upper right quadrant. It is a premolar in the upper arch with typically 1 root.
- Universal number: 4
- FDI / ISO 3950 designation: 15
- Palmer designation: 5 UR
- Plain-language name: Upper Right Second Premolar
- Anatomical name: Maxillary Right Second Premolar
- Quadrant: Upper Right
- Arch and side: upper, right
- Type: premolar
- Typical roots: 1

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | 4 |
| FDI / ISO 3950 | 15 |
| Palmer notation | 5 UR |
| Tooth name | Upper Right Second Premolar |

## Search terms

- which tooth is number 4?
- tooth 4
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- upper right second premolar
- maxillary right second premolar
- fdi 15
- palmer 5
- upper right tooth 5
- upper right 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 3: Upper Right First Molar](https://dentovio.com/tools/tooth-numbering-chart/tooth-3/index.html.md)
- [Next tooth: Tooth 5: Upper Right First Premolar](https://dentovio.com/tools/tooth-numbering-chart/tooth-5/index.html.md)