# Tooth 28: Lower Right First Premolar

> In the Universal Numbering System, tooth 28 is the lower right first premolar (mandibular right first premolar). Its FDI (ISO 3950) designation is 44 and its Palmer designation is 4 in the lower right quadrant. It is a premolar in the lower 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 28? In the Universal Numbering System, tooth 28 is the lower right first premolar (mandibular right first premolar). Its FDI (ISO 3950) designation is 44 and its Palmer designation is 4 in the lower right quadrant. It is a premolar in the lower arch with typically 1 root.
- Universal number: 28
- FDI / ISO 3950 designation: 44
- Palmer designation: 4 LR
- Plain-language name: Lower Right First Premolar
- Anatomical name: Mandibular Right First Premolar
- Quadrant: Lower Right
- Arch and side: lower, right
- Type: premolar
- Typical roots: 1

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | 28 |
| FDI / ISO 3950 | 44 |
| Palmer notation | 4 LR |
| Tooth name | Lower Right First Premolar |

## Search terms

- which tooth is number 28?
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- lower 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 27: Lower Right Canine](https://dentovio.com/tools/tooth-numbering-chart/tooth-27/index.html.md)
- [Next tooth: Tooth 29: Lower Right Second Premolar](https://dentovio.com/tools/tooth-numbering-chart/tooth-29/index.html.md)