# Tooth 24: Lower Left Central Incisor

> In the Universal Numbering System, tooth 24 is the lower left central incisor (mandibular left central incisor). Its FDI (ISO 3950) designation is 31 and its Palmer designation is 1 in the lower left quadrant. It is a incisor in the lower arch with typically 1 root.

URL: https://dentovio.com/tools/tooth-numbering-chart/tooth-24

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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 24? In the Universal Numbering System, tooth 24 is the lower left central incisor (mandibular left central incisor). Its FDI (ISO 3950) designation is 31 and its Palmer designation is 1 in the lower left quadrant. It is a incisor in the lower arch with typically 1 root.
- Universal number: 24
- FDI / ISO 3950 designation: 31
- Palmer designation: 1 LL
- Plain-language name: Lower Left Central Incisor
- Anatomical name: Mandibular Left Central Incisor
- Quadrant: Lower Left
- Arch and side: lower, left
- Type: incisor
- Typical roots: 1

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | 24 |
| FDI / ISO 3950 | 31 |
| Palmer notation | 1 LL |
| Tooth name | Lower Left Central Incisor |

## Search terms

- which tooth is number 24?
- tooth 24
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- universal tooth 24
- adult tooth 24
- lower left central incisor
- mandibular left central incisor
- fdi 31
- palmer 1
- lower left tooth 1
- lower left incisor

## 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 23: Lower Left Lateral Incisor](https://dentovio.com/tools/tooth-numbering-chart/tooth-23/index.html.md)
- [Next tooth: Tooth 25: Lower Right Central Incisor](https://dentovio.com/tools/tooth-numbering-chart/tooth-25/index.html.md)