# Tooth L: Primary Lower Left First Molar

> In the Universal Numbering System, primary tooth L is the primary lower left first molar (primary mandibular left first molar). Its FDI (ISO 3950) designation is 74 and its Palmer designation is D in the lower left quadrant. It is a molar in the lower arch with typically 2 roots.

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Last verified: 2026-07-08

Neutral tooth-designation reference only; not clinical, diagnostic, or treatment advice. Root counts describe typical primary-tooth morphology and vary between individuals.

## Direct answer

- Which baby tooth is letter L? In the Universal Numbering System, primary tooth L is the primary lower left first molar (primary mandibular left first molar). Its FDI (ISO 3950) designation is 74 and its Palmer designation is D in the lower left quadrant. It is a molar in the lower arch with typically 2 roots.
- Universal letter: L
- FDI / ISO 3950 designation: 74
- Palmer designation: D LL
- Plain-language name: Primary Lower Left First Molar
- Anatomical name: Primary Mandibular Left First Molar
- Quadrant: Lower Left
- Arch and side: lower, left
- Type: molar
- Typical roots: 2

## Conversion table

| System | Designation |
| --- | --- |
| Universal Numbering System | L |
| FDI / ISO 3950 | 74 |
| Palmer notation | D LL |
| Tooth name | Primary Lower Left First Molar |

## Search terms

- which baby tooth is letter l?
- tooth L
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- primary mandibular left first molar
- fdi 74
- palmer D
- lower left tooth 4
- lower left molar

## 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 K: Primary Lower Left Second Molar](https://dentovio.com/tools/tooth-numbering-chart/tooth-k/index.html.md)
- [Next tooth: Tooth M: Primary Lower Left Canine](https://dentovio.com/tools/tooth-numbering-chart/tooth-m/index.html.md)