# Which baby tooth is letter K?

Answer: In the Universal Numbering System, primary tooth K is the primary lower left second molar (primary mandibular left second molar). Its FDI (ISO 3950) designation is 75 and its Palmer designation is E in the lower left quadrant. It is a molar in the lower arch with typically 2 roots.

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

## Direct answer

In the Universal Numbering System, primary tooth K is the primary lower left second molar (primary mandibular left second molar). Its FDI (ISO 3950) designation is 75 and its Palmer designation is E in the lower left quadrant. It is a molar in the lower arch with typically 2 roots.

## Query patterns

- Which baby tooth is letter K?
- Tooth K: Primary Lower Left Second Molar
- Which tooth is K?
- What is baby tooth K in FDI and Palmer notation?
- Which tooth is FDI 75?
- What is FDI 75 in Universal numbering?
- FDI 75 to Universal tooth number
- ISO 3950 tooth 75
- Which tooth is Palmer E Lower Left?
- Palmer E Lower Left to Universal
- Lower Left Palmer E tooth
- LL Palmer E primary tooth
- Primary Lower Left Second Molar tooth number
- Universal K FDI 75 Palmer E
- which baby tooth is letter k?
- tooth K
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- primary lower left second molar
- primary mandibular left second molar
- fdi 75

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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- [/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-k](https://dentovio.com/tools/tooth-numbering-chart/tooth-k)

## Related answers

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- [Which tooth is number 2?](https://dentovio.com/answers/tooth-number-2)