[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Dentistry](https://durgical.com/en/dentistry/) › [Dental anatomy and histology](https://durgical.com/en/dentistry/areas/anatomy-histology/) › The periodontium: gingiva, ligament, cementum and alveolar bone

# The periodontium: gingiva, ligament, cementum and alveolar bone

- Anatomy and histology

The periodontium is everything that holds a tooth in place: the gum, the ligament, the root surface and the bone. Gum disease destroys it.

Updated Nov 12, 2026

**See it in 3D:** [Gums (gingiva)](https://durgical.com/en/anatomy/gums/) · [Mandible](https://durgical.com/en/anatomy/mandible/) · [Maxillae](https://durgical.com/en/anatomy/maxilla/)

## Key points

- Periodontium = gingiva, periodontal ligament, cementum and alveolar bone.
- A normal sulcus is up to about three millimetres; deeper is a pocket.
- Alveolar bone resorbs once the tooth is lost.

## What it is

The periodontium is the supporting apparatus of the tooth. It has four parts: the gingiva, which seals the bone and roots from the mouth; the periodontal ligament, a thin layer of collagen fibres that suspends the tooth in its socket and senses pressure; the cementum on the root surface, into which the ligament fibres insert; and the alveolar bone that forms the socket. Healthy gingiva is pink, firm and stippled, and a shallow groove (the gingival sulcus) surrounds each tooth.

## Clinical anatomy

- Gingiva: free gingiva around the neck, attached gingiva bound to bone, and the papillae between teeth.
- Gingival sulcus: normally up to about three millimetres deep; deeper measurements on probing are periodontal pockets.
- Junctional epithelium: attaches the gum to the tooth at the bottom of the sulcus; it is the first barrier bacteria break.
- Periodontal ligament: collagen (Sharpey) fibres between cementum and bone; it absorbs chewing forces and gives the sense of bite.
- Alveolar bone: exists because the teeth exist; it resorbs after a tooth is lost.

## Clinical correlation

- Gingivitis inflames only the gingiva and is reversible; periodontitis destroys ligament and bone and is not.
- Bone loss around teeth is seen on radiographs and is what makes teeth loose and drift.
- After extractions the alveolar ridge shrinks, which affects dentures and implants.

## Next step / Initial management

- Bleeding gums: look for plaque, swelling and pocketing; reinforce brushing and flossing and refer to the dentist for cleaning.
- Loose teeth in an adult without trauma: refer to the dentist for periodontal assessment and radiographs.
- Rapid periodontal destruction in a young person: refer and screen for diabetes and immune disorders.

## Test yourself

Think of the answer, then tap the question to see it.

## What are the four tissues of the periodontium?

Gingiva, periodontal ligament, cementum and alveolar bone.

## What is the difference between gingivitis and periodontitis?

Gingivitis is reversible inflammation of the gum only; periodontitis destroys ligament and bone and causes irreversible attachment loss.

## What happens to the alveolar bone after a tooth is extracted?

It resorbs and the ridge shrinks, because the bone exists to support the tooth.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/dentistry/the-periodontium-gingiva-ligament-cementum-and-alveolar-bone/)

## Connections

## See it in 3D 3

The structures of Durgical's 3D anatomy where it is found.

- [Gums (gingiva)](https://durgical.com/en/anatomy/gums/)
- [Mandible](https://durgical.com/en/anatomy/mandible/)
- [Maxillae](https://durgical.com/en/anatomy/maxilla/)

## Related 3

- [Gingivitis: bleeding gums](https://durgical.com/en/dentistry/gingivitis-bleeding-gums/)
- [Periodontitis: stages, grades and links with general health](https://durgical.com/en/dentistry/periodontitis-stages-grades-and-links-with-general-health/)
- [Periodontal probing: pockets, bleeding and attachment loss](https://durgical.com/en/dentistry/periodontal-probing-pockets-bleeding-and-attachment-loss/)

## Related conditions 1

- [Periodontitis](https://durgical.com/en/conditions/periodontitis/)

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Educational content; it does not replace assessment by a dentist or doctor and is not a clinical instruction. For facial or neck swelling with difficulty swallowing or breathing, a knocked-out tooth or bleeding that will not stop, go to an emergency department at once.

Sources: [Histology, Periodontium](https://www.ncbi.nlm.nih.gov/books/NBK570604/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Anatomy, Head and Neck, Oral Gingiva](https://www.ncbi.nlm.nih.gov/books/NBK560662/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Periodontitis](https://www.ncbi.nlm.nih.gov/books/NBK541126/) (StatPearls Publishing (NCBI Bookshelf), 2023).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/dentistry/the-periodontium-gingiva-ligament-cementum-and-alveolar-bone/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/dentistry/the-periodontium-gingiva-ligament-cementum-and-alveolar-bone/