[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Dentistry](https://durgical.com/en/dentistry/) › [Restorative dentistry and materials](https://durgical.com/en/dentistry/areas/restorative/) › Liners, bases and protecting the pulp

# Liners, bases and protecting the pulp

- Dental material

A deep cavity may get a thin layer over the dentine nearest the pulp. The best protection is keeping dentine and a good seal, not a thick base.

Updated Nov 12, 2026

## Key points

- Remaining dentine thickness and a good seal protect the pulp most.
- Calcium silicate cements are preferred for direct pulp capping.
- Eugenol inhibits resin setting.

## What it is

Liners are thin layers placed on the deepest dentine; bases are thicker layers that replace lost dentine under a restoration. Their roles are to seal the dentine tubules, to calm or protect the pulp, and, for some materials, to stimulate a new layer of hard tissue. The single most protective factor is the thickness of sound dentine left over the pulp and a restoration that seals out bacteria.

## Composition and properties

- Calcium hydroxide: strongly alkaline and antibacterial, it stimulates reparative dentine, but it dissolves over time and does not seal.
- Calcium silicate cements (mineral trioxide aggregate and newer ones): seal well and form a more reliable hard tissue bridge; preferred for pulp capping.
- Glass ionomer or resin-modified glass ionomer: seals and bonds, used as a liner or base under composite.
- Zinc oxide–eugenol: soothing and sealing as a temporary filling, but eugenol stops resin from setting, so not under composite.
- The pulp reacts to deep caries by forming tertiary dentine beneath the lesion.

## Uses, limits and safety

- Indirect pulp capping: a liner over thin dentine without exposure. Direct pulp capping: material placed on a small exposure of healthy pulp.
- A thick base is no substitute for a sealed restoration: bacteria leaking at the margin harm the pulp more than the filling material.
- Lingering pain after a deep filling suggests irreversible pulpitis, not just irritation from the material.

## Next step / Initial management

- Deep lesion with no pain or only short pain to cold: selective removal, a liner where needed and a sealed restoration, then review vitality.
- Spontaneous or lingering pain after a deep filling: refer to the dentist for pulp assessment.
- Do not place eugenol-containing materials under composite restorations.

## Test yourself

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

## What is the difference between a liner and a base?

A liner is a thin layer on the deepest dentine; a base is a thicker layer that replaces lost dentine under the restoration.

## Why is zinc oxide–eugenol not placed under a composite?

Eugenol inhibits the polymerisation of the resin, weakening the restoration and its bond.

## Which material is preferred for direct pulp capping and why?

A calcium silicate cement, because it seals well and induces a more reliable dentine bridge than calcium hydroxide.

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## Connections

## Related 5

- [Pulpitis: reversible or irreversible](https://durgical.com/en/dentistry/pulpitis-reversible-or-irreversible/)
- [Minimal intervention: when to drill and when not](https://durgical.com/en/dentistry/minimal-intervention-when-to-drill-and-when-not/)
- [Glass ionomer cements](https://durgical.com/en/dentistry/glass-ionomer-cements/)
- [Vital pulp therapy: pulp capping and pulpotomy](https://durgical.com/en/dentistry/vital-pulp-therapy-pulp-capping-and-pulpotomy/)
- [Enamel, dentine, cementum and pulp: histology and defects](https://durgical.com/en/dentistry/enamel-dentine-cementum-and-pulp-histology-and-defects/)

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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: [Dental Materials: Biodentine, a Calcium Silicate Bioactive](https://www.ncbi.nlm.nih.gov/books/NBK599506/) (StatPearls Publishing (NCBI Bookshelf), 2024); [Current and future options for dental pulp therapy](https://pmc.ncbi.nlm.nih.gov/articles/PMC6354285/) (Japanese Dental Science Review (PMC open access), 2019); [Biological Characteristics and Odontogenic Differentiation Effects of Calcium Silicate-Based Pulp Capping Materials](https://pmc.ncbi.nlm.nih.gov/articles/PMC8399810/) (Materials (Basel) (PMC open access), 2021); [Anatomy, Head and Neck, Dental Pulp](https://www.ncbi.nlm.nih.gov/books/NBK537112/) (StatPearls Publishing (NCBI Bookshelf), 2025).

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Representative model, for educational purposes only.

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