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# The mouth during cancer treatment: mucositis, dry mouth and osteonecrosis

- Mouth and systemic disease

Chemotherapy and head and neck radiotherapy damage the mouth. A dental check before treatment prevents many complications.

Updated Nov 12, 2026

## Key points

- Dental check before cancer treatment.
- Radiotherapy: dry mouth, radiation caries, osteoradionecrosis.
- Exposed bone: refer, do not extract routinely.

## What it is

Chemotherapy and radiotherapy to the head and neck cause oral mucositis, painful ulceration that limits eating and can open the way to infection, usually starting a week or two into treatment. Radiotherapy also destroys salivary glands (often permanently), causes rampant «radiation caries», trismus from fibrosis, altered taste and, most seriously, osteoradionecrosis: dead bone in the irradiated jaw, usually the mandible, often after an extraction. Bone-modifying drugs used in cancer (high-dose bisphosphonates, denosumab) can cause medication-related osteonecrosis of the jaw. Neutropenia brings severe candidiasis, herpes and dental infections.

## Oral findings

- Before treatment: dental assessment and removal of infected or hopeless teeth with time to heal.
- Mucositis: basic oral care, bland rinses, pain control; specialised measures per oncology protocols.
- After radiotherapy: lifelong high-fluoride toothpaste and frequent dental review.
- Osteoradionecrosis risk is lifelong; extractions in irradiated bone need specialist planning.
- Jaw exercises reduce radiation trismus.

## What the doctor does

- Exposed bone in an irradiated jaw or in a patient on antiresorptives must not be treated by routine extraction.
- Candidiasis and herpes in neutropenic patients can spread systemically.
- Dry mouth after radiotherapy makes dentures hard to wear and caries progresses fast.

## Next step / Initial management

- Refer every patient due for head and neck radiotherapy, high-dose antiresorptives or chemotherapy to the dentist before starting.
- During treatment: oral care plan with the oncology team; treat candidiasis and herpes promptly.
- Exposed bone, non-healing sockets, swelling or numbness in the jaw: refer to oral and maxillofacial surgery.

## Test yourself

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

## What is osteoradionecrosis?

Death of irradiated bone, usually the mandible, that fails to heal and is exposed, often after an extraction.

## Why is a dental assessment done before head and neck radiotherapy?

To remove infected or hopeless teeth while healing is still possible and reduce later osteoradionecrosis and infection.

## What lifelong measure protects teeth after head and neck radiotherapy?

Daily high-fluoride toothpaste or gel and frequent dental review.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/dentistry/the-mouth-during-cancer-treatment-mucositis-dry-mouth-and-osteonecrosis/)

## Elsewhere in DurgiPedia

- [After head and neck cancer treatment: dry mouth, swallowing, voice and bone](https://durgical.com/en/ent/after-head-and-neck-cancer-treatment-dry-mouth-swallowing-voice-and-bone/)

## Connections

## Related 4

- [Dry mouth (xerostomia): approach](https://durgical.com/en/dentistry/dry-mouth-approach/)
- [Medication-related osteonecrosis of the jaw](https://durgical.com/en/dentistry/medication-related-osteonecrosis-of-the-jaw/)
- [Oral candidiasis (thrush)](https://durgical.com/en/dentistry/oral-candidiasis/)
- [Blood disorders in the mouth: leukaemia, anaemia and bleeding](https://durgical.com/en/dentistry/blood-disorders-in-the-mouth-leukaemia-anaemia-and-bleeding/)

## Related conditions 1

- [Head and neck squamous cell carcinoma (oral cavity and oropharynx, HPV)](https://durgical.com/en/conditions/head-and-neck-squamous-cell-carcinoma/)

## In Pharmacology 4

- [Fluoride](https://durgical.com/en/pharmacology/fluoride/)
- [Chlorhexidine](https://durgical.com/en/pharmacology/chlorhexidine/)
- [Bisphosphonates](https://durgical.com/en/pharmacology/classes/bisphosphonates/)
- [Denosumab](https://durgical.com/en/pharmacology/denosumab/)

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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: [Oral Mucositis](https://www.ncbi.nlm.nih.gov/books/NBK565848/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Oral Management of Patients Undergoing Radiation Therapy](https://www.ncbi.nlm.nih.gov/books/NBK587448/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Mandible Osteoradionecrosis](https://www.ncbi.nlm.nih.gov/books/NBK430917/) (StatPearls Publishing (NCBI Bookshelf), 2026); [Bisphosphonate-Related Jaw Osteonecrosis](https://www.ncbi.nlm.nih.gov/books/NBK534771/) (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-mouth-during-cancer-treatment-mucositis-dry-mouth-and-osteonecrosis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/dentistry/the-mouth-during-cancer-treatment-mucositis-dry-mouth-and-osteonecrosis/