The weeks between a head and neck cancer diagnosis and the first radiotherapy session are busy, and a dental appointment can feel like the least of your worries. It is one of the most useful things to fit in. Radiation aimed at a tumour also reaches the salivary glands, jawbone and lining of the mouth, and a tooth that becomes a problem after treatment is much harder to deal with than one sorted out beforehand.
Irradiated bone heals poorly, which is why timing matters
Radiation reduces the blood supply and healing capacity of the jawbone within the treatment field, and the change is long-lasting. If a tooth is removed from that bone later, or if the gum over it breaks down, the bone may fail to heal and become exposed. This is called osteoradionecrosis. It can be painful and difficult to treat.
The best protection is to identify teeth with a poor outlook and deal with them before radiotherapy, while the bone still heals normally. Guidance on prevention and management was updated in 2024 by the International Society of Oral Oncology, the Multinational Association of Supportive Care in Cancer and the American Society of Clinical Oncology (Peterson and colleagues, Journal of Clinical Oncology), with good dental care before treatment among its central points.
Healing time between an extraction and the start of radiotherapy may also matter. A 2026 meta-analysis in the World Journal of Otorhinolaryngology, Head and Neck Surgery (Liu and colleagues) found no clear link overall, but in Western populations starting radiotherapy within 14 days of an extraction was associated with a higher risk. In practice, the dental and cancer teams agree on timing so that the gum has a chance to heal without delaying cancer treatment.
What a pre-radiotherapy dental visit covers
The aim is to leave you with a mouth that is free of active infection and as easy to look after as possible. A dentist will usually:
- examine the teeth, gums and any dentures, and take X-rays
- treat active decay and gum infection
- recommend removing teeth that are unlikely to last, especially in the area that will receive radiation
- smooth sharp edges on teeth or dentures that could rub sore tissue
- start a fluoride plan, often with a high-strength toothpaste or custom trays
- show you how to clean gently once the mouth becomes tender
Bring details of your radiation plan, treatment dates and any surgery planned, or give your dentist permission to speak to your cancer team. Our article on chemotherapy and oral mucositis covers related care if chemotherapy is part of your treatment.
Changes you may notice during and after treatment
Dry mouth
When salivary glands lie in the treatment field, saliva can become thick, scant or almost absent. It may improve over months but often does not return fully. Frequent sips of water, saliva substitutes, sugar-free gum and avoiding alcohol-based mouthwashes can help, and our guide to dry mouth has more practical ideas.
Sore mouth
The lining of the mouth can become inflamed and ulcerated during treatment, a condition called mucositis. Gentle brushing with a very soft brush, bland food and the rinses recommended by your cancer team make it more manageable.
Fast-moving decay
Without enough saliva to rinse and protect the teeth, decay can develop quickly, often around the necks of the teeth near the gum. This is sometimes called radiation caries.
A stiff jaw
Muscles and tissues in the treatment field can tighten over time, making it harder to open the mouth. This is called trismus. Jaw exercises, sometimes with an opening device, are usually started early and kept up, often with help from a speech pathologist or physiotherapist.
Taste changes
Food may taste different or bland for a while. For many people this improves gradually after treatment ends.
Daily fluoride is the habit that protects teeth most
Fluoride is the main defence against radiation decay. A 2022 systematic review in Oral Oncology (Agarwal and colleagues) concluded that fluoride prevents radiation caries, although the studies were too varied to settle the best product, dose or frequency. Your dentist will recommend a routine, which may be a prescription-strength toothpaste used every day, fluoride gel in custom trays, or both.
Alongside fluoride, keep sugary food and drinks to mealtimes, clean between the teeth daily if the gums allow, and keep up regular dental reviews. For most people these habits continue for life, because the risk from dry mouth persists.
Dental treatment after radiotherapy
Fillings, cleans and most routine care can usually go ahead after radiotherapy. Extractions in bone that received radiation need more caution and are avoided where another option exists. If one is necessary, it is planned carefully, with input from your cancer team or an oral surgeon, and you should always tell any dentist that you have had head and neck radiotherapy. The same applies to implants and new dentures.
Contact your dentist or cancer team promptly if you notice exposed bone in the mouth, a sore that is not healing, swelling, or new pain in the jaw. As a general rule, any mouth ulcer or patch that has not healed or changed within three weeks should be checked by a dentist or GP.
Questions we are often asked
Is it too late if radiotherapy has already started?
No. A dental check during or after treatment is still worthwhile, particularly to start a fluoride routine and to catch decay early. Your dentist will work around your treatment schedule.
Can I keep wearing my dentures?
Often yes, but they may rub when the mouth is sore or dry. Your dentist may suggest leaving them out at times during treatment and checking the fit afterwards.
Is hyperbaric oxygen used to prevent bone problems?
The 2024 international guideline found limited evidence to support it for preventing or managing osteoradionecrosis, so it is not routinely recommended. Your cancer team will advise on your own situation.
Information about the wider picture of oral cancer risk is in our guide to HPV and oral cancer. If you are about to start, or have finished, radiotherapy to the head or neck, the team at Lumi Dental in Melrose Park can arrange an assessment and work alongside your cancer team. Book a general check-up, see our current deals, or contact us through our contact page.
This article is general information about a sensitive topic and is not a substitute for individual advice. Always follow the guidance of your treating cancer team.
