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Common Oral Complications of Head and Neck Cancer Therapy

Is there anything I should do before starting my radiation therapy?

Radiation therapy of the head and neck can increase your risk of getting dental decay. Oral care is therefore aimed at preventing oral problems before they occur. Before starting radiation therapy, your radiation oncologist will refer you for a dental examination. Dental X-rays will be taken and a comprehensive examination will be carried out to check for:

  • Tooth decay (caries)
  • Gum (periodontal) disease
  • Infected teeth
  • Retained root tips

Any other conditions that may cause problems during or after radiation therapy.

It is important to undergo the necessary dental treatments before radiation therapy starts and continue to see a dentist after you have completed your radiation therapy.

What are the common side effects of head and neck cancer therapy?

Most of the side effects start within 2-3 weeks of treatment but can increase throughout the duration of the radiation. Some side effects are temporary and will improve with time; however, others may be permanent.

Some common side effects:

  • Skin redness and irritation
  • Changes in taste (Dysgeusia)
  • Sores in the mouth (Mucositis)
  • Dry mouth (Xerostomia)
  • Tooth decay (Caries)
  • Bone death (Osteoradionecrosis)
  • Difficulty in Using Dentures or Prosthesis.

Skin redness and irritation

The skin area undergoing radiation may become red and itchy. Be very careful not to apply anything unless instructed by your radiation oncologist. Depending on the area treated and dosage used, your skin may or may not return to normal.

Changes in taste (Dysgeusia)

Changes in taste (Dysgeusia) - SingHealth Duke-NUS Head and Neck Centre

Food will taste differently during your radiation therapy. The taste buds are affected by the radiation. Usually the sense of taste will improve over time. In most people the ability to taste foods return to normal within 6 months to a year.

Sores in the mouth (Mucositis)

Soreness in your mouth will usually appear in the second and third week of the radiation therapy. It is likely to decrease from the fifth week onwards up to a month after your treatment ends. The sores and ulcers can get uncomfortable and may interfere with proper intake of food, speech and oral hygiene. You can soothe the soreness by rinsing with warm alkaline solution or applying anaesthetic gel to numb the mouth before eating or brushing. If you experience difficulties with these activities, your physician or dentist can prescribe the appropriate medication for you.

Dry mouth (Xerostomia)

Saliva serves to lubricate the mouth and protect teeth. Radiation affects the salivary glands resulting in a decrease in normal salivary flow. Saliva will thicken and make swallowing difficult.

Drinking as much fluid as possible will loosen the thick saliva and lubricate the mouth. When eating, try to take a drink between each bite of food. Pureed food will be easier to eat, as with foods served with sauces, gravy and butter.

Eating more often with smaller portions will be easier than eating the traditional three meals daily. If you have difficulty eating, ask your physician for liquid food supplements. If the dryness worsens, salivary substitutes are available to help your mouth feel more comfortable.

Tooth decay (Caries)

When salivary flow is decreased, the protective mechanism of the saliva is diminished, resulting in teeth being susceptible to decay. It is very important that you avoid foods high in sugar and brush regularly after each meal to prevent decay.

The use of fluoride will help prevent caries and your dentist can fabricate a customised tray to help apply fluoride to your teeth. It is important to see your dentist regularly every 3 to 6 months to check on your dental health.

Bone death (Osteoradionecrosis)

The most debilitating side effect of radiation therapy is bone death from the destruction of small vessels which carry nutrients and oxygen to the living bone. This reduces the bone’s ability to heal itself. Should you require tooth extraction after radiation therapy, you are at risk of developing bone death.

This is a difficult condition to treat; therefore, it is important that dental extractions are done before the start of radiation therapy and after treatment, maintenance of good oral health is crucial.

Limited mouth opening (Trismus)

Trismus is another complication that may develop after radiation therapy. It is a result of scarring of the facial muscles from radiation. Limited mouth opening, combined with dry mouth, may interfere with speech, eating and the ability to maintain oral hygiene.

Stretching exercises are important to minimise post-treatment trismus. Your doctors and therapists may prescribe jaw stretching exercises suitable for you. It is advisable to do these exercises as often as prescribed to minimise post-treatment trismus.

Difficulty in Using Dentures or Prosthesis

Difficulty in Using Dentures or Prosthesis - SingHealth Duke-NUS Head and Neck Centre

Due to less saliva and soreness in the mouth, you should avoid wearing dentures during the treatment period. After completing your radiation therapy, you should consult your dentist before you begin to wear dentures again. If you find major differences in fit, your dentist will be able to help you correct it.

General Care Tips


  • Rinse with warm alkaline solution (1 teaspoon salt and 1 teaspoon baking soda dissolved in a 240ml glass of warm water) to lubricate and soothe sore tissues
  • Brush and apply fluoride regularly to prevent decay
  • Exercise mouth opening to reduce trismus


  • Avoid using deodorants or deodorant soap on radiated skin areas
  • Avoid rubbing the skin in the areas that have been exposed to radiation
  • Avoid direct sun exposure on the radiated areas
  • Avoid shaving with a razor; using an electric razor is safer
  • Avoid alcoholic beverages & tobacco use
  • Avoid very sweet and spicy foods
  • Avoid alcohol-based mouthwash as it may worsen mouth sores
  • Avoid wearing dentures during the treatment period