Oral Side Effects of Radiation Therapy
Radiation therapy is used in the treatment or palliation of head and neck cancer patients. Although this therapy is beneficial, it also has serious side effects, all of which decrease the patient's quality of life. Patients are at an increased risk for xerostomia (dry mouth), mucositis (inflammation of the soft tissues of the mouth), dental caries (decay), loss of taste, fibrosis of the muscle, vascular, and lymphatic tissues, malaise, and infection.
One of the most common side effects of radiation therapy is salivary gland dysfunction. Radiation causes irreversible harm to the cells of the salivary glands, damaging the cells that produce the more serous or flowable saliva leaving what remains thick and sticky. This often appears during the first week of radiation and is permanent. Permanent damage to the salivary glands is seen when the radiation dose exceeds 6000cGy. The total cumulative dose of radiation prescribed for head and neck cancer patients is 6500 cGy to 7000 cGy. The dose of radiation and the amount of the glands in the direct line of the beam determine the degree and permanence of salivary gland dysfunction. This decrease in salivary output is different for each individual patient and is dependent on his or her initial salivary output and amount of radiation that is delivered during therapy.
Normal salivary flow aids in cleansing the oral cavity by rinsing food and debris from the area. Once the salivary glands have been radiated, there is less saliva flowing from the glands to aid in the cleansing of the oral cavity. If a strict daily oral hygiene regimen is not followed the retention of the food and debris will lead to increased tooth decay and oral infection.
In the oral cavity saliva also acts as a lubricant. With out saliva the cheeks, lips, teeth, and tongue will not slide over one another properly for comfort at rest, during speech and eating, and movement of food to the stomach. The structures of the oral cavity will stick to one another making normal activity difficult. Saliva also initiates the breakdown of foods for proper digestion and acts as a lubricant so the food flows down to the stomach without feeling as if it is getting caught in the throat or esophagus.
The loss of taste is also a complication of radiation therapy. The taste buds are very sensitive to radiation and a partial to complete loss of taste will occur during treatment. The sense of taste will recur after treatment is complete but when and how much taste will be restored is different for each patient. Unfortunately the taste for sweets may be the first sense to recur. This may pose serious complications for patients who are not taking proper care of their teeth. Saliva naturally contains a balance of good and bad entities to maintain oral health. Once this balance to disturbed by radiation therapy the oral environment changes from good to bad. For instance the pH decreases to become more acidic and the bacterial balance is shifted to one that helps promote dental decay.
Mucositis is another common and painful side effect of radiation therapy. It is an inflammatory reaction that can occur starting during the first week of radiation therapy and normally subsides shortly after radiation treatments have ended. The severity of mucositis depends on the radiation dose and the amount of tissues in the line of the radiation beam. It may be compared to a very bad coffee or pizza burn to the soft tissues of the oral cavity making it difficult to eat or speak.
Finally radiation therapy will change the cellular make up of the tissues. The soft tissues such as the skin, muscles and ligaments will be come firm or hard. This may be noticed in the inability to open the mouth as wide as before radiation and or the inability to move your head around. In addition the bone is also affected. If a dental extraction is necessary after radiation therapy there is a possibility that the bone would not heal properly leading to infection. These are life long problems that will not resolve after radiation therapy is complete.
These documents and links are intended to inform you of issues, sequelae, and treatment options related to various diagnoses and maxillofacial prosthodontic treatments that may interest you. The information is not intended to suggest or dictate treatment or outcomes, but may serve to begin a discussion with your physician and prosthodontist.