Saliva is needed for taste, swallowing, and speech. It helps prevent infection and tooth decay by neutralizing acid and cleaning the teeth and gums. Radiation therapy can damage salivary glands, causing them to make too little saliva. The mouth is less able to clean itself. Acid in the mouth is not neutralized, and minerals are lost from the teeth. Tooth decay and gum disease are more likely to develop. In addition, there is some evidence that salivary glands may be damaged by certain types of chemotherapy drugs given alone or in combination. Symptoms of dry mouth include the following:

• Thick, stringy saliva.
• Increased thirst.
• Changes in taste, swallowing, and speech.
• A sore or burning feeling (especially on the tongue).
• Cuts or cracks in the lips or at the corners of the mouth.
• Changes in the surface of the tongue.
• Difficulty wearing dentures.

Salivary glands may not recover completely after radiation therapy ends.

Saliva production drops within 1 week after starting radiation therapy to the head and/or neck and continues to decrease as treatment continues. The severity of dry mouth depends on the dose of radiation and the number of glands irradiated. The salivary glands in the upper cheeks near the ears are more affected than other salivary glands.

Partial recovery of salivary glands may occur in the first year after radiation therapy, but recovery is usually not complete, especially if the salivary glands were directly irradiated. Salivary glands that were not irradiated may become more active to offset the loss of saliva from the destroyed glands.

Careful oral hygiene can help prevent mouth sores, gum disease, and tooth decay caused by dry mouth.

The following are guidelines for managing dry mouth:

• Clean the mouth and teeth at least 4 times a day.
• Floss once a day.
• Use a fluoride toothpaste when brushing.
• Apply fluoride gel once a day at bedtime, after cleaning the teeth.
• Rinse 4 to 6 times a day with a solution of salt and baking soda (mix ½ teaspoon salt and ½ teaspoon baking soda in 1 cup of warm water). Avoid foods and liquids that contain a lot of sugar. Sip water to relieve mouth dryness.

A dentist can provide the following treatments:

• Solutions to replace minerals in the teeth.
• Rinses to fight infection in the mouth.
• Saliva substitutes or medications to stimulate the salivary glands.
• Fluoride treatments to prevent tooth decay.

Tooth Decay

Dry mouth and changes in the balance of oral bacteria increase the risk of tooth decay. Meticulous oral hygiene (as described in Routine Oral Care) and regular care by a dentist can help prevent cavities.

Damage to the lining of the mouth and a weakened immune system make it easier for infection to occur.

Oral mucositis breaks down the lining of the mouth, allowing germs and viruses to get into the bloodstream. When the immune system is weakened by chemotherapy, even good bacteria in the mouth can cause infections, as can disease-causing organisms picked up from the hospital or other sources. As the white blood cell count gets lower, infections may occur more often and become more serious. Patients who have low white blood cell counts for a long time are more at risk of developing serious infections. Dry mouth, common during radiation therapy to the head and neck, may also raise the risk of infections in the mouth. Preventive dental care during chemotherapy and radiation therapy can reduce the risk of mouth, tooth, and gum infections.

The following types of infections may occur:

Bacterial infections

Treatment of bacterial infections in patients who have gum disease and receive high-dose chemotherapy may include the following:

• Medicated and peroxide mouth rinses.
• Brushing and flossing.
• Wearing dentures as little as possible.

Bacterial infections in patients undergoing radiation therapy are usually treated with antibiotics.

Fungal infections

The mouth normally contains fungi that can exist on or in the body without causing any problems. An overgrowth of fungi, however, can be serious and requires treatment.

Antibiotics and steroid drugs are often used when a patient receiving chemotherapy has a low white blood cell count. These drugs change the balance of bacteria in the mouth, making it easier for a fungal overgrowth to occur. Fungal infections are common in patients treated with radiation therapy.

Drugs may be given to prevent fungal infections from occurring. Treatment of surface fungal infections in the mouth only may include mouthwashes and lozenges that contain antifungal drugs. These are used after removing dentures, brushing the teeth, and cleaning the mouth. An antibacterial rinse should be used on dentures and dental appliances and to rinse the mouth.

Deeper fungal infections, such as those in the esophagus or intestines, are treated with drugs taken by mouth or injection.

Viral infections

Patients receiving chemotherapy, especially those with weakened immune systems, are at risk of mild to serious viral infections. Finding and treating the infections early is important. Drugs may be used to prevent or treat viral infections.

Herpes virus infections may recur in radiation therapy patients who have these infections.

Bleeding

Bleeding may occur during chemotherapy when anticancer drugs affect the ability of blood to clot.

Areas of gum disease may bleed on their own or when irritated by eating, brushing, or flossing. Bleeding may be mild (small red spots on the lips, soft palate, or bottom of the mouth) or severe, especially at the gumline and from ulcers in the mouth. When blood counts drop below certain levels, blood may ooze from the gums.

With close monitoring, most patients can safely brush and floss throughout the entire time of decreased blood counts.

Continuing regular oral care will help prevent infections that may further complicate bleeding problems. The dentist or doctor can provide guidance on how to treat bleeding and safely keep the mouth clean when blood counts are low.

Treatment for bleeding during chemotherapy may include the following:

• Medications to reduce blood flow and help clots form.
• Topical products that cover and seal bleeding areas.
• Rinsing with a mixture of one part 3% hydrogen peroxide to 2 or 3 parts saltwater solution (1 teaspoon of salt in 4 cups of water) to help clean oral wounds. Rinsing must be done carefully so clots are not disturbed.