Dental hygiene is important for everyone. But taking care of your teeth and gums becomes even more important if you're receiving radiation therapy to treat head and neck cancer.

"Radiation therapy is particularly effective for treating cancers that occur in the head and neck region, including the oral cavity, throat, voice box, nasal cavity and salivary glands," says Dr. Kathleen Shadle, a radiation oncologist at Houston Methodist. "It's often part of a person's treatment plan for these cancers."

External beam radiation therapy is the most common type of radiation used for head and neck cancers. High energy rays — generated by a machine, directed toward the site of the tumor — are used to damage and ultimately destroy cancerous cells.

But when directed at the head and neck region, radiation therapy can have implications for a person's oral health.

Cancer and oral health: How radiation therapy during head and neck cancer treatment affects the mouth

It's a powerful cancer-killing treatment option, but radiation doesn't just affect cancer cells. It can harm normal cells that surround the tumor, too.

"We have methods to preserve healthy tissue — ways to target the tumor as precisely as possible, for instance," says Dr. Shadle. "But radiation therapy can still affect normal cells to some extent, leading to side effects."

In the case of head and neck cancer treatment, the potential effects of radiation therapy on teeth and gums warrant serious attention.

"Radiation doesn't directly damage the mouth," says Dr. Shadle. "But the oral-related side effects it causes can increase the risk of tooth decay and gum disease, especially if a person isn't taking steps to protect their oral health during treatment."

Most physicians require a complete dental evaluation be performed prior to receiving radiation therapy directed toward this area.

"Any teeth that are in poor condition will need to be removed," says Dr. Shadle. "This is important since, if teeth need to be extracted after radiation, there is an increased risk of osteoradionecrosis — which can cause poor healing of the bone and bone death."

Dr. Shadle adds that radiation directed to other parts of the body — to treat other types of cancer, such as bladder or liver cancer, for instance — doesn't affect a person's oral health.

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

The oral side effects of radiation therapy can include:

• Mouth irritation
• Dry mouth
• Mouth sores
• Changes to saliva (thicker saliva, decreased salivary flow)
• Changes in taste
• Mouth infections
• Jaw stiffness and pain

In particular, dry mouth and decreased salivary flow can have the most significant impacts on oral health.

"These changes can increase a person's risk of developing tooth decay and gum disease," explains Dr. Shadle. "Saliva does more than lubricate the mouth. It also aids in keeping bacteria that cause tooth decay in check."

Fortunately, most of these side effects improve after radiation treatment is completed.

How to protect teeth and gums during radiation therapy for head and neck cancer

Given how head and neck radiation therapy can impact oral health, it's important to take steps to keep your mouth healthy during treatment.

"Patients should see their dentist on a regular basis for routine oral care," recommends Dr. Shadle. "It's best to work with a dentist or oral surgeon who has experience treating patients undergoing radiation."

Other tips for reducing the risk of dental cavities during therapy:

• Avoid high-sugar foods
• Practice good oral hygiene, including flossing daily and brushing after each meal and before bedtime
• Use fluoride trays daily to strengthen teeth
• Keep your mouth moist

"If you smoke, we also recommend that you stop," adds Dr. Shadle. "Smoking can worsen oral health and increase the risk of complications, as well as increase the risk of cancer recurrence."