Cancer and its aggressive treatments significantly affect the health of the mouth and teeth. While a tumor’s physical presence causes immediate damage, the systemic and localized side effects of therapies like chemotherapy and radiation cause the most widespread dental issues. These complications arise because cancer treatments target rapidly dividing cells, which are also found in healthy oral tissues, such as the mouth lining and salivary glands. Understanding these potential side effects is the first step in protecting oral health during treatment.
Direct Impact of Cancers on the Mouth
Cancers originating in the oral cavity or adjacent throat area have the most direct impact. Oral and oropharyngeal cancers, typically squamous cell carcinomas, physically invade surrounding structures. This tumor growth can destroy the jawbone, leading to tooth looseness or complete tooth loss. Surgery to remove these tumors often requires removing sections of the jawbone or nearby teeth to achieve clear margins, drastically altering the mouth’s structure. Metastasis to the jawbone from a distant location is much rarer than local invasion by head and neck cancers.
Dental Changes Caused by Chemotherapy
Chemotherapy drugs circulate throughout the body, affecting rapidly dividing cells, including the epithelial cells lining the mouth. This targeting frequently leads to oral mucositis: painful, inflamed, and ulcerated sores on the gums, tongue, and inner cheeks. Mucositis typically starts five to ten days after chemotherapy begins and can interfere with eating, swallowing, and speaking.
The drugs also suppress the immune system by reducing white blood cell production (myelosuppression). This leaves the mouth vulnerable to opportunistic infections, such as oral candidiasis (thrush), or bacterial and viral infections. Many patients also experience dysgeusia, an alteration in taste perception that can make food taste metallic or bland, which, combined with painful sores, can reduce nutritional intake.
The Specific Risks of Radiation to the Head and Neck
Radiation therapy directed at tumors in the head or neck causes localized and often permanent damage to tissues within the treatment field. A primary, long-lasting side effect is xerostomia, or severe dry mouth, resulting from irreversible damage to the major and minor salivary glands. Saliva is protective; its loss eliminates the mouth’s natural cleansing and buffering capacity, which normally neutralizes acids and washes away food particles. The lack of saliva creates an environment for rapid, aggressive tooth decay known as “radiation caries.” This decay is caused by an altered oral microbiome and quickly affects the entire tooth, often progressing rapidly.
An even more serious, long-term complication is osteoradionecrosis (ORN), which involves the death of the jawbone tissue. Radiation damages the blood vessels and bone cells, leading to poor blood flow and a reduced ability for the bone to heal. ORN is most often triggered by trauma, such as a tooth extraction in the radiated field, and requires specialized medical management.
Proactive Dental Care Before, During, and After Treatment
A comprehensive dental evaluation is recommended before cancer treatment begins to minimize the risk of complications that could interrupt therapy. Teeth with a poor prognosis, such as those with severe infection or advanced periodontal disease, should be extracted at least one week before starting chemotherapy or radiation to allow for initial healing. Existing cavities should be filled, and a professional cleaning should be performed to eliminate sources of infection.
During active treatment, meticulous oral hygiene is necessary to manage side effects and prevent infection. Patients should use a soft-bristled toothbrush and a non-abrasive fluoride toothpaste, rinsing the mouth frequently with a mild saltwater or baking soda solution.
After treatment, especially for those who received head and neck radiation, long-term specialized care is essential due to the permanent risk of xerostomia and radiation caries. This care plan often includes prescription-strength fluoride gels or rinses and custom trays to apply the fluoride directly to the teeth. Patients with chronic dry mouth may also benefit from saliva substitutes to restore moisture and comfort.