Cancer and Dental Treatment: Precautions for People Taking Bone-Protective Medicines

Oral and dental problems related to cancer or treatment include mouth sores (mucositis); taste changes; gum infections; bleeding from low platelet counts; jawbone problems (osteonecrosis); dry mouth (xerostomia) and reduced salivary function; difficulty eating, tasting, swallowing or speaking; and abnormal tooth development.

Head and neck cancer patients receiving radiation almost universally, stem-cell transplant recipients in %80 of cases and chemotherapy recipients in %40 may develop oral problems; for bone metastases treated with bisphosphonates (zolendronate), %1-21 and denosumab (Xgeva), %0.7-1.9 may experience oral or dental problems during or after treatment.

Bisphosphonates and denosumab reduce bone pain and fracture risk from cancer metastases. While reducing adverse skeletal events, they introduce an important risk called osteonecrosis during their use.

Dental Risks of Bisphosphonates and Denosumab for Bone Metastases

Advanced prostate, bladder, kidney, breast and lung cancers tend to metastasize to bone. Patients call bisphosphonates and denosumab bone medicines . Bisphosphonates (zolendronic acid) and denosumab (Xgeva) slow or prevent progressive metastatic bone destruction, but may also damage bone. This rare osteonecrosis occurs in the tooth-bearing jaw, with tooth loss and localized bone breakdown, a form of decay, often accompanied by infection.

Osteonecrosis of the Jaw

Bisphosphonates for bone metastases may disrupt bone nutrition, killing bone cells and particularly damaging the jaw. A commonly used agent, zolendronic acid (zolendronate) , is intravenous. Jaw osteonecrosis incidence in breast cancer patients with bone metastases taking it ranges from %1.2 to %12. Studies show risk increases beyond 1 year and at 2 years or more approaches %12-15. The necessity of bisphosphonates, particularly beyond one year, should therefore be reviewed. If not essential or serious oral problems exist, weigh benefits and harms and stop if needed.

Denosumab exposure in cancer carries jaw osteonecrosis risk of %0.7 to 1.9 (among 10.000 patients, 70 to 90 cases), reportedly similar to zoledronic acid. Denosumab is used until skeletal cancer progression in breast cancer, hormone-refractory prostate cancer or non-small cell lung cancer patients not previously receiving zoledronic acid, with high-risk metastases in weight-bearing bones such as vertebrae, femur or humerus at risk of fracture or compression. 

Why these drugs cause osteonecrosis only in the jaw while protecting metastatic bone is unclear. Direct exposure of jawbones to oral microorganisms may contribute. Oral health and hygiene are therefore particularly important during cancer treatment.

Jaw osteonecrosis may occur spontaneously after bisphosphonates or denosumab or following oral surgery. Except for emergencies, cancer patients using bone medicines should avoid dental procedures involving jawbone intervention. Poor hygiene, smoking, alcohol and diabetes also increase risk.

How Can Jaw Osteonecrosis Be Prevented?

• Before starting bisphosphonates or denosumab, improve oral hygiene, establish regular brushing, stop smoking, regulate blood sugar in diabetes and treat decayed teeth. These are important preventive measures.
• Continue regular dental checkups and oral health efforts after starting these medicines.
• Routine oral care can be performed freely, but invasive procedures such as extraction, root canal treatment or implants should occur only when necessary.
• Cancer patients visiting dentists should provide a report of disease status, treatment and blood counts.
• If unavoidable traumatic jaw intervention is needed, stop these bone-active medicines at least 2 months beforehand if possible.
• Suspected jaw osteonecrosis should be referred, if possible, to a dentist specializing in its treatment, a dental oncology specialist.

Can Cancer Patients Have Teeth Extracted? Oral and Dental Health Advice

• Oral hygiene and dental problems are common in our country. All cancer patients should see a dentist before treatment and plan necessary care.
• For toothache or infection during chemotherapy, visit the dentist with recent blood tests and information on cancer treatments. Connecting the dentist with the medical oncologist or oncology nurse may help.
• Choose a soft toothbrush rather than an electric one. If already flossing regularly, use waxed ribbon floss; if not, this is not the right time to start.
• If toothpaste causes mouth or tooth sensitivity or brushing causes nausea, use a baking soda rinse instead. 
• Remove and clean dentures after meals and at bedtime.

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