The short answer
Bisphosphonates and denosumab are bone-modifying drugs used to strengthen bone and reduce fractures when cancer affects bone, or when hormone therapy weakens it. Both carry a small but real risk of a jaw condition called osteonecrosis, which is why a dental checkup before starting, and good oral hygiene throughout, matters.
Bone-modifying drugs, including bisphosphonates like zoledronic acid and denosumab, are used to strengthen bone and lower fracture risk when cancer affects bone or when treatment weakens it.
These drugs work differently in the body but both reduce the activity of cells that break down bone, called osteoclasts.
Osteonecrosis of the jaw, a rare but serious condition where jaw bone tissue is damaged, is a known risk with both bisphosphonates and denosumab, especially with longer use.
A dental checkup and any needed dental work before starting these drugs, plus good ongoing oral hygiene, are the main ways to lower this risk.
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The full explanation.
Why bone-modifying drugs are used
Sometimes cancer spreads to bone. Sometimes cancer treatment weakens bone as a side effect. In either case, doctors often recommend bone-modifying drugs. These drugs lower fracture risk and strengthen bone.
There are two main types: bisphosphonates, such as zoledronic acid, and denosumab, given by injection. Both work by slowing down osteoclasts. Osteoclasts are cells that normally break down old bone, as part of the body's ongoing bone renewal process. Slowing them helps bone stay stronger, when cancer or treatment side effects are wearing it down faster than usual.
Doctors commonly use these drugs for bone metastases (cancer that has spread to bone) from several cancer types. They also use them for bone loss caused by hormone therapies used in breast and prostate cancer.
The main risk to know about: osteonecrosis of the jaw
Osteonecrosis of the jaw, often shortened to ONJ, is a rare but serious condition. A section of jaw bone loses its blood supply and fails to heal properly. Sometimes it becomes exposed.
Both bisphosphonates and denosumab carry this risk. Research has helped define how the risk builds over time. A large NCI-funded study followed nearly 3,500 cancer patients. It found the risk was around 1% after one year of treatment, roughly 2% after two years, and about 3% after three years.
Risk varies by cancer type. The highest rates appear in multiple myeloma, and lower rates in breast cancer. Risk also varies by how often the drug is dosed. Smokers were about twice as likely to develop the condition.
Researchers initially hoped denosumab might avoid this risk. Later studies found it carries a broadly similar risk to bisphosphonates.
Why dental care before starting matters
Poor dental health raises your risk of developing osteonecrosis of the jaw once you are on one of these medicines. This includes missing teeth, dentures that do not fit well, gum disease, or an upcoming need for dental surgery.
The clearest, most consistently recommended way to lower this risk is straightforward.
- Get a dental checkup before starting treatment, if possible.
- Complete any needed dental work first.
- Keep up good oral hygiene throughout treatment.
- If you smoke, cut back or quit. Smoking is one of the clearer risk factors research has identified.
What this means for ongoing dental care
You do not need to stop bisphosphonates or denosumab for routine dental cleanings or checkups. Dental organizations have found no good evidence that pausing the drug beforehand reduces jaw problems. Stopping a bone-strengthening drug also carries its own downsides.
What matters is telling your dentist you are taking one of these medicines. Do this before any dental surgery, extraction, or implant procedure, so they can plan your care appropriately. Keep up regular dental checkups and good hygiene for as long as you are on treatment.
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Common questions
What are bone-modifying drugs used for in cancer care?
They're used to strengthen bone and reduce the risk of fractures in two main situations: when cancer has spread to bone, and when certain hormone therapies (used for breast or prostate cancer) cause bone loss as a side effect. Bisphosphonates, such as zoledronic acid, and denosumab are the main drugs in this category.
How do bisphosphonates and denosumab work?
Both reduce the activity of osteoclasts, cells that normally break down old bone as part of the body's natural bone renewal process. By slowing this breakdown, these drugs help bone stay stronger, which is especially useful when cancer or treatment side effects are weakening bone faster than normal.
What is osteonecrosis of the jaw?
It's a rare but serious condition where an area of jaw bone loses its blood supply and doesn't heal properly, sometimes becoming exposed. It's a known risk with both bisphosphonates and denosumab, particularly with more frequent, longer-term use in cancer treatment, and after certain dental procedures like extractions. Research following nearly 3,500 patients found the risk builds gradually — roughly 1% after a year of treatment, rising with more years of use — and that risk varies somewhat by cancer type and dosing frequency.
Why does dental care matter before starting these drugs?
Poor dental health, including missing teeth, dentures, or the need for dental surgery, raises the risk of osteonecrosis of the jaw once you're on these medicines. Getting a dental checkup and completing any needed dental work before starting treatment — and maintaining good oral hygiene throughout — is the main recommended way to lower this risk. Smoking also increases risk, so quitting or cutting back matters here too.
Do I need to stop these drugs for a dental cleaning or other dental care?
Routine dental cleanings and checkups are not a reason to stop these medicines, and dental organizations have found no good evidence that stopping the drug before a dental procedure reduces the risk of jaw problems. What matters most is telling your dentist you're taking a bisphosphonate or denosumab before any dental surgery or extraction, so they can plan appropriately, and keeping up with good oral hygiene and regular checkups throughout treatment.
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Last updated: 2026-08-03Next planned review: 2027-02-03
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source verified — This page was created with AI assistance and checked against the sources listed on it. Source checking is not a medical review.
Human medical review: not completed. Cancer Explained is not clinician-reviewed, and that is a deliberate design choice rather than a gap we are waiting to close. We restate published federal guidance and cite it; the authority belongs to the source, not to us. That is why every page names where its claims come from — so you can verify us instead of trusting us. Use it to understand your situation and to ask better questions of the people treating you.
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