When you're diagnosed with osteoporosis, your doctor likely talks about reducing fracture risk. That makes sense - broken hips and spine fractures can change your life overnight. But somewhere in the conversation, you might hear a quiet warning: bisphosphonates can rarely cause jaw bone death. It sounds scary. And it’s true - but not in the way most people think.
What Exactly Is MRONJ?
Medication-related osteonecrosis of the jaw, or MRONJ, is when part of the jawbone becomes exposed and doesn’t heal. It’s not cancer. It’s not infection alone. It’s a breakdown in the bone’s ability to repair itself. This happens because drugs like alendronate (Fosamax), risedronate (Actonel), and zoledronic acid (Reclast) stop bone cells called osteoclasts from doing their job. Normally, these cells break down old bone so new bone can take its place. When they’re shut down too hard, especially in the jaw, tiny injuries from brushing, flossing, or dental work can’t heal. The bone dies and stays exposed for more than eight weeks.
It’s rare. Really rare. For someone taking oral bisphosphonates for osteoporosis, the risk is about 0.7 out of every 100,000 people each year. That’s less than one in a million. Compare that to the 50% reduction in spine fractures and 51% drop in hip fractures these drugs deliver. The trade-off isn’t even close.
Why the Jaw? Why Not the Hip?
Here’s the key thing most people miss: the jawbone is not like your femur or spine. It’s thin. It’s covered by thin gum tissue. And it’s constantly under stress - chewing, talking, brushing. It also has the highest concentration of bacteria in your body. When a bisphosphonate slows bone turnover, the jaw is the first place it shows up because it’s always working, always healing, always under pressure.
Studies show jawbone turns over 10 times faster than long bones. That means bisphosphonates build up there more than anywhere else. Intravenous versions - like zoledronic acid - deliver even higher doses. A single 5mg IV infusion for osteoporosis is far stronger than a weekly 70mg pill. That’s why IV users have a higher risk. But even then, it’s still under 1 in 100,000 per year.
Oral vs. IV: The Real Risk Difference
Let’s break it down plainly:
- Oral bisphosphonates (alendronate, risedronate): Risk of MRONJ is 0.7 per 100,000 person-years. Some studies show no increased risk at all.
- IV bisphosphonates (zoledronic acid): Risk jumps to about 1 in 100,000 per year - still extremely low.
- Denosumab (Prolia): A newer drug, not a bisphosphonate, but similar in action. It carries about 1.7 to 2.5 times the risk of MRONJ compared to oral bisphosphonates.
- Cancer patients on high-dose IV drugs: Risk can hit 3% to 12%. But these patients get doses 10x higher than osteoporosis patients.
Here’s the truth: if you’re taking a weekly pill for osteoporosis, your odds of developing jaw necrosis are lower than getting hit by lightning. But if you’re getting a yearly IV infusion, you need to be smarter about dental care.
What Triggers MRONJ?
It almost never happens out of nowhere. Most cases - 63% - follow a dental procedure. Tooth extraction is the biggest trigger. Root canals, dentures that rub, gum disease - all can open the door. The problem isn’t the drug alone. It’s the drug plus trauma to the jaw.
One 2024 study followed 639 breast cancer patients. Those on denosumab had a 12% rate of jaw necrosis. Those on bisphosphonates? Only 3%. But here’s the twist: the same study found that if you stop IV bisphosphonates for over a year, your MRONJ risk drops by 82%. Sounds great, right? Not quite. Stopping means your fracture risk goes up by 28%. That’s not a trade-off you want to make lightly.
What Should You Do?
If you’re on bisphosphonates, here’s what actually matters:
- Get a dental checkup before starting. Fix cavities, remove loose teeth, treat gum disease. Do this before the first pill or IV.
- Keep going to the dentist. Cleanings every six months. No skipping. Tell your dentist you’re on a bisphosphonate. Most dentists know what to look for.
- Avoid invasive procedures if possible. If you need a tooth pulled, ask if it’s absolutely necessary. Sometimes, a root canal saves the tooth. Sometimes, a crown works better than extraction.
- Don’t panic about stopping. Stopping your medication to avoid MRONJ is riskier than keeping it. The fracture risk is real. A broken hip at 70 has a 20% chance of killing you within a year.
The American Dental Association says it best: the risk of a fracture from untreated osteoporosis far outweighs the tiny chance of jaw necrosis. That’s why 8 million Americans are still on these drugs.
What About Denosumab?
Denosumab (Prolia) works differently. Instead of targeting bone cells directly, it blocks a protein that activates them. It’s just as good at preventing fractures. But it may carry a slightly higher MRONJ risk than oral bisphosphonates. It also needs to be given every six months - and if you miss a dose, your bone protection drops fast. That’s why many doctors still start with bisphosphonates. They’re cheaper, longer-lasting, and have 30 years of safety data.
Real Stories, Real Fear
Online forums are full of people terrified of MRONJ. One woman on a patient forum spent 18 months on antibiotics after a cleaning exposed her jawbone. Another guy on Reddit said he’s been on Fosamax for 22 years, had three extractions and two implants - zero problems.
Most patients never get it. But those who do? Their stories stick. That’s why dentists sometimes refuse to pull teeth, even when it’s needed. A 2023 survey found many dentists overestimate the risk. They’re scared - and so are patients. But fear shouldn’t stop you from getting care.
What’s Next?
Researchers are working on ways to predict who’s at risk. Some are testing urine markers to see how fast your bone turns over. If your levels are still high on the drug, you might be safe. If they’re low, you might need a break. Clinical trials are underway, with results expected by late 2025.
For now, the advice hasn’t changed: take your pill. See your dentist. Fix problems early. Don’t stop your medicine unless your doctor says so. The bone in your jaw is important - but your hip, your spine, your ability to walk, to live - those matter more.
Can bisphosphonates cause jaw necrosis even if I never had dental work?
It’s extremely rare. Most cases of MRONJ happen after dental procedures like extractions or gum surgery. There are isolated reports of spontaneous jaw exposure, but these are usually linked to severe gum disease or poor oral hygiene before starting treatment. If your mouth is healthy and you’re on oral bisphosphonates, the chance of developing MRONJ without any dental trauma is practically zero.
Should I stop my bisphosphonate before a tooth extraction?
For oral bisphosphonates, stopping isn’t recommended. The risk of fracture increases quickly after stopping, and there’s no strong evidence that pausing reduces MRONJ risk. For IV bisphosphonates, some doctors may suggest a 3- to 6-month pause if you’ve been on it for more than 3 years - but only if your fracture risk is low. Never stop without talking to both your doctor and oral surgeon. The decision needs to be personalized.
Is MRONJ treatable?
Yes, but it’s not simple. Early-stage MRONJ (exposed bone with no infection) can be managed with mouth rinses, antibiotics, and avoiding trauma. More advanced cases may need surgery to remove dead bone, along with long-term antibiotics. Healing can take months. In some cases, the bone eventually heals on its own. The key is early detection - don’t wait until it hurts.
Do all bisphosphonates carry the same risk?
No. Nitrogen-containing bisphosphonates - like alendronate, risedronate, and zoledronic acid - are more potent and have a higher association with MRONJ than older non-nitrogen types like etidronate. However, even among these, the risk is much higher with IV use than oral. Alendronate (Fosamax), the most common oral form, has the lowest risk profile among all bisphosphonates used for osteoporosis.
Can I switch from bisphosphonates to avoid MRONJ?
Switching isn’t a guaranteed solution. Denosumab (Prolia) may carry a slightly higher MRONJ risk than oral bisphosphonates. Newer drugs like romosozumab don’t have long-term MRONJ data yet. And stopping treatment altogether increases fracture risk significantly. The best strategy isn’t switching - it’s prevention: good dental care, early treatment of oral issues, and continuing medication unless your doctor advises otherwise.
Final Thought: Don’t Let Fear Stop You
Every year, 300,000 Americans break a hip because they didn’t treat their osteoporosis. Thousands die from complications. Meanwhile, fewer than 100 cases of MRONJ occur annually in osteoporosis patients on oral bisphosphonates. The math is clear. The fear is understandable. But the choice shouldn’t be fear - it should be informed action.
Take your medicine. See your dentist. Keep your bones strong. Your jaw will thank you - but so will your whole body.