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Medication-Related Osteonecrosis of the Jaws (MRONJ)

What is medication-related osteonecrosis of the jaws (MRONJ)?

MRONJ stands for medication-related osteonecrosis of the jaws.  It is seen in patients who have a history of taking certain medications such as bisphosphonates for osteoporosis.  This condition results in impaired wound healing and death (necrosis) of the jaw bone usually after a dental extraction.  In susceptible patients (see below), a dental extraction (or other surgical procedure) can cause problems with healing resulting in exposed jaw bone within the mouth and possibly infection.  While MRONJ is a very rare disorder, it is important to understand due to its potentially severe complications should it develop.


What are the symptoms of medication-related osteonecrosis of the jaws (MRONJ)?

MRONJ results in exposed jaw bone in your mouth i.e. failure of the gum tissue to cover over your jaw bone after extraction.  This happens because the bone undergoes necrosis (death) and cannot support gum tissue over it. Occasionally, the necrotic (dead) bone can become infected which may result in swelling, redness, pain, and drainage of pus.


Which medications place me at increased risk for MRONJ?

Medications associated with the development of MRONJ include medications used to treat osteoporosis and certain types of bone cancer.  The most common class of medications associated with MRONJ is bisphosphonates.  Examples of commonly used bisphosphonates are:


Alendronate (Fosamax)

Risedronate (Actonel)

Ibandronate (Boniva)

Zolendronate (Reclast)


Not all bisphosphonates cause an equal risk of MRONJ.  Those used to treat cancer and those given via the IV route are generally associated with a higher risk of MRONJ.  


Another medication commonly used to treat osteoporosis is denosumab (Prolia).  Prolia has also been associated with MRONJ.


Why do bisphosphonates cause MRONJ?

Bisphosphonates deactivate a certain type of cell involved in bone healing, therefore decreasing the bone’s ability to heal properly after a surgical procedure.  Bisphosphonate medications also can decrease the blood supply to the jaw bones during healing. This can result in lack of oxygen to the area and death of that area of the jaw bone.


What is my risk of MRONJ if I have an oral surgical procedure?

Even if you have taken the above medications, your risk of developing MRONJ is relatively low.  It is important to understand that the risk of MRONJ varies greatly depending on which form of medication was used and how long the medication was used.  Below are some useful numbers to help you estimate your risk of developing MRONJ. The following was taken from the American Association of Oral and Maxillofacial Surgeons’ position paper on MRONJ:


Risk of MRONJ after dental extractions in patients who have taken oral (not IV) bisphosphonates for osteoporosis:  ~0.5% (1 in 200 people).  Note the risk is lower in patients who have taken bisphosphonates for less than 4 years.


Risk of MRONJ after dental extractions in patients who have had IV bisphosphonates for the treatment of cancer:  ~2-15% (depending on the study)


Risk of MRONJ after dental extractions in patients who have taken prolia (denosumab) for treatment of osteoporosis:  Low but currently unknown due to lack of studies


What can be done to help prevent MRONJ?

If you have taken oral bisphosphonates for the treatment of osteoporosis for a duration of less than 4 years, there is no need for alteration of treatment since your risk of MRONJ is exceedingly low.


If you require oral surgery and have been exposed to bisphosphonate medications for longer than 4 years (or are also taking steroid medications), your risk of MRONJ is higher and there are some measures which can be taken to help prevent MRONJ.  It should be noted that these measures will not always prevent MRONJ.


  • Stopping the bisphosphonate medication 2 months before and 2 months after your surgery (only with approval from your prescribing doctor)

  • Beginning antibiotics 2 days prior and continuing antibiotics 7 days after your surgery

  • Antibiotic mouth rinse for 7 days after your surgery


How is existing MRONJ treated?

If you have MRONJ, there are several things which can be done to help treat the disease. Treatment of localized MRONJ (exposed bone) usually involves antibiotics (if infection) and an antibiotic rinse.  Obvious loose pieces of dead bone are removed.  In more advanced disease, surgery may be necessary to remove non-healing areas of bone.


Can MRONJ get worse?

As you can see above, MRONJ is rare even in people who have been exposed to bisphosphonate medications; however, it is a serious condition which can be progressive in some patients (meaning it can continue to get worse over time).  

Can MRONJ be cured?

In short, it varies from patient to patient.  In a best-case scenario, MRONJ may be cured (resolve) with the treatments discussed above.  In some cases the necrotic (dead) bone can spread, requiring surgery. Unfortunately, in a patient with MRONJ, it is impossible to predict which patients will get better, stay the same, or get worse over time.  


I have a history of bisphosphonate use.  Are there any options other than extraction for my failing tooth which can decrease the risk of MRONJ?

In teeth with severe dental decay that are non-restorable, a procedure called root banking can sometimes be used to maintain the root of the tooth and avoid the trauma of extraction, thereby reducing the risk of MRONJ.  With this procedure, a root canal is performed on the root of the tooth and the tooth structure is reduced to below the gumline.  This is usually performed by an endodontist (root canal specialist) or general dentist.

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