“Bone strengthening drugs” are often prescribed to patients with multiple myeloma, metastatic disease to the bone, including breast or prostate cancer, bone cancers, Gorham's disease or other bone conditions. “Bone strengthening drugs” is a broad colloquial term used to describe anti-resorptive medications, which include bisphosphonates and denosumab. But why is a dentist interested if a patient has a history of taking bisphosphonates or denosumab? As anti-resorptive drugs, bisphosphonates and denosumab may alter the functioning of bone cells. Thus, they may be associated with a condition marked by abnormal wound healing known as medication related osteonecrosis of the jaw, or MRONJ. While this condition has also been associated with some other drugs, such as bevacizumab, sunitinib and ipilimumab, the incidence of MRONJ tends to be higher with bisphosphonates and denosumab.
What’s osteonecrosis of the jaw?
The American Society of Bone and Mineral Research defines MRONJ as an area of exposed bone in the head and neck region that persists for greater than eight weeks in a patient with no history of radiation to the jaws. In other words, MRONJ usually shows up as an area of exposed bone that fails to heal.
What are the signs and symptoms of ONJ?
Aside from presenting as exposed dead bone, MRONJ may present as a non-healing wound or ulcer. Other signs and symptoms include swelling, a foul odor and numbness or tingling in the mouth. Additionally, MRONJ may or may not present with pain, and it may also manifest as a draining abscess. In severe cases, it may progress to fracturing of the jaw.
Who is at risk of developing MRONJ?
MRONJ most commonly results from manipulation of the bone through trauma such as dental extractions, periodontal surgery or implant surgery. Nonetheless, MRONJ may occur spontaneously without an unknown association. Additionally, the risk of MRONJ increases with the number of doses of the anti-resorptive medication and the frequency at which the medication is administered.
Patients who have taken bisphosphonates. Patients with a history of IV bisphosphonates have a much higher likelihood of developing MRONJ than do patients with a history of oral bisphosphonates. It is important to note that because bisphosphonates have a long half-life (approximately 10 years), even after stopping to use these medications, they remain in the body for an extended period of time. This means that after 10 years, only half of the drug has been eliminated from the body.
Patients who have received denosumab. Denosumab, with a shorter half-life than bisphosphonates, does not last as long as bisphosphonates, but still remains in the body for an extended period of time.
How common is MRONJ?
The true incidence is unknown, but the estimated cumulative incidence ranges from 0.7 percent to 24.5 percent in cancer patients with a history of taking IV bisphosphonates. While the incidence of denosumab-related MRONJ remains unclear, it appears to be similar to that of bisphosphonate-related MRONJ. The majority of bisphosphonate-related MRONJ cases are seen in patients with a history of IV bisphosphonates rather than oral bisphosphonates.
How can MRONJ be prevented?
Maintaining good oral hygiene and visiting the dentist regularly (at least two times a year, but preferably four times a year) are both essential. Regular dental check-ups may minimize a patient’s risk of developing dental decay (cavities), which can lead to dental infection and the need for a dental extraction. Thus, visiting a dentist regularly may help reduce one’s risk of developing MRONJ. All questionable teeth should be extracted or restored at least 14 to 21 days before a patient starts treatment with drugs associated with MRONJ. Extractions after receiving drugs believed to be associated with MRONJ should be avoided.
How is ONJ treated?
MRONJ is mainly treated through wound care. This means keeping the area extremely clean with either antimicrobial rinses or saline. If you think you are at risk of ONJ or are experiencing MRONJ it is important to visit your oncologist and your dentist.
What’s the bottom line?
There is still a lot of research needed in this field. While theories exist for how MRONJ develops, we are not fully certain how the condition arises. In patients who have taken a variety of drugs associated with MRONJ, we cannot yet pinpoint which drugs specifically are responsible.
It is essential to inform your dentist if you have a history of taking “bone strengthening drugs.” Also, you should visit the dentist prior to being administered IV bisphosphonates, denosumab or other drugs associated with MRONJ.
Suggested reading
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