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Osteonecrosis of the jaw, commonly called ONJ, occurs when the jaw bone is exposed and begins to starve from a lack of blood.
Most cases of osteocronosis of the jaw happen after a dental extraction. Osteo means bone and necrosis means death. As the name indicates, the bone begins to weaken and die with OJN, which usually (but not always), causes pain.
ONJ is associated with cancer treatments (including radiation), infection, steroid use, or potent antiresorptive medications. Antiresorptive medications
help slow down bone loss in patients suffering from conditions such as
osteoporosis. Examples of potent antiresorptive medications include bisphosphonates such as alendronate (Fosamax);
risedronate (Actonel and Atelvia); ibandronate (Boniva); and denosumab (Prolia).
While ONJ is associated with these conditions, it also can occur without any identifiable risk factors.
Osteocronosis of the jaw is a condition in which an area of jawbone is not covered by the gums. The condition must last for more than eight weeks to be called ONJ. When the bone is left uncovered, it does not receive blood and begins to die. ONJ most often develops after an invasive (surgical) dental procedure such as dental extraction. ONJ also may occur spontaneously over boney growths in the roof or inner parts of the mouth.
ONJ has occurred in patients with herpes zoster virus infections, in those who are undergoing radiation therapy of the head and neck (radiation osteonecrosis), osteomyelitis (bone infection) and in persons taking steroid therapy chronically.
Patients taking antiresorptive medications to reduce their risk of bone fracture also may experience ONJ. Why some patients taking antiresorptive medications get ONJ is unknown. It may be due to: a decrease in the bone’s ability to repair itself; a decrease in blood vessel formation; or possible effects of infection.
Patients taking medicines that are classified as bisphosphonates (also called BON), may develop osteocronosis of the jaw (ONJ) after taking the medication for as little as 12 months. The risk increases the longer bisphosphonates are taken. Most cases occur after prolonged therapy (more than five years).
Study results vary from less than 1 in 100,000 getting ONJ from bisphosphonate therapy to 1 patient in 263,158. One recent study suggested no increased incidence of ONJ with osteoporosis medication. However, the risk of ONJ in patients on bisphosphonates who have invasive dental like an extraction may be higher. The risk of ONJ in patients taking denosumab (Prolia) has not been studied as well.
The risk of developing ONJ also depends on the medical condition the bisphosphonate is being used to treat. For example, cancer patients have a higher risk for developing ONJ, particularly if they receive treatment through an IV (a needle placed in the vein). The doses of IV bisphosphonates used to treat cancer can be 10 times higher or more than the doses used for osteoporosis. The risk of developing ONJ is low for osteoporosis patients who do not have cancer and are treated with osteoporosis medications.
Furthermore, cancer patients receive IV bisphosphonates as often as every 3-4 weeks, while osteoporosis patients receive only a single IV dose yearly. As a result, the risk of ONJ in cancer patients varies, but it is higher. Even with many risk factors, the incidence of ONJ in some European countries for cancer patients receiving IV bisphosphonates and other cancer treatments may be as high as 1 in 10 patients. ONJ has been most commonly observed in cancer patients with multiple myeloma and breast cancer.
Besides cancer, other risk factors include advanced age, steroid use, diabetes, gum disease and smoking.
There is no diagnostic test to determine if an individual patient is at increased risk for ONJ. The condition itself is diagnosed only by the presence of exposed bone, lasting more than 8 weeks. Patients typically complain of pain, which is often related to infection, soft tissue swelling, drainage and exposed bone.
Most patients with osteoporosis who develop ONJ are treated conservatively with rinses, antibiotics and oral analgesics. Studies have shown conservative treatment to be effective. There are case reports of the use of teriparatide in management of ONJ.
Rheumatologists are specialists in musculoskeletal disorders including osteoporosis and, therefore, are best qualified to review the risks and benefits of antiresorptive therapy for osteoporosis. They can also advise patients about the best treatment options available.
A health program of oral hygiene and regular dental care is the optimal approach for lowering osteocronosis of the jaw risk. Patients should inform their dentists that they are taking potent antiresorptive therapy. Dentists should consider conservative invasive dental care in patients taking potent antiresorptive therapies.
For instance, endodontic (root canal) treatment is preferred to dental extraction if the tooth can be saved. If dental extraction is needed, full mouth dental extractions or periodontal surgery should be avoided. (It may be better to assess healing by doing individual extractions.)
Patients with periodontal disease should consider non-surgical therapy before agreeing to surgical treatment. Many patients taking bisphosphonates may undergo dental implants without problems. Although some dentists recommend the use of blood tests to decide who is at risk, this practice is controversial due to a very limited evidence base and should not be used at this time.
Those on oral bisphosphonates are at low risk for BON. However, they are not without risk. Any problems developing in the mouth should signal the need for dental review. There is no data to suggest that bisphosphonates should be stopped prior to a dental procedure. However, patients about to start bisphosphonate therapy should consider waiting until any immediate invasive dental surgery is completed.
Updated September 2013. Written by Stuart Silverman MD, and reviewed by the American College of Rheumatology Communications and Marketing Committee. This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.
© 2013 American College of Rheumatology
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