Patient Education - Osteonecrosis of the Jaw (ONJ)

OSTEONECROSIS OF THE JAW (ONJ)

Osteonecrosis of the jaw (ONJ) occurs when a facial bone begins to starve from a permanent or temporary lack of blood. As the name indicates (osteo meaning bone and necrosis meaning death), the bone begins to die, causing pain and deterioration. While ONJ is associated with radiation, infection, steroid use or bisphosphonate therapy, this condition can also just happen.

Fast facts

The risk of ONJ in patients taking bisphosphonates depends on the amount of medication and length of time it is taken. As a result, cancer patients taking higher doses of bisphosphonates, particularly by IV, are at higher risk.
The number of ONJ cases in patients taking bisphosphonates by mouth is probably less than 1 in 100,000 person-years.
Most patients with ONJ who are taking bisphosphonates for osteoporosis can be healed with conservative treatment.
Good oral hygiene and regular dental care is the best approach to lowering the risk of ONJ.

What is ONJ?

Osteonecrosis of the jaw, or ONJ, 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. This problem has occurred in patients with herpes zoster virus infections, in those who are undergoing radiation therapy of the head and neck and in persons taking steroid therapy chronically. Patients taking bisphosphonate therapy to increase bone density may also experience ONJ. In this latter case, ONJ most often develops after an invasive (surgical) dental procedure such as dental extraction. ONJ may also occur spontaneously over boney growths in the roof or inner parts of the mouth.

What causes ONJ?

Why some patients taking bisphosphonates get ONJ is unknown. It may be due to: 1) a decrease in blood vessel formation, 2) a decrease in bone formation at the site or 3) toxic effects on overlying tissue.

Who gets ONJ?

ONJ resulting from bisphosphonate use, also referred to as BON, may develop in patients after taking the medication for 1 to 2 years, but most cases occur after prolonged therapy (more than five years).

For patients with osteoporosis who are treated bisphosphonates, the risk of BON is low. Studies results vary from only 1 patient in 263,158 getting ONJ from bisphosphonate therapy to less than 1 in 100,000. In a recent randomized controlled trial of an IV bisphosphonate for osteoporosis in 7,700 patients, there were two bisphosphonate cases—one in a patient taking a placebo and one in a patient on IV treatment, suggesting no increased incidence.

However, because doses of IV bisphosphonates used to treat cancer can be ten times higher or more than the doses used for osteoporosis, cancer patients are more at risk. 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 is higher, with estimates as high as 11% in some European countries for patients receiving IV bisphosphonates for cancer (multiple myeloma and breast cancer being the most common).

Other risk factors include advanced age, steroid use, diabetes, gum disease and smoking.

How is ONJ diagnosed?

There is no diagnostic test to determine if an individual patient is at increased risk for BON. The condition itself is diagnosed only by the presence of exposed bone, lasting more than eight weeks. Patients typically complain of pain, which is often related to infection, soft tissue swelling, drainage and exposed bone.

How is ONJ treated?

Most patients with osteoporosis who develop ONJ are treated conservatively with rinses, antibiotics and oral analgesics. In the IV trial in osteoporosis mentioned above, both cases resolved within months on such conservative treatment

Prevention

A health program of oral hygiene and regular dental care is the optimal approach for lowering ONJ risk. Those not receiving routine dental care should get a comprehensive oral exam as soon as possible after beginning bisphosphonate therapy. Dentists should be informed of the treatment and consider only conservative invasive dental care.

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 approach non-surgical therapy before agreeing to surgical treatment. There is little data available concerning the risks of dental implants in patients taking oral bisphosphonates. However, the use of bone markers such as serum CTX to decide who is at risk is controversial and should not be used at this time.

Those on oral bisphosphonates are at low risk for BON. However, they are not eliminated from 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.

Points to remember

One out of every two women will sustain an osteoporotic fracture (such as wrist, spine or hip) in her lifetime. Of these, 250,000 are hip fractures with mortality of over 20% in women and 30% in men; less than 25% regain full function. Vertebral fractures, which are more than double the prevalence of hip fractures, also cause back pain and increased mortality.
Oral or IV bisphosphonates have been shown to prevent 50%-70% of vertebral fractures in postmenopausal women and 40-50% of hip fractures in clinical trials.
Given the risk of osteoporotic fracture, and the low risk of ONJ associated with bisphosphonate use, the benefit of preventing osteoporotic fracture clearly far exceeds the risk of ONJ.

The role of the rheumatologist

Rheumatologists are specialists in musculoskeletal disorders including osteoporosis and, therefore, are best qualified to review the risks and benefits of bisphosphonate therapy for osteoporosis. They can also advise patients about the best treatment options available.

To find a rheumatologist

For more information about rheumatologists, click here.

For a listing of rheumatologists in your area, click here.

For more information

The American Academy of Oral Medicine
www.aaom.com/

The American Society of Bone and Mineral Research
www.asbmr.org

Written June 2008

Written by Stuart Silverman MD, and reviewed by the American College of Rheumatology Patient Education Task Force.

This patient fact sheet is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnoses and treatment of a medical or health condition.