Risk for Osteonecrosis of the Jaws
N Z Med J. 2006 Dec 1:119(1246):U2339, Osteonecrosis of the jaw and bisphosphonates—putting the risk in perspective, Bolland, M and others. PMID: 17151713.
General info and risk. This article gives a brief summary of osteonecrosis of the jaw (ONJ) and puts the risk in perspective for those on IV or oral bisphosphonates. The authors point out the risk is far greater for those on IV bisphosphonates, with estimates from 1 to 10% in those patients treated with very high bisphosphonate doses for malignancies. Typical IV doses for malignancies are 12-fold higher than oral doses given to patients with Paget's disease or osteoporosis. In a recent review, in fact, 95% of published cases of ONJ were in patients with malignant diseases where patients received high-dose IV bisphosphonates. Three cases were in patients with Paget's disease, but two of these had been given inappropriately high doses of either alendronate (Fosamax) or pamidronate (Aredia). Fifteen cases of ONJ were in osteoporosis patients on bisphosphonates. Additionally, 170 ONJ cases worldwide have been reported to Merck, the manufacturer of Fosamax. When Bolland and others compare the number of reported cases to the approximately 20 million patient-years (2004 data) of alendronate treatment for both Paget's disease and osteoporosis, they conclude the following for risks of ONJ: “Therefore, while the incidence of ONJ in patients treated with bisphosphonate for Paget's disease and osteoporosis is difficult to determine, it is very likely to be less than 1/60,000 and is perhaps as low as 1/200,000.” They also note that some estimates for ONJ in IV medication users are as high as 10%, but the best available data suggests the risk is more like 0.85%.
Putting the risks in perspective. The authors note that in women with osteoporosis, the number needed to treat (NNT) to prevent a fracture runs from 35 to 4.5 for 65-year-olds and 80-year-olds, respectively. In comparison, the number needed to harm (NNH) using the same medication (Fosamax), is likely at least 60,000. They also note that osteoporotic fractures are not trivial, with hip fractures associated with a 25% risk of death within 12 months, as well as other debilitating problems after the fracture. The authors conclude: “Current evidence suggests that the risk of ONJ in patients with non-malignant skeletal conditions who are receiving conventional doses of bisphosphonates is so low that (a) systematic screening or prevention programmes and (b) withholding dental procedures are not justified in this setting.”
Editor's comments. We are early in the learning curve on ONJ, with it first being described in 2003. Surely in time it will become clearer as to the exact cause and risks for those taking bisphosphonates. For now the risk for ONJ appears to be extremely low for all persons taking oral bisphosphonates. As such, it is important not to get overly concerned about the risk of ONJ--to believe the sky is falling or similar—there simply is not that kind of risk. Yet, since there is some risk of a very unpleasant condition, it behooves all of us taking bisphosphonates to be aware that ONJ exists and to be educated regarding oral health and dental procedures that affect the jaw bones. I stand by my recommendations in the June 2006 Update on jaw osteonecrosis concerning dental procedures. Basically, take good care of your teeth and gums, avoid extensive elective dental procedures that involve the jaw bones, consider endondontic (root canal) procedures which don't expose the jaw bones as opposed to extractions, keep dentures and partial dentures in good order to avoid sore spots that might expose jaw bones, and discuss your care and the fact that you are taking bisphosphonates with your dentist to assure you'll be treated correctly. I agree with Bolland and others that dental procedures should not be withheld just because you are taking a bisphosphonate. But I do suggest that you consider not having extensive surgical procedures that are totally elective. You must feel the reward from the elective surgical dental procedure overrides any (however slight) risk of ONJ. And, if you do decide to have the surgical procedure, I would definitely suggest using an antimicrobial mouth rinse until all bone is covered with fully healed soft tissue. I especially suggest a rinse containing chlorhexidine, such as Peridex, since it is so effective against bacteria and so long lasting.