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Bisphosphonate-related osteonecrosis of the jaw (ONJ) consists of exposed necrotic bone that persists for weeks or months; it can occur spontaneously or after invasive dental procedures. The condition was noted initially after high-dose intravenous bisphosphonate treatment for malignant conditions, but some evidence suggests that it can develop in users of oral bisphosphonate for osteoporosis (NEJM JW Gen Med Apr 8 2008). A report from Taiwan adds to the evidence.
Among 7332 patients who were taking oral alendronate (according to a hospital pharmacy database), 40 (0.55%) were diagnosed with ONJ an average of 4 years after initiating alendronate. Cases were verified by manual review of radiographic, operative, and pathology reports. In contrast, in a control group of 1882 patients who were treated for osteoporosis with raloxifene (a non-bisphosphonate), only 1 patient developed ONJ. After adjustment for potentially confounding factors, the incidence of ONJ was sevenfold higher with alendronate than with raloxifene. Risk factors for developing ONJ among users of alendronate included diabetes, rheumatoid arthritis, older age, and alendronate use for >3 years.
Chiu W-Y et al. The risk of osteonecrosis of the jaws in Taiwanese osteoporotic patients treated with oral alendronate or raloxifene. J Clin Endocrinol Metab 2014 Aug; 99:2729. (http://dx.doi.org/10.1210/jc.2013-4119)
Comment
The possibility that oral bisphosphonate therapy might cause osteonecrosis of the jaw (ONJ) received quite a bit of attention about 5 years ago; more recently, the literature has focused on atypical femur fractures after long-term use of oral bisphosphonates (NEJM JW Gen Med Dec 29 2011). This new study provides additional support for jaw osteonecrosis as a likely — although uncommon — adverse effect of oral bisphosphonate therapy.