What is the approximate prevalence of osteonecrosis in patients treated with bisphosphonates?

• A. 10%
• B. 0.1%
• C. 1%
• D. 5%

Answer: (B)

Osteonecrosis of the jaw is a rare complication of bisphosphonate therapy. When these drugs are used at standard, lower doses for osteoporosis, the risk remains very small compared with high-dose intravenous therapy used in cancer patients. The best estimate for how often it occurs in typical osteoporosis treatment is about 0.1%, meaning roughly one in a thousand patients. The lower prevalence reflects the less intense suppression of bone turnover with oral, long-term bisphosphonates, which reduces the likelihood of jawbone exposure and necrosis after dental procedures or trauma. The mechanism involves the drugs' strong, prolonged action on osteoclasts, impairing healing in the jawbone. Factors like invasive dental work, poor oral hygiene, concurrent chemotherapy or steroids, and smoking can increase risk, but for standard-dose therapy the overall prevalence remains around this low level.