[New development in bisphosphonate treatment. Bisphosphonate therapy and osteonecrosis of the jaws]

Bisphosphonates (BP) have clinically been used as a highly effective drug in the treatment of hypercalcemia of malignancy, multiple myeloma, skeletal events associated with metastatic breast cancer and prostate cancer, and osteoporosis. Despite these benefits, however, the emergence of BP-related osteonecrosis of the jaws (BRONJ) becomes a growing and significant problem in a subset of patients receiving these drugs, especially intravenous preparations. It has also been reported in the patients receiving oral BP, although the incidence is extremely low. Most of BRONJ cases occur after dental treatments such as tooth extraction, periodontal surgery, and dental implants, and are refractory to conventional treatment modalities such as debridement, antibiotics and hyperbaric oxygen therapy. As compared to EU and USA, the number of BRONJ case is still small in Japan, but it is exactly increasing year by year. The ratio of the number of BRONJ in patients receiving oral BP to that in patients receiving intravenous BP is higher in Japan than in EU and USA, speculating due to the difference of time of approval. In this communication, the practical guidelines for prevention, diagnosis and treatment of BRONJ recently released from USA and Canada were introduced. Although no effective therapy for BRONJ is established yet, the importance of oral hygiene, patient education and treatments suitable for clinical stage is emphasized. In addition, it is considered that the survey of incidence of BRONJ in Japan and the preparation of Japanese guideline are urgent need.