[Encounter of cancer cells with bone. Present status and problems in occurrence of bisphosphonate-related osteonecrosis of the jaws].

Bisphosphonate-related osteonecrosis of the jaws (BRONJ) develops as a side effect of long-term administration of bisphosphonates (BP) , especially intravenous preparations. The lesion is a new disease entity which was first reported in 2003 in the United States. Since then, the number of patients with BRONJ is increasing year by year. In Japan, the first case was reported in 2006, and at that time 30 cases of BRONJ were registered in the nationwide survey by the Japanese Society of Oral and Maxillofacial Surgeons. However, the patients with BRONJ increased rapidly in the second survey after 2 years, and more than 250 cases of BRONJ which met the criteria of clinical diagnosis were determined. Approximately 95% of the BRONJ patients received intravenous BPs and less than 5% received oral BPs in the United States and European Union, whereas 58% of the patients received intravenous BPs and 40% received oral BPs in Japan. The relative ratio of BRONJ associated with the use of oral BPs was higher in Japan than in the United States and European Union. BRONJ is refractory to treatment, and an efficient and useful therapy is not yet established.