National Survey on Bisphosphonate-Related Osteonecrosis of the Jaws in Japan

From 2011 to 2013, a nationwide retrospective cohort study was conducted by the Japanese Society of Oral and Maxillofacial Surgeons and the Japanese Society of Dentistry for Medically Compromised Patients to assess the development of bisphosphonate (BP)-related osteonecrosis of the jaws (BRONJ) and to elucidate the outcomes and factors associated with remission.

A written questionnaire, including clinical characteristics, management, and outcomes of patients with BRONJ, was sent to 501 institutions.

This large-scale study included 4,797 cases with a female preponderance. BRONJ occurred twice as often in the mandible as in the maxilla. Most patients had BRONJ stage 2 (61.4%), followed by stage 1 (20.7%) and stage 3 (16.8%); stage 0 was excluded. The most common primary disease was malignant neoplasm (46.5%), followed by osteoporosis (including prevention; 45.3%). The proportion of patients on oral BPs increased, with the incidence approaching that of patients receiving parenteral BP. Surgical therapy rates of patients with BRONJ stages 1, 2, and 3 were 14.0, 37.6, and 53.5%, respectively. Outcome assessment for 936 patients with BRONJ stage 2 who underwent surgical therapy indicated remission in 46.3% of cases, improvement in 30.6%, disease progression in 5.4%, and no change in 6.1%. Good prognosis (remission or improvement) was seen in 76.9% of cases and poor prognosis (disease progression or no change) was seen in 11.5%. Analysis showed that risk factors for onset of BRONJ (P = .031), surgical procedure (P < .024), condition of the wound (P = .017), and discontinuation of BP (P < .001) were factors affecting prognosis.

The number of patients with BRONJ has increased in Japan. Attention to oral BP and proper treatment is required to minimize the number of cases. Surgical therapy seems to be effective for BRONJ stage 2.