Osteonecrosis of the jaw (ONJ) has emerged as a new adverse drug reaction (ADR) related to treatment with bisphosphonates and possibly other drugs.

Objectives: To assess the officially reported numbers of ONJ cases in the Nordic countries; Norway, Sweden, Denmark and Finland. Secondly, to compare the figures with ONJ numbers reported in an e-mail survey to oral and maxillofacial surgeons (OMS) in Norway.

Methods: The study included ONJ cases reported to the national Medical Agency (MA) in each country from January the 1st 2003 to September the 30th 2010. A questionnaire regarding ONJ patients seen in practice during the same time period was sent to all active members of the Norwegian Association of Oral and Maxillofacial Surgeons.

Results: The included countries have the same reporting system of ADRs; health care professionals file pre-made forms to a national MA. In total 253 ONJ cases were reported (per os/intravenous/unknown); 51 (17/22/14) in Norway (4.8 mill citizens), 39 (8/18/15) in Denmark (5.5 mill citizens), 44 (3/41/0) in Finland (5.4 mill citizens) and 119 (57/88/0) in Sweden (9.3 mill citizens). Both intravenous and per os bisphosphonate medication were used in some of the reported cases. In the e-mail survey 35 (65%) of 54 Norwegian OMS answered the questionnaire, reporting 214 cases of ONJ.

Conclusions: The results suggest that there is an underreporting of ONJ cases in the Nordic countries. To better understand the scope of this ADR, there is a need to increase the level of ONJ reporting among health care professionals.

Conflict of interest: None declared.