Nature and frequency of bisphosphonate-associated osteonecrosis of the jaws in Australia

Abstract

Purpose: The purpose of this study is to estimate the frequency and describe the clinical characteristics of patients diagnosed with bisphosphonate-associated osteonecrosis of the jaws (ONJ) in Australia.

Materials and methods: Cases of ONJ were identified in 2004 and 2005 primarily by a postal survey of Australian Oral and Maxillofacial Surgeons (OMS) with additional cases from other dental specialists and the Commonwealth of Australia Adverse Drug Reaction Committee (ADRAC). The clinical characteristics were recorded. The frequency of ONJ cases was estimated from prescription and dental extraction data. Univariate and bivariate statistics were calculated.

Results: One hundred fifty-eight cases of ONJ were identified. These were primarily in patients with bone malignancy (72%) and the main trigger was dental extraction (73%). The reported number of cases varied between different Australian States with the highest frequency being reported in the States with the best integrated health systems. The frequency of ONJ in osteoporotic patients, mainly on weekly oral alendronate was 1 in 2,260 to 8,470 (0.01% to 0.04%) patients. If extractions were carried out, the calculated frequency was 1 in 296 to 1,130 cases (0.09% to 0.34%). The total dose of oral alendronate at the onset of ONJ was 9,060 (+/-7,269) mg. The frequency of ONJ for Paget's disease cases was 1 in 56 to 380 (0.26% to 1.8%). If extractions were carried out, the calculated frequency of ONJ was 1 in 7.4 to 48 (2.1% to 13.5%). The frequency of ONJ in bone malignancy cases, treated with mainly intravenous zoledronate or pamidronate was 1 in 87 to 114 (0.88% to 1.15%). If extractions were carried out, the calculated frequency of ONJ was 1 in 11 to 15 (6.67% to 9.1%) The total dose of pamidronate was 3,285 (+/-2,530) mg and zoledronate 62 (+/-54.28) mg at the onset of ONJ. The median time to onset of ONJ was 12 months for zoledronate, 24 months for pamidronate, and 24 months alendronate.

Conclusions: Before the prescription of bisphosphonates for bone disease the patient should be made dentally fit so that the need for subsequent dental extractions is minimized. Appropriate informed consent for the risk of ONJ for different bisphosphonates, for osteoporosis, and malignancy both in general and in particular for dental extractions can be provided using this data.