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News Bulletin : ADA News Bulletin April 2011
38 APRIL 2011 feedback PROPHYLAxIS fOR bISPHOSPHOnATES And OSTEOnECROSIS Of THE JAWS Sir, The information sheet on ‘Bisphosphonates and osteonecrosis of the jaws (ONJ)’ put out in September 2010 conjointly by the Australian Dental Association (ADA) and Osteoporosis Australia (OA) differs in many respects to the NSW Health Guideline document GL2010_010 published by NSW Health 23rd July 2010 ‘Prevention of Osteoporosis of the Jaws (ONJ) in patients on Bisphosphonate Therapies’ (http://www. health.nsw.gov.au/policies/). In particular the ten day course of clindamycin recommended in the NSW Guidelines, commencing five days before an oral surgery procedure or extraction compared with the 2 gram amoxicillin one hour prior to the extraction recommended in Therapeutic Guidelines, cited in the OA / ADA document. This and other discrepancies have caused some confusion particularly amongst dental students and NSW Health staff dentists. It appears logical to commence prophylaxis immediately prior to any procedure to reduce the likelihood of the emergence of resistant organisms. The agent of choice should have a spectrum most suited to act on those pathogens likely to infect the surgical site. In BONJ the most common pathogens appear to be Actinomyces, Eikenella and Moraxella species. Therefore penicillin V 500 mg four times a day is a suitable antibacterial drug. In penicillin allergic patients doxycline 100 mg per day is suitable. Metronidazole 200 mg three times a day has proven effective in refractory cases... (N Malden, et al. BDJ 2009; 206:29.) As the readers of the ADA News Bulletin would know clindamycin is a restricted drug under the Australian Pharmaceutical Benefits scheme for “Gram positive coccal infections where they cannot be safely and effectively treated with penicillin.” Whilst there does not appear to be a universal consensus on appropriate Guidelines for the prevention of BONJ, I am unaware of any other published Guidelines or recommendation which would favour or support the NSW Health Guidelines. I would welcome comment and advice concerning these discrepancies. Michael Buchanan Greenwich 2065 RESPOnSE nEW SOUTH WALES GUIdELInES – bISPHOSPHOnATES Sir, The letter by Dr Buchanan, Consultant Oral and Maxillofacial Surgeon, from New South Wales, is timely as it draws attention to the major divergent opinions on the dental management of patients on oral bisphosphonates. Guidelines as set out by the New South Wales Health Department are quite at odds with those of Therapeutic Guidelines: Oral and Dental Version 1, the Australian Dental Association and Osteoporosis Australia within Australia and internationally with those of the American, Canadian and British Dental Associations and The American Association of Oral and Maxillofacial Surgeons and The American Academy of Oral Medicine, all of which have published essentially similar guidelines. The main areas of concern are: • The incidence of bisphosphonates associated (or related or induced) osteonecrosis of the jaws ONJ following extractions for patients on oral bisphosphonates • The nature of the ONJ lesion • Patient management • Antibiotic guidelines Following publication of the first version of the New South Wales Guidelines, the Dental Therapeutic Committee of the Australian Dental Association (ADA) sought independent advice from Therapeutic Guidelines Australia on the antibiotic treatments proposed. This advice was forwarded to the New South Wales Health Department. The ADA also facilitated a meeting with New South Wales Health Department representatives and made written submissions to them. The key proposals from both the ADA and Therapeutic Guidelines were unfortunately not incorporated into the second edition of the New South Wales Guidelines. Although it is commonly stated that bisphosphonate associated ONJ is a new condition and that there is incomplete information, it must be noted that by the end of 2010, there were well over 1,000 peer reviewed papers in the international literature, considerably more than the 16 papers by March 2006 referred to in the current New South Wales Guidelines. Thus, there is now good data available independent of the pharmaceutical industry and their advisors. Prevalence The initial view based on pharmaceutical industry data was that bisphosphonate associated ONJ from the oral bisphosphonates was rare at 1 in 10,000 to 1 in 100,000 patients. However, independent Australian, Californian and Canadian data all show a higher prevalence of 1 in 500 to 1 in 1,500 patients. Although bisphosphonate associated ONJ occurring in oral medication cases is generally milder than in IV cases, about 25% of these ONJ cases develop severe end stage ONJ. In discussing the prevalence, the New South Wales Guidelines state that there is “a very small or almost negligible risk of BRONJ occurring in those patients using oral bisphosphonates”. This seriously underestimates both the risk and the effect of ONJ on patients. The nature of ONJ The purpose of bisphosphonate therapy is to slow bone turnover. Unfortunately, jaw bones are different to long bones and vertebrae and are much more susceptible to the effects of bisphosphonates. Following tooth extraction, alveolar bone may not be able to respond to the demands of healing and so the bone may die. A microbial biofilm containing various species including Actinomyces, Eikenella and Moraxella species then develops over this dead bone. However, the same microbial biofilm develops on all dead alveolar bone whether caused by osteoradionecrosis, devascularisation, osteomyelitis or ONJ. The presence of these organisms does not mean that ONJ is primarily an infection. The New South Wales guidelines state that “while not well defined, bacterial infection is noted in the existing literature as having some role in the aetiopathogenesis of BRONJ ...” The subsequent New South Wales antibiotic proposals seem to be based on the premise that ONJ is primarily an infection. However, the overwhelming evidence supports suppressed bone turn-over as the principal cause. ONJ is not primarily an infection of bone. Patient management All patients on oral bisphosphonates are potentially at risk of ONJ if they have extractions. This can be minimised by making the patient dentally fit before bisphosphonate therapy starts and subsequently maintaining oral health. For patients already on oral bisphosphonates, careful evaluation of treatment options including avoidance of bone invasive procedures is indicated. The onset of ONJ is not dependent on the degree of bone invasion and hence there
ADA News Bulletin March 2011
ADA News Bulletin May 2011