Dentists’ restorative decision-making and implications for an ‘amalgamless’ profession. Part 1: a review
G Alexander,*† MS Hopcraft,* MJ Tyas,* RHK Wong* *Melbourne Dental School, The University of Melbourne, Victoria. †Department of Dentistry and Oral Health, La Trobe University, Victoria.
The Minamata Convention has agreed to a worldwide reduction and ultimate elimination in the production and use of mercury containing products. This will have implications for the practice of dentistry. Australian organizations’ pronouncements on the issue are limited and research examining the Australian context dated.
The restoration of teeth with direct materials has changed significantly since the 1980s. Up to this time amalgam was the material of choice for direct posterior restorations. Its properties and guidelines for placement were, and remain, well established. Resin composite has replaced amalgam as the material of choice in many clinical situations. Despite inherent clinical disadvantages compared to amalgam, there continues to be a shift toward greater use of resin composite. There is consensus worldwide that the restoration of posterior teeth using resin composite now exceeds that of amalgam. The reasons for this are reviewed in this article along with current evidence and commentary relating to direct restorative and evidence-based decision-making, minimally invasive approaches, and approaches to education. The implications for these in an ‘amalgamless’ profession are identified.
Keywords: Amalgam, decision-making, dentist, direct restoration, resin composite.
Abbreviations and acronyms: AAPD = American Academy of Pediatric Dentistry; IADR = International Association for Dental
Research; MID = minimal intervention dentistry; NHMRC = National Health and Medical Research Council; UNEP = United Nations
Environment Programme; WHO = World Health Organization. (Accepted for publication 12 February 2014.)
The restoration of teeth with direct restorative materials has changed significantly since the 1980s. Up to this time amalgam was the material of choice for direct posterior restorations.1a The material’s properties and guidelines for placement were well established and proven by most measures.
Many factors have emerged to change its status as the material of choice for some clinical situations.
These include: • improvements in prevention, healing and control of caries • emphasis on conservation of tooth structure2 including decisions for amalgam replacement and repair • development and improvement of new restorative materials3 and techniques fostered by patients seeking ‘tooth-coloured’ or more aesthetic restorations4 • acceptance of a shorter lifespan for a restoration5 • patient concerns for amalgam use compounded by continual negative emphasis on the mercury content of dental amalgam • concerns as to possible environmental effects of mercury6,7 • improvements in other approaches such as indirect restorations.
Resin composite has replaced amalgam in many clinical situations. It possesses inherent clinical disadvantages compared to amalgam including reduced wear resistance, compressive strength, fracture resistance, coupled with increased microleakage, marginal staining and secondary caries. The clinical procedure is also more time-consuming and technique sensitive.8 Despite this, there continues to be a shift toward the use of resin composite for posterior restorations. One study found that while dentists were concerned with the factors outlined above, they would place resin composite primarily because of patient choice.5 a The term ‘amalgam’ is intended to include the various terms found in the literature including ‘dental amalgam’ and ‘silver amalgam’. © 2014 Australian Dental Association 1
Australian Dental Journal 2014; 59: 1–12 doi: 10.1111/adj.12209
Australian Dental Journal
The official journal of the Australian Dental Association
In 2009 the World Health Organization (WHO) published Future Use of Materials for Dental Restoration.6 An emphasis of this report was the possible health effects and contamination of the environment from mercury in amalgam. Its objectives included: ‘To assess the scientific evidence available on use of dental restorative materials, including dental amalgam, and the implications of using alternatives to amalgam for dental restorative care.’
The term ‘phase-out’ to describe an approach to the elimination of dental amalgam as a restorative material was first proposed by the Global Mercury
Partnership, an organization formed by the United
Nations Environment Programme (UNEP) in collaboration with the WHO.b One objective of this partnership is: ‘To phase-out and eventually eliminate mercury in products and to eliminate releases during manufacturing and other industrial processes via environmentally sound production, transportation, storage, and disposal procedures.’ Pacyna et al.9 provide an overview of the possible implications of actions to reduce mercury emissions on a global scale.
More recently the term ‘phase-down’ has been adopted to describe the preferred approach to the reduction of mercury by decreased use of amalgam: ‘a complete ban is not yet appropriate.’6 As stated in a separate communication, ‘It may be prudent to consider “phasing down” instead of “phasing out” of dental amalgam at this stage. A multi-pronged approach should be considered. Short-, medium- and long-term strategies should be developed’.c This represents a realization that the complete cessation of amalgam as a restorative material is inappropriate at this time and much needs to be done before the material can be completely replaced by appropriate alternatives. The WHO report provides a summary of the issues pertaining to the use of amalgam, including: encouraging better use of quality alternatives to amalgam; investigating different materials and developing appropriate criteria for their use; increasing the study of dental materials alternative to amalgam; and identifying implications for training in the use of materials alternative to amalgam.