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Not many clinicians in the UK will have missed the publicity surrounding the Minamata Agreement, which was signed by the UK and over one hundred countries from all over the world in October 2013. This was a far reaching agreement to limit the use of mercury from all sources, including LED light bulbs, fluorescent tubes, fertilisers, thermometers and, of course, dental amalgam. The agreement intimated that the mercury limitation would commence within four years, and Annex A Part II dealt specifically with dentistry. Of course, an obvious way to cut down the use of dental amalgam would be to reduce the number of new cavities, but this is a laudable aim which the dental profession, worldwide, has been wrestling with, ever since GV Black, in the late 1800s, suggested that we should ‘soon be practising preventive rather than reparative dentistry’. A clause in the annex to the agreement mentioned the phasing down of mercury-containing restoratives. Two years on, it is timely to reflect how close we are to achieving this, given that two years is half of the suggested four! We have also agreed to ‘Promote the development of cost-effective and clinically effective mercury-free alternatives’, so how far down that road are we?
The second question is possibly the easier to answer. There have been a number of advances in resin composite materials in the past couple of years. These have been principally aimed at making composite faster to place in posterior teeth by obviating the need to place in increments. Given that clinician time is a major factor in the cost of any restoration, the development of these bulk-fill materials should make these cheaper to place, an advantage, since posterior composite restorations have been estimated to take 2.5 times longer to place than amalgam.1 Early bulk-fill base materials (such as Dentsply's SDR) required the placement of a layer of conventional composite on their surface because their wear resistance wasn't good enough, but there are now materials for which this does not appear to present a problem; the bulk-fill restorative materials (such as Filtek Bulk Fill [3M ESPE] and Tetric Evo-Ceram Bulk Fill [Ivoclar]). Not needing to place a capping layer also seems to reduce stress in a restored MOD cavity.2
Now for the first question! Professor Chris Lynch, speaking at the recent British Society for Oral and Dental Research meeting, stated that ‘the phasedown of amalgam is an inevitable trend’. There is information in the literature on how to move away from amalgam completely – Norway has achieved that!3 They now have a situation where dentists wishing to use amalgam have to apply for special approval and I am not aware of any reports of patients being damaged by this arrangement. Dental students are now being taught the placement of posterior composite restorations more than ever before,4 so we may not have to worry about them having the competence to manage without amalgam. But, what about the older generations of dentists who have not had this experience? Should hands-on courses in posterior composite placement be arranged for this group? I am not aware of any increase in the numbers of such courses.
Lastly, there seems to have been a deafening silence from the Department of Health and the Postgraduate Deaneries on how to manage the post-Minamata era. Perhaps it is time for them to let us know what they are planning. Might it all come down to money? The Department of Health in England and Wales abandoned fee per item for UDAs, so that they would know exactly how much the cost of NHS dentistry per annum would be. Given that the proven amalgam alternative, resin composite (which has demonstrably good survival rates5), takes longer to place,1 having to abandon amalgam will necessarily cost more. However, there is no end in sight to the austerity facing our country. Balancing the books and abandoning amalgam make the post Minamata era a difficult conundrum, at least until that new dream self-adhesive, low stress, strong, 5 mm depth of cure material comes along. You can bet that the manufacturers of our current materials are working day and night on that!