Amalgam Fillings

Dental amalgam is the traditional silver colour fillings we are all familiar with. Mercury Amalgam is still the only material provided on the NHS for filling the biting surface (occlusal) of back teeth. Tooth coloured (white) fillings can be provided privately, although there are circumstances where your dentist would not be able to provide white fillings where an amalgam filling can be placed – although there are often other alternative such as crowns or inlays.

Advantages of Amalgam

• Robust – Amalgam is a strong material which takes biting forces well. Although the strength of white filling materials has improved greatly over recent years, they still cannot perform as well as Amalgam fillings, particularly in large cavities.
• Dental Compatibility – There are numerous aspects of materials that are analysed to produce the ideal filling material, including the wear characteristics and thermal expansion of the material. Mercury Amalgam behaves in a very similar manner to natural teeth making it a very compatible material. Ease of Use. The working characteristics of mercury amalgam make it very easy and reliable to place. It is not sensitive to moisture, ideal where access if difficult and the setting is progressive, allowing the filing to be worked to an ideal form.
• Cost effective – The ease of placement means that amalgam fillings can be placed much quicker than white fillings. This, coupled with the cheaper material, means they are roughly half the price of a tooth coloured filling.

Disadvantages of Amalgam

• Cosmetics – We all know what an Amalgam filling looks like – grey or black. They never look natural…like a tooth…and many people prefer to use more cosmetic restoration which, when placed with care, can be invisible to the naked eye. No adhesion to the tooth. Amalgam fillings are held in place by physical locking, undercut. More modern materials chemically bond to the tooth so can be used with less reduction of healthy tooth tissue.
• Galvanic currents – When different metals, such as different compositions of amalgam or other metals used in dentistry, are put into a solution – saliva – they can setup a galvanic current. Basically the metals can act as terminals in a battery producing an electric current. This can cause sensitivity problems and can result in a metallic taste in the mouth.
• Heat Conduction – Like all metals, Amalgam conducts heat very easily. This is obviously a bad thing for a tooth, with a nerve, that is exposed to hot and cold temperatures. Care has to be taken when placing amalgam fillings to insulate the nerve to prevent this from causing problems.

Concerns over Amalgam

Mercury Amalgam has been used in dentistry for over 150 years. The material out of favour in recent years with fears over the effects of the mercury on the body. Despite countless researchers investigating this, there has been no link found between the filling material and any systemic disease. The most recent, significant update in dental amalgam came from the US Food and Drug Administration FDA, who in July 2009 stated “he levels released by dental amalgam fillings are not high enough to cause harm in patients” (http://www.fda.gov/NewsEvents/Newsroom/Pressannouncements/ucm173992.htm). Amalgam as a dental material has been banned in several Scandinavian countries, including Sweden, however this has primarily been for environmental reasons. Measures within the UK reduce the amount of mercury that is produced by a dental surgery from reaching the water system.

The material is mixed in the surgery, a powder containing, amongst other things, Silver and Tin. Once combined, the composition chemically changes from a powder/liquid mix, to a solid alloy. The mercury chemically combines with the other components such that little or no free mercury remains.

Alternatives to Amalgam

The most popular alternative remains composite (tooth coloured) fillings, although for certain teeth these are only available privately. See here for more details.