Amalgam is the most commonly used filling material for posterior teeth dentistry. The definition of an amalgam is an alloy of mercury with a number of other metals. Mercury is mixed with an alloy paste to give a plastic material that can be packed into a prepared cavity.

Amalgam is a mixture of metals, usually in the following proportions: Silver (between 67-74%), Tin (between 25-27%), Copper (0-6%) and Zinc (0-2.1%).

The alloy is prepared forming together the pure metals to form an ingot that is the homogenised or reheated and then cooled slowly. Historically, the mercury was mixed with the metal by hand using a mortar and pestle. This has now been replaced by mechanical methods to reduce the risk of exposure to mercury!

The dentist then cuts the ingot into the shape of the filling. He or she will pack it into the cavity in increments so that it fits properly. As the mix condenses mercury rich material rises to the surface and can be removed to reduce the final mercury content. A cavity would normally be overfilled to ensure the resultant filling after removal of mercury residue is at an appropriate level.

The filling is then polished to leave a lovely, smooth highly polished surface.

There is increasing awareness that amalgam materials can cause hypersensitivity in patients and dental workers alike. Although uncommon, hypersensitivity presents itself as soreness or redness in the area directly surrounding the amalgam filling. This is called an lichenoid reaction. Rarer still, amalgam material can cause an allergic reaction in the lining of the mouth and skin of the face. A simple patch test for this allergy can confirm this.

There is very little evidence to support the fact the amalgam can cause a general toxicity risk to foetuses but it is not recommended for use on pregnant women.

Amalgam is still the most widely used material for filling cavities. Its physical properties in terms of strength and non-leakage still outweigh its disadvantages - making it a superior product to white filling materials.

So how much should an Amalgam filling cost?

The costs for an amalgam filling will vary depending on whether you have the work done under the NHS or privately. Typically a filling on a back tooth costs about £13.50 on the NHS and about £25 privately. Don't forget that you may also have to pay for an examination, which will cost about £10 on the NHS and about £30 privately.

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