What the two materials are made of
Amalgam is an alloy made by mixing powdered silver, tin and copper with mercury. Once it sets, the mercury is bound within the alloy. Composite is a resin filled with glass or ceramic particles; it is bonded to the tooth and hardened with a light. Amalgam does not bond to the tooth. It stays in place because of the shape of the cavity.
Durability and tooth preparation
Amalgam is known for lasting many years in back teeth and can be placed even where it is hard to keep the tooth dry. In return, some sound tooth sometimes has to be removed so that it holds. Because composite bonds to the tooth, removing the decayed part alone is usually enough. In very large back fillings composite can wear sooner, and an inlay, onlay or crown is then discussed.
Why amalgam is being phased out
The reason is not only patient health but largely the environment: mercury is a persistent pollutant once it reaches nature. The European Union banned the use of dental amalgam from 1 January 2025, except where the dentist considers it medically necessary. Its use in children and pregnant women had already been restricted. In many countries amalgam is now rarely placed.
Old amalgam fillings in your mouth
Removing a sound amalgam filling with sealed edges and no decay only because it is amalgam is generally not advised. Drilling it out releases mercury vapour for a short time and costs tooth structure. A filling is replaced when it has broken, leaks at the edge or has decay beneath it. During replacement the dentist uses suction and isolation.
Frequently asked questions
Are amalgam fillings harmful to health?
Established scientific reviews do not show that intact amalgam fillings cause health problems in the general population. The main reason for restrictions is the environmental effect of mercury.
Should I have my old amalgam fillings replaced?
Usually not if the filling is sound. Your dentist will advise replacement if it is broken, leaking at the edge or has decay underneath.
Does a composite filling last as long as amalgam?
In small and medium fillings composite can last many years. In very large back fillings it can wear sooner, and other options are considered there.
Is amalgam placed during pregnancy?
In many countries amalgam is avoided in pregnant women and young children. Non-urgent filling replacement is generally postponed during pregnancy.
Do amalgam fillings prevent an MRI scan?
No. Amalgam fillings do not prevent an MRI scan. In images of the head there may only be a small distortion around the filling.
This content is for general information only and does not replace an examination.
Edited by
Papatya Dental
This article draws on the clinical experience of the Papatya Dental team and is reviewed for accuracy before publication.
- Last updated:
- 2026-10-08
- Editorial contact:
- icerik@papatyadental.com