Amalgam Filling or Black Filling? What You Need to Know
Amalgam fillings — commonly referred to as black or silver fillings — have been used in dentistry for over 150 years. While they remain in use in some practices, growing clinical and regulatory concern about their mercury content has led to a significant shift towards composite alternatives. Here is what you need to know before making a decision about your own dental care.
What Is an Amalgam Filling?
Amalgam is a metallic alloy produced by combining mercury — a liquid metal at room temperature — with silver, tin, copper and zinc powders. Mercury accounts for approximately 50% of the mixture by weight. Once set, amalgam is hard, durable and relatively inexpensive to place, which has historically made it a common choice for posterior (back) teeth restorations.
However, amalgam fillings are not inert once placed. Mercury continues to interact with surrounding tissues throughout the life of the filling.
EU Regulation: Under current European Union rules, amalgam fillings are already prohibited for patients under 15 years of age, and for pregnant or breastfeeding women. The production and import of dental amalgam will be prohibited across the EU as of 1 July 2026.
The Concerns Around Mercury
Mercury is classified as the most harmful metal after lead and arsenic. In the context of amalgam fillings, exposure occurs through several routes:
- During placement and removal of amalgam fillings
- During polishing procedures
- Through chewing, tooth brushing and other mechanical stimuli
- Via temperature — hot food, drinks and smoking all increase mercury vapour release from the filling surface
Research has confirmed that oral mercury concentration is measurably higher in individuals with amalgam fillings following mechanical stimulation. Teeth grinding has also been shown to increase mercury levels in urine and blood, albeit to a limited degree.
Additional Drawbacks of Amalgam
- Unaesthetic grey-silver appearance, visible when smiling or opening the mouth
- Can cause grey discolouration of surrounding tooth tissue and gums — known as amalgam tattooing
- Not chemically bonded to tooth structure — relies on mechanical retention only
- Expands slightly during setting, which can cause cracks and fractures in the surrounding tooth over time
- Unsuitable for patients with mercury, silver or tin allergies
What Is a Composite Filling?
Composite fillings are made from a tooth-coloured resin material that bonds directly to the tooth surface. They restore both the function and the natural appearance of the tooth, and have become the standard of care in modern restorative dentistry.
Composite is a versatile material with a wide range of clinical applications:
- Decay restoration in both front and back teeth
- Repair of chipped, cracked or broken teeth
- Correction of shape or colour irregularities in anterior teeth
- Closing gaps between teeth
- Coverage of exposed root surfaces caused by gum recession
- Treatment of dentine hypersensitivity
Key advantage: Composite fillings require less removal of healthy tooth tissue than amalgam during preparation — preserving more of the natural tooth structure and reducing long-term risk to the tooth.
Composite vs Amalgam — A Clinical Summary
- Composite bonds chemically to tooth structure; amalgam does not
- Composite is tooth-coloured and aesthetically invisible; amalgam is visibly metallic
- Composite requires less tooth reduction; amalgam requires more
- Composite contains no mercury; amalgam is approximately 50% mercury by weight
- Composite durability has improved significantly with advances in resin technology
At DentAkademi London, we practice mercury-free dentistry. We do not place new amalgam fillings, and we offer safe amalgam removal for patients wishing to replace existing restorations with modern composite or ceramic alternatives.
Want to replace your amalgam fillings?
Our team offers safe amalgam removal and mercury-free composite restorations at our Harley Street clinic.
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