White composite fillings vs amalgam: a clinical comparison for patients

White composite fillings vs amalgam: a clinical comparison for patients

White composite fillings bond directly to tooth structure using a resin material matched to your natural tooth colour, while amalgam fillings are a silver-coloured alloy of mercury, silver, tin and copper that pack into a prepared cavity without bonding. For most patients choosing a filling in 2026, composite is now the standard option at most UK dental practices, including Battersea Smiles, though amalgam retains specific clinical advantages in certain situations.

Key takeaways

• Composite resin fillings require roughly 10–15% less healthy tooth removal than amalgam, because the material bonds to enamel and dentine rather than relying on mechanical retention.
• The UK Medicines and Healthcare products Regulatory Agency (MHRA) recommended phasing out amalgam use by 2025 in line with the Minamata Convention on Mercury, making composite the de facto default at most practices.
• Composite fillings typically cost £150–£300 per tooth privately in London, compared with £60–£150 for amalgam where it is still available.
• Amalgam fillings have a documented clinical lifespan of 10–15 years on average, while modern composite resins last 7–12 years, though placement technique significantly affects longevity.
• Composite fillings are moisture-sensitive during placement, meaning any contamination from saliva reduces bond strength and shortens lifespan.

What is a white composite filling?

A composite filling is a tooth-coloured restorative material made from a mixture of acrylic resin and finely ground ceramic or glass particles. The dentist applies it in layers, curing each layer with a blue-spectrum light at around 470 nm, which triggers polymerisation and hardens the material within seconds. The result is a restoration that mimics both the colour and translucency of natural enamel.

What is an amalgam filling?

Amalgam is a metallic alloy containing approximately 50% elemental mercury combined with a powder of silver, tin and copper. It does not bond to tooth structure chemically. Instead, the dentist cuts a retentive cavity shape, often an undercut, so the hardened amalgam is mechanically locked in place. It sets within a few hours and reaches full strength over approximately 24 hours.

How do composite and amalgam fillings compare clinically?

Does composite last as long as amalgam?

Amalgam has a longer average documented lifespan than composite, at 10–15 years versus 7–12 years for resin, but the gap narrows considerably when placement conditions are well controlled. At Battersea Smiles, we find that composites placed with rubber dam isolation, which completely excludes saliva, consistently outperform those placed without it. Technique is the single most important variable in composite longevity.

Is amalgam safe?

Regulatory bodies including the MHRA and the European Commission have concluded that amalgam fillings, once set, release very low levels of mercury vapour but do not pose a health risk to the general population. The phase-out is driven by environmental concerns under the Minamata Convention rather than evidence of patient harm. Certain groups, including pregnant women and children under 15, were already advised to avoid new amalgam placements under MHRA guidance.

How much do composite fillings cost in London?

Privately, a white composite filling in London ranges from £150 to £300 per tooth depending on the size of the cavity and the number of tooth surfaces involved. On the NHS, composite fillings fall under Band 2 treatment, costing patients £68.50 in 2026. Amalgam is no longer routinely placed on NHS patients in England following the phase-out. For patients interested in restoring several teeth or improving the appearance of existing work, composite bonding is a related treatment that uses the same resin material to reshape or resurface teeth without drilling. If you are also considering improving the colour of surrounding teeth, a course of teeth whitening before any composite work allows the dentist to match the new filling to a lighter, brighter shade.

What should you ask your dentist before choosing a filling material?

1. Ask whether rubber dam isolation will be used, as this significantly improves composite bond strength and longevity.
2. Ask how many surfaces the cavity involves, as large multi-surface cavities on back teeth may still justify alternative materials such as ceramic inlays.
3. Ask to see the shade guide so you can approve the colour match before the material is placed.
4. Confirm whether the quoted fee includes a follow-up polish, as composite benefits from a final finishing appointment.

Frequently Asked Questions

Can old amalgam fillings be replaced with composite?

Yes, but replacement is only recommended when an existing filling is failing, cracked or causing symptoms. Removing a sound amalgam filling exposes you to a brief, temporary increase in mercury vapour during drilling and destroys healthy tooth structure unnecessarily. A dentist in London will assess whether replacement is clinically justified rather than cosmetically motivated.

Do composite fillings stain over time?

Composite resin is more porous than enamel and absorbs pigment from coffee, tea and red wine over time. Surface staining can often be removed by polishing at a routine appointment, but deep matrix staining after 8–10 years typically warrants replacement.

Are composite fillings painful to have placed?

The procedure is performed under local anaesthetic and should not be painful. Some patients experience temporary sensitivity to cold in the days following placement, which usually resolves within two weeks as the pulp settles.

Why is amalgam being phased out in the UK?

The phase-out is driven by the Minamata Convention on Mercury, an international environmental treaty aimed at reducing global mercury pollution. Dental amalgam accounts for a significant proportion of mercury entering waste water and cremation emissions. The clinical case for composite has also strengthened as the material has improved.

Does a composite filling require any special aftercare?

Composite fillings are fully set immediately after the light-curing process, so you can eat as soon as the local anaesthetic wears off. Avoid very hard foods such as ice or hard sweets, which can fracture composite resin, and maintain good flossing habits around the restoration margins to prevent secondary decay.

Is composite suitable for large cavities on back teeth?

Composite can be used for moderate cavities on posterior teeth, but very large cavities covering multiple cusps may be better restored with a ceramic or gold inlay, which is fabricated in a laboratory and offers greater fracture resistance. Your dentist will advise based on the extent of the cavity at examination.