Tooth-Coloured Fillings: Composite, Glass Ionomer, and the Modern Standard

Tooth-coloured fillings — sometimes called “white fillings” — have largely replaced silver amalgam in modern UK dentistry for both clinical and cosmetic reasons. Within the white-filling category, several distinct materials serve different clinical purposes. Here is the practical map.

Why tooth-coloured fillings have replaced amalgam

The shift from silver amalgam to composite resin in UK dentistry has accelerated since 2020, driven by:

• Patient preference for tooth-coloured aesthetics.
• Adhesive bonding means modern composite bonds to the tooth structure, allowing more conservative preparation. Amalgam requires mechanical retention and removal of healthy tooth structure to anchor the filling.
• Mercury reduction under the Minamata Convention. The EU has restricted amalgam use in pregnant women, children under six, and breastfeeding women since 2018, with broader phase-down through 2025.
• Improved durability of modern composite materials. The 7–10 year average lifespan of composite has narrowed the gap with amalgam (12–15 years average).

The main tooth-coloured filling materials

Composite resin (the workhorse)

A mix of resin matrix and ceramic filler particles. Available in multiple shades to match natural teeth. Light-cured to harden in seconds. Used for front tooth fillings, back tooth fillings of small to medium size, cosmetic shape changes (composite bonding), repair of chipped teeth. Lifespan 7–10 years average for posterior cases.

Glass ionomer cement

A glass-ionomer chemical reaction creates the bond and the material structure. Releases fluoride into surrounding tooth structure. Used for high-caries-risk patients, children’s fillings, root surface fillings, temporary fillings. Less aesthetic than composite. Lifespan 5–7 years for posterior cases.

Resin-modified glass ionomer

A hybrid of composite and glass ionomer — the bonding and fluoride release of glass ionomer with some of the strength and aesthetics of composite. Used as a middle-ground material in specific clinical situations.

Indirect composite onlays

For larger restorations where direct chairside composite would be overstressed, lab-fabricated composite onlays bonded into the tooth.

The procedure

• Local anaesthesia for moderate to deep cavities.
• Decay removed with high-speed handpiece, conservative shape preparation.
• Tooth isolated with rubber dam.
• Etched with phosphoric acid for 15–30 seconds.
• Bonding agent applied and light-cured.
• Composite placed in 2 mm layers, each layer light-cured for 20 seconds.
• Shaped, contoured, polished.

Total chair time 30–60 minutes per tooth depending on size.

What to expect after

• Local anaesthesia wears off over 2–4 hours; eat carefully during this period.
• Mild sensitivity to cold for 1–2 weeks is common, particularly in deeper restorations.
• Bite may feel slightly different until you adapt over a few days.
• If bite feels unevenly high after numbness wears off, return for adjustment.

Longevity factors

The variables affecting composite lifespan: filling size, tooth position, bite forces (bruxism), hygiene quality, and quality of original placement (moisture control during bonding is critical). Replacement at 7–10 years is realistic for medium posterior fillings.

Replacing old amalgam fillings

If your existing amalgam fillings are intact, the BDA advises leaving them in place. Removing intact amalgam releases more mercury vapour during drilling than the filling releases over its remaining lifetime. Replacement is appropriate for fracture, recurrent decay, sensitivity, or specific medical/allergy contraindications. Our amalgam guide covers safety considerations.

The bonding question

Modern composite is bonded — chemically attached to the tooth structure rather than mechanically held. The bond is what allows conservative preparation. Quality of moisture control during bonding is the single biggest factor in long-term success. Rubber dam isolation is best practice; clinics that consistently use rubber dam typically have better restorative outcomes.

For UK patients

NHS Band 2 covers composite fillings for posterior teeth where clinically appropriate. Front tooth composite is universally NHS where indicated. Cosmetic-only replacement of amalgam is private. Pricing for cosmetic restorative work is part of broader treatment packages — see the packages page.

Frequently asked questions

Are tooth-coloured fillings as good as silver fillings?

Modern composite fillings last 7–10 years on average compared to 12–15 years for amalgam — the gap has narrowed substantially. The trade-off is composite’s tooth-coloured appearance, adhesive bonding (less drilling), and absence of mercury, vs amalgam’s longer lifespan.

Will my insurance cover white fillings?

NHS coverage for posterior composite varies — Band 2 covers it where clinically appropriate; some practices interpret this strictly and charge privately for posterior composite. Front tooth composite is universally NHS. Private dental insurance varies; check policy specifics.

Is composite filling safe?

Yes — composite resin and the bonding agents used are biocompatible and have decades of clinical safety data. BPA concerns relate to certain older composite formulations; modern materials use BPA-free chemistry.

How long does a tooth-coloured filling last?

Average lifespan 7–10 years for medium posterior fillings; longer for anterior teeth and small fillings. The variables that reduce lifespan are bruxism, large filling size, recurrent caries around the margin.