Tooth-Coloured vs Silver Fillings: What to Know

If you had fillings done some years ago, some of them may well be dark silver ones. Tooth-coloured fillings are now widely used, and patients often ask whether the white ones are better, whether silver fillings are safe, and whether the old ones should be swapped. This guide gives a balanced answer.

The two materials

Fillings repair a hole in a tooth caused by decay. The two most common types are white (composite) fillings and amalgam, a mixture of mercury, silver, tin and copper. Your dentist offers the most suitable type for your clinical needs (NHS).

Composite (tooth-coloured)

A tooth-coloured resin is placed in layers, each hardened with a special light, then shaped and polished to match the tooth. Because it bonds to the tooth, the dentist usually has to remove less healthy tooth to hold it in place. It can also repair chips and small gaps on front teeth.

Amalgam (silver)

Amalgam is packed into the cavity and hardens. It does not bond to the tooth, so the cavity is shaped to lock it in, which can mean removing a little more tooth. It is strong, tolerant of moisture while it is placed, and has a very long track record.

What happens during a tooth-coloured filling

1. 1

   Examination

   Your dentist checks the tooth, with an X-ray where needed, to see how deep the decay goes.

2. 2

   Numbing and cleaning

   The tooth is numbed with local anaesthetic and the decayed or damaged part is removed.

3. 3

   Keeping it dry

   The tooth is isolated from saliva, because composite bonds best to a clean, dry surface.

4. 4

   Filling in layers

   The resin is placed in thin layers, each hardened with a special light.

5. 5

   Shaping and polishing

   The filling is shaped to your bite and polished so it blends in and feels smooth to your tongue.

Side by side

What the evidence says about lifespan

A 2021 Cochrane review compared composite and amalgam fillings in back teeth. Combining two large trials in children, it found low-certainty evidence that composite fillings had almost double the risk of failure and a higher risk of new decay at the edge of the filling, but not a higher risk of the filling breaking (Worthington et al., 2021).

There are important caveats. The trials were at high risk of bias, and the review authors note that composite materials have improved considerably since those trials were run. In everyday practice, how long any filling lasts also depends on its size, where it is, how well it was placed, your bite, grinding habits and how much sugar you have.

Are silver fillings safe?

This is the question patients ask most. The same Cochrane review looked at possible harms. Children with amalgam fillings had higher mercury levels in their urine, but below levels known to be toxic, and the review found no consistent or clinically important harms for either material, though the evidence on harms was of very low certainty (Worthington et al., 2021).

Separately, countries that have ratified the international Minamata Convention on Mercury commit to measures that phase down mercury use, including dental amalgam, to protect health and the environment from mercury released by human activity (Worthington et al., 2021).

Should old silver fillings be replaced?

Not automatically. Drilling out a sound filling removes some healthy tooth every time, and each replacement makes the next one larger. Replacement makes sense when:

• the filling is cracked, chipped or loose;
• there is decay underneath or at the edge;
• the tooth has a crack near the filling;
• the filling is in a visible place and you would like it to look natural, accepting the trade-off above.

If a filling is very large, or the tooth has had a root canal, a crown may protect it better than another filling. See Do you need a crown after a root canal?.

Looking after any filling

• Brush twice a day with fluoride toothpaste and clean between your teeth daily; spit after brushing rather than rinsing (NHS).
• Keep sugary snacks and drinks to mealtimes.
• After a new filling, wait for the numbness to wear off before eating. Some sensitivity for a few days can be normal; tell your dentist if it lasts.
• Keep up check-ups, so worn edges or new decay are caught while they are small. See how often to see a dentist.

This article is general information, not a diagnosis or treatment plan. What suits you depends on an examination at the clinic, and every treatment plan and cost is explained before treatment begins.

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