Amalgam to White Fillings

Should They Be Replaced at All?

In some cases yes, in others no. Amalgam, a silver-grey blend of mercury with silver, tin and copper, has filled back teeth since the 1800s and is remarkably durable. Official UK advice is that amalgam fillings in good order are safe and do not need to be removed. Each time a filling is redone the cavity grows a little, so replacing a sound one sacrifices a small amount of healthy tooth.

Sensible reasons to change a filling include:

• You can see it when you smile or laugh, and would rather not
• A crack has formed, or a dark line or gap shows along its edge
• The X-ray shows decay starting beneath or beside it
• The tooth around it is cracked, or part of it has broken away
• It traps food, feels rough against your tongue, or the tooth has become sensitive

At your examination we go through every filling you have and give you a straight answer about which ones are failing, which remain sound, and which you might choose to change purely for looks.

The Mercury Question

Amalgam releases tiny amounts of mercury vapour, chiefly when it is being placed or drilled away. UK health guidance holds that the quantities released by fillings that are intact are too small to cause harm. As a precaution, it has not been used since 2018 in children under 15 or in women who are pregnant or breastfeeding, unless there is a compelling clinical reason.

Tell your dentist about any specific health concern or any known allergy to one of the metals. We will discuss it openly without steering you one way or the other. During pregnancy we would normally advise leaving sound amalgam alone until after the birth and the end of breastfeeding, because drilling it out is the point at which exposure peaks.

What Goes in Its Place

The best replacement depends on how large the old filling was and how much tooth is left around it.

• Composite (white filling). Small and medium cavities. A tooth-coloured resin that is bonded in and sculpted on the spot, in a single appointment
• Ceramic onlay. Big fillings, or teeth with walls that have worn thin. Built by a technician from a scan, then bonded in at a follow-up visit. It covers the cusps and guards against the tooth splitting
• Ceramic crown. Teeth that are already mostly filling, or that have cracked. Covers the whole tooth

Composite, unlike amalgam, bonds to the tooth, so less of the healthy structure has to be removed to keep it in. Where a back tooth has a large cavity, a ceramic onlay will outlast the alternatives. How we make the decision is explained in our filling, onlay or crown guide.

What It Costs

You get every fee in writing before treatment begins. ¹ The NHS does not cover replacing a sound filling purely to change its colour, so that is always private. A filling that is genuinely failing can be replaced under NHS care where you are registered as an NHS patient.

Removing the Old Filling

1. First, an X-ray reveals how deep the amalgam reaches and whether decay lurks beneath it
2. Numbing gel goes on first, then local anaesthetic
3. Where it is practical, a rubber dam is stretched over the tooth, separating it from the rest of your mouth, keeping the area dry and catching any debris
4. The amalgam is removed carefully, with powerful suction running throughout to capture particles and vapour
5. Any decay underneath is cleared and the cavity readied for its new filling
6. Composite is placed in thin layers, each one set with a curing light, and is then trimmed and polished to fit your bite. Where an onlay is planned, we instead take a digital scan with the iTero Lumina and fit a temporary that protects the tooth until the fitting visit

Expect 30 to 60 minutes for one filling. Expect two or three hours of numbness afterwards, so steer clear of hot drinks and chewing until feeling returns.

All at Once, or in Stages?

Our usual order is failing fillings first, then those most on show, leaving intact fillings in the rear molars alone until they actually need attention. Replacing everything in one go brings no health advantage, and many patients are content to change only the visible ones.

If you would like several replaced for cosmetic reasons, we can bundle them into a couple of longer appointments, treating one side of the mouth at a time so you always have a comfortable side to chew on. Thinking about whitening too? Do that first. Composite is colour-matched to your teeth as they are now and will not lighten later, so we would whiten with our home whitening kit, £350, give the colour a fortnight to settle, and then match the new fillings to the result.

How Strong, and How Long

Today's composites are strong enough for most back teeth and give many years of service in small and medium cavities. They are more demanding to place than amalgam, since the tooth has to stay bone dry while the bond forms, which is partly why we use a rubber dam. For the largest cavities a ceramic onlay generally lasts longer than composite: it is laboratory-made, does not shrink on setting and shields the cusps.

Look after new white fillings the way you look after your teeth: twice-daily brushing with a fluoride toothpaste and daily cleaning between the teeth. Composite can take on slight staining from coffee, tea, red wine and tobacco, which a polish at your hygiene appointment removes. Mild cold sensitivity for a week or so is normal. If biting makes the tooth ache, the filling may be fractionally high, and a five-minute adjustment puts that right. Grinders should consider a night guard, £210, to protect the new work.

Questions

This guide is general information, not a diagnosis. A dentist needs to examine you to say what is right for your teeth.