Dental fillings: materials, what happens and how to look after them

What it is

A filling restores a tooth that has been damaged by decay, wear or a small fracture. The dentist removes the softened or broken part of the tooth, cleans the cavity and packs it with a material that hardens and restores the tooth's shape so you can chew on it again. Fillings are among the most common dental procedures worldwide.

The main materials are:

• Composite resin, a tooth-coloured mixture of resin and glass or quartz filler. The American Dental Association's MouthHealthy site describes it as durable and fracture-resistant in small to mid-sized fillings that take moderate chewing pressure, and suitable for front or back teeth.
• Dental amalgam, a silver-coloured alloy of mercury, silver, tin and copper. The ADA describes it as very durable and generally less expensive than tooth-coloured or gold options.
• Glass ionomer, a tooth-coloured cement that releases fluoride, often used for small fillings, for children's teeth and near the gumline.
• Gold or ceramic inlays and onlays, made in a laboratory and cemented in; these are less common and usually cost more.

Who it is for and when it is recommended

The NHS tooth decay page (reviewed 13 August 2025) sets out a ladder of treatment. Very early decay may be reversed with fluoride treatments such as varnish. Once decay has created a hole (a cavity), a filling is usually needed. If decay reaches the pulp, the soft tissue inside the tooth, root canal treatment may be needed, and a tooth that is too damaged may have to be extracted. Catching decay at the filling stage is therefore considerably less involved than what follows if it is left.

Decay often causes no symptoms at first. It may be found at a routine check-up or on an X-ray before you feel anything. Later signs include toothache, sensitivity to hot, cold or sweet foods and visible white, brown or black spots. A filling may also be recommended to replace an old filling that has cracked or leaked, or to repair a chipped tooth.

What happens at the appointment

1. The dentist confirms which tooth needs treatment, sometimes with an X-ray.
2. A local anaesthetic is usually injected to numb the tooth and surrounding gum. Very small fillings sometimes do not need it.
3. The decayed or damaged tooth material is removed with a drill or hand instruments and the cavity is shaped and cleaned.
4. For composite, the dentist may place a thin rubber sheet or cotton rolls to keep the tooth dry, applies a bonding agent, then builds up the filling in layers, setting each with a blue light. Amalgam and glass ionomer are packed directly into the cavity.
5. The filling is shaped to match the tooth and your bite, then polished.

A single filling typically takes 20 to 60 minutes, depending on size and position.

How to prepare

Tell the dentist about medicines you take, allergies (including any known sensitivity to metals or resins), pregnancy or plans to become pregnant, and any previous reaction to local anaesthetic. Eat beforehand if your appointment is likely to leave you numb for a while. If you are anxious, ask what options the clinic offers to help you feel comfortable. Ask in advance which material the dentist proposes and why, so the decision is made with you rather than for you.

Afterwards and recovery

Numbness from the anaesthetic wears off over one to three hours; take care not to bite your cheek or tongue in that time. Composite fillings are fully set when you leave, so you can eat once the numbness has gone. Amalgam takes longer to reach full hardness, and your dentist may ask you to avoid chewing on that side for a day. Some sensitivity to cold or pressure for a few days to a few weeks is common and usually settles. Contact the clinic if the filling feels too high when you bite, if pain gets worse rather than better, or if the filling cracks or falls out. The NHS dental abscess page (reviewed 18 March 2026) advises urgent dental care for intense toothache with swelling, as an abscess will not go away on its own.

Risks and limitations (sourced)

Fillings do not last forever. They can wear, chip, stain or develop gaps that let decay in, and a tooth with a large filling may later need a crown. Short-term sensitivity is common.

On amalgam, the United States Food and Drug Administration's page on dental amalgam fillings states that amalgam releases low levels of mercury vapour, that available evidence does not show harm in the general population, and that the FDA nonetheless encourages non-amalgam materials, where appropriate, for pregnant women, women planning pregnancy, nursing women, children (especially under six), people with certain neurological or kidney conditions and people with a known sensitivity to mercury or other components. The FDA also says it does not recommend removing intact amalgam fillings, because removal destroys healthy tooth structure and temporarily increases mercury exposure. The World Health Organization's mercury fact sheet (24 October 2024) notes that one target of its Global oral health action plan 2023 to 2030 is for 90 percent of countries to have measures in place to phase down amalgam use in line with the Minamata Convention. Discuss material choice with your dentist rather than relying on marketing claims about any one option.

What affects the cost

Prices vary by country, city and clinic. Common factors:

• Material: composite and ceramic generally cost more than amalgam or glass ionomer.
• Size and number of surfaces the filling covers.
• Position: back teeth are harder to reach and may take longer.
• Whether X-rays and anaesthetic are itemised separately.
• Whether a laboratory makes an inlay or onlay.
• Coverage by a national scheme or insurance.

Ask for an itemised written estimate before treatment. HealthNaro does not publish prices unless they come from a named, dated source.

Questions to ask the provider

1. Which material do you propose for this tooth, and what are the alternatives?
2. How large is the cavity, and is a filling still appropriate or is a crown or root canal likely?
3. How long would you expect this filling to last, and what shortens its life?
4. Will the filling be covered by a scheme or insurance I hold?
5. What should I do if the tooth is still sensitive after a few weeks?
6. Can I have the price in writing before we start?

How to find and check a provider

HealthNaro lists dental clinics and dentists with a verification label on every listing. Public listing means the details came from public sources and have not yet been checked. Contact verified means the provider has confirmed their phone number and email address. Reviewed by HealthNaro means our team has looked over the listing's details. Credentials verified means we have seen a licence or registration document. A label describes what has been checked; it is not a recommendation or a ranking, and HealthNaro does not endorse any provider.

Check the dentist's registration with your national dental regulator and ask for a written treatment plan. You can browse providers under General Dentistry. If you would like help finding a suitable clinic, our consulting service is free: send a request through the inquiry form and we will come back to you with options. You choose whom to contact.

This guide is general information, not dental advice. Speak to a registered dentist about your own situation.