Oral Health›Dental visits and treatments

Fillings and Root Canal Treatment: What to Expect

A filling repairs a tooth damaged by decay or injury. When the soft tissue inside the tooth is infected, root canal treatment can often save the tooth. Here is what each involves and how to look after your tooth afterwards.

Updated September 2026·By the OHA editorial team·8 min read·How we write
Key takeaways
  • A filling repairs a hole (cavity) in a tooth. Common materials are tooth-coloured composite resin, glass-ionomer cement and silver-coloured amalgam.
  • Health bodies in Australia and the US say amalgam is safe for most people and that fillings in good condition do not need replacing. It is being phased out worldwide under a global treaty on mercury.
  • Root canal treatment removes infected tissue from inside a tooth, then seals it, under local anaesthetic.
  • Back teeth often need a crown afterwards to protect them from breaking.
  • Get urgent help for a swollen face or jaw, a high temperature, or trouble breathing, swallowing or opening your mouth.

Fillings repair holes in teeth, and healthdirect Australia describes root canal treatment as a common dental procedure. Our guide to tooth decay explains how the damage starts.

What is a filling?

The Better Health Channel (Victoria) explains that a filling repairs a decayed, worn or damaged tooth. The dentist removes the decay, usually with a drill, then fills the hole with a material that sets hard. If needed, the tooth is numbed first with a local anaesthetic (an injection that numbs the area while you stay awake). The Better Health Channel adds that an intact tooth is stronger than a filled one.

What are fillings made of?

The Australian Dental Association says the best material depends on where the tooth is, how your teeth bite together and the size of the filling.

  • Composite resin is tooth-coloured and glued (bonded) to the tooth. Because it sticks to the surface, the Australian Dental Association says less healthy tooth needs to be cut away than for amalgam.
  • Glass-ionomer cement is also tooth-coloured but, according to healthdirect, not as strong as composite. The Australian Dental Association notes that it contains fluoride and is often used for temporary fillings.
  • Amalgam is the silver-coloured material used for more than 150 years. healthdirect describes it as very strong. It does not bond to the tooth, so the Australian Dental Association says more tooth has to be cut away, and it can darken over time.
  • Gold and porcelain fillings are made in a laboratory and need at least two visits.

The NHS in England provides white fillings when clinically necessary, for example on front teeth. For back teeth it says amalgam may be more effective, and a white filling may have to be paid for privately.

Is amalgam safe?

Amalgam is about half mercury by weight, mixed with silver, tin and copper, according to the US Food and Drug Administration (FDA). The main health bodies say it is safe for most people:

  • The FDA says the available evidence does not show that mercury from amalgam harms the general population. For groups who may be more sensitive, such as pregnant or breastfeeding women, children under 6 and people with kidney problems or a metal allergy, it encourages other materials where suitable.
  • The American Dental Association says no properly designed study has shown that amalgam causes long-term health effects.
  • The Australian Dental Association says it remains a safe option where clinically needed, and that dentists should minimise its use in children, pregnant or breastfeeding women and people with kidney disease.

The FDA and the American Dental Association advise against removing amalgam fillings in good condition because of mercury worries: removal takes away healthy tooth and, the FDA says, briefly increases mercury exposure.

What regulators are doing

Amalgam is being phased out anyway.

  • Worldwide: the World Health Organization (WHO) reports that countries in the Minamata Convention, a treaty to protect health and the environment from mercury, agreed in 2025 to move to a complete phase-out by 2034. The Australian Dental Association notes that the treaty still allows a dentist to use amalgam where a patient's needs make it necessary.
  • European Union: use of amalgam has been banned since 1 January 2025, according to a UK government explanatory memorandum.
  • UK: since July 2018, amalgam has been restricted for children under 15 and pregnant or breastfeeding women unless the dentist judges it strictly necessary. Northern Ireland's Department of Health says the EU regulation behind these rules was introduced for environmental reasons rather than patient safety. In Great Britain, the UK's own version of the earlier EU rules still applies, according to the same memorandum. Northern Ireland, which follows current EU rules, may continue to use amalgam until the end of 2034 at the latest.
  • US: the American Dental Association says the treaty decision is non-binding, and the US government had not commented on it as of February 2026.

What happens after a filling?

The tooth may be sensitive to hot, cold or biting. The Australian Dental Association says this usually settles within a few days but can last 1 or 2 weeks; healthdirect suggests going back if it has not settled after a few days.

Fillings do not last forever. The Australian Dental Association explains that the join between filling and tooth can open over time and let in bacteria that cause new decay. The Better Health Channel says to see your dentist as soon as possible if part of a filling breaks off or it falls out.

What is root canal treatment?

The pulp is the soft tissue inside a tooth, containing nerves and blood vessels. The NHS says it can become infected because of tooth decay, gum disease, a chipped or cracked tooth, or a dental abscess (a build-up of pus). Root canal treatment removes the infected pulp, then cleans, fills and seals the inside of the tooth. The Australian Dental Association says the alternative is usually to take the tooth out.

The Australian Dental Association's list of warning signs includes severe pain that painkillers do not ease, pain when biting, a pimple on the gum next to a tooth, and lingering pain from hot or cold.

What happens during treatment?

According to the NHS, healthdirect and the Australian Dental Association:

  1. The dentist takes an x-ray and numbs the area with local anaesthetic.
  2. A thin rubber sheet (a rubber dam) is placed around the tooth to keep it clean and dry.
  3. A small opening is made in the tooth and the pulp is removed.
  4. The canals are cleaned, shaped and disinfected. A temporary filling may be placed between visits.
  5. The canals are filled and sealed, and the tooth is restored with a filling or crown.

The NHS says this usually takes 2 or more appointments; the American Dental Association (MouthHealthy) says 1 or 2. It may be done by your dentist or an endodontist (a root canal specialist). If you feel nervous, see dental anxiety.

Recovery

The NHS says your jaw may stay numb for several hours, and the area may feel swollen and sore but should improve within a couple of weeks. It advises paracetamol or ibuprofen if needed and going to any follow-up appointments. The American Association of Endodontists says most people can go back to work or school straight away, but should not eat until the numbness wears off.

Will I need a crown?

A crown is a cap that covers the whole tooth. The Oral Health Foundation (UK) explains that a tooth without a living nerve can become brittle. The Australian Dental Association says back teeth are often crowned after root canal treatment because they take heavy chewing forces, and cites a study finding that root-treated teeth without a crown were 6 times more likely to be removed.

How long does a root-treated tooth last?

Sources differ. The Better Health Channel says about 90 to 95 per cent of people can expect a working tooth afterwards. The American Association of Endodontists and the American Dental Association say most treated teeth can last a lifetime with proper care. The Oral Health Foundation gives a more cautious average of 5 to 10 years, adding that many last much longer. The tooth can still decay, so cleaning between your teeth and check-ups still matter. If a tooth cannot be saved, see replacing missing teeth.

When to see a dentist
  • Sensitivity after a filling is not settling, or is getting worse.
  • A filling has cracked, chipped or fallen out.
  • You have lingering pain from hot or cold, pain when biting, or a pimple on the gum next to a tooth.
  • Pain or swelling after root canal treatment is not improving.
Get help urgently
  • Ask for an urgent dental appointment if you think you have a dental abscess: intense toothache, a swollen face or jaw, a bad taste in your mouth or a high temperature. In the UK, the NHS says to call your dentist or NHS 111. In Australia, healthdirect advises an urgent appointment for severe pain or swelling, and its helpline (1800 022 222) can advise 24 hours a day.
  • Call emergency services or go to an emergency department if you are finding it hard to breathe, speak or swallow, have a swollen or painful eye or problems with your eyesight, have a lot of swelling in your mouth, or are finding it hard to open your mouth.

Frequently asked questions

Should I have my old amalgam fillings replaced?

Not if they are in good condition. The Australian Dental Association says there is no evidence that replacing sound amalgam fillings without a clinical reason improves health. If you have a mercury allergy or kidney disease, the FDA suggests discussing it with your dentist or doctor.

Does root canal treatment hurt?

The Oral Health Foundation says that, with local anaesthetic, it should feel similar to having a filling, though the tooth may be tender for a few days.

Why can't I just take antibiotics for an infected tooth?

healthdirect says antibiotics alone do not cure a root canal infection: the infected tissue has to be removed. The American Dental Association (MouthHealthy) says antibiotics may be added if the infection has spread.

Sources

  1. Dental fillings, Better Health Channel (Victoria), accessed September 2026
  2. Dental fillings, healthdirect Australia, accessed September 2026
  3. Fillings, Australian Dental Association, accessed September 2026
  4. Policy Statement 6.18: Safety of Dental Amalgam, Australian Dental Association, accessed September 2026
  5. How much NHS dental treatment costs, NHS, accessed September 2026
  6. Dental amalgam fillings, US Food and Drug Administration, accessed September 2026
  7. Dental amalgam, American Dental Association (MouthHealthy), accessed September 2026
  8. ADA statement on use of dental amalgam in the U.S., American Dental Association, February 2026, accessed September 2026
  9. Oral health care and the environment, World Health Organization, accessed September 2026
  10. Explanatory memorandum to the Control of Mercury (Enforcement) (Amendment) Regulations 2025, UK Department for Environment, Food and Rural Affairs, accessed September 2026
  11. Phase down plan for amalgam fillings published, Department of Health (Northern Ireland), accessed September 2026
  12. Health Minister welcomes EU derogation for NI, Department of Health (Northern Ireland), accessed September 2026
  13. Root canal treatment, NHS, accessed September 2026
  14. Dental abscess, NHS, accessed September 2026
  15. Root canal treatment, healthdirect Australia, accessed September 2026
  16. Root canal treatment, Better Health Channel (Victoria), accessed September 2026
  17. Root canal treatment, Australian Dental Association, accessed September 2026
  18. Root canals, American Dental Association (MouthHealthy), accessed September 2026
  19. What is a root canal?, American Association of Endodontists, accessed September 2026
  20. Root canal treatment, Oral Health Foundation, accessed September 2026

This article is general information about oral health. It is not a diagnosis or a substitute for advice from a dentist or doctor who knows your situation. If you have pain, swelling, bleeding that does not settle, or a problem that is getting worse, see a dental professional. In an emergency, contact your local emergency service.

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