Cavities and fillings: how tooth decay is treated

A cavity is a hole in a tooth caused by decay. Decay is often slow and may not hurt at first, which is one reason regular check-ups matter.

How cavities form

Decay starts when plaque bacteria damage the surface of a tooth over time. It is more likely when sugary food and drink are frequent and teeth are not cleaned well every day.

Early decay may cause no symptoms. As it gets worse you may notice toothache, sharp pain with hot, cold or sweet things, or white, brown or black spots on a tooth. A dentist can sometimes reverse very early decay with fluoride treatment. Once a hole has formed, a filling is usually needed.

What happens when a tooth is filled

Your dentist will usually numb the area first. The decayed part of the tooth is then removed and the space is filled with a material that restores the tooth. Some materials are set with a special light.

Your lip, cheek or tongue may stay numb for a while afterwards. Take care not to bite them, and wait until feeling returns before having very hot drinks.

Filling materials

• Tooth-coloured (composite) fillings blend with the natural tooth and bond to it. They can be used on front or back teeth. They can take longer to place and may need replacing sooner than some other materials.
• Silver-coloured (amalgam) fillings are made from a mix of metals. They are strong and quick to place, but they are more noticeable and may need more of the tooth to be prepared. Dental organisations describe amalgam as a safe filling material, and your dentist can talk through your own situation.

Your dentist will suggest the material that suits the tooth and your needs. No filling lasts forever, so regular check-ups help your dentist spot a worn or damaged filling early.

Looking after a filled tooth

A newly filled tooth may feel sensitive for a short while. If sensitivity or pain does not settle, or it hurts when you bite, tell your dentist so it can be checked.

• Brush twice a day with fluoride toothpaste
• Clean between your teeth every day
• Have sugary food and drink less often
• Keep up regular check-ups

When to see a dentist

• Toothache, or sharp pain with hot, cold or sweet food
• A visible hole or dark spot on a tooth
• A filling that has cracked, loosened or fallen out
• Pain or swelling in the gum, cheek or jaw

Get urgent help now if swelling is spreading across your face or neck, or if you have trouble breathing or swallowing.

• Learn about Tooth Filling →
• Book an appointment →

Educational information. It does not replace advice from your dentist or doctor.