Dental fillings: types, process and what to expect

What a filling does

When a dentist removes decay from a tooth, the space has to be sealed. A filling does that. It blocks bacteria from getting back in, rebuilds the tooth's shape and strength, and lets you bite, chew and speak comfortably. Most adults need one at some point, and treating a cavity early often avoids a crown or root canal later.

Filling materials

The best material depends on where the cavity is, how large it is, how much bite force the tooth takes and your preferences. Your dentist will go over the options with you.

• Composite resin: a tooth-colored mix of plastic and glass particles that blends in with your tooth. It suits visible teeth and is placed in layers or in a single bulk-fill layer. See our page on composite fillings.
• Porcelain (ceramic): stain-resistant, durable and very natural-looking, but usually costs more than other options.
• Amalgam (silver): a mix of metals that includes silver, tin, copper and mercury. It is strong and affordable, and mostly used on back teeth because it is easy to see.
• Gold: long-lasting, well tolerated by the body and resistant to wear. It is dark and usually the most expensive choice.
• Glass ionomer: releases fluoride to help protect the tooth, but it is less durable than other materials, so it is used mainly in baby teeth.

Are silver fillings safe?

Amalgam contains mercury, which binds the metals into a stable material. Once the filling hardens, the mercury stays locked inside. The American Dental Association, the World Health Organization and the U.S. FDA have supported its safety for the general population. People with metal allergies or sensitivities may be advised to choose another material. Intact amalgam fillings are generally not removed unless there is damage or decay.

Direct and indirect fillings

Direct fillings are shaped and hardened inside the cavity in one visit. They suit small to moderate cavities and minor fractures. Indirect fillings, such as inlays and onlays, are made outside the mouth from impressions of your tooth. They take at least two visits: the first to prepare the tooth and take impressions, with a temporary filling placed in between, and the second to bond the finished piece. They are used for larger damage or when the tooth needs extra strength.

What happens at your appointment

1. Exam. The dentist checks the tooth, often with X-rays, and may use a dye or a small instrument to find decayed or weak areas.
2. Numbing. A gel and then a local anesthetic numb the tooth, and the injection feels like a small pinprick. Nitrous oxide or oral sedation can help if you feel anxious, so tell us beforehand.
3. Removing the decay. The dentist removes the damaged part of the tooth with a handheld instrument, water and suction, or sometimes a laser, and may use a dye to confirm that all the decay is gone.
4. Preparing the tooth. The area is cleaned, disinfected, dried and, for a bonded filling, treated with an adhesive.
5. Placing the filling. The material is placed and shaped. Composite is hardened with a curing light, and amalgam sets on its own in a few minutes.
6. Checking your bite. You bite on a thin piece of marking paper so the dentist can find and smooth any high spot.
7. Polishing. The filling is polished so it feels smooth and blends in with your tooth.

A single filling usually takes under an hour. Several teeth may need more than one visit. Most people go back to work or school afterward. For what comes next, read our aftercare guide.

Wondering whether you need one? See the signs you need a dental filling, or call (781) 289-3331.

Common questions