A filling is one of the most common dental procedures. It’s basically a repair job to fix the damage done by tooth decay. It’s typically a painless procedure and generally takes about an hour.

Cavities are common in the United States. According to the National Institutes of Health, about 92 percent of U.S. adults ages 20 to 64 have had a cavity. A filling helps prevent further decay and allows your tooth to function normally.

Keep reading to learn more about what to expect if you need a filling, the materials that are most commonly used, and how long it takes for a filling to set and heal.

Fillings are generally a simple procedure. To start, your dentist will examine your mouth and use dental instruments to check the cavity. They may take an X-ray of the tooth or teeth to see the extent of tooth decay.

You’ll have a local anesthetic to numb the tooth area. This will help prevent any pain. You may not need an anesthetic if the filling is just on the tooth surface.

Once the area is numb, your dentist will most likely use a dental drill to drill through the tooth enamel to remove the decay. Some dentists may use a laser or an air abrasion tool, but these techniques are less common.

Next, your dentist will sterilize and prepare the area for the filling and then fill the hole. Some types of fillings are hardened, or cured, with a blue wavelength light.

Finally, your dentist will polish the tooth and check to make sure that your bite is correct.

Once the numbing has worn off, your tooth may feel a little sore or sensitive after the filling, but you shouldn’t have any pain. You should avoid very hot or very cold foods and drinks for a day or two, but for the most part, you can eat normally.

In general, a filling takes an hour or less. A simple filling may take as little as 20 minutes. A larger filling or multiple fillings can take longer.

Also, depending on the materials used for the filling, it could take longer, or require a second visit. For instance:

  • Composite resin material that’s layered into your tooth takes more time, but it’s completed in one visit.
  • Some composite fillings may be made from an impression and require a second visit to bond the filling.
  • Gold or porcelain fillings, also called inlays or onlays, usually can’t be done in one sitting. In the first visit, the cavity will be removed and an impression will be made of your tooth, which is sent to a lab to fabricate the filling. In the next visit, the filling is bonded to your tooth.

Replacing an older filling takes about the same amount of time as the original filling or slightly longer if the old filling material has to be drilled out. The cavity and old filling material are cleaned out and new filling material inserted.

Your dentist will discuss the various materials that can be used to fill your cavity. Some of the most widely used options include the following materials:

  • Silver-color fillings. These are metal amalgams — a combination of mercury, silver, tin, and copper. This material is more durable than tooth-color fillings and generally more affordable than other materials. Some people may have concerns about the mercury content, but experts have found no clinical evidence that amalgam fillings are harmful, though they are being phased out.
  • White tooth-color fillings (composites). These are a mix of glass or quartz particles and acrylic resin. This material is durable and costs a little more than metal amalgams.
  • Gold fillings. This mix of gold, copper, and other metals is very durable but more expensive. They’re also not natural looking. Gold fillings are usually made in a lab after the dentist takes an impression of your tooth.
  • Glass ionomer fillings. These are also tooth-colored but not as strong as composites. They’re made of acrylic and a type of glass that contains fluoride which can help prevent cavities. They’re often used for children’s teeth and are more expensive than amalgams.
  • Porcelain fillings. These, while about as expensive as gold fillings, look natural. They’re made in a lab after the dentist takes an impression of your tooth.

According to Kenneth Rothschild, DDS, who has 40 years of experience as a general dentist, composite plastics have been used with more success over the last few decades because of their greater strength, better color varieties, and superior expected longevity.

“Composites may be used not only for fillings placed in more aesthetically sensitive front areas but also on posterior teeth, such as molars and bicuspids,” he explained.

How long your filling will take to set depends on the material your dentist uses.

According to Rothschild, amalgam fillings set weakly in 1 hour and are at full strength in about 24 hours. With this type of filling, it’s best to avoid eating hard foods until the filling has completely set.

Composite fillings and glass ionomer fillings are usually light cured. They are set in 1 to 2 millimeter thick layers, Rothschild said, taking about 2 to 20 seconds per layer.

Ceramic fillings set immediately, with the aid of the dentist’s blue wavelength light. “It’s already milled or fired, and the bonding adhesive that holds it in place is cured in seconds,” Rothschild explained.

Most fillings heal quickly with no problem. After the anesthetic wears off, your tooth may feel a little sensitive, but this usually goes away in a day or so.

“Metal fillings, like amalgam and gold, occasionally have a period of post-op cold sensitivity for a few days or even weeks,” Rothschild said. “This is less likely but still possible with a bonded composite or glass ionomer filling.”

You can reduce tooth sensitivity by:

  • chewing on the other side of your mouth for a couple of days
  • brushing and flossing more gently than usual around the filling
  • avoiding hot or cold food or drinks
  • avoiding acidic foods
  • using a desensitizing toothpaste
  • taking a nonsteroidal anti-inflammatory drug (NSAID)

Let your dentist know if your bite feels off, or if you have any long-lasting pain or sensitivity. Your dentist may need to adjust the filling surface to improve your bite.

How long your filling lasts depends, in part, on your dental hygiene. Diligent dental care can extend the life of your filling and prevent a new cavity from forming on your tooth. The lifetime of a filling can also vary depending on the materials used.

Remember that everyone’s teeth and lifestyle are different, so these timeframes can vary from person to person. In general:

  • amalgam fillings last 5 to 25 years
  • composite fillings last 5 to 15 years
  • gold fillings last 15 to 20 years

If you see your dentist for regular checkups, they’ll find cavities early. The sooner a cavity is treated, the better the outcome for your tooth, and the less invasive the treatment is likely to be. So it’s a good investment to get regular dental checkups.

Usually, there are some warning signs of a cavity, such as:

  • teeth sensitivity to hot or cold foods and drinks
  • sensitivity to sugary foods and drinks
  • ongoing ache in a tooth
  • a hole or pit in a tooth
  • a tooth stain, either white or a darker color

If you suspect you may have a cavity, make sure to visit your dentist. They can determine whether you need a filling or other treatment.

Dental fillings are very common and typically aren’t painful. The procedure usually takes about an hour for a standard, uncomplicated filling.

Ask your dentist about the pros and cons of possible filling materials for your tooth. They can also let you know the best way to care for your filling.

If you have dental insurance, check to find out what types of fillings are covered. Your insurance may not cover more expensive materials.

With diligent dental hygiene, you can expect your fillings to last for many years.