What Is A Filling? Key Information

A dental filling is a material used to repair a tooth damaged by decay, cracks, or wear, restoring its function and shape while preventing further damage. The dentist removes the decayed portion of the tooth, cleans the area, and fills the cavity with a chosen material. This stops the decay from spreading deeper into the tooth, where it could cause infection, pain, or the need for a root canal. Without a filling, a cavity will only get larger and more problematic over time.

What materials are used for dental fillings?

There isn’t one best material for everyone. The right choice depends on the tooth’s location, the size of the cavity, your budget, and your dentist’s recommendation. Each material has strengths and weaknesses.

Amalgam fillings have been used for over 150 years. They are a mix of metals including silver, tin, copper, and mercury. Research shows they are extremely durable and can last 10 to 15 years or longer. They are also the least expensive option. The main downside is their dark silver color, which stands out against natural teeth. Some people worry about the mercury content, but the American Dental Association and the FDA have stated that amalgam is safe for most adults and children over six. The mercury is bound to the other metals and not released in harmful amounts.

Composite resin fillings are made of a tooth-colored plastic and glass mixture. They are popular because they can be matched to the shade of your tooth, making them nearly invisible. Studies have found they bond well to the tooth structure, which can help strengthen it. However, they are not as durable as amalgam, especially for large cavities on back teeth used for chewing. They typically last 5 to 7 years before needing replacement. They also cost more than amalgam.

Gold fillings, also called inlays, are custom-made in a lab and then cemented into place. They are extremely durable, often lasting 15 to 20 years or more. Gold does not corrode and is very strong. The downsides are the high cost, which can be several times more than other materials, and the obvious gold color. This procedure also usually requires two dental visits.

Ceramic fillings, usually made of porcelain, are another tooth-colored option. They are very strong and resistant to staining. They can last 10 to 15 years. They are more expensive than composite but less than gold. They can be brittle if the filling is thin, and the procedure often requires two visits as well.

How do I know if I need a filling?

Tooth decay is the most common reason for a filling, but it is not the only one. You might need a filling if you have a cracked tooth, a worn-down surface from grinding, or a damaged filling from an old procedure. The symptoms are not always obvious at first.

Pain is the most common sign. This can be a sharp pain when eating something sweet, hot, or cold. It can also be a dull ache that comes and goes. Sensitivity that does not go away quickly after eating or drinking is another clue. You might see a visible hole or dark spot on your tooth. Some people feel a rough edge with their tongue. Sometimes there are no symptoms at all, which is why regular dental checkups are important. Your dentist can spot early decay with an exam and X-rays before you feel anything.

As of 2026, current research suggests that some early-stage cavities can be reversed without a filling. This process is called remineralization. It requires excellent oral hygiene, a low-sugar diet, and fluoride treatment. But once a cavity has broken through the enamel surface, a filling is the only reliable way to stop it from getting worse. Ignoring it will not make it go away.

What happens during a filling procedure?

The process is straightforward and usually takes less than an hour for a single tooth. Your dentist will first numb the area around the tooth with a local anesthetic. You will feel a small pinch from the needle, but the numbing works quickly. If the cavity is very small, some dentists may skip the anesthetic.

Once you are numb, the dentist uses a drill, laser, or air abrasion tool to remove the decayed part of the tooth. You may feel vibration and pressure, but not pain. The dentist then cleans the cavity to remove any bacteria or debris. For composite fillings, the tooth is etched with a mild acid gel to help the material bond. For amalgam, the cavity is shaped to hold the filling in place mechanically.

The filling material is then placed in layers. For composite, each layer is hardened with a special blue light. The dentist shapes and smooths the filling to match your natural tooth bite. They will ask you to bite down on a piece of paper to check the fit. Any high spots are filed down. The whole process is precise but routine for most dentists. Some people report minor sensitivity to cold or pressure for a few days after, but this usually fades quickly.

What are the risks or side effects of fillings?

Most people have no problems after a filling. But there are some common issues to be aware of. Sensitivity to temperature is the most frequent side effect. It usually goes away within a few days or weeks. If it persists, it may mean the filling is too high or there is a deeper issue.

Pain when biting down is another common problem. This usually means the filling is slightly too high. A simple adjustment by your dentist fixes this quickly. Do not wait too long, as it can cause tooth or jaw pain.

Allergic reactions are rare. They are more likely with amalgam due to the metals. Symptoms include skin rashes or mouth sores near the filling. If you have a known metal allergy, tell your dentist before the procedure. Composite or ceramic fillings are better options in this case.

Fillings do not last forever. They can chip, crack, or wear down over time. They can also pull away from the tooth, creating a gap where bacteria can get in and cause new decay. This is called recurrent decay. It is one reason why regular dental checkups are important even after you get a filling. Your dentist can spot a failing filling before it causes a bigger problem.

How can I make a filling last longer?

Your daily habits matter more than the filling material itself. Good oral hygiene is the foundation. Brush twice a day with fluoride toothpaste and floss once a day. This removes plaque and food particles that cause decay at the edges of the filling.

Watch what you eat. Sticky and hard foods can pull out or crack a filling. Chewing ice, hard candy, or popcorn kernels is risky. Sugary foods and drinks feed the bacteria that cause decay around the filling. Limiting sugar intake protects both your fillings and your natural teeth.

If you grind your teeth at night, talk to your dentist. Grinding puts extreme pressure on fillings, especially on back teeth. A custom night guard can protect your teeth and your fillings from this damage. Many people grind without knowing it, so ask your dentist if you wake up with jaw pain or headaches.

See your dentist regularly. Most people need a checkup every six months. Your dentist can check your fillings for wear, cracks, or gaps. They can also clean areas that are hard to reach with brushing and flossing. Catching a small problem early is much easier than fixing a big one later.

Common misconceptions about fillings

Many people believe that fillings are permanent. They are not. All fillings will eventually need replacement. The lifespan depends on the material, the size of the filling, and how well you care for your teeth. Think of a filling as a repair, not a one-time fix.

Another myth is that a filling will stop all tooth pain. A filling only fixes the damage that was already there. If the decay was deep and close to the nerve, you may still have some sensitivity afterward. This is normal and usually fades. If the pain is severe or gets worse, it could mean the nerve is damaged and a root canal is needed.

Some people think that amalgam fillings are dangerous because of mercury. As of 2026, extensive research has found no reliable evidence that amalgam fillings cause health problems in the general population. The mercury is chemically bound to the other metals. The amount released is very small and well below safety limits. The main reason dentists use less amalgam now is cosmetic, not medical. Patients prefer tooth-colored materials.