A dental filling is a material used to repair a small hole, or cavity, in a tooth. Your dentist removes the decayed portion of the tooth and fills the space with a durable material that restores the tooth’s shape and function. Fillings are one of the most common dental procedures, and understanding your options helps you make better decisions when you’re sitting in that chair.
How Fillings Work
Cavities form when bacteria in your mouth produce acids that eat through the hard outer layer of your tooth (enamel). Left alone, that damage spreads deeper into the tooth, eventually reaching the nerve and causing serious pain or infection. A filling stops that process by sealing the hole and protecting what’s underneath.
Fillings work best when the decay is small, localized, and the tooth still has enough healthy structure to stay strong after treatment. If the cavity is too large or deep, or if the tooth is already cracked, a filling may not provide enough support, and your dentist will recommend a crown instead. The decision comes down to a few factors: the size and depth of the decay, whether there are any cracks or fractures, how much chewing pressure the tooth handles, and whether the tooth has had previous restorations that have weakened it over time.
Types of Filling Materials
Not all fillings are the same material. The main options differ in appearance, durability, and cost.
- Composite resin is the most popular choice today. It’s a tooth-colored plastic material that can be closely matched to your natural teeth, making it nearly invisible. Composites are especially well suited for front teeth or any visible area. They can also repair chipped, broken, or worn teeth. They typically last 5 to 15 years.
- Silver amalgam is a mix of mercury, silver, tin, zinc, and copper. It’s extremely durable, lasting 10 to 20 years, but it doesn’t match the color of natural teeth. Amalgam has been used for over a century and remains an effective option for back teeth where appearance matters less.
- Gold is the most expensive option. Some people prefer the look of gold over silver, and gold fillings are very durable. They can also repair cracked or broken teeth and teeth worn down by habits like nail-biting or grinding.
- Glass ionomer is a newer category that releases fluoride, calcium, and phosphorus into the surrounding tooth structure. These materials react to changes in acidity in your mouth: when conditions become more acidic (the environment that causes cavities), they release more protective minerals. This helps prevent new decay from forming around the filling’s edges. Glass ionomer fillings are less durable than composite or amalgam, so they’re often used in areas with less chewing pressure or in children’s teeth.
What Happens During the Procedure
A standard filling appointment takes 20 to 60 minutes depending on the size and location of the cavity. Here’s what to expect:
Your dentist numbs the tooth and surrounding area with a local anesthetic. Once you’re numb, they use specialized instruments to remove the damaged or decayed tissue. After the hole is cleaned out, they pack the filling material into the space. For composite fillings, a special blue curing light is used to harden the material in layers. Your dentist then polishes and smooths any rough edges and checks your bite to make sure it feels normal. You’ll be asked to bite down on a thin piece of paper and report whether anything feels high or off.
The numbness typically wears off within one to three hours. You can eat on the other side of your mouth during that time, but it’s best to avoid biting your cheek or tongue while you can’t feel them.
Sensitivity After a Filling
Some tooth pain or sensitivity after a filling is normal and usually improves within a few days to a couple of weeks. The most common cause is simple nerve irritation. The filling procedure can aggravate the nerve inside the tooth, especially with deeper cavities where the drill gets closer to those nerve endings. The outer layers of your tooth normally shield the nerve, but a deep filling reduces that buffer.
If the sensitivity gets worse instead of better, or if it hurts sharply when you bite down, the filling may be slightly too tall. Even a fraction of a millimeter makes a difference. That extra height concentrates pressure on one spot every time you chew, creating pain that feels more intense than typical post-filling soreness. This is an easy fix: your dentist can adjust the height in a quick visit.
In rare cases, a very deep filling can cause inflammation of the pulp, the soft tissue at the center of the tooth that contains nerves and blood vessels. This is more likely when the cavity was extremely deep, the tooth had previous trauma, or it has undergone multiple procedures. Allergic reactions to filling materials are also possible but uncommon. Amalgam, nickel, and cobalt are the materials most likely to trigger a reaction.
Is Amalgam Safe?
Because silver amalgam contains mercury, its safety has been debated for decades. The FDA does not support a ban on dental amalgam but does recommend that certain groups avoid it if possible. Those groups include children (especially under six), pregnant women, nursing mothers, people with neurological conditions or kidney dysfunction, and anyone with a known sensitivity to mercury, silver, copper, tin, or zinc.
If you already have amalgam fillings, the FDA recommends leaving them in place as long as they’re in good condition and there’s no decay underneath. Removing an intact amalgam filling is unnecessary and actually exposes you to more mercury vapor during the removal process than leaving it alone.
How Long Fillings Last
No filling lasts forever. Composite resin fillings typically hold up for 5 to 15 years, while amalgam fillings last 10 to 20 years. The actual lifespan of your filling depends on where it is in your mouth, how large it is, whether you grind your teeth, and how well you care for your teeth overall. Fillings on back molars take more punishment from chewing and tend to wear out faster than those on front teeth.
Over time, the seal between a filling and the surrounding tooth can break down. Bacteria slip into those gaps and cause new decay underneath the old filling. This is why your dentist checks existing fillings at every visit, looking for cracks, wear, or signs that the edges are pulling away from the tooth. Replacing a filling before it fails completely is far simpler than dealing with the deeper decay that follows.
Cost and Insurance Coverage
A dental filling typically costs between $150 and $400 per tooth. Simpler fillings on small cavities can run as low as $100, while larger or more complex restorations may exceed $450. The price varies by material, the number of tooth surfaces involved, and your geographic area.
Most dental insurance plans classify fillings as a “basic” procedure and cover 50% to 80% of the cost after your deductible. If you choose a premium material or need a more complex restoration, your insurance may cover a smaller percentage of the total. Some plans will only pay the equivalent of an amalgam filling even if you choose composite, leaving you to cover the difference.