If you have a cavity, your dentist will remove the decayed portion of your tooth and fill the space with a durable material to restore its shape and function. The whole process typically takes one visit and about 20 to 60 minutes depending on the size and location of the cavity. But not every cavity gets the same treatment. What your dentist does depends on how deep the decay has gone.
Early Decay Doesn’t Always Need a Filling
Tooth decay is a spectrum, and catching it early enough can mean avoiding the drill entirely. When decay is still in the outermost layer of your tooth (the enamel) and hasn’t formed an actual hole yet, it can sometimes be reversed. Enamel repairs itself using minerals from your saliva and fluoride from toothpaste or professional treatments. Your dentist may recommend a prescription-strength fluoride rinse or varnish and ask you to come back in a few months to check whether the spot has stabilized.
Once decay breaks through the enamel and creates a true cavity, though, the damage is permanent. No amount of fluoride or brushing will close that hole. That’s when a filling becomes necessary.
What Happens During a Filling
Getting a filling is the most common cavity treatment, and the process is straightforward. Here’s what to expect from start to finish.
Your dentist begins by numbing the tooth and the area around it with a local anesthetic, usually delivered as a small injection in your gum. You’ll feel a brief pinch, and within a few minutes the area goes numb. Some dentists also apply a topical numbing gel before the injection so you barely feel the needle at all.
Once you’re numb, the dentist uses a small drill or laser to remove the decayed part of the tooth. This is the part people tend to dread, but you shouldn’t feel pain, just pressure and vibration. After the decay is cleared out, the dentist cleans the cavity to remove bacteria and debris, then fills the space.
If you’re getting a tooth-colored composite filling (the most common type today), your dentist will have already matched the shade of the resin to your natural teeth at the start of the visit, before your mouth dries out and changes the apparent color. Composite fillings are applied in layers. Each layer is hardened with a special curing light before the next one goes on. This layering process takes a bit longer than older-style silver fillings, but the result blends in with your tooth. Once the final layer is cured, the dentist shapes and polishes the filling so your bite feels normal.
Composite vs. Amalgam Fillings
You may have a choice between two main filling materials:
- Composite resin (tooth-colored): Matches your natural tooth color and bonds directly to the tooth structure. These last about 5 to 7 years on average, though they can last longer with good care.
- Amalgam (silver): A metal alloy that’s extremely durable, typically lasting 10 to 15 years or more. It’s more noticeable since it’s silver-colored, so it’s used less often for front teeth.
Many dental offices now default to composite for most cavities. Amalgam is still a solid option for back teeth that take heavy chewing force, and some insurance plans cover it at a higher rate. Your dentist can help you weigh appearance, durability, and cost for your specific situation.
When a Cavity Is Too Deep for a Filling
If decay has spread past the inner layer of the tooth and reached the pulp, the soft tissue that contains nerves and blood vessels, a simple filling won’t be enough. At that point, the infection needs to be addressed at the root level.
Signs that decay may have reached this stage include persistent pain that doesn’t go away on its own, lingering sensitivity to hot or cold that continues even after you stop eating or drinking, pain that radiates into your jaw or face, and visible discoloration of the tooth (sometimes a grayish-black appearance from internal tissue breakdown). Your dentist will confirm the extent of the damage with an X-ray.
The treatment for pulp-level decay is a root canal. During this procedure, the dentist or an endodontist removes the infected pulp from inside the tooth, cleans and disinfects the inner chambers, then fills and seals them. Afterward, most teeth that have had root canals need a crown (a cap that fits over the tooth) to protect the remaining structure from cracking. This process usually takes one or two visits.
If the tooth is too damaged even for a root canal, extraction becomes the last resort, often followed by an implant or bridge to fill the gap.
Options When Drilling Isn’t Possible
For some patients, traditional cavity treatment isn’t immediately feasible. Young children who can’t sit still for a procedure, people with special needs, or patients for whom sedation isn’t safe may benefit from an alternative called silver diamine fluoride (SDF). This is a liquid that’s painted directly onto the cavity. It doesn’t remove the decay or restore the tooth’s shape, but it kills bacteria and hardens the decayed area to stop the cavity from growing. The American Dental Association recognizes it as a viable interim treatment, particularly when multiple cavities can’t all be addressed in one session or when access to dental care is limited. The main downside is that SDF permanently stains the treated area black, which makes it a less popular choice for visible teeth.
How Numbness and Recovery Feel
After a filling, the numbness from local anesthesia typically wears off within about two hours. Until it does, avoid eating or drinking, since you could accidentally bite your cheek or tongue without realizing it.
Once the numbness fades, some sensitivity is normal. You may notice a mild ache or a zing when you bite down, drink something cold, or eat something hot. For composite fillings, it helps to avoid hard, crunchy, or sticky foods for the first 24 to 48 hours. If the filling is on a tooth you chew with, try to chew on the opposite side for at least a day.
This sensitivity typically resolves on its own within a few days. If it persists beyond a week, or if you feel sharp pain when you bite down, contact your dentist. The filling may need a minor adjustment to correct your bite, which is a quick fix.