Dentists treat most cavities by numbing the tooth, removing the decayed portion, and filling the hole with a durable material. The whole process typically takes 20 to 60 minutes depending on the size and location of the cavity. But not every cavity gets the same treatment. Small, early-stage decay might not need drilling at all, while deep cavities that reach the tooth’s nerve require more involved procedures like root canals.
How Your Dentist Finds the Cavity
Treatment starts with diagnosis, and your dentist uses several tools beyond just looking in your mouth. A visual exam on a dry tooth surface comes first, sometimes with magnifying loupes to spot subtle changes in color or texture. Dentists classify what they see using a standardized scale from 0 to 6, where higher numbers mean more extensive damage. Interestingly, the old-school method of poking teeth with a sharp explorer has fallen out of favor because studies show it can actually damage the enamel and help the cavity progress.
X-rays are the next step. Bitewing X-rays, where you bite down on a small tab while the image is taken, are the standard for spotting cavities between teeth that aren’t visible to the eye. These are especially useful for catching decay on the surfaces where your teeth touch each other. Some offices also use laser fluorescence devices, which scan each tooth with a beam of light and measure how much fluorescence bounces back. Healthy tooth structure and decayed tooth structure reflect light differently, giving the dentist a numerical reading that indicates whether decay is present and how advanced it is.
The Standard Filling Procedure
Once your dentist confirms a cavity needs a filling, the process follows a predictable sequence. First, you’ll get a local anesthetic injection near the affected tooth. The numbing agent kicks in within about 2 to 5 minutes and lasts roughly 35 to 45 minutes, which is more than enough time for most fillings.
With the area numb, your dentist uses a small drill or laser to remove the decayed tissue, leaving only healthy tooth structure behind. The cleaned-out space is then filled with one of two main materials: composite resin (tooth-colored) or amalgam (silver-colored metal). If composite resin is used, your dentist applies it in layers and hardens each layer with a blue curing light. The final steps are polishing the filling smooth and checking your bite to make sure your teeth come together normally. You shouldn’t feel any sharp edges or high spots when you close your mouth.
Composite Resin vs. Amalgam Fillings
Most patients today get composite resin fillings, which are made of a plastic and glass mixture that can be color-matched to your natural tooth. Amalgam fillings, a blend of mercury (about 50%), silver, tin, and copper, are less common now but still used in some situations, particularly for back teeth that take heavy chewing forces.
On durability, the picture has shifted in recent years. A large real-world study found that composite resin fillings had an 8-year failure rate of about 12%, compared to roughly 17% for amalgam. That’s a reversal from older research, which generally favored amalgam’s longevity. Newer composite formulations have significantly improved their resistance to stress and wear. Cost-wise, amalgam fillings average around $160 per tooth while composite runs about $191, based on 2022 data from the American Dental Association. Insurance typically covers both, though your out-of-pocket amount depends on your plan’s specifics and whether your dentist is in-network.
When a Filling Isn’t Enough
Standard fillings work well for small to moderate cavities, but larger areas of decay need a different approach. When too much tooth structure is lost, a filling alone can’t provide enough support. In these cases, your dentist may recommend an inlay or onlay. These are custom-made restorations, typically crafted in a lab from porcelain or composite, that fit precisely into or over the damaged area. Think of them as a middle ground between a filling and a full crown. They require two visits: one to prepare the tooth and take impressions, and a second to bond the finished piece in place.
If decay has reached the pulp, the soft tissue inside the tooth that contains nerves and blood vessels, a filling won’t solve the problem. Signs that a cavity has gone this deep include constant throbbing pain, lingering sensitivity to hot or cold that lasts more than a few seconds, darkening of the tooth, pain when biting down, or swollen gums near the affected tooth. At this point, the treatment is a root canal: your dentist or an endodontist removes the infected pulp, cleans and seals the inner canals, and then places a crown over the tooth to restore its strength.
Non-Invasive Options for Early Cavities
Not every cavity requires a drill. Silver diamine fluoride (SDF) is a liquid solution that can stop early decay in its tracks without any drilling, injections, or pain. The silver component kills the bacteria driving the cavity, while the fluoride promotes remineralization, essentially helping the tooth rebuild its mineral structure. SDF also protects the protein scaffolding inside the tooth from breaking down further.
The treatment is remarkably simple: your dentist paints the solution directly onto the affected area. It’s especially useful for young children who can’t sit through traditional procedures, older adults with limited mobility or access to dental care, and people with special needs. The main drawback is cosmetic. SDF permanently stains the decayed area black, which makes it a tough sell for visible front teeth. It’s also not a permanent fix for larger cavities that have already caused structural damage. But for arresting early decay and buying time, it’s one of the least invasive tools available.
What Recovery Looks Like
Recovery depends largely on what type of filling you received. Composite resin fillings harden instantly under the curing light, so the material itself is ready to go the moment you leave the chair. Amalgam fillings take up to 24 hours to fully set, which means you need to be more careful about what you eat and drink in the first day.
Regardless of material, the main thing to wait for is the numbness to wear off. Eating or drinking while your mouth is still numb is a recipe for accidentally biting your cheek or tongue. Once sensation returns, you can drink cool water right away with a composite filling or after about an hour with amalgam. Hot beverages like coffee or tea should wait 2 to 3 hours after composite and a full 24 hours after amalgam. Skip soda and sugary drinks for 24 hours with either type, as the sugar and acidity can trigger sensitivity and encourage bacterial activity around the new restoration.
Mild sensitivity to hot and cold is normal for the first 24 to 48 hours. If sensitivity persists beyond a week or two, or if you notice pain when biting down, contact your dentist. The filling may be sitting slightly too high and need a quick adjustment, which usually takes just a few minutes.