If you have a cavity, your dentist will remove the decayed portion of your tooth and fill the hole with a durable material, typically in a single appointment lasting 30 to 60 minutes. The exact treatment depends on how deep the decay has spread. A small cavity gets a straightforward filling, while a larger one may need a crown, and decay that has reached the nerve inside the tooth requires a root canal.
How Your Dentist Finds a Cavity
Cavities aren’t always obvious, and many cause no pain in their early stages. Your dentist uses several tools to catch them. The most basic is a visual exam with magnification and bright lighting, paired with a dental explorer (the thin metal pick you’ve probably felt tapping along your teeth). When the explorer “sticks” in a soft spot, that’s a sign of decay. Your dentist may also use a spoon excavator to feel whether tooth structure is soft and crumbling or firm and healthy.
X-rays remain the best way to find cavities hiding between teeth, where they’re invisible to the naked eye. Digital X-rays let your dentist enlarge the image, adjust contrast, and zoom in on a suspicious area for a clearer picture. Some offices also use a laser-based device that shines a light on the tooth surface and returns a number from 1 to 99, with higher numbers indicating more decay beneath the enamel. These devices are roughly 90% accurate. Another technology uses violet-blue LED light to make bacteria byproducts glow red on a screen, while healthy tooth structure appears green.
The Standard Filling Process
A filling is the most common cavity treatment, and the procedure is straightforward. Your dentist numbs the tooth and surrounding gum with a local anesthetic, most commonly lidocaine. Numbness typically lasts two to four hours depending on the formulation, so expect a tingly lip or cheek for a while after you leave.
Once you’re numb, the dentist uses a drill or other instrument to remove the decayed tissue, leaving only solid, healthy tooth behind. The resulting hole is filled with a dental material, shaped to match the contour of your tooth, then polished smooth. For tooth-colored composite resin fillings, a blue curing light is used to harden the material in layers. The final step is checking your bite: you’ll be asked to tap your teeth together so the dentist can adjust any high spots.
Some offices now offer laser cavity removal instead of a traditional drill. The laser uses a focused light beam to cut away decay with less vibration, and several studies have found that patients can sometimes skip the numbing injection entirely. This can be especially helpful for children or anyone anxious about needles. That said, lasers aren’t suitable for every cavity, particularly larger or deeper ones.
Filling Materials Compared
You’ll generally choose between two types of filling material:
- Composite resin is tooth-colored and blends in with your natural teeth. It bonds directly to tooth structure, which can allow the dentist to preserve more of the healthy tooth. The trade-off is durability: composite fillings typically last 5 to 10 years before needing replacement.
- Amalgam (silver fillings) is a metal alloy that’s been used for over a century. It’s stronger under heavy chewing forces and lasts 10 to 12 years on average, but its dark silver color makes it visible when you open your mouth. Many dental offices have moved away from amalgam, and some no longer offer it.
Without insurance, a filling generally costs between $200 and $335, though the price varies by location and the size of the cavity. Dental insurance typically covers up to 80% of the cost once you’ve met your annual deductible.
When a Filling Isn’t Enough
Not every cavity can be fixed with a simple filling. The deciding factor is how much tooth structure has been lost. If the cavity is wide enough that the filling would span more than one-third to one-half the width of the tooth, a crown is the better option. A filling that large would leave the remaining walls of the tooth too thin, making it vulnerable to cracking under normal chewing pressure. A crown covers the entire visible portion of the tooth, holding everything together. This usually takes two appointments: one to prepare the tooth and place a temporary crown, and a second to cement the permanent one (though same-day crowns are available at some offices).
What Happens if Decay Reaches the Nerve
Deep inside every tooth is a chamber of soft tissue containing nerves and blood vessels, called the pulp. When a cavity goes untreated long enough to reach this area, a root canal becomes necessary. Signs that decay has gone this far include sharp or worsening pain while chewing, a tooth that appears gray or dark compared to neighboring teeth, or drainage of pus from the gum near the tooth. Sometimes there are no symptoms at all, and the infection only shows up on a routine X-ray.
During a root canal, the dentist or an endodontist removes the infected pulp tissue from inside the tooth, cleans and disinfects the inner chambers, then fills them with a sealing material. The tooth is typically capped with a crown afterward because it becomes more brittle without a living blood supply. The procedure has a reputation for being painful, but with modern anesthesia, most people report it feels similar to getting a large filling.
A No-Drill Option for Some Cavities
Silver diamine fluoride (SDF) is a liquid that can stop a cavity from growing without any drilling. A dentist simply brushes it onto the decayed area, and the treatment takes only a few minutes. The American Dental Association notes that SDF can arrest or slow cavity progression in both baby teeth and permanent teeth without removing any tooth structure.
SDF is particularly useful for young children who can’t sit through a traditional filling, older adults with physical limitations, people with multiple cavities that can’t all be treated in one visit, and situations where sedation isn’t safe or available. The biggest drawback is cosmetic: SDF permanently stains the decayed area black. For that reason, it’s most often used on baby teeth that will fall out, on back teeth that aren’t visible, or as a temporary measure to stabilize cavities before conventional treatment.
What Recovery Feels Like
After a filling, some sensitivity to hot, cold, or pressure is normal. For most people, this fades within two to four weeks as the tooth settles. You can eat once the numbness wears off, though sticking to softer foods for the first day or two can help you avoid biting your cheek while it’s still tingly.
Discomfort lasting more than a month is not normal and may point to an issue like a filling that sits too high, decay that was deeper than expected, or irritation of the nerve. Sharp pain that gets worse over time, difficulty eating, or visible swelling around the tooth are all reasons to go back to your dentist sooner rather than later.