When you have a cavity, the standard treatment is a dental filling: your dentist numbs the area, removes the decayed portion of the tooth, and fills 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 fillings aren’t the only option. Depending on how far the decay has progressed, treatment can range from a non-invasive liquid applied to the tooth surface all the way to a root canal and crown.
How Your Dentist Finds the Cavity
Most cavities are caught during a routine exam. Your dentist visually inspects each tooth under a bright light, using a small mirror to check angles and look for dark shadows beneath the enamel. They may blast air onto a tooth with a syringe to dry the surface, which makes early-stage decay easier to spot. A blunt-ended instrument can be used to check for rough or soft spots on the enamel, though sharp probes have fallen out of favor because they can actually damage weakened enamel and create new cavities.
X-rays are the main tool for finding decay between teeth or below the surface, where it’s invisible to the naked eye. In some cases, your dentist may use fiber-optic transillumination, a technique that shines a bright light through the tooth. If the light casts a shadow inside the tooth, that’s a sign of decay. For teeth that are hard to examine, orthodontic separators can be placed between them for two to three days to create a small gap for a closer look.
What Happens During a Filling
A filling is the most common cavity treatment, and the steps are straightforward. First, your dentist injects a local anesthetic near the tooth to numb the area. Once the numbness sets in, they use a high-speed drill or other instrument to remove the decayed tissue, leaving only healthy tooth structure behind. The cleaned-out space is then filled with a dental material, shaped to match the tooth’s natural contours, and polished smooth. For composite resin (the tooth-colored option), a special curing light is used to harden the material. The final step is checking your bite to make sure the filling isn’t too high, which would cause discomfort when you chew.
Some dental offices now offer laser treatment as an alternative to the traditional drill. Lasers use focused light energy to vaporize decay with less noise, less vibration, and more precision. Because the laser targets only the damaged area, it preserves more healthy tooth structure. Small cavities treated with a laser may not even require numbing, which means no lingering numbness afterward. The catch is that lasers work best for small, early-stage cavities. Deep decay, large restorations, or teeth that need extensive reshaping still require a conventional drill.
Filling Materials and How Long They Last
The two most common filling materials are composite resin and amalgam (the silver-colored metal blend). Composite resin is tooth-colored and blends in with natural enamel, which makes it the popular choice for visible teeth. Amalgam is less common than it used to be but remains an option, particularly for back teeth where durability matters and appearance is less of a concern.
A large-scale study analyzing over 668,000 restorations found that composite resin fillings actually had a lower failure rate than amalgam: about 12% compared to roughly 17%. On a yearly basis, amalgam fillings failed at a rate of 3.55% per year versus 3.06% for composite. The gap widened for fillings covering multiple surfaces of a tooth. Single-surface composites failed about 11% of the time, while single-surface amalgams failed 14% of the time. Both materials performed slightly better on premolars than molars.
Cost varies by material and size. Amalgam fillings generally run $100 to $350, while composite resin fillings range from $150 to $450. A small filling on one surface costs less than a larger filling spanning two or three surfaces. Your insurance plan, the specific tooth, and your geographic location all affect the final price.
When a Filling Isn’t Enough
If the cavity is large enough that the remaining tooth structure can’t support a filling, your dentist will recommend a crown instead. A crown is a custom-made cap that fits over the entire visible portion of the tooth, restoring its shape and strength. This is common when decay has eaten away a significant portion of the tooth or when the tooth is cracked.
When decay reaches the pulp, the soft tissue inside the tooth that contains nerves and blood vessels, a root canal becomes necessary. Signs that decay has gone this deep include lingering sensitivity to hot or cold that doesn’t fade quickly, throbbing pain when chewing, darkening of the tooth, swollen gums near the affected tooth, or a small bump on the gum line. During a root canal, your dentist or an endodontist removes the infected pulp, cleans and disinfects the interior of the tooth, and seals it. A crown is almost always placed afterward because a tooth without its pulp becomes brittle and prone to fracture.
A No-Drill Option for Some Cavities
For certain patients, a liquid treatment called silver diamine fluoride (SDF) can stop a cavity from getting worse without any drilling at all. SDF is painted directly onto the decayed area. The silver component kills bacteria by disrupting their cell membranes, while the fluoride promotes remineralization, essentially hardening the weakened tooth surface. In clinical research, SDF has proven as effective at halting cavity progression as traditional restorative treatment, and it prevented root cavities in adults at rates 72% higher than placebo.
The trade-off is cosmetic: SDF permanently stains the decayed area black. It also doesn’t restore the tooth’s shape, so it’s not a replacement for a filling on a tooth that has lost significant structure. SDF is most commonly used for young children who can’t sit through a traditional filling, patients with special needs, older adults with root decay, or situations where multiple cavities need to be managed and can’t all be drilled in one visit.
What Recovery Feels Like
After a standard filling, the first two days tend to involve the most noticeable sensitivity, especially to temperature and pressure. Most people feel completely normal within two weeks for shallow to moderate fillings. Deeper fillings placed close to the nerve may take three to four weeks for sensitivity to fully resolve. Some mild discomfort when biting down is common and usually means the filling just needs a minor adjustment.
Certain signs after a filling suggest something more serious. Pain that gets worse over several days instead of gradually improving, throbbing that happens on its own without any trigger, or sensitivity to cold or sweets that lingers for several minutes all point to inflamed or infected pulp tissue. Visible swelling around the tooth (especially with warmth or redness), a bad taste or odor near the treated area, pus, swollen lymph nodes under the jaw, or even a low-grade fever all signal infection. Any of these warrant a prompt call to your dentist, as they may indicate the cavity was deeper than initially assessed and a root canal is needed.