When a dentist finds a cavity, the treatment depends entirely on how far the decay has progressed. A small spot caught early might not need drilling at all, while a deep cavity that has reached the tooth’s nerve could require a root canal. Most cavities fall somewhere in between and are treated with a straightforward filling that takes about an hour from start to finish.
How Dentists Find Cavities
Detection starts with a visual exam using a dental mirror and a sharp probe, with the tooth dried off so the dentist can see clearly. Small cavities between teeth are invisible to the naked eye, so bitewing X-rays are the standard follow-up. These catch 50 to 70 percent of cavities that have reached the inner layer of the tooth, making them far more reliable than a visual check alone for decay hiding between teeth. Some offices also use a laser fluorescence device that measures changes in tooth structure and can flag decay before it shows up on an X-ray.
When a Cavity Can Be Reversed Without Drilling
If decay is still in its earliest stage, showing up as a chalky white spot on the enamel but without an actual hole, your dentist may skip the drill entirely. At this point the goal is remineralization: pushing minerals back into the weakened enamel to harden it again.
Professional fluoride varnish is one common approach, applied directly to the tooth a few times a year. At home, using a toothpaste with at least 1,000 ppm fluoride is the baseline for an anti-cavity effect. Products containing a milk-derived protein called casein phosphopeptide paired with calcium phosphate have also been shown to remineralize white spot lesions more effectively than products without it. These come as creams or pastes you apply after brushing. Combined with fluoride, this approach delivers the highest concentrations of calcium, phosphate, and fluoride to the tooth surface.
Another option gaining traction is silver diamine fluoride (SDF), a liquid painted onto a cavity to stop it from growing. It combines silver, which kills bacteria, with fluoride, which strengthens the tooth. Arrest rates range from 25 to 99 percent depending on the study and how it’s applied. The trade-off: SDF permanently stains decayed areas black, so it’s used most often on baby teeth, back teeth, or in situations where drilling isn’t practical.
What Happens During a Filling
A standard filling is the most common cavity treatment. The process follows a predictable sequence:
- Numbing. Your dentist injects local anesthesia near the tooth. You’ll feel pressure but no pain once it takes effect.
- Decay removal. Specialized instruments, typically a high-speed drill, remove the damaged tooth structure until only healthy material remains.
- Filling. The cleaned-out space is filled with a dental material. For tooth-colored composite resin, the dentist applies it in layers and hardens each layer with a curing light.
- Shaping and polishing. Rough edges are smoothed down, and you’ll be asked to bite on a thin piece of paper so the dentist can check that the filling sits level with your other teeth.
The whole visit usually takes 30 to 60 minutes, depending on the cavity’s size and location.
Filling Materials and How Long They Last
Composite resin is the most popular filling material today because it matches your tooth color. It lasts about 7 years on average. Amalgam (the silver-colored metal filling) is more durable at around 15 years and costs less, though many patients prefer the look of composite. Ceramic fillings, sometimes called inlays or onlays, also last roughly 15 years and resist staining better than composite. Gold fillings outlast everything at 20 years or more but are the most expensive and require two visits.
Your dentist will recommend a material based on the cavity’s size, its location in your mouth, and your budget. Front teeth almost always get composite for cosmetic reasons. Back teeth that take heavy chewing force may benefit from a more durable material.
Laser Dentistry as an Alternative to Drilling
Some dental offices use lasers instead of traditional drills to remove decay. The laser precisely targets damaged areas while preserving more healthy tooth structure. For many patients, the real appeal is comfort: there’s no vibration, no high-pitched noise, and in many cases little to no anesthesia is needed. The laser also sterilizes the area it touches, which lowers the risk of infection during and after the procedure. Recovery tends to be faster because the surrounding tissue experiences less trauma. Not every cavity qualifies for laser treatment, and the equipment is expensive, so it’s not yet available in every practice.
When a Cavity Is Too Large for a Filling
Once a cavity destroys enough of the tooth, removing the remaining decay would leave too little structure to hold a filling securely. At that point, a crown is the better option. A crown is a custom-made cap that fits over the entire visible portion of the tooth, restoring its shape and strength. This typically takes two appointments: one to prepare the tooth and take impressions, and a second to cement the permanent crown in place. Some offices have same-day milling technology that compresses this into a single visit.
When Decay Reaches the Nerve
A cavity that goes deep enough can allow bacteria to reach the pulp, the soft tissue inside the tooth that contains nerves and blood vessels. When this happens, you may notice pain when chewing or touching the tooth, lingering sensitivity to hot or cold, darkening of the tooth, swelling in the gums, or even a small pimple-like bump on the gum that oozes pus. Sometimes, though, an infected tooth causes no obvious symptoms at first.
To confirm the infection, your dentist will take X-rays, tap on the tooth, apply hot and cold, and may use an electric pulp test to check whether the nerve is still alive. If the pulp is infected or inflamed beyond recovery, the treatment is a root canal. During this procedure, the infected pulp is removed, the inside of the tooth is cleaned and disinfected, and the space is filled with a rubber-like material. The tooth then gets a crown to protect it, since it becomes more brittle without a living nerve. Despite its reputation, a root canal feels similar to getting a filling done, with the area fully numbed throughout.
What Recovery Feels Like
After a filling, numbness from the anesthesia typically wears off within 1 to 3 hours. During that window, avoid chewing on the treated side so you don’t accidentally bite your cheek or tongue. Mild sensitivity to hot, cold, and pressure is normal for the first few days, especially with composite fillings. Some soreness around the gum line is also common if the cavity was close to the gums.
You can return to your normal diet within a day, but it’s smart to skip very hard or sticky foods for the first 24 hours. If your bite feels off after the numbness fades, like the filling is sitting too high, call your dentist. A quick adjustment to shave down the high spot takes just a few minutes and solves the problem immediately.