How a cavity is treated depends entirely on how far the decay has progressed. A very early cavity, one that hasn’t yet broken through the enamel surface, can actually be reversed without a drill. Once decay creates a visible hole or reaches the softer layer beneath your enamel, you’ll need a filling or a more involved restoration. Here’s what to expect at each stage.
Early Cavities Can Be Reversed
Tooth decay doesn’t start as a hole. It begins as a patch of weakened enamel where minerals have been lost, sometimes visible as a white or chalky spot on the tooth surface. At this stage, the damage is reversible through a process called remineralization, which essentially means rebuilding those lost minerals before the surface breaks down.
The most effective tool for this is topical fluoride. Fluoride toothpaste is the baseline, but it needs to contain at least 1,000 parts per million (ppm) of fluoride to be effective. Most major brands meet this threshold. For higher-risk situations, your dentist can apply a professional-strength fluoride varnish or gel, with concentrations reaching 12,300 ppm or more. These professional treatments are typically done twice a year for people at average risk and every three months for those with a higher likelihood of developing new cavities.
At home, you can also use a fluoride mouth rinse. Daily rinses contain about 230 ppm of fluoride, while weekly-use rinses contain 900 ppm and are designed for people over 11 who are at higher risk. The key principle across all of these: fluoride works by concentrating in weakened spots on the tooth, hardening the enamel before it collapses into a full cavity.
Silver Diamine Fluoride: A No-Drill Option
Silver diamine fluoride (SDF) is a liquid that a dentist paints directly onto a cavity to stop it from growing. It doesn’t restore the tooth’s shape or remove the decay, but it arrests the process. A systematic review found that SDF halts roughly 80% of treated lesions, and about 70% of active cavities in children’s baby teeth were stopped after a single application.
The trade-off is cosmetic: SDF permanently stains the decayed area black. That makes it a better fit for back teeth, baby teeth that will fall out, or situations where drilling isn’t practical, such as very young children, elderly patients, or people with severe dental anxiety. It’s not appropriate for teeth showing signs of deep infection or nerve damage. The American Dental Association issued its first formal recommendations for SDF use in 2018, placing it among nine recognized non-restorative treatments for cavities.
What Happens During a Filling
Once decay has broken through the enamel surface and created an actual hole, remineralization won’t fix it. The standard treatment is a dental filling, and the process is straightforward. Your dentist numbs the area with local anesthetic, removes the decayed tissue with a drill or similar instrument, fills the cleaned-out space with a restorative material, and then shapes and polishes the result. For tooth-colored composite fillings, a special curing light is used to harden the material. The whole process for a single filling usually takes under an hour.
The two most common filling materials are amalgam (the traditional silver-colored mixture of metals) and resin composite (tooth-colored, made from a blend of resin and fine glass particles). Composite fillings are far more popular today because they match the tooth’s appearance. Both types last a long time. Depending on the material, location, and how well you care for your teeth, a filling can last 10 to 20 years.
Cost varies by how much of the tooth needs to be restored. A single-surface composite filling typically runs $150 to $300 without insurance. If the cavity is larger and spans multiple surfaces of the tooth, expect $200 to $550. Insurance usually covers a significant portion of basic fillings.
Recovery After a Filling
Some sensitivity after a filling is completely normal. Most people notice mild discomfort for one to two weeks, with improvement beginning within the first 48 hours. Shallow to moderate fillings generally heal completely within two weeks. Deeper fillings, especially those close to the nerve inside the tooth, can cause sensitivity for three to four weeks before fully resolving.
There are a few warning signs that something isn’t right. Pain that gets worse over the days following your appointment rather than gradually improving suggests a problem. Spontaneous throbbing pain that happens without any trigger (no hot drinks, no chewing) points to inflammation or infection of the nerve. If pain lingers for several minutes after contact with cold water or sweet foods, that’s another signal the nerve tissue may be compromised. Swelling, fever, a bad taste near the tooth, or pus are signs of infection that need prompt attention. As a general rule, if your discomfort hasn’t improved at all after three weeks, or if it’s getting worse rather than better, follow up with your dentist.
When a Filling Isn’t Enough
If decay reaches the pulp, the soft tissue inside your tooth that contains nerves and blood vessels, a filling alone won’t solve the problem. At this point, the infection needs to be cleared out through a root canal. During this procedure, the dentist or endodontist removes the infected pulp, cleans and disinfects the interior of the tooth, and seals it.
After a root canal, you may also need a crown, which is a cap that fits over the entire visible portion of the tooth. Whether you need one depends on a few factors. Back teeth (molars and premolars) bear heavy chewing forces and almost always need a crown for reinforcement. If a large amount of tooth structure was removed during the procedure, a crown is also likely. Front teeth or teeth that retained most of their structure may do fine with just a filling placed over the sealed canal.
How Dentists Catch Cavities Early
Traditional cavity detection relies on visual examination and X-rays, but these methods have limitations, particularly for catching decay in its earliest stages. Newer tools like laser fluorescence devices can detect demineralization before it’s visible to the eye or shows up on a standard X-ray. Digital imaging and fiber-optic transillumination are other light-based methods that help identify weak spots in enamel earlier in the process. The earlier a cavity is detected, the more likely it can be managed with fluoride and remineralization rather than a drill.
This is one of the practical reasons regular dental visits matter. A cavity caught at the white-spot stage can be treated with a fluoride varnish in minutes. That same cavity six months later might require a $300 filling. And a year after that, it could mean a root canal and crown. The biology of decay is progressive, but at every stage, there’s a treatment that can stop it.