How you fix a cavity depends entirely on how far it has progressed. Very early decay, before an actual hole forms, can sometimes be reversed at home through remineralization. Once a cavity breaks through the enamel surface, though, you need professional treatment to restore the tooth. The good news is that dentistry offers effective options at every stage, from simple fillings to crowns to treatments that can stop decay in its tracks without drilling.
Early Decay Can Actually Be Reversed
Cavities don’t appear overnight. They start as invisible mineral loss beneath the enamel surface, eventually becoming visible as a chalky white spot on the tooth. At this stage, no hole has formed yet, and the damage is reversible.
Your enamel is made of a mineral crystal called hydroxyapatite. When bacteria in your mouth feed on sugars, they produce acids that drop the pH in your mouth below 5.5, which is the threshold where enamel starts dissolving. But your saliva naturally contains calcium and phosphate, and when conditions improve, those minerals can redeposit back into weakened enamel. This process is called remineralization, and fluoride supercharges it. When fluoride gets incorporated into the enamel crystal, it forms stronger chemical bonds that shrink the crystal structure, making the repaired enamel harder and more acid-resistant than the original.
To push early white-spot lesions back toward health, the strategy is straightforward: brush with fluoride toothpaste twice daily, reduce how often you eat sugary or acidic foods (frequency matters more than quantity), drink water throughout the day to keep saliva flowing, and consider a fluoride rinse. Your dentist may also apply a concentrated fluoride varnish during a checkup. These steps won’t help once an actual hole has formed, but for early mineral loss, they can genuinely reverse the damage.
What Happens When a Cavity Needs a Filling
Once decay eats through enough enamel to create a physical hole, remineralization is off the table. The tooth needs a filling. This is the most common cavity fix: the dentist removes the decayed portion, then fills the space with a restorative material.
You’ll typically choose between two main types. Composite resin fillings are made of plastic and glass compounds and can be color-matched to your natural tooth, making them nearly invisible. They’re the standard choice for visible teeth. Amalgam fillings, sometimes called “silver fillings,” are a mixture of metals including silver, tin, copper, and mercury. They last longer and cost less than composite, but their metallic appearance makes them less popular for front teeth. For back molars where appearance matters less, amalgam remains a durable option.
A straightforward filling appointment usually takes 30 to 60 minutes. After the procedure, expect some sensitivity for one to two weeks, with deep fillings sometimes taking three to four weeks to fully settle. If pain starts improving and then gets worse again after a few days, or if you notice throbbing that happens on its own without any trigger, contact your dentist. Those patterns suggest the nerve inside the tooth may be inflamed or infected. Similarly, if chewing hurts beyond the first few days, the filling may be sitting slightly too high and needs a quick adjustment.
Silver Diamine Fluoride: Stopping Decay Without Drilling
For people who can’t easily undergo traditional dental work, such as young children, elderly patients, or anyone with dental anxiety, there’s a non-invasive option that can stop a cavity from getting worse. Silver diamine fluoride (SDF) is a liquid painted directly onto the decayed area. It kills bacteria, hardens the softened tooth structure, and arrests the decay process.
In a study of children with early cavities, SDF achieved an 85% caries arrest rate at six months, compared to 50% for standard fluoride varnish. The major trade-off is cosmetic: SDF permanently stains the treated decay black. It doesn’t restore the tooth’s shape or fill any hole, so it’s best thought of as a way to buy time or manage decay that’s difficult to treat conventionally.
When Decay Reaches the Nerve
A cavity that grows deep enough to reach the pulp, the soft tissue inside the tooth containing nerves and blood vessels, causes a different level of pain. You might notice sharp sensitivity that lingers for minutes after eating something cold or sweet, spontaneous throbbing, or pain that wakes you up at night. At this point, a filling alone won’t solve the problem.
A root canal removes the infected pulp tissue, cleans and seals the interior canals, and preserves the outer tooth structure. The tooth then typically needs a crown placed over it for protection, since a pulp-treated tooth becomes more brittle over time. Crowns generally cost between $1,000 and $2,500 per tooth, depending on the material. Zirconia and all-ceramic options sit at the higher end, while porcelain fused to metal tends to be more affordable.
Not every tooth can be saved. If decay has destroyed most of the tooth structure above the gumline, or if the surrounding bone support has dropped below about 30%, extraction may be the more predictable option. A tooth with a vertical root fracture is also generally considered beyond repair.
Sealants: Fixing the Problem Before It Starts
Dental sealants are thin coatings applied to the chewing surfaces of back teeth, where nine out of ten cavities occur. The grooves on molars are natural traps for food and bacteria, and sealants essentially fill those grooves with a protective barrier. According to the CDC, sealants prevent 80% of cavities in back teeth over a two-year period.
Sealants are most commonly placed on children’s permanent molars as they come in, usually between ages 6 and 12. But adults with deep grooves and no existing fillings on those surfaces can benefit too. The application is quick, painless, and involves no drilling.
How to Protect Fillings and Prevent New Cavities
Once a cavity has been treated, the restored tooth needs ongoing care. Composite fillings can last 5 to 10 years, and amalgam fillings often last longer, but all restorations eventually wear down or develop gaps at the margins where new decay can creep in.
The biology of cavity formation doesn’t change after treatment. Bacteria still produce acid every time you eat, and the critical pH threshold of 5.5 still applies. What you can control is how often that acid attack happens and how quickly your mouth recovers. Spacing out snacks rather than grazing continuously gives your saliva time to neutralize acids and remineralize enamel between meals. Drinking water after eating helps too. Fluoride toothpaste remains the single most effective daily tool for keeping enamel strong, and flossing clears bacteria from between teeth where your brush can’t reach.
Regular dental visits catch new decay early, when it’s still a white spot that can be reversed rather than a hole that needs drilling. The difference between a $0 remineralization strategy and a $1,000+ crown often comes down to timing.