If you think you have a cavity, the most important step is booking a dental appointment. Only a dentist can confirm whether the dark spot, sensitivity, or pain you’re noticing is actually a cavity and how deep it goes. What happens next depends entirely on how far the decay has progressed, and in some cases, very early damage can actually be reversed without a filling.
How to Tell If It’s Really a Cavity
Early tooth decay often has no symptoms at all. The first visible sign is usually a white spot on the tooth where minerals have been lost. As decay progresses, that spot may turn brown or black, and you might notice sensitivity to sweets, hot drinks, or cold foods. If you can see or feel an actual hole in the tooth, the decay has broken through the enamel and a filling will be necessary.
At a dental visit, your dentist will check for soft or sticky areas on the tooth surface and likely take an X-ray to see how deep the decay extends. This is the only reliable way to know what you’re dealing with. Tooth pain doesn’t always mean a cavity, and cavities don’t always cause pain, so guessing at home isn’t a good substitute.
Early Decay Can Sometimes Be Reversed
Before a cavity becomes an actual hole, there’s a window where the damage is reversible. Your enamel naturally repairs itself through a process called remineralization, where minerals from saliva and fluoride rebuild weakened spots. Fluoride is the most effective tool for this. It won’t fill in a formed cavity, but it can halt early-stage decay and strengthen enamel before a hole develops.
To give remineralization the best chance of working:
- Brush twice daily with fluoride toothpaste containing at least 1,000 ppm fluoride
- Add a fluoride rinse before bed to coat your teeth overnight
- Eat meals instead of grazing throughout the day, since constant snacking keeps acid levels high in your mouth
- Drink water after eating to rinse away food particles and acid
- Chew sugar-free gum with xylitol, which fights the bacteria that cause decay
- Get enough calcium and phosphorus through dairy, leafy greens, or supplements to support enamel repair
Your dentist may also apply a concentrated fluoride treatment in the office. If they catch it at the white-spot stage, they might recommend monitoring the area rather than drilling. But once decay breaks through the enamel, it can’t be reversed, and professional treatment is the only fix.
What Happens at the Dentist
The treatment your dentist recommends depends on how far the decay has spread. For most cavities, a filling is all you need. The dentist removes the decayed portion of the tooth and fills the space with a material that restores its shape and function. The whole process typically takes under an hour.
You’ll usually choose between two main filling materials. Composite resin is tooth-colored and blends in with your natural teeth, making it the go-to choice for visible areas. It bonds directly to the tooth structure, which provides extra support. Silver amalgam is the traditional silver-colored filling. It’s durable and slightly less expensive, and studies have found no link between amalgam fillings and health problems. The FDA considers them safe for adults and children over age 6, though roughly 1% of people have an allergic reaction to the mercury in amalgam.
If the cavity has grown too large for a filling to hold, your dentist may recommend a crown, which is a cap that covers the entire tooth to protect it and keep it strong. And if bacteria have reached the innermost part of the tooth (the soft tissue containing nerves and blood vessels), you’ll likely need a root canal. At that stage, the infection is causing significant pain and the nerve tissue may already be dying. A root canal removes the infected tissue, saves the tooth, and is followed by a crown.
Managing Pain While You Wait
If your cavity is causing discomfort and you can’t get in to see a dentist right away, a few steps can help. Rinse your mouth with warm water and use dental floss to clear any food trapped near the affected tooth. An over-the-counter pain reliever can dull the ache, but don’t place aspirin directly against your gums because it can burn the tissue. Use caution with numbing gels containing benzocaine, particularly for children under 2, and don’t exceed the recommended dose.
Avoid very hot, very cold, or sugary foods and drinks that trigger sensitivity. These measures are temporary. They won’t stop the decay from progressing.
What Happens If You Wait Too Long
Cavities don’t stabilize or heal on their own once they’ve formed a hole. They keep growing. Decay that starts in the enamel moves into the softer layer underneath, then eventually reaches the nerve-rich pulp at the center of the tooth. When bacteria enter the pulp, the nerve tissue becomes inflamed and can die, which makes the tooth highly vulnerable to a dental abscess (a pocket of pus that forms at the root).
An abscess causes intense, throbbing pain, facial swelling, and sometimes fever. Left untreated, the infection can spread to the jawbone, causing bone loss. In rare but serious cases, dental infections lead to cellulitis (a spreading skin infection), bacterial meningitis, or sepsis. An untreated abscess can become a medical emergency. What could have been a simple filling becomes a root canal, an extraction, or a hospital visit.
A Non-Drill Option for Some Cavities
Silver diamine fluoride (SDF) is a liquid that a dentist paints onto a cavity to stop decay in its tracks without drilling. The American Dental Association’s expert panel recommends it for arresting advanced cavities on both baby teeth and permanent teeth, applied twice a year. For root cavities in adults, SDF prevented new decay at rates 72% higher than placebo in clinical reviews.
The trade-off is cosmetic: SDF permanently stains the decayed area black. It’s most commonly used for young children, older adults, or people with special health care needs who may have difficulty tolerating traditional dental procedures. It stops the cavity from growing but doesn’t restore the tooth’s shape, so a filling may still be needed eventually.
What It Costs
A standard filling starts at around $160 for amalgam and $191 for composite resin, based on American Dental Association fee survey data. The final price depends on the size of the cavity, which tooth is affected, and where you live. Gold fillings and porcelain inlays cost significantly more but can last 15 to 30 years. With dental insurance, your out-of-pocket cost drops depending on your plan’s deductible and coinsurance, especially if you see an in-network dentist. Without insurance, you pay the full amount.
Waiting longer almost always costs more. A filling is far cheaper than a crown, and a crown is far cheaper than a root canal followed by a crown. The financial math, along with the pain math, strongly favors getting in sooner rather than later.