Tooth decay begins when acids made by bacteria repeatedly attack the outer surface of a tooth. Early damage may not cause pain, but untreated decay can progress into the deeper layers of the tooth and lead to sensitivity, infection or tooth loss.
How tooth decay develops
Bacteria in dental plaque use sugars and starches from food and drinks to produce acids. Frequent exposure gives the tooth less time to recover between attacks. Fluoride strengthens enamel and helps repair very early damage before a cavity forms.
Symptoms
- White, brown or dark spots on a tooth
- Sensitivity to hot, cold or sweet foods and drinks
- Toothache or pain when biting
- A visible hole or rough area
- Food repeatedly becoming trapped between teeth
- Swelling, a bad taste or fever if infection develops
A cavity can be present without obvious symptoms. Regular dental examinations help find decay before it becomes painful.
Who is more likely to develop cavities?
Risk rises with frequent sugary drinks or snacks, inadequate fluoride exposure, dry mouth, difficulty cleaning the teeth, exposed tooth roots and a previous history of cavities. Braces, certain medications and medical conditions can make oral care more difficult. Babies and young children can develop decay when teeth are frequently exposed to sweetened liquids.
Treatment
Treatment depends on how far the decay has progressed. Early mineral loss may be managed with fluoride and improved daily care. A cavity usually needs a filling. Decay that reaches the tooth pulp may require root canal treatment or removal of the tooth. A dental abscess needs prompt dental treatment.
Contact a dentist promptly for persistent toothache, swelling, pain when biting or a broken tooth. Seek urgent care if facial or neck swelling affects breathing or swallowing, spreads rapidly or is accompanied by severe illness.
Preventing tooth decay
- Brush twice daily with fluoride toothpaste.
- Clean between the teeth every day.
- Limit how often you have sugary foods and drinks.
- Drink water regularly and discuss persistent dry mouth with a dentist or healthcare professional.
- Attend dental checkups at intervals recommended for you.
- Ask whether fluoride varnish or dental sealants are appropriate, especially for children or people at higher risk.
See Oral Health for more information about caring for your teeth, gums and mouth.
Sources
- Centers for Disease Control and Prevention: Cavities and Tooth Decay
- Centers for Disease Control and Prevention: Preventing Oral Diseases
- MedlinePlus: Tooth Decay
Reviewed September 2026.
Medical disclaimer: This information is general and does not replace an individual dental or medical assessment.