Cavities form when bacteria in the mouth turn sugars and starches into acids that attack teeth. These acids collect in sticky plaque, especially in grooves, between teeth, and near the gumline. Over time, acid removes minerals from enamel, the hard outer layer of a tooth.
Understanding this process matters because early decay can often be stopped or slowed before it becomes painful or permanent.
A tooth has layers, including enamel on the outside, dentin underneath, and pulp in the center with nerves and blood vessels. Once decay breaks through enamel, it can spread faster through softer dentin and may eventually reach the pulp. Brushing, flossing, limiting frequent sugar, and using fluoride help disrupt plaque and replace lost minerals.
Dental checkups can find early weak spots before they become deep cavities.
Key Facts
- Mouth bacteria + sugar produce acid that can dissolve minerals in enamel.
- Plaque is a sticky biofilm that holds bacteria and acid against the tooth surface.
- Demineralization is mineral loss from enamel, mainly calcium and phosphate.
- Remineralization can repair early enamel damage when minerals and fluoride return to the tooth.
- Enamel is hard but has no living cells, so deep enamel damage cannot heal like skin.
- Decay usually spreads faster after it reaches dentin because dentin is softer and more porous than enamel.
Vocabulary
- Cavity
- A cavity is a hole or damaged area in a tooth caused by tooth decay.
- Plaque
- Plaque is a sticky layer of bacteria, food particles, and saliva that forms on teeth.
- Enamel
- Enamel is the hard mineral-rich outer covering that protects the crown of a tooth.
- Dentin
- Dentin is the softer tooth layer under enamel that can carry sensations toward the nerve.
- Pulp
- Pulp is the soft center of a tooth that contains nerves and blood vessels.
Common Mistakes to Avoid
- Thinking sugar directly drills holes in teeth. Sugar feeds bacteria, and the acids made by bacteria dissolve tooth minerals over time.
- Brushing hard instead of brushing well. Scrubbing too hard can damage gums and enamel, while gentle brushing for enough time removes plaque more safely.
- Assuming pain is the first sign of a cavity. Early enamel decay often has no pain, so white spots or dentist findings can appear before symptoms.
- Believing fluoride fills large cavities. Fluoride helps remineralize early weak enamel, but holes that reach dentin usually need dental treatment.
Practice Questions
- 1 A student drinks a sugary soda 4 times in one afternoon. If each drink creates about 20 minutes of acid attack, how many total minutes are the teeth exposed to extra acid?
- 2 A tooth has an enamel layer about 2.0 mm thick. Early decay has weakened 0.5 mm of the enamel. What fraction and percent of the enamel thickness is affected?
- 3 Explain why sipping a sugary drink slowly for an hour can be more harmful to teeth than drinking the same amount with a meal.