How could toothpaste prevent tooth decay?

Decay: When you brush your teeth you use toothpaste. Right? Good brushing with tooth paste will remove plaque from your teeth. And plaque is what causes cavities and gingivitis.

Fluoride: Bacteria breaks down enamel crystal hydroxyapatite. Fluoride can form new crystal fluorohydroxyapatite. This crystal is much more resistant to decay.

Fluoride: Cleaning the plaque from the tooth and the cavity prevention effects of fluoride help prevent tooth decay. Keep brushing with a fluoride toothpaste.

Abrasive & fluoride: Toothpastes contain mild abrasives which physically scrub away the plaque and bacteria. The fluoride is making your tooth more resistant to future acid attacks. However, toothpaste alone is not enough. If you can't find the answer to your question here or if an answer posted is unclear, please contact your dentist for more information and check up.