How does the physical action of toothbrushing help protect teeth and gums?

Answer: Bristles disrupt and remove the sticky film of bacteria on teeth

Bristles press minerals into enamel to harden it — Bristles do not strengthen enamel by pressing minerals into it. Fluoride toothpaste helps protect enamel through a separate chemical process, while brushing physically removes plaque.

Bristles disrupt and remove the sticky film of bacteria on teeth ✓ — Brushing disrupts plaque, the sticky bacterial film that builds up on teeth. Plaque bacteria can make acids from sugars and contribute to gum inflammation, so removing the film matters beyond appearance.

Bristles remove stains that would otherwise cause tooth decay — Removing surface stains is not the main protection against decay or gum disease. Teeth can look white and still carry plaque, a bacterial film that brushing helps remove.