Why does plaque reform within hours even after thorough brushing? Plaque is not loose debris — it is a biofilm. Within minutes of cleaning, salivary proteins coat the tooth (acquired pellicle); pioneer bacteria attach, multiply, and secrete a sticky polysaccharide matrix that anchors the community. This organized structure is why mechanical disruption (brushing, flossing) is essential — rinsing alone cannot tear a mature biofilm apart.