What protects bacteria in the plaque from saliva?

• A. Pellicle
• B. Enamel
• C. Biofilm
• D. Calculus

Answer: (C)

Bacteria in dental plaque are organized into a biofilm, and the protective shield comes from this biofilm’s extracellular matrix. This matrix, along with the close community structure, creates diffusion barriers and microenvironments that limit how much saliva and its antimicrobial components can reach the bacteria inside. That means deeper layers in the plaque can persist despite salivary cleansing and defenses. The pellicle is just the initial protein film on the tooth surface that bacteria attach to; it doesn’t protect the bacteria from saliva on its own. Enamel is the tooth surface, and calculus is mineralized plaque—neither provides the protective barrier for the bacteria inside plaque. So the biofilm itself is the key protector.