What is biofilm?

• A. Induced acid demineralization of the tooth surface.
• B. A protective bacterial layer
• C. A mineralized biofilm
• D. A type of saliva

Answer: (A)

Biofilm is a community of microorganisms that attach to a surface and live within a self-produced, sticky matrix. In the mouth, this is dental plaque that forms on tooth surfaces and along the gumline. The matrix helps bacteria cling, protects them from shear forces, and creates microenvironments where metabolism happens—like producing acids from sugars that can lead to enamel demineralization over time.

Think of biofilm as a structured, cooperative community rather than a simple film or surface layer. Describing biofilm as a direct cause of demineralization misses the broader idea that the biofilm itself is the organized group of organisms; the acid it produces is a consequence of its activity. It isn’t just a protective layer on its own, nor is it something mineralized or a type of saliva. Calculus is mineralized plaque, not the biofilm itself.