In dental biofilm, cell-to-cell contact is mediated by:

• A. Protein adhesins
• B. Polysaccharide receptors
• C. Both protein adhesins and polysaccharide receptors
• D. Lipids

Answer: (C)

Cell-to-cell contact in dental biofilm relies on specific interactions between bacterial surface molecules. Proteins called adhesins on one cell bind to complementary receptors on a neighboring cell, providing a targeted way for bacteria to stick together. At the same time, extracellular polysaccharides produced by the bacteria create a sticky matrix and can serve as receptors or binding substrates for these adhesins, promoting close contact and stable associations within the biofilm. In dental plaque, both mechanisms work together to enable co-aggregation and biofilm maturation, so both protein adhesins and polysaccharide receptors contribute to cell-to-cell adhesion. Lipids don’t play the primary role in mediating these targeted interactions.