Plaque and stains attach to which feature on the tooth?

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

Answer: (C)

The key idea is that the first layer on a tooth surface is the acquired pellicle, a thin protein film derived from saliva that coats enamel (and other surfaces). This pellicle provides binding sites and receptors that allow bacteria to attach, so plaque (the bacterial biofilm) forms on this film. Stains also adhere to pellicle components, making them appear on the tooth surface as part of or alongside the biofilm.

Enamel is the underlying surface, but the immediate attachment happens to the pellicle coating rather than to enamel itself. Dentin is a different tooth tissue beneath enamel, and biofilm refers to the bacterial community that forms after attachment to the pellicle, not the substrate itself. So the feature that plaque and stains attach to is the acquired pellicle.