Which statement best describes the effect of a dentin barrier on cytotoxicity?

• A. It increases cytotoxicity
• B. No effect
• C. It reduces cytotoxicity
• D. It causes inflammation

Answer: (C)

A dentin barrier reduces cytotoxicity by slowing the diffusion of toxic components from a restorative material toward the dental pulp. Dentin contains tubules with dentinal fluid and a mineralized matrix; together they act like a natural shield. According to diffusion principles, the flux of cytotoxic substances is lower when the barrier is thicker or less permeable, so less material reaches the pulp and the pulp’s exposure—and potential inflammatory response—is diminished. This barrier does not create cytotoxicity or inflammation by itself; those outcomes occur if the barrier is compromised or the material is highly toxic and the dentin is thin. So, the barrier best described is that it reduces cytotoxicity.