When bonding agents placed on dentin, cytotoxicity is

• A. Increased
• B. Reduced
• C. Unchanged
• D. Variable

Answer: (B)

When bonding agents are placed on dentin, the dentin itself acts as a natural barrier that limits the amount of potentially toxic components reaching the pulp. The mineralized dentin and dentinal fluid slow diffusion, and once the adhesive polymerizes and a hybrid layer forms, the permeability to residual monomers and acids decreases further. Because the pulp is shielded by this barrier, cytotoxic effects are generally reduced compared with direct exposure to pulp or very thin dentin. Of course, if dentin is extremely thin or compromised, the protection can lessen and cytotoxic exposure may rise, but under typical clinical conditions the barrier effect makes cytotoxicity lower.