Which factor dramatically reduces fluid convection in dentin?

• A. Cavity liners
• B. Bonding agents
• C. Sealers
• D. Smear layer

Answer: (C)

Fluid convection in dentin happens when pulpal pressure drives fluid through the dentinal tubules. To dramatically cut that flow, you need to block the pathways that permit movement across the canal walls. Sealers placed during endodontic obturation seal the dentinal tubules and create a continuous barrier at the dentin–gutta-percha interface and along the canal walls. That comprehensive seal greatly lowers hydraulic conductance and dampens fluid movement in response to pulpal pressure or temperature changes.

Other materials provide important functions, but they don’t offer the same level of canal-wide sealing of tubules. Cavity liners protect the pulp but don’t uniformly occlude dentinal tubules throughout the dentin. Bonding agents can reduce permeability locally at bonding interfaces but aren’t designed to seal the entire canal wall against fluid flow. The smear layer can obscure tubules and reduce permeability to some extent, but it is often altered or removed in adhesive procedures and doesn’t provide the robust, long-lasting conduit-blocking effect that a properly placed sealer does.