_____ forms a barrier through which toxic materials must diffuse through to reach the pulp tissue?

_____ forms a barrier through which toxic materials must diffuse through to reach the pulp tissue?

• A. Pulp tissue
• B. Enamel
• C. Dentin
• D. Cementum

Answer: (C)

Dentin acts as the diffusion barrier between the outer environment and the pulp. It is the mineralized tissue just beneath the enamel (and surrounding cementum on roots) and contains many dentinal tubules filled with fluid. Toxic materials must pass through these tubules and the dentinal fluid to reach the pulp, so dentin largely governs how readily substances diffuse toward the pulp. The presence or absence of the smear layer and the degree of dentin permeability (sclerosis, tubule openness) influence how easily diffusion occurs. Enamel sits on top as the outer cover, but the actual barrier that controls diffusion to the pulp is dentin.

Dentin acts as the diffusion barrier between the outer environment and the pulp. It is the mineralized tissue just beneath the enamel (and surrounding cementum on roots) and contains many dentinal tubules filled with fluid. Toxic materials must pass through these tubules and the dentinal fluid to reach the pulp, so dentin largely governs how readily substances diffuse toward the pulp. The presence or absence of the smear layer and the degree of dentin permeability (sclerosis, tubule openness) influence how easily diffusion occurs. Enamel sits on top as the outer cover, but the actual barrier that controls diffusion to the pulp is dentin.