The thickness of the dentin correlates directly with the

• A. Permeability decrease
• B. Fracture resistance
• C. Color of tooth
• D. Protection to the pulp

Answer: (D)

Dentin thickness acts as a protective barrier for the dental pulp. The dentin layer sits between the enamel and the pulp and contains tubules that transmit stimuli such as heat, cold, chemicals, and bacteria. When dentin is thin, these stimuli have a shorter distance to travel and can more easily reach the pulp, increasing the chance of irritation or inflammation. A thicker dentin layer increases the diffusion distance and, often, tubule occlusion with age or sclerosis, which reduces permeability and shields the pulp from irritants. While reduced permeability is part of the mechanism, the overall effect of having more dentin is stronger protection of the pulp. The color of the tooth and fracture resistance are influenced by other factors and aren’t the direct correlate of dentin thickness in this context.