Extreme sensitivity to heat and cold in hyposalivation is especially evident if what is exposed?

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

Answer: (A)

Dentin exposure is what drives extreme heat and cold sensitivity, especially when saliva is scarce. Dentin is full of tiny tubules that run from the surface to the pulp. When there’s a temperature change, fluid inside those tubules moves. This fluid movement alters the electrical and chemical environment near the nerve endings in the pulp, triggering a sharp pain through the hydrodynamic mechanism. Saliva normally helps protect dentin by lubricating the surface, helping form a barrier, and decreasing tubule permeability; when saliva is reduced, these protective effects are lost, so the fluid shifts in the tubules provoke even stronger nerve responses. Enamel doesn’t cause sensitivity because it has no nerves or tubules, so it doesn’t transmit these rapid fluid movements. Cementum can be involved if exposed, but the direct, most pronounced pathway for temperature-induced pain is through dentinal tubules, making exposed dentin the culprit.