What do desensitizing agents precipitate on the dentin surface?

Desensitizing agents are formulated to reduce the sensitivity of teeth, often targeting the exposed dentin. When applied, these agents work by creating a barrier over the dentin tubules, which are channels that connect the nerves of the tooth to external stimuli such as temperature changes or certain substances.

The correct answer identifies that desensitizing agents precipitate crystalline salts on the dentin surface. This precipitation occurs as the components of the desensitizing agent react with the fluid and minerals present in the dentin. The formation of these crystalline salts effectively plugs the dentinal tubules, which diminishes the ability of stimuli to trigger nerve response, thereby reducing sensitivity.

The other options provide substances that do not typically form as a direct result of the action of desensitizing agents on the dentin surface. Liquid enamel, calcium ions, and gold particles do not align with the intended mechanism of desensitization, which relies on the creation of a physical barrier through the precipitation of salts rather than liquid formation or the introduction of specific ions unrelated to the desensitization process.