What happens when hypertonic fluid is applied to dentine?

When hypertonic fluid is applied to dentine, the concentration of solutes outside the tooth is greater than that inside. This creates an osmotic gradient. Water moves from an area of lower solute concentration (inside the dentine) to an area of higher solute concentration (the hypertonic fluid outside). As a result, fluid moves from inside to outside, causing dehydration of the dentine and potentially leading to increased tooth sensitivity or discomfort.

This movement occurs because cells and tissues strive to balance solute concentrations across their membranes. In this specific scenario, the hypertonic solution draws moisture out from the dentine, confirming that fluid indeed moves from inside to outside the tooth structure.