Previous investigations of dentine sensitivity using osmotic stimuli have noted that very high molar concentrations (2-6 M) were required to elicit pain. When hydrostatic pressures were used, far smaller pressures were required, indicating that only a fraction of the theoretical osmotic pressure of solutions is effective for moving fluid across dentine. The ratio of the effective to theoretical osmotic pressures, termed the reflection coefficient (σ). is a measure of the degree of semi-permeability of dentine and can vary from 0 (complete solute permeability) to 1.0 (complete solute impermeability). Dentine discs were placed in a split chamber device connected to a pressure transducer. The effective osmotic pressures of solutions containing solutes of various molecular sizes were determined on sanded, acid-etched and oxalate-treated dentine. Reflection coefficients in sanded dentine increased with increasing molecular size from 3 × 10-4 for sucrose to 0.38 for albumin. Acid-etching produced a statistically significant 5-9 fold decrease in reflection coefficients (increased solute permeability) but oxalate treatment restored them to sanded dentine levels.
ASJC Scopus subject areas
- Cell Biology