Effects of evaporation on the properties of water-based dental luting agents.

The most commonly used luting agents for fixed prosthodontics are water-based cements: zinc phosphate, zinc polycarboxylate, glass ionomer, and resin-modified glass ionomer. Properties were tested at baseline and after the cement liquids were allowed to evaporate for 10, 20, and 30 minutes. Viscosity, pH, contact angle, and surface tension were determined using the cement liquids only; tensile strength, hardness, film thickness, and working/setting times were determined after the cements had been mixed with the various liquids. pH decreased over 30 minutes, while viscosity, contact angle, and film thickness all increased, especially for the zinc polycarboxylate and glass ionomer cements. Changes in mechanical properties depended upon time and material.