Water absorption, dimensional change and radial pressure in resin matrix dental restorative materials.

摘要

The purpose of this work was to study the relationship between water absorption, dimensional change (swelling) under cavity constraint and radial stress generation in resin matrix dental restorative materials. Water absorption was determined on disc specimens whilst swelling was determined on samples of materials restrained within cavities cut in cast polymethylmethacrylate and pressure generated was determined using a 'push-out' test. Four commercially available resin matrix materials were used. A giomer material gave significantly greater water absorption than two compomers and a fluoride releasing composite ( [Formula: see text] ). The giomer material was the only material which produced a significant degree of swelling ( [Formula: see text] ) when restrained within a cavity. The giomer product produced the greatest radial pressure (over 20MPa in 1 month) following water storage, however a significant pressure generation was also observed for other materials despite their much lower water absorptionvalues. The mechanism of water absorption and the amount of water absorbed determine the dimensional changes and radial pressure generated by resin matrix materials in a moist environment.