2002 Volume 22 Issue 4 Pages 352-359
Three kinds of resin-modified glass ionomer (RMGI) cements (PF, LC, LCII) for restoration were evaluated by the observation of cement particles and measurement of mechanical properties. Especially, the influences of powder/liquid ratio on the mechanical properties of LCII were investigated.
SEM images of the RMGI cement particles showed that LCII improved cement particles, with consisting uniform fine particles as compared to particles of other RMGI cements. Hardness and compressive properties of LCII were significantly higher (p<<0.05) than those of other RMGI cements since these mechanical properties were enhanced by particle size. The change in powder/liquid ratio on LCII significantly influenced hardness (p<<0.05) but did not influence compressive properties. The evaluation of compressive yield ratio indicated that brittleness increased with the increases in the powder/liquid ratio. The bending strength of LCII was the lowest even when the elastic modulus was the highest. Moreover, that of LCII decreased with increases in powder/liquid ratio. These results suggest that the characteristics of RMGI cements were not only affected by the cement particle size and powder/liquid ratio conventionally important for GI cements, but also by the degree of ductility obtained from the relative resin content in the bulk.
