The purpose of this study was to observe the effect of different condi
tions of storage on the surface and in the depth of luting glass ionom
er cement by measuring microhardness. The hardness of a glass ionomer
cement was measured after storage in wet and dry conditions and in an
atmosphere of 80% relative humidity, for times up to 1000 h. Storage i
n distilled water produced a softening effect, but the depth hardness
increased progressively. The penetration of the water is a surface phe
nomenon and does not affect the depth of the cement. However, the ceme
nt is vulnerable to moisture to a depth of 600 mu m and marginal gaps
evolve in the range of 40 to 80 mu m when the luting cement at the too
th crown margin is always destroyed.