The effect of strontium oxide in glass-ionomer cements

The reaction of strontium oxide powder with poly(acrylic acid) has been stu died both alone and within glass-ionomer cements. Reaction was found to be slow and the strontium-carboxylate structure was found to be partially cova lent in character, as determined by Fourier transform infrared spectroscopy (FTIR). These are similar to the structures formed by calcium in glass-ion omer cements, but are different from typical monomeric strontium carboxylat es, which tend to be purely ionic. Strontium oxide powder introduced in two types of glass-ionomer cements, slowed down the setting reaction at both 2 1 degrees C and 37 degrees C, but at low levels (5 wt %), increased the com pressive strength in both cement formulations studied. However, at higher l evels, it was found to decrease the compressive strength. This study confir ms the view that strontium is a cement-forming ion; but concludes that, exc ept at very low levels, strontium oxide powder does not improve the propert ies of glass-ionomer cements. (C) 1999 Kluwer Academic Publishers.