Addition of either Al(NO3)(3) or Fe(NO3)(3) to zinc polycarboxylate and glass polyalkenoate dental cements has been shown to cause an acceleration to their setting reactions. In the case of Fe(NO3)(3), the reaction was so fast that cements could not be mixed, but Al(NO3)(3) had a less severe effect, and cements containing various amounts of this additive were prepared. Their compressive strength at 24 h was lower than for the original cements, with zinc polycarboxylate being more affected than the glass polyalkenoate. Both cements are made from poly(acrylic acid), and infrared spectroscopy showed that both Al(NO3)(3) and Fe(NO3)(3) form adducts with this polymer, the interaction of aluminum with the polymer being significantly different from that of the iron (III) species. The binding by Al(NO3)(3) was also shown to reduce the pH of a poly(acrylic acid) solution.