Polycarboxylate cements are a combination of aqueous polyacrylic acid and zinc oxide. They have an excellent biocompatibility with the pulp and are almost equivalent to zinc oxide eugenol cements. The pH of the cement liquid is approximately 1.7. The pH of the mix rises rapidly as the setting reaction proceeds.
Despite the initial acidic nature of the polycarboxylate cements, these products produce minimal irritation to the pulp probably because the larger size of the polyacrylic acid molecule limits its diffusion through the dentinal tubules. At all times, the pH of the polycarboxylate cement is higher than the pH of the phosphate cements. Also in the set cement the acrylic acid ions bind the metallic ions so tightly that they are not easily leached out from the set cement.
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