Adhesion mechanism of polyelectrolyte cements to tooth structure--polyelectrolyte behavior of the cement polymers obtained by potentiometric titration in the presence of calcium ion.

Potentiomeric titration of aqueous solutions of polyacrylic acid and commercial polyelectrolyte cement polymers with sodium hydroxide solution was carried out in the presence of different concentrations of Ca2+. Polyelectrolytes all behave as weak acids without the coexisting Ca2+. However, in the presence of Ca2+, in amounts over one-half of the equivalent amount to the carboxyl group in the polymer, they have a strong acid-like behavior. This means that the carboxyl groups in the polymer chain tend to react strongly with coexisting Ca2+ as they are partially neutralized by the alkaline solution. This is also strong evidence supporting polyelectrolyte cement as an adhesion mechanism to tooth structure during cementation.