Calcium phosphate-based solutions promote dentin tubule occlusions less susceptible to acid dissolution

To determine the efficacy supersaturated calcium phosphate (CaP) solutions containing fluoride (F) and zinc (Zn) ions in occluding dentin tubules with precipitates less susceptible to acid dissolution and to compare the performance of these solutions with the oxalate solutions containing calcium (Ca) or phosphate (P) ions.

Dentin sections from human molars divided into groups: Group A - control (treated with double distilled H2O), Groups A1, A2 and A3 were treated with experimental solutions supersaturated with respect to F and Zn-substituted calcium phosphates. Solutions A1 and A2 were similar in composition but differed in pH values (A1, pH 7; A2, pH 5.5). Solutions A2 and A3 were similar in pH (pH 5.5) but the A3 solution had twice the concentrations of F and Zn2+ ions compared to A2. Another group of dentin sections were treated with A3 solution, oxalate solution containing Ca (OX/Ca) and OX solution containing P (OX/P). The control and treated dentin sections were characterized using scanning electron microscopy.

All treated dentin sections showed occluded dentin tubules; with the group A3 showing the highest percent of occluded dentin tubules. The precipitates in the dentin tubules treated with A3 remained while those treated with OX/Ca or OX/P dissolved after exposure to an acidic buffer.