Effect of a bonding agent on in vitro biochemical activities of remineralizing resin-based calcium phosphate cements

Objectives To test whether fluoride in a resin-based Ca–PO4 ion releasing cement or coating with an acidic bonding agent for improved adhesion compromised the cement remineralization potential. Methods Cements were formulated without fluoride (Cement A) or with fluoride (Cement B). The treatment groups were A = Cement A; A2 = Cement A + bonding agent; B = Cement B; B2 = Cement B + bonding agent. The calcium, phosphate, and fluoride ion release in saliva-like solution (SLS) was determined from hardened cement disks without or with a coating of bonding agent. For the remineralization, two cavities were prepared in dentin of extracted human molars and demineralized. One cavity received composite resin (control); the other received treatment A, A2, B or B2. After 6 week incubation in SLS, 180 μm cross-sections were cut. The percentage remineralization was determined by transverse microradiography comparing the dentin mineral density under the cement to that under the control. Results The percentage of remineralization (mean ± S.D.) was A (39 ± 14) = B (37 ± 18), A2 (23 ± 13), B2 (14 ± 7). Two-way analysis of variance (ANOVA) and Holm-Sidak test showed a significant effect from the presence of bonding agent (p < 0.05), but not from fluoride (p > 0.05). The ion solution concentrations of all groups showed undersaturation with respect to dicalcium phosphate dihydrate and calcium fluoride and supersaturation for fluorapatite and hydroxyapatite suggesting a positive remineralization potential. Significance Compared to the control all treatments resulted in mineral increase. The remineralization was negatively affected by the presence of the bonding agent.