Effect of Amorphous-Calcium-Phosphate on an Universal Adhesive

Objectives: The aim of the present investigation was to evaluate the effect of an amorphous-calcium-phosphate paste (ACP) on microtensile bond strength of a recently introduced universal adhesive system (Futurabond U, Voco, Cuxhaven, Germany) on enamel in vitro.
Methods: 80 freshly extracted third molars were included. All teeth were specially prepared allowing the simulation of dentin perfusion. The specimens were randomly assigned to four experimental groups: group A: enamel, etch&rinse; group B; enamel, self-etch, group C: enamel, etch&rinse, ACP; group D: enamel, self-etch, ACP. All materials were applied on a surface area of 0.785mm² as recommended by the manufacturer. An amorphous-calcium-phosphate paste was applied in advance in group C and D. Microtensile bond strength (µ-TBS) of the above mentioned adhesive systems was measured 15 minutes after application and light curing of the composite material (GrandioSo, Voco, Germany, colour A2) using an universal testing machine. Statistical analysis was performed using SPSS 20.0.
Results: For the four test series following microtensile bond strengths were evaluated (mean value and standard deviation in MPa): group A 12.96 (+/- 3.43), group B 7.01 (+/- 3.51), group C 7.15 (+/- 2.20) and group D 8.41 (+/- 4.60). Statistical analysis showed a significant influence of the used bonding mode (p< 0.001, ANOVA). Bond strengths of Futurabond U used on enamel in etch&rinse mode without ACP (group A) was significantly increased compared to all other groups (p< 0.05, Tukey´s test). Regarding the ACP (group C and D) no significant differences could be detected between the different modes of action (p> 0.05, Tukey´s test).
Conclusions: Regarding the limitations of an in vitro study it can be concluded that the universal adhesives system showed promising results, especially when used in etch&rinse mode on enamel without ACP. The impact of ACP was higher in etch&rinse mode as in self-etch mode.