Effect of Incorporation of Amorphous Calcium Phosphate on Bonding Strength of a Dental Adhesive

Amorphous calcium phosphate (ACP) which is a transient phase in the natural bio-mineralization process has recently gained the spotlight. This study aimed to assess the effect of the incorporation of nano-ACP (NACP) in a dental adhesive with/without surface treatment with silane coupling agent on bond strength. NACP was synthesized by the wet chemical precipitation technique. To characterize the structure of NACP, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used. Forty molars were randomized into 4 groups of 10. The teeth were restored with composite resin and the bonding agent (one of the four groups). Adper Single Bond 2 was used as the control group. In the 4 wt% NACP group, NACP fillers were added to the bonding agent. In 0.4 wt% and 4 wt% SNACP groups, silanized NACP fillers were added to the bonding agent. Finally, the mode of failure of specimens was determined. Data were analyzed by one-way ANOVA and Tukey's post-hoc tests. P< 0.05 was considered statistically significant. The addition of 4 wt% non-silanized NACP decreased the bond strength compared with the control group (P< 0.05). The bond strength of the groups with silanized fillers was not significantly different from that of the control group. The addition of silanized NACP to dental adhesive had no significant adverse effect on bond strength, which is a promising finding to pave the way for the synthesis of bonding agents containing bioactive fillers.