Effect of natural cross-linkers incorporation in a self-etching primer on dentine bond strength

The aim of this in vitro study was to investigate the effect of incorporation of natural cross-linkers into the primer of a self-etching adhesive on resin-dentine bond strength.

Flat dentine surfaces were prepared from extracted human molar teeth and were applied with the following self-etching primers. The 0.5% hesperidin (HPN), 0.5% chlorhexidine (CHX) or 0.5% grape seed extract (GSE) was incorporated into Clearfil SE primer (Kuraray Medical, Inc.) to formulate three experimental primers. The original SE primer served as control. Following primer application, the teeth were bonded with Clearfil SE bond, restored with resin composite and stored in water for 24 h at 37 °C. The bonded specimens were sectioned into beams and subjected to micro tensile bond testing (μTBS). Failure analysis and morphological evaluation of the dentine surfaces were performed using a scanning electron microscope (SEM). Hardness (H) and elastic modulus (EM) were measured using nano-indentation technique to examine the mechanical properties of the bonded interfaces.

One-way ANOVA showed significant differences in μTBS, H and EM among the tested and control groups (p < 0.001). Tukey post hoc test revealed that incorporation of HPN significantly increased μTBS, H and EM, when compared with the other groups (p < 0.006). The GSE-incorporated group significantly decreased μTBS, H and EM, when compared with the other groups (p < 0.006); while CHX-incorporated group did not show any statistical significant difference when compared with the control group.

Incorporation of HPN into Clearfil SE primer had a positive influence on the immediate μTBS and mechanical properties of the bonded interface.