Arrabidaea chica Extract Incorporated into an Adhesive System: Physico-mechanical Characterization and Bonding Stability

Objectives: This study evaluated the effects of Arrabidaea chica 2.5% (Ac) incorporated into the system Clearfil SE Bond (CL) regarding degree of conversion; zeta potential; particle size; polydispersibility; flexural strength; elasticity and resilience modules; longevity of the bond strength to dentin; and failure mode.
Methods: The degree of conversion of Ac-incorporated into the primer of the CL was determined via Fourier-transform infrared spectroscopy. Particle size, polydispersibility and zeta potencial were determined using a Zetasizer Nano. 15 sticks were used to assess the primer and the CL bond with and without Ac to determine flexural strength, elasticity and resilience modules. Bond strength to dentin was evaluated by the use of flat dentin surfaces from 50 human 3rd molars that were divided into 5 groups (n=10): pre-treatment with Ac aqueous solution + CL (Ac); pre-treatment distilled water + CL (W); primer with Ac + bond CL (AcP); primer CL +bond with Ac (AcB) and CL. After preparing blocks with composite resin, the specimens were cut in a metallographic cutting machine. After 24 hours and 1 year, the samples were subjected to the μTBS test in an universal testing machine, and the surfaces of the fractured test specimens were visually examined and classified according to the fracture mode.
Results: No significant difference was found for the degree of conversion between CL and Ac-incorporated Clearfil. The Ac extract showed no influence on the bond strength do dentin regardless of concentration at 24-hour and 1-year storage in comparison with the control group (CL). An increase in longevity of the bond strength on dentin was observed in all groups after one year. The adhesive fracture was the most frequent mode observed in all groups at 24-hour evaluation, except the group pre-treated with W.
Conclusions: There was no difference in the degree of conversion between Clearfil and Clearfil incorporated with Ac. The zeta potential of Ac in the aqueous solution and in the primer remained stable over time. The average particle size for group AcP increased over time. Flexural resistance, elastic modulus and resilience modulus were lower in the group AcB than in the other groups. There was no difference between groups regarding bond strength, however resistance was higher after one year in all groups.