Self-etching dental adhesive containing a natural essential oil: anti-biofouling performance and mechanical properties

This study assessed the anti-biofouling performance of an experimental adhesive system containing a naturally occurring essential vegetable oil and examined the following physical and mechanical properties: water sorption (WS) and solubility (SL), microtensile bond strength to dentin (mu TBS), and degree of conversion. The following six groups were tested: a self-etching experimental adhesive containing refined essential oil from the seeds of the Butia capitata tree (EA(O)); an oil-free version of the experimental adhesive (EA(NO)); one group without adhesive as the control (C); and the three following commercial self-etching adhesives: Clearfil Protect Bond (CPB), Clearfil SE Bond, and Adper SE Plus. The antibacterial effect was estimated by microbiological culture on selective/non-selective media, and the results expressed as colony-forming units per unit weight of dry biofilm (CFU mg(-1)). The data were submitted to ANOVA and Tukey's post hoc test (alpha=0.05). After 24 h, pH changes were similar in the storage medium of all tested adhesive systems. EA(O) showed similar levels of antimicrobial activity in a model biofilm microcosm as the commercial self-etching adhesive CPB. Both were effective against total microorganisms, aciduric bacteria, lactobacilli, and Streptococcus mutans. WS and SL were not affected by the presence of the essential oil; the values of EA(O) were similar to or less than those of commercial equivalents. The incorporation of an essential oil into an experimental adhesive did not influence its monomer conversion result. Immediate mu TBS values of EA(O) and EA(NO) were similar and were greater than those of commercial equivalents. After storage for 6 months, the mu TBS of the EA(O) decreased significantly and became similar to the values of commercial equivalents, while the strength of the EA(NO) was not affected.