Antibacterial effect of experimental chlorhexidine-releasing polymethyl methacrylate-based root canal sealers

This study evaluated the extent of chlorhexidine release from experimental chlorhexidine-containing polymethyl methacrylate (PMMA)-based root canal sealers prepared from a methacrylate-based sealer (SuperBond Sealer, Sun Medical Co Ltd, Shiga, Japan) and to examine its antimicrobial effect against Enterococcus faecalis using the direct contact test.

Chlorhexidine diacetate powder was mixed with PMMA powder of SuperBond Sealer to obtain chlorhexidine concentrations of 1 wt%, 2 wt%, and 3 wt%, respectively. PMMA disks were fabricated by self-curing the experimental PMMA powder and pure SuperBond sealer (control) and immersing them in distilled water at 37 degrees C for 12 weeks. Chlorhexidine release was analyzed by high-performance liquid chromatography. The direct contact test was performed on wells of 96-well plates coated with the respective experimental root canal sealers (n = 6). Bacterial suspensions were placed directly on the sealers that were aged for 12 weeks.

The cumulative chlorhexidine release after 12 weeks of water immersion was largely dependent on the amount of chlorhexidine powder that was initially incorporated into the PMMA-based sealer. Kruskal-Wallis test revealed that chlorhexidine concentration had a significant effect on the cumulative release (p = 0.0005). Experimental sealers with the incorporation of 2 wt% and 3 wt% chlorhexidine exhibited sustained antimicrobial effect for at least 4 weeks and 8 weeks.

The incorporation of 2 wt% and 3 wt% chlorhexidine in the PMMA-based sealer had a long lasing antimicrobial effect against Enterococcus faecalis as a result of the turbidimetric determination of bacterial growth.