(PO85) Relative Efficacy of Innovative Endodontic Antimicrobial Agents

Abstract: Novel endodontic antimicrobial agents could potentially improve the outcomes of endodontic treatment, including regenerative endodontic therapy. The aim of this study was to determine the efficacy of a novel experimental compound, analogue #66, compared to tigecycline and other controls in an ex vivo model. MIC determination for Streptococcus mutans and Streptococcus intermedius was carried out with tigecycline and analogue #66. Forty single-rooted extracted teeth were inoculated weekly for three weeks with S. intermedius to create a biofilm. All teeth were instrumented to a 40/06 size to working length and irrigated with 5% NaOCl. The teeth were randomly divided into four groups (n=10 per group): (1) DMSO as a negative control; (2) calcium hydroxide as a positive control; (3) the analogue #66 (10 mg/mL) group; and (4) tigecycline (10 mg/mL). Microbiological sampling from all groups was performed after one week. Log colony-forming units (CFUs) from calcium hydroxide (5.07 ± 0.12), analogue #66 (4.94 ± 0.15), and tigecycline (0.58 ± 1.22) showed statistically significant (p <.05) bacterial reduction when compared with the negative control of DMSO (5.71 ± 0.17). All antimicrobial agents significantly reduced the CFUs compared to DMSO (p <.05). Although a higher microbial reduction was observed with analogue #66 compared to calcium hydroxide, the difference was not statistically significant (p>.05). Residual CFUs were lowest in the tigecycline group, significantly lower than all other groups (p <.05). Calcium hydroxide, analogue #66, and tigecycline all showed significant antimicrobial efficacy against S. intermedius biofilm, with tigecycline being the most efficacious in this model.