In Vitro Evaluation of a New Combination of Three Antibiotic Paste Against Common Endodontic Pathogens

Removing the pathogenic microorganisms from the root canal system is the key to a successful endodontic therapy. This study aimed to evaluate the antibacterial efficiency of three antibacterial agents and a new combination against selected endodontic pathogens.

In this in vitro study, the efficacy of three different antibacterial agents namely clindamycin, metronidazole, doxycycline, and their com-bination (CMD) was evaluated against seven bacterial strains associated with endo-dontic infections to determine their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). selective media were used to culture Candida albicans (C. albicans), Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Enterococcus faecalis (E. faecalis), Streptococcus mutans (S. mutans), Bacillus subtilis (B. subtilis) subsp. spizizenii, and Actinomyces actinomycetemcomitans (A. actinomycetemcomitans). All the tests were repeated in triplicate. The MIC and MBC values were reported as mean ± standard deviation. Data were analyzed by the Shapiro-Wilk test, the Kruskal-Wallis test, and Wilcoxon signed-rank test (P<0.05).

The intergroup comparisons of MIC for clindamycin versus CMD (P=0.036), metronidazole versus CMD (P=0.016), and doxycycline versus CMD (P=0.016) demonstrated significant differences. No other significant difference was noted (P>0.05). Intergroup comparisons of MBC for clindamycin versus CMD (p=0.036), metronidazole versus CMD (P=0.022), and doxycycline versus CMD (p=0.016) demonstrated significant differences. No other significant difference was noted (P>0.05).

CMD showed superior antibacterial efficacy than each individual antibiotic, and can be used effectively against the abovementioned endodontic patho-gens for their predictable elimination during endodontic therapy.