EFFECTIVENESS OF SIMVASTATIN ON BACTERIA FROM UNSUCCESSFUL ROOT CANAL TREATMENT (In-vitro)

Abstract

Background: In clinical cases of primary root canal treatment failure, the main cause is bacteria that can survive within the complex root canal anatomy. Many of these bacteria are resistant to antibiotics and antiseptic techniques. As there is an increasing number of studies that detail the attenuation of microbial growth, both in vitro and in vivo virulence, by using Simvastatin (SMV) treatment, evaluation in vitro of SMV for intracanal disinfection is required, and this was the main focus of this study. Aim: To assess the antimicrobial activity and effectiveness of SMV in vitro on bacteria commonly persisting in patients after primary root canal treatment (RCT). Methodology: Microbial samples were taken of 2 patients. Advanced microbiological culturing techniques were used to isolate the microbiota; subsequently, biochemical tests and 16S ribosomal RNA were performed. The antimicrobial assessment of SMV comparing to NaOCl was achieved via disk-diffusion agar method (DD), minimum inhibitory concentration (MIC) test, plastic-surface biofilm models and killing profile assay. Additionally, the antimicrobial resistance (AMR) profile of the strains isolated was assessed. The focus was made on a panel of Enterococcus faecalis (E. faecalis) strains OS16, OMGS3197, OG1RF, V583 and other novel strains, which were isolated from patients as part of this study. Results: RCR with universal primers and biochemical tests identified nonhemolytic Streptococci (NHS-MW1) and coagulase-negative Staphylococci (CoNS-MW2). In the DD test, all four strains of E. faecalis, NHS-MW1 and CoNS-MW2 seem sensitive to SMV. The MICs of SMV with E. faecalis strains OS16, OMGS3197, OG1RF, V583 were 17.47, 157.60, 10,44 and 14.79µg/ml, respectively; with NHS-MW1 and CoNS-MW2 were 12.55 and 14.60µg/ml, respectively. The MICs of NaOCl for all tested strains were ranged between 0.1% to 0.3% of NaOCl on all tested strains, except for CoNS-MW2 was higher at 0.6%. NHS-MW1 and CoNS-MW2 biofilms effectively inhibited by 150 to 37.5 µg/ml of SMV, however a high level of the biofilm detected when high concentrations of SMV were used. SMV has a bactericidal effect at concentrations two to four times higher than the MIC and bacteriostatic at concentrations equal to the MIC levels on NHSMW1 strain. On CoNS-MW2 strain, SMV exhibit only a bacteriostatic effect. CoNS-MW2 was resistance to Erythromycin. Conclusion: The results obtained from the current in-vitro study raise the possibility of a potentially important antimicrobial effect of SMV as it significantly inhibits biofilm growth and it is effective against antimicrobial resistance strains. However, further investigation is required.