Objectives: to evaluate the antimicrobial efficacy of chlorhexidine-loaded silver nanoparticles (CHX-loaded AgNPs), silver nanoparticles (AgNPs), and 2% chlorhexidine (CHX) solutions on Enterococcus faecalis biofilm.
Methods: Forty-five root specimens were chemo-mechanically prepared using rotary files, cleaned in ultrasonic bath and autoclaved. The specimens were then inoculated with a pure strain of E faecalis to develop a 6 weeks old biofilm. A fresh
broth adjusted to No. 1 MacFarland turbidity standard was replenished every 72 hours. After 6 weeks, 5 specimens were examined with scanning electron microscope (SEM) to confirm biofilm formation. The rest were divided into 4 groups (n=10), group I: CHX-loaded AgNPs, group II: 100 ppm AgNPs, group III: 2% CHX, and group IV: sterile saline (negative control). The antimicrobial effectiveness was determined using colony forming units (CFU) method and verified via confocal microscopy, via calculating bacterial reduction (Cr%) and red intensity percentages (%R) for both tests respectively. Statistical analysis was done using one-way ANOVA, followed by Tukey's and Bonferroni post hoc tests.
Results: The highest C_(r%) was seen after 10 minutes of application (46.21%) and in group I (65.30%), followed by groups II (43.30%) and III (38.37%), and the least in group IV (10.36%). The highest %R was observed after 10 minutes (40.93%) of application and in groups I (48.54%) and II (42.15%), while groups III (31.09%) and IV (27.78%) were significantly lowest.
Conclusions: The combination between CHX and AgNPs showed a synergistic activity against E faecalis biofilm compared to either of them alone.