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Abstract Summary and Conclusions The purpose of this study was to compare the antimicrobial effect of acidic media (gluconic acid and citric acid) and alkaline media (calcium hydroxide) against Enterococcus faecalis and Candida albicans. Suspensions of Enterococcus faecalis and Candida albicans were adjusted to approximately 0.5 McFarland standards. This study consisted of two parts: Part I: agar diffusion method, agar plates were swabbed with the prepared microbial suspensions using sterile swabs. Four sterile filter paper discs were applied to each plate. Then the tested medicaments and saline were pipetted onto the paper discs. The plates were maintained at room temperature for 2- hours and were incubated at 37 ºC for 24- hours. Then, the diameters of inhibition zones were recorded in millimeters using transparent ruler for data analysis. The test was repeated for each material 6-time with each of Enterococcus faecalis and Candida albicans. Part II: eighty extracted single rooted human teeth were included in the study. Root lengths were standardized. The root canals were instrumented using Protaper Universal rotary system to F5. A 2.5% sodium hypochlorite was used for irrigation in conjunction with 17% EDTA. The root surfaces were coated with varnish and root apices were sealed with resin. Each root was placed separately inside Eppenorf tube. After proper sterilization, paper points were used to confirm sterilization. The canals were contaminated with the prepared suspensions containing either Enterococcus faecalis or Candida albicans. The contaminated roots were incubated for 7- days at 37 ºC. On the fourth day; replenishing of the microbial suspensions was done, then the tubes were closed again 68 until 7- days were completed. After 7- days; 20-μl of Mueller Hinton broth (MHB) was added to confirm contamination using sterile paper points. Then the root canals were irrigated with saline and were dried using sterile paper points. The root canals were divided according to microorganism contamination. Group I: Enterococcus faecalis, Group II: Candida albicans. Each group was divided into 4 equal subgroups according to the tested material. Subgroup A: 10% calcium hydroxide, subgroup B: 10% citric acid, subgroup C: 5% gluconic acid, subgroup D: saline (control). The roots were incubated at 37 ºC for 7- days. After the 7- days, the tubes were opened and the medicaments were removed. Postoperative paper point samples were obtained and plated on agar plates. The plates were incubated at 37°C for 24-48 hour. The number of colony forming units of Enterococcus faecalis and Candida albicans were counted for data analysis and confirmed by Gram stain with light microscope. The results of part I of this study showed that for Enterococcus faecalis, citric acid had the highest statistically significant mean inhibition zone diameter. This was followed by calcium hydroxide, then gluconic acid then saline. For Candida albicans, there was no statistically significant difference between calcium hydroxide and citric acid; both showed the highest statistically significant mean Candida albicans inhibition zone diameters. While, both gluconic acid and saline showed the lowest statistically significant mean Candida albicans inhibition zone diameters. The results of part II of this study showed that for both Enterococcus faecalis and Candida albicans, there was no statistical significant difference between calcium hydroxide, citric acid and gluconic acid. While saline showed the statistically significantly lowest 69 mean % reduction in Enterococcus faecalis and Candida albicans counts compared to other groups. Conclusions: Within the limitation of this study, it can be concluded that different intra-canal irrigants and medicaments used in this study exerted different antimicrobial effect against Enterococcus faecalis and Candida albicans as follows: 1- A 5% gluconic acid has better antimicrobial effect than 10% citric acid against Candida albicans. 2- A 10% citric acid is more effective against Enterococcus faecalis than 5% gluconic acid. 3- A 10% calcium hydroxide is more effective against both microorganisms. |