الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This in vitro study was conducted to compare the antibacterial efficacy of chitosan nanoparticles, calcium hydroxide, and double antibiotic paste, all in methylcellulose vehicles, when used as intracanal medications against three-week-old Enterococcus faecalis biofilm by quantification of bacterial colony forming units per milliliter after seven and 14 days.
Sixty extracted single-canaled mandibular premolars with mature apices were selected for this study. Each tooth was reduced occlusally to standardize the specimen length (14 mm). Access cavity and root canal preparation were then performed. After sterilization, specimens were inoculated with E. faecalis for three weeks. Biofilm formation was confirmed by scanning electron microscopy in four randomly selected specimens. The remaining fifty six specimens were equally divided into four groups. group 1: 20 mg/mL chitosan naoparticles in methylcellulose, group 2: 35% calcium hydroxide in methylcellulose, group 3: 1 mg/mL double antibiotic paste in methylcellulose, and group 4: methylcellulose (control group). Each group was sectioned into two equal subgroups and incubated for seven or 14 days. After each treatment period, the biofilms were collected from the root canals, diluted, and smeared on blood agar plates. The antimicrobial efficacy was assessed according to the number of bacterial colony forming units per milliliter.
Data were then recorded and statistically analyzed. The results showed that all the tested antibacterial agents resulted in complete eradication of E. faecalis after 14 days. However, calcium hydroxide was the only medication that exhibited a significant bacterial count reduction in seven days. No statistically significant difference was found between chitosan nanoparticles, calcium hydroxide, and double antibiotic paste at both time intervals.