Antimicrobial effect of nano Calcium Hydryoxide on the Enterococcus faecalis biofilm at different developmental stage

Abstract

Background for Treatment: Enterococcus faecalis is one of the most resistant bacteries in root canals and is considered as a root canal treatment failure agent which is resistant to antimicrobial agents and its biofilm resistance is much higher than planktonic state. Therefore, antimicrobial resistance study of newly introduced substances in endodontics field, like nano-calcium hydroxide, seems essential. The aim of this study was to determine antimicrobial effect of nano-calcium hydroxide against 4 and 6 week old Enterococcus faecalis biofilm.

Method: In this study, 70 single root and single canal teeth without anomalies and decay were used. After cleaning and preparing the canals, a solution containing Enterococcus faecalis was placed inside the canal of the teeth and new culture medium was added everyday to form biofilm of bacteria. In the first group, this procedure was performed for 4 weeks and in the second group for 6 weeks. Then, 5 samples from each group were examined for confirmation of biofilm formation under scanning electron microscope. Subsequently, each group was divided into three subgroups and the antimicrobial agent was administered as a intracanal medicament. In the first subgroup,nano-calcium hydroxide and in the second subgroup calcium hydroxide and in the third subgroup phosphate buffered saline (control) was used for one week. The results of the study were reported using descriptive statistics (mean ± standard deviation). Kruskal-Wallis test was used to compare the CFU level in three groups of nano-calcium hydroxide, calcium hydroxide and phosphorous-buffered saline (PBS) separately at 4 and 6 weeks, due to unusual distribution of data. The comparison between CFU at 4 and 6 weeks in each group based on the abnormal distribution of data was performed by U-Mann-Whitney test. Statistical analysis was performed using SPSS17 software. The significance level was considered as P <0.05.

Results: The mean CFU in the 4-week subgroup in nano-calcium hydroxide and calcium hydroxide and PBS was 282 ± 188.79 and 561± 656.97 and 5005.50±3.02 and in the 6 weeks, 89±56.26 and 333±337.64 and 5505.50±3.02 , which showed a significant difference between used materials. (P value<0.05)

Conclusion: According to the results of this study, the antibacterial properties of nano-calcium hydroxide against 6 weeks old Enterococcus faecalis biofilm are higher than Calcium hydroxide although there was no difference between calcium hydroxide and nano-calcium hydroxide in 4 week old biofilm.