Abstract
Background and objectives: One of the main steps of root canal therapy has been revealed as root canal irrigation. An important requirement for an endodontic irrigant is antimicrobial activity. The purpose of this study was to determine the minimal antimicrobial concentrations of citric acid and doxycycline in combination with Tween 80 - a detergent - against Enteroccocus faecalis to gain a suitable irrigant with antibacterial properties.
Materials and Methods: In this experiment, at first antibacterial activity of citric acid solutions of different concentrations (10%,15%,20%...50%) with using of Enteroccocus faecalis suspension in contact with citric acid was evaluated .Then for testing antibacterial activity of doxycycline against Enteroccocus faecalis, an antibiogram disk was used. At last antibacterial activity of different concentrations of doxycycline and citric acid and Tween 80 were determined by measuring the zones of inhibitions (mm) and was compared with routine intra canal irrigants like EDTA and sodium hypochlorite. The test groups were 12 as:1, 2,3,7,8 and 9 contained citric acid 5% ,Tween 80 and doxycycline 1.5,2.5,5,15,25and 50mg/ml respectively .Group 4,5,and 6 contained citric acid 10% ,Tween 80 and doxycycline 1.5,2.5 and 5mg/ml respectively .Group 10,11and 12 were sodium hypochlorite 5.25%,EDTA 17% and citric acid 5%.
Results: Comparison between groups (1,4),(2,5),(3,6),(7,8)and (7,9) showed that differences were not significant statistically (Mann Withney U).The difference between groups 1,2,3,7,8 and 9 was significant.(Kruskal Wallis P=0.000 ) Our study indicated that increasing citric acid concentration has not any effect on its antibacterial activity. Measurement of zones of inhibitions showed that increasing doxycycline concentration more than saturated point (15mg/ml) in 5% citric acid dose not increases antibacterial activity of the solutions.
Conclusion: Based on this study it seems that a solution with combination of 15mg/ml doxycycline, 5%citric acid and Tween 80 has maximum antibacterial effect on Enteroccocus faecalis. Using tooth models is suggested to get more findings.