الفهرس 
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Abstract
The present study evaluated in vitro the antimicrobial efficacy of a new sonic system (EndoActivator) and its capability to promote cleaning, disinfection, removal of debris and
elimination of E. faecalis.
Eighty single rooted teeth were selected for the study. After decoronation, the working length was standardized and the root canals were prepared up to size ISO 45 K-file. The roots were then grooved vertically buccally and lingually using diamond disc.
The apical foramen was sealed with cyanoacrylate and they were coated with two layers of nail varnish. Each root canal was filled with the E. faecalis suspension that was adjusted for 0.5
McFarland turbidity standard, and then submersed in the prepared bacterial suspension in sterile coded sealed flasks incubated for 72
hours. The colony forming units (CFU) were counted. The samples were divided into 2 main groups (40 teeth each) according to the method of evaluation. Each group was then classified into 2 main subgroups (20 teeth each) according to the
method of irrigation. Each subgroup was then divided into 3 divisions according to the type of the final irrigant used.
Group Ι: Bacterial count (n=40) :
• Subgroup A: using EndoActivator (n=20).
Division A1: 8 teeth irrigated with 3ml 5.25% NaOCl (n=8).
Division A2: 8 teeth irrigated with 3ml 2% CHX (n=8).
Division A3: 4 teeth irrigated with 3ml saline (n=4) [control].
• Subgroup B: using disposable plastic syringe (n=20).
Division B1: 8 teeth irrigated with 3ml 5.25% NaOCl (n=8).
Division B2: 8 teeth irrigated with 3ml 2% CHX (n=8).
Division B3: 4 teeth irrigated with 3ml saline (n=4) [control].
Group Π: Debris count (n=40) :
• Subgroup A: using EndoActivator (n=20).
Division A1: 8 teeth irrigated with 3ml 5.25% NaOCl (n=8).
Division A2: 8 teeth irrigated with 3ml 2% CHX (n=8).
Division A3: 4 teeth irrigated with 3ml saline (n=4) [control].
•Subgroup B: using disposable plastic syringe (n=20).
Division B1: 8 teeth irrigated with 3ml 5.25% NaOCl (n=8).
Division B2: 8 teeth irrigated with 3ml 2% CHX (n=8).
Division B3: 4 teeth irrigated with 3ml saline (n=4) [control].
The present study showed that the difference between standard syringe irrigation and EndoActivator was statistically non-significant (p>0.05), although the absolute mean bacterial
count resulting from using EndoActivator group was slightly higher than standard syringe irrigation. There was a significance increase of bacterial reduction achieved by irrigation with NaOCl and CHX more than saline (P<0.05).There was no significant difference between NaOCl and CHX in the reduction of bacterial count (P>0.05) although the absolute mean bacterial count of
NaOCl was lower than that of CHX.
Regarding the debris removal, the present study showed that plastic syringe recorded higher debris % than EndoActivator and this was statistically significant. However for both of them,NaOCl recorded the lowest statistically significant debris % mean value followed by CHX, while saline recorded the highest statistically significant debris % mean value. Also, we found that the coronal region recorded the lowest statistically significant
debris % mean value followed by middle, while apical one recorded the highest statistically significant debris % mean value.
CONCLUSIONS
Under the condition of the present study, it was concluded that:
1. Both 5.25% NaOCl, 2% CHX, were effective in removal of Enterococcus faecalis.
2. Apical portions of the root canals recorded the highest percentage of debris.
3. 5.25% NaOCl is found to be the most efficient irrigating solution for removal of debris.
4. Sonic devices are more effective in debris removal than the disposable plastic syringe.