الفهرس 
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Abstract
The present study aimed to evaluate the effect of QMix irrigating solution on the Enterococcus faecalis population cultivated within root canal of extracted anterior teeth using different irrigant agitation methods by the aid of scanning electron microscope and direct count of colony forming units (CFUs).
A total of 75 freshly extracted teeth with single root were selected for the study. Teeth were collected from out patient’s clinic of oral surgery department, Faculty of Oral and Dental Medicine, Ain shams University. Decoronation was done using water cooled diamond disc in a low speed hand piece and the root length was standardized at 16 mm. The root canals were instrumented and enlarged by rotary ProTaper system in a crown down manner. Each tooth was enlarged to file F4. During instrumentation, 1 mL of sterile saline was used at each change of file. The teeth then sterilized in autoclave for 20 minutes at 121OC and then placed in a nutrient broth to confirm that they are totally sterilized. The samples were considered completely disinfected in the absence of any turbidity. The teeth were then filled with a 30 mL 24-hour pure culture suspension of E. faecalis grown in Brain Heart Infusion (BHI) broth. All teeth were incubated at 37°C in sealed vials for 7 days, replacing the intracanal fluids with freshly prepared 0.9% physiologic saline solution adjusted to No. 1 MacFarland turbidity standard. The suspension was replenished every 72 hours.
5 teeth were subjected to scanning electron microscopy to allow visualization of the pattern of colonization. Longitudinal grooves were prepared on the buccal and lingual surfaces of each root by using a diamond disc at a slow speed without penetrating the canal, the two halves then separated by a chisel. Half of each was then mounted on metallic stubs and examined using xT microscope Server and xT microscope Control software under the Environmental Scanning Electron Microscope, Inspect S50 (FEI, Eindhoven, Netherlands) to observe the mode of colonization and biofilm formation .
70 Teeth were randomly divided into 3 experimental groups of 20 teeth each according to the technique used during final rinse (FR), and a control group of 10 teeth without irrigation.
Group I using Max I prob (n=20) In passive irrigation group (PI), Solutions will be delivered by a syringe and a 30-gauge needle that is inserted as deep apically as possible without binding
Group II using MDA (n=20), In MDA group, a size 40/.06 gutta-percha cones will be used for activation of the irrigant. Initially, the canals are flooded with the irrigant then the cone is used in push-pull strokes at an approximate rate of 100 strokes per minute for 60 seconds.
Group III: using Endoactivator (n=20) Sonic activation was delivered by using the Endoactivator set at 10,000 cycles per minute with a blue 35/.04 tip, inserted at working length and activated for 60 seconds.
Each group was subdivided into two sub-groups according to the type of irrigant. The first sub-group was irrigated using 2.5% NaOCl followed by 17% EDTA. For the second sub-group, QMix™ 2 in1 was used for final irrigation.
At the end of the irrigation process, the samples were filled with sterile Brain Heart Infusion broth as a transport fluid. Each sample was taken using three paper points. The sterile paper point absorbed the transport fluid, and was
transferred to a test tube containing 1.0 ml of saline. Each sample was carefully homogenized by vortexing for 30 seconds. Serial 10-fold dilution (1:10, 1:100 and 1:1000) was made in saline. Then 0.1 mm from each dilution was smeared to be inoculated on surface of the plate media (BHI agar plates), incubated at 37°C for 48 hours, andcolony-forming units (CFU) per 1 ml were enumerated.
Visible colonies of E. faecalis were counted in every plate and the number of colonies/plate was multiplied by the corresponding dilution factor and by 10 to determine the total colony forming units (CFU) per ml of sample.
One tooth of each experimental group was subjected to environmental scanning electron microscopy to confirm the disruption of biofilm.
The results showed that both irrigants decreased bacterial counts significantly when compared to the control group with no statistically significant difference between both of them. Results also showed that various agitation techniques used caused slight decrease in bacterial counts for two irrigants yet the difference was not statistically significant.
Within the limits of this study the following conclusions could be withdrawn:
1. Final flush with either QMixTM or 2.5% NaOCl and 17% EDTA are as efficient in reduction of bacterial counts, with QmixTM being a one-step irrigation rendering it easier in clinical use.
2. Agitation didn’t significantly influence the antimicrobial effect of both sodium hypochlorite and EDTA nor QMixTM.