Abstract
Objective: To compare the disinfecting efficacy of the sodium hypochlorite irrigation by root canal preparation with stainless steel hand files, taper 0.02 and nickel-titanium Mtwo files with taper 0.04-0.06. Study Design: 40 extracted human teeth were sterilized, and then inoculated with Enterococcus faecalis (ATCC 29212). After 6 day incubation time the root canals were prepared by hand with K-files (n=20) and by engine-driven Mtwo files (VDW, Munich, Germany) (n=20). Irrigation was carried out with 2.5% NaOCl in both cases. Samples were taken and determined in colony forming units (CFU) from the root canals before and after the preparation with instruments #25 and #35. Results: Significant reduction in bacterial count was determined after filing at both groups. The number of bacteria kept on decreasing with the extension of apical preparation diameter. There was no significant difference between the preparation sizes in the bacterial counts after hand or engine-driven instrumentation at the same apical size. Statistical analysis was carried out with Mann-Whitney test, paired t-test and independent sample t-test. Conclusions: Significant reduction in CFU was achieved after the root canal preparation completed with 2.5% NaOCl irrigation, both with stainless steel hand or nickel-titanium rotary files. The root canal remained slightly infected after chemo mechanical preparation in both groups. Key words:Chemomechanical preparation, root canal disinfection, nickel-titanium, conicity, greater taper, apical size.
Highlights
Microorganisms play an essential role in the initiation, progression and persistence of apical periodontitis [1,2]
In our model the root canals were filled with E. feacalis containing medium to ensure more even bacterial distribution even in the deeper areas in the root canal system
Root canal preparation was performed with chemo mechanical method in both experimental groups
Summary
Microorganisms play an essential role in the initiation, progression and persistence of apical periodontitis [1,2]. In the hard-to-reach areas and in the dentinal tubules of the root canal system microorganisms putatively will be left behind contrary to the instrumentation and irrigation [5,6,7,8,9,10,11,12].Bacteria are able to penetrate into dentinal tubules up to 400 μm [13,14,15,16,17]. Instrumentation opens a way for disinfectant solution to reach most of the enclosed infected parts of root canals [18], but the extension of shaping is restricted by the thickness of the dentine wall and threatens with the possibility of perforation [10,11,19]. The aim of the present study was to compare the disinfection effectiveness of the chemomechanical instrumentation of rotary nickel-titanium files and hand files at two apical diameters.
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