الفهرس 
Microbiological aspects of endodontic infectionsOnly 14 pages are availabe for public view
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Abstract
T
he first part of this study was to evaluate the antimicrobial effect of sodium hypochlorite solutions using different pH values.
The pH values were adjusted through addition of acetic acid to sodium hypochlorite.
The antimicrobial effect of test solutions was assessed quantitatively through performing minimum inhibitory concentration, bacterial count and qualitatively through SEM examination.
The results of MIC showed that the minimum inhibitory concentration recorded for the neutral solution was significantly higher in comparison with either the acidic or alkaline solutions, on the other hand the difference in the mean minimum inhibitory concentration between the acidic solution versus the alkaline solution was statistically non-significant.
Single rooted canines and cellulose nitrate membrane filter were choosen as samples for the evaluation through the bacterial count and the scanning electron microscope.
Enterococcus Faecalis biofilm was developed onto both root canal dentin and cellulose nitrate membrane filters.
Specimens were classified according to the test solutions into three equal groups of thirty-nine specimens each and were further subdivided into another three equal groups of thirteen specimens each according to the immersion time (5 min, 30 min and 60 min).
The results of bacterial count showed that the difference in the mean bacterial count between all groups after all immersion time was statistically significant, except for the difference in the mean bacterial count of acidic sodium hypochlorite solution versus alkaline sodium hypochlorite solution after 60 min immersion period , it has been recorded to be statistically non-significant.
While regarding the antimicrobial effect of test solutions against E.Faecalis biofilm developed onto cellulose nitrate membrane filters , results showed that the mean bacterial count recorded after 5 min immersion period was statistically significant, except for the difference in the mean bacterial count of acidic sodium hypochlorite solution versus the alkaline sodium hypochlorite solution, it has been recorded to be statistically non-significant
After 30 min immersion period, it was reported that the mean bacterial count for the neutral sodium hypochlorite solution was significantly higher in comparison with either the acidic or the alkaline solutions, on the other hand the difference in the mean bacterial count between the acidic versus the alkaline solutions was statistically non-significant.
While after 60 min immersion period, no bacterial growth was observed on the membrane sample with any of the tested solutions.
The second part of the study was performed to examine the effect of the experimental solutions on smear layer and cleanliness of dentin.
The samples selected were classified into four equal groups according to the solution used throughout the cleaning and shaping procedures.
SEM examination revealed no smear layer at the coronal dentin with enlarged entrances for the tubules, with partially removed smear layer at the middle and apical dentin after irrigation with the acidic sodium hypochlorite solution throughout the cleaning and shaping procedures and as a final flush.
For the neutral solution, SEM examination showed complete coverage of dentin walls with smear layer.
Regarding the alkaline solution, SEM examination revealed the typical appearance of amorphous smear layer at the coronal dentin, the dentinal tubule openings are obscured by the adherent smear layer at the middle while the apical dentin was covered by a heavy smear layer.
Finally, when root canals were irrigated with alkaline sodium hypochlorite and received EDTA as the final flush, the resultant radicular dentin walls were free of debris, and the dentinal tubule entrances were visible.