Microbial analysis of ground water, as the sole supplying water source in many areas, must be evaluated. Because the treatment of water cannot remove all pathogenic bacteria leaked from domestic wastewater, bacterial analysis of Bojnourd groundwater sources was performed. For this reason, membrane filter (MF) technique and Most Probable Number (MPN) method were used to evaluate the microbial quality of the water. Escherichia coli (E. coli) and Enteroccocus faecalis (E. faecalis) were traced as excremental indices. E. coli was detected from three out of six stations and E. faecalis was only isolated from one station. Although molecular techniques are very rapid and exact methods for detection of microbial community and can identify ‘Viable But Not Cultivable’ (VBNC) bacteria, they are unable to make a distinction between living and non-living microorganisms. By means of a standard technique, it is possible to study living and metabolically active microorganisms. Due to the detection of E. coli and E. feacalis in some stations the sanitization of groundwater must be revised to lessen the microbial population in this groundwater.

Background and Aim: Researches have shown that bacteria play the main role in development of pulpal and periapical diseases. Chemo-mechanical cleaning of infected root-canal system can not remove all of the microorganisms. Thus interappointment medicaments are necessary to aid this goal. Calcium hydroxide is one of the most useful medicaments in root canal therapy, but this medicament can not eliminated all of the bacteria in root canal system. Carvacrol is an edible plant extract that has antimicrobial and anti-inflammatory effects. If this extract is effective against endodontic bacteria, it can be used as an root canal medicament.Materials and Methods: In this experimental study, Initially, MIC and MBC of carvacrol detected with Macro broth dilution method and determined as 0.3% and 0.6%, respectively. After that, 30 single root and single canal extracted human teeth were used in this study. The number of specimens determined in a pilot study on 4 extracted teeth. After preparation to apical size #30 with hand and rotary instruments, teeth were randomly divided into two experimental and two control groups. After culturing Enterococcus faecalis in prepared canals, we used emulsion of 0.6% carvacrol and calcium hydroxide in two A and B experimental groups for 7 days as the intracanal medicament. Microbial samples obtained before and after experiment. Then, canals with negative culture selected to obtain dentinal shaving to culture. Data obtained from microbiological samples analyzed with kruskal-wallis and Bonferroni tests.Results: Results of this study showed that emulsion of 0.6% carvacrol has no significant difference with calcium hydroxide in elimination Enterococcus faecalis after 7 days dressing (p>0.05).Conclusion: Carvacrol can be used as an intrappointment intracanal medicament.

Introduction since microorganisms play a fundamental role in the ethology of pulp and peri apical diseases, and reduction or elimination of the intra canal population, is of the main principles of a successful root canal treatment. The aim of this study was the in vitro comparison of bacterial population reduction in root canal by mechanical instrumentation, using two single file systems and multi file rotary system in root canals infected with Enterococous faecalis Materials and Methods In this experimental laboratory study, the root canals of 48 human mandibular premolar teeth were selected and were infected with a culture of E.faecalis for 30 days. Then the specimens were randomly divided into 3 groups (n=16): Reciproce, Neolix and Mtwo files. Four other teeth that were contaminated and not instrumented, were used as control group. Samples were taken before (S1) and after instrumentation (S2). Bacterial quantification was performed using quantitive PCR. Statistical analyses were performed by Mann-Whitney and Kruskal-Wallis tests Results Comparing the average number of bacteria before and after preparation, the number of bacteria increased significantly between the three groups of Reciproc, Neolix and MTO after preparation (p < 0.001). But in the control group, there was no significant difference in the number of bacteria before and after preparation (p = 0.144). Conclusion single file canal preparation systems are as effective as multifile rotary system in reduction of the bacterial load of canals

Aim: The information about the microbiology of root canal treated teeth with persistent periapical lesion is very important, because the main cause of endodontic failure in such cases is persistent infection. The purpose of this study was to determine the occurrence of Enterococcus faecalis in teeth with failed endodontic treatment inan Iranian population.Methods &Materials: Twenty two asymptomatic root-filled teeth with chronic apical periodontitis were selected for retreatment. After removal of the root - filling material, the canal was sampled with paper points. All samples were grown under aerobic condition at 35ºc, then the bacterial growth was accurately analyzed.Results: The finding indicated that bacteria were cultivated in 13 of the 22 (%59) teeth examined in the study.Enterococcus faecalis and staphylococcus aurous were the most commonly recovered bacteria. All cultivable bacteria were isolated in pure culture (monoinfection).Conclusion: It seems that some bacterial species (facultative anaerobes) with a special ecological resistance and high penetration ability have an important role in endodontic failures.