in-vitro evaluation of survival of entrococcus faecalis [E.F.] in infected root canals after root canal obturation with or without using of calcium hydroxide

The main goal of root canal therapy is total elimination of bacteria from root canals. Studies have shown that the cleaning and shaping of root canals can not complexly eliminate these bacteria from the root canals. Obturation may kill the bacteria due to entrapment of them into the canals and prevent their access to nutrition. On the other hand, using of Ca [OH][2] before obturation may help to promise a better reduction of bacteria from root canals. The purpose of this study is an in vitro evaluation of antibacterial effect of obturaiton solely, or with using Ca [OH][2] as an intracanal dressing on E.F. in infected human root canals. For this experimental study, 50 single rooted human teeth without significant curvature were chosen. After cutting the crowns and preparing root canals, the samples were sterilized and then contaminated with Entrococcus faecalis bacteria for 5 days. The samples were divided randomly into 4 groups. The first experimental group which included 20 teeth, were filled by Ca [OH][2] for one week before obturation by lateral condensation technique. The second experimental group [20 samples] were obturated by ZOE sealer and gutta percha with lateral condensation for 2 weeks. Five roots considered as positive control were contaminated with bacteria but were not obturated, and 5 other roots were obturated after sterilization without contamination as negative control group. All samples were incubated in 35°C and 10% moisture for 2 weeks. Then the coronal and apical part of roots were removed and the dentin powder were collected from the middle parts by drilling the canals in sterile condition. Two mg of dentin powder was weighed from each root and cultured in blood agar for 48 hours. The results were recorded and compared with each other by Chi-Square test. All samples were positive in culture of positive control group, and negative in culture of negative control group. First experimental group did not show any positive growth after the incubation period and there was only one positive culture in the second experimental group. The findings of this study illustrated no significant difference between the two experimental groups. In other words, the obturation of canals with gutta percha and sealer merely could kill the E.F. in the infected root canals and application of Ca [OH][2] before obturation was not necessary for disinfection of canals

[ in vitro comparison of anti bacterial effect of AH26 and AHplus sealers on infected root canals with enterococcus faecalis bacteria]

Statement of Problem: Bacteria and their destructive byproducts are the main causes of pulpal and periapical diseases. The main goal of the root canal therapy is to eliminate these bacteria from the root canal systems to prepare a suitable environment for the healing of periradicular tissues. Total elimination of these bacteria from root canal system is impossible, even by cleaning, shaping and irrigating with antibacterial solutions; therefore, utilization of antibacterial filling materials can help to achieve a better result

Aim: The purpose of this study was an in vitro comparison of antibacterial effect of AH26 and AHplus sealers on infected root canals with enterococcus faecalis bacteria

Materials and Methods: For this experimental study, 90 single rooted human teeth including upper incisors and canine were chosen. The crowns were removed and the root canals were cleaned and shaped. Smear layer was removed from canals and the roots were contaminated with entrococcuous faecalis bacteria following their sterilization. The roots were randomly divided into four experimental groups. The root canals of two groups were obturated using gutta percha and AH26 sealer with the lateral condensation technique. Root canals of the remaining groups were obturated by the same method but by using AHplus sealer. After incubation periods of 2 and 7 days, 4 mm segments were prepared from the middle third of roots and following removal of gutta percha from the segments, dentinal shavings were collected from the inside walls of the segments. The dentinal shavings were cultured and the presence of bacteria and the number of colonies were evaluated. The data were compared with each other by Mann-Withney and Chi-Square tests

Results: The findings of this study demonstrated that AH26 sealer can kill all the bacteria in 2 and 7 days but AHplus sealer can not eliminate the bacteria from the infected root canals and a significant rise in the number of colonies was seen when comparing the incubation period of 2 days with 7 days

Conclusion: The findings of this survey illustrated a strong antibacterial effect of AH26 in comparing with AHplus which may be due to the greater amount of formaldehyde releases from this sealer

In vitro susceptibility of fungal isolates of keratomycosis to antiseptic agents

Fungal corneal ulcer is the most dangerous and challenging type of infective keratitis. Since most of the ophthalmic antifungal drops are scarce and expensive in developing countries, attempts have been made to study fungicidal property of some readily available antiseptic agents as a substitute. Povidone iodine [PI] and chlorhexidine gluconate [CHx] has been postulated to be effective against fungi. To study in vitro antifungal efficacy of PI and CHx. Fungi isolated from cases of keratomycosis were entered in a prospective study from June 2001 to March 2002. In vitro susceptibility of these fungi was tested by broth dilution method of NCCLS Standard to PI [1%, 2%, 5%, 10%] and CHx [0.04%, 0.1%, 0.2%] after 5 minutes, 1 hr, 24 hrs and 48 hrs exposure times. From a total of 16 culture-proven cases of fungal keratitis, the isolated fungi were 8 Aspergillus sp, 3 Fusarium sp, 2 sterile hyphae, 1 Candida sp, 1 Drechslera sp, 1 Rhodotorula sp. PI showed 100% fungicidal effect with all tested concentrations, after 5 minutes of exposure to all fungal species. CHx. 0.1% and 0.2% after 1 hr exposure were as effective as PI [p>0.34]. The fungicidal efficacy of CHx 0.1% and 0.2% was significantly less than PI after 5 minutes [p<0.001]. Both PI and CHx have strong in vitro fungicidal effect. The kill rate of CHx, however, is less than PI. Since in vitro efficacy of topical ophthalmic preparations is affected by multiple factors, our study provides a good idea for further in vivo investigations about this subject

Etiology and antimicrobial sensitivity pattern of bacteria, causing summer diarrhea in children

During a four month period from July to November 1992, five hundred stool samples from children with acute diarrhea were examined for pus cells, parasites and cultured for pathogens including Salmonella, Shigella, Campylobacter, E. coli, and the ELISA test for Rotavirus. The isolated bacteria were then tested for antimicrobial sensitivity. Inflammatory cells were observed in 110 [22%] and correlated with positive culture in 65.5%. Giardia lamblia was isolated in 56 [11.2%] and Entamoeba histolytica in 8 [1.6%]. Bacteria were isolated in 148 [29.6%] samples and included, E. coli 96 [19.2%] Shigella 26 [5.2%], Campylobacter 25 [5%] and Salmonella 15 [3%]. Rotavirus was isolated in 140 of 419 [33.5%] samples and was accompanied by other agents in 34%. The isolated bacteria were sensitive to nalidixic acid in 99.6%, trimethoprim-sulfamethoxazole [TMP-SMZ] in 30% and ampicillin in 26%. The demonstration of pus cells in stool is an important indication of an invasive pathogen, isolation of rotavirus from stool does not necessarily implicate the virus as an etiologic agent of diarrhea. The majority of enteric bacteria are resistant to ampicillin, TMP-SMZ and moderately sensitive to first generation cephalosporin. The bacteria were highly sensitive to nalidixic acid