Observation of bacteria and fungi in infected root canals and dentinal tubules by SEM

Şen, Bilge Hakan; Pişkin, Beyser; Demirci, Tevfik

doi:10.1111/j.1600-9657.1995.tb00671.x

Cited by 231 publications

(181 citation statements)

References 14 publications

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“…In previous SEM studies, bacteria have been observed colonizing the periapical tissues (17,18) and root canal (9,19). In some of these studies, structures typical of bacterial colonization have been observed, including filaments that seem to hold the bacteria to each other or to the dentin surface (18) and an amorphous material, presumably polysaccharide, covering the bacteria (17).…”

Section: Discussionmentioning

confidence: 99%

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Biofilm Formation in Medicated Root Canals

Distel¹,

Hatton²,

Gillespie³

2002

Journal of Endodontics

318

224

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The hypothesis that Enterococcus faecalis resists common intracanal medications by forming biofilms was tested. E. faecalis colonization of 46 extracted, medicated roots was observed with scanning electron microscopy (SEM) and scanning confocal laser microscopy. SEM detected colonization of root canals medicated with calcium hydroxide points and the positive control within 2 days. SEM detected biofilms in canals medicated with calcium hydroxide paste in an average of 77 days. Scanning confocal laser microscopy analysis of two calcium hydroxide paste medicated roots showed viable colonies forming in a root canal infected for 86 days, whereas in a canal infected for 160 days, a mushroom-shape typical of a biofilm was observed.Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis showed no differences between the protein profiles of bacteria in freefloating (planktonic) and inoculum cultures. Analysis of biofilm bacteria was inconclusive.These observations support potential E. faecalis biofilm formation in vivo in medicated root canals.The most common reasons for failures in conservative root canal therapy are related to problems in instrumentation. However, occasionally, bacteria resistant to conservative therapy may also be involved (1). "Bacteria-associated endodontic failures together with pulp-periapical infections refractory to conventional treatment represent the unresolved bacteriological problems in endodontics" (2). Numerous studies have shown that persistent endodontic infections are often caused by Enterococcus faecalis (1, 3).Virulence factors of E. faecalis, such as hemolysin, gelatinase, and enterococcal aggregation substance (EAS) play an important role in the bacterium's pathogenesis (4). However, the mechanism through which E. faecalis persists in the root canal is not well understood. E. faecalis seems to be highly resistant to the medications used during treatment and is one of the few organisms that has been shown to resist the antibacterial effect of calcium hydroxide (5, 6). There is little research to explain why E. faecalis is resistant to root canal therapy. It is easily destroyed when grown in vitro, but it becomes resistant when present in the environment of the root canal system (7). Therefore, E. faecalis must undergo some type of change while in the root canal system, possibly activating some virulence factor that makes it more resistant. Alternatively, it may form a biofilm.Biofilms, also known as plaque, are complex communities of bacteria embedded in a polysaccharide matrix (8). Suspended, i.e. planktonic, bacteria that are either leaving or joining the biofilm surround the biofilm. The growth conditions vary between biofilm and planktonic environments. For this reason, proteins expressed by biofilm bacteria may differ from those expressed by their planktonic counter parts, and both the biofilm bacteria and the planktonic bacteria may differ from bacteria maintained in the laboratory.The purpose of this study was to test the hypothesis that E. faecalis forms a biofi...

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Section: Discussionmentioning

confidence: 99%

“…Longitudinal grooves were cut along the entire length of each root. The roots were then split with a hammer and chisel into two halves as described by Sen et al (9). Each root half was then gently washed in 0.2 M potassium phosphate buffer (PBS), pH 7.2, at 4°C to 6°C.…”

Section: Sem Analysismentioning

confidence: 99%

Biofilm Formation in Medicated Root Canals

Distel¹,

Hatton²,

Gillespie³

2002

Journal of Endodontics

318

224

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“…Several studies have revealed the presence of fungi in endodontic infections. Sen et al (4) used scanning electronic microscopy (SEM) to observe bacteria and fungi in root canals and dentinal tubules of teeth with endodontic infection, revealing the presence of fungi in 4 out of 10 teeth. Yeasts were identified by microscopic exploration of single cells, either spherical or oval, measuring 4-6 mm in diameter.…”

Section: In Vitro Susceptibility Of Oral Candida Albicansmentioning

confidence: 99%

In vitro susceptibility of oral Candida albicans strains to different pH levels and calcium hydroxide saturated aqueous solution

et al. 2012

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Candida albicans is present in the oral cavity and in the whole digestive tract of humans and other animals, being frequently related to endodontic treatment failure. The present study determined the incidence of C. albicans in the oral cavity and the susceptibility of isolates to different pH values and saturated calcium hydroxide aqueous solution at pH 12.5. Sixty-five patients attending the Endodontic Clinic at the Sagrado Coração University participated in the study. The collected samples were cultivated in selective media for C. albicans and the isolates were tested in terms of resistance to both alkaline pH and saturated aqueous solution of calcium hydroxide. In relation to time variables, yeast viability was assessed by the Sabouraud's agar culture and fluorescein diacetate and ethidium bromide fluorescent staining method. Results from the different pHs and experimental times, including those from different techniques measuring fungal viability, were compared using the chi-square and Fisher's exact tests (α=0.05). The yeasts became completely inviable after 48 h of contact with the calcium hydroxide solution. On the other hand, when exposed to the alkaline culture broth, the yeasts were found to be viable at pHs 9.5 and 10.5 for up to 7 days. In conclusion, C. albicans can only be completely inhibited by direct contact with saturated calcium hydroxide aqueous solution after 48 h of exposure.

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“…Penetration of bacteria into the dentinal tubules has been reported to range from 10 to 300 m. 9,42 Despite the controversy regarding the effect of the smear layer on the bacterial colonization of the dentinal tubules 43,44 and because the smear layer itself can be contaminated and has the potential to protect bacteria within the dentinal tubules, it is sensible to remove the smear layer and allow disinfection of the entire root canal system. 45 Although NaOCl is efficient in dissolving organic components of the smear layer, its ability to remove inorganic components is limited.…”

mentioning

confidence: 99%