Microorganisms In Root Canals Research Articles

Evaluation of root canal microorganisms isolated from teeth with endodontic failure and their antimicrobial susceptibility.

Studies of the microbiota from the canals of teeth with failure of endodontic therapy have revealed that it differs markedly from that of untreated necrotic dental pulps. This study aimed to evaluate the microbiota of 30 root-filled teeth with persisting periapical lesions and to test the antibiotic susceptibility of the most prevalent species. Microbial samples, isolation and speciation were done using advanced microbiologic techniques for anaerobic species. A total of 55 bacterial species were isolated, 80% were gram-positives and 58% facultative anaerobic microorganisms. The bacterial genera most frequently recovered were Enterococcus, Streptococcus, Peptostreptococcus and Actinomyces. Antibiotic sensitivity of Enterococcus faecalis and Peptostreptococcus spp. was accomplished with the E-test system. All species studied were susceptible to benzylpenicillin, amoxicillin, amoxicillin combined with clavulanate. However, 20% of the E.faecalis strains were resistant to erythromycin and 60% to azithromycin. It was concluded that microbial flora in canals after endodontic failure comprised predominantly facultative anaerobes and gram-positive species. E.faecalis was the species most frequently isolated and showed erythromycin and azithromycin resistance among the isolates.

Anaerobic bacteremia and fungemia in patients undergoing endodontic therapy: an overview.

Oral focal infection, a concept neglected for several decades, is a subject of controversy. Recent progress in classification and identification of oral microorganisms has renewed interest in focal infection. The aim of this study was to use phenotypic and genetic methods to trace microorganisms released into the bloodstream during and after endodontic treatment back to their presumed source--the root canal. Microbiological samples were taken from the root canals of 26 patients with asymptomatic apical periodontitis of single-rooted teeth. The blood of the patients was drawn during and 10 minutes after endodontic therapy. Microorganisms in blood were collected after anaerobic lysis filtration and cultured anaerobically on blood agar plates. The phenotypic methods used for characterization and tracing of microorganisms in blood and root canals were: biochemical and antimicrobial susceptibility test, SDS-PAGE of whole-cell soluble proteins, and gas chromatography of cellular fatty acids. Phenotypic data were verified by DNA restriction patterns and corresponding ribotypes of the root canal and blood isolates by using a computer-assisted system fro gel analysis. All root canals contained anaerobic bacteria. The frequency of bacteremia varied from 31% to 54%. The microorganisms from the root canal and blood presented identical phenotype and genetic characteristics within the patients examined. These characteristics differed between patients. The present study demonstrated that endodontic treatment can be the cause of anaerobic bacteremia and fungemia. The phenotypic and genetic methods used appeared valuable for tracing microorganisms in the blood back to their origin.

Microorganisms in closed periapical lesions

The purpose of this study was to investigate the microorganisms of strictly selected closed periapical lesions associated with both refractory endodontic therapy and pulpal calcification. Definitive criteria were established that assured complete clinical isolation of the periapical lesion from the oral and periodontal environment. A total of 13 criteria-referenced lesions were selected from 70 patients with endodontic surgical indications. A well controlled culturing method was used in all cases and samples were taken by one clinician at three separate sites during each surgery. Samples taken at the surgical window and within the body of the lesion served as controls, whilst a third sample was taken at the apex. In all 13 cases, samples taken from the apex yielded microorganisms comprising 63.6% obligate anaerobes and 36.4% facultative anaerobes. Prevalence of the isolated species was 31.8% for Actinomyces sp., 22.7%, Propionibacterium sp., 18.2%Streptococcus sp., 13.6%Staphlyococcus sp., 4.6%Porphyromonas gingivalis, 4.6%Peptostreptococcus micros and 4.6% Gram-negative enterics. The results of this investigation indicate that closed periapical lesions associated with calcified teeth or those resistant to root canal treatment harbour bacteria. The inability to eradicate all root canal microorganisms during root canal treatment, along with anatomical factors, may allow further bacterial colonization of the root apex and surrounding periapical tissues, and consequently prevent healing.

Microorganisms in closed periapical lesions

The purpose of this study was to investigate the microorganisms of strictly selected closed periapical lesions associated with both refractory endodontic therapy and pulpal calcification. Definitive criteria were established that assured complete clinical isolation of the periapical lesion from the oral and periodontal environment. A total of 13 criteria-referenced lesions were selected from 70 patients with endodontic surgical indications. A well controlled culturing method was used in all cases and samples were taken by one clinician at three separate sites during each surgery. Samples taken at the surgical window and within the body of the lesion served as controls, whilst a third sample was taken at the apex. In all 13 cases, samples taken from the apex yielded microorganisms comprising 63.6% obligate anaerobes and 36.4% facultative anaerobes. Prevalence of the isolated species was 31.8% for Actinomyces sp., 22.7% Propionibacterium sp., 18.2% Streptococcus sp., 13.6% Staphlyococcus sp., 4.6% Porphyromonas gingivalis, 4.6% Peptostreptococcus micros and 4.6% Gram-negative enterics. The results of this investigation indicate that closed periapical lesions associated with calcified teeth or those resistant to root canal treatment harbour bacteria. The inability to eradicate all root canal microorganisms during root canal treatment, along with anatomical factors, may allow further bacterial colonization of the root apex and surrounding periapical tissues, and consequently prevent healing.

Anaerobic microorganisms in root canals of human teeth with chronic apical periodontitis detected by indirect immunofluorescence.

Aiming to assess the presence of selected anaerobic microorganisms in root canals of human teeth with chronic apical periodontitis. 25 central and lateral upper incisors presenting with radiographic evidence of chronic apical periodontitis were studied. The pulp chamber was opened under aseptic conditions and samples of the root canal content were collected with sterile absorbent paper points, which were placed and dispersed in test tubes containing reduced transport medium RTT. Aliquots were dried on glass slides and stained by indirect immunofluorescence for detection of Actinomyces viscosus, Fusobacterium nucleatum, Porphyromonas gingivalis and Prevotella intermedia. The results showed a positive indirect immunofluorescence reaction in 24 of the 25 samples. Fourteen were positive for the specie Actinomyces viscosus, 12 for Prevotella intermedia, 10 for Fusobacterium nucleatum and 4 for Porphyromonas gingivalis. A semiquantitative assay was easily implemented for assessment of degree of infection by the organisms in individual cases.

Incidence of antibiotic resistance in microorganisms isolated from root canals

This study was undertaken to determine the antibiotic resistance of microorganisms in root canals. A total of 37 samples were studied. Of the seven antibiotics tested, erythromycin was the most effective. Gentamicin sulfate, a relatively new antibiotic, was the least effective antibiotic. This study was undertaken to determine the antibiotic resistance of microorganisms in root canals. A total of 37 samples were studied. Of the seven antibiotics tested, erythromycin was the most effective. Gentamicin sulfate, a relatively new antibiotic, was the least effective antibiotic.

Some comments on the microbiological examination of root canals

The continuing controversy over the culturing of root canals is discussed and shown to be due to a combination of historical mischance, misuse of terms, and a misunderstanding of the information provided by microbiological tests. The abuse of the term ‘sterile’, its inapplicability in endodontics, and the formidable problem of trying to prove sterility by cultural methods are commented on. The significance of micro-organisms in root canals with regard to preparation for filling, periapical infection, and treatment failure is discussed. Broth cultures are shown to be over-sensitive yet inadequate tests which are inappropriate and misleading; a better, more informative method of culturing root canals is suggested. The curious procedure adopted in endodontics of testing the end product in each individual case for the absence of microbes is contrasted with the more usual method of thoroughly testing a technique which is thereafter relied upon to produce the desired result without further testing; a change to this latter approach is recommended.