It has been recognized for some time that bacterial species exist in complexes in subgingival plaque. The purpose of the present investigation was to attempt to define such communities using data from large numbers of plaque samples and different clustering and ordination techniques. Subgingival plaque samples were taken from the mesial aspect of each tooth in 185 subjects (mean age 51 +/- 16 years) with (n = 160) or without (n = 25) periodontitis. The presence and levels of 40 subgingival taxa were determined in 13,261 plaque samples using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Clinical assessments were made at 6 sites per tooth at each visit. Similarities between pairs of species were computed using phi coefficients and species clustered using an averaged unweighted linkage sort. Community ordination was performed using principal components analysis and correspondence analysis. 5 major complexes were consistently observed using any of the analytical methods. One complex consisted of the tightly related group: Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola. The 2nd complex consisted of a tightly related core group including members of the Fusobacterium nucleatum/periodonticum subspecies, Prevotella intermedia, Prevotella nigrescens and Peptostreptococcus micros. Species associated with this group included: Eubacterium nodatum, Campylobacter rectus, Campylobacter showae, Streptococcus constellatus and Campylobacter gracilis. The 3rd complex consisted of Streptococcus sanguis, S. oralis, S. mitis, S. gordonii and S. intermedius. The 4th complex was comprised of 3 Capnocytophaga species, Campylobacter concisus, Eikenella corrodens and Actinobacillus actinomycetemcomitans serotype a. The 5th complex consisted of Veillonella parvula and Actinomyces odontolyticus. A. actinomycetemcomitans serotype b, Selenomonas noxia and Actinomyces naeslundii genospecies 2 (A. viscosus) were outliers with little relation to each other and the 5 major complexes. The 1st complex related strikingly to clinical measures of periodontal disease particularly pocket depth and bleeding on probing.

Microbial complexes in subgingival plaque

http://www.endoexperience.com/documents/Sjogren-1990.pdf

Factors affecting the long-term results of endodontic treatment

Microbial etiological agents of destructive periodontal diseases

Root canal irrigants.

Objective. The purposes of this study were to determine what microbial flora were present in teeth after failed root canal therapy and to establish the outcome of conservative re-treatment.

Study design. Fifty-four root-filled teeth with persisting periapical lesions were selected for re-treatment. After removal of the root filling, canals were sampled by means of advanced microbiologic techniques. The teeth were then re-treated and followed for up to 5 years.

Results. The microbial flora was mainly single species of predominantly gram-positive organisms. The isolates most commonly recovered were bacteria of the species Enterococcus faecalis. The overall success rate of re-treatment was 74%.

Conclusions. The microbial flora in canals after failed endodontic therapy differed markedly from the flora in untreated teeth. Infection at the time of root filling and size of the periapical lesion were factors that had a negative influence on the prognosis. Three of four endodontic failures were successfully managed by re-treatment.

Microbiologic analysis of teeth with failed endodontic treatment and the outcome of conservative re-treatment

This study investigated the role of infection on the prognosis of endodontic therapy by following-up teeth that had had their canals cleaned and obturated during a single appointment. The root canals of 55 single-rooted teeth with apical periodontitis were thoroughly instrumented and irrigated with sodium hypochlorite solution. Using advanced anaerobic bacteriological techniques, post-instrumentation samples were taken and the teeth were then root-filled during the same appointment. All teeth were initially infected; after instrumentation low numbers of bacteria were detected in 22 of 55 root canals. Periapical healing was followed-up for 5 years. Complete periapical healing occurred in 94% of cases that yielded a negative culture. Where the samples were positive prior to root filling, the success rate of treatment was just 68%--a statistically significant difference. Further investigation of three failures revealed the presence of Actinomyces species in each case; no other specific bacteria were implicated in failure cases. These findings emphasize the importance of completely eliminating bacteria from the root canal system before obturation. This objective cannot be reliably achieved in a one-visit treatment because it is not possible to eradicate all infection from the root canal without the support of an inter-appointment antimicrobial dressing.

Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis

The presence of bacteria in 17 single-rooted teeth, with periapical lesions, was studied throughout a whole period of treatment. The root canals were irrigated with physiologic saline solution during instrumentation. No antibacterial solutions or dressings were used. Bacteria were found in all initial specimens from the teeth (median number of bacterial cells 4 x 10(5), range 10(2) - 10(7)) and the number of strains in the specimens ranged from 1 to 10.88% of the strains were anaerobic. The most commonly isolated species were: Peptostreptococcus micros, Peptostreptococcus anaerobius, Fusobacterium nucleatum, Bacteroides oralis, Bacteroides melaninogenicus subsp intermedius and Eubacterium alactolyticum. Mechanical instrumentation reduced the number of bacteria considerably. Specimens taken at the beginning of each appointment usually contained 10(4) - 10(6) bacterial cells and at the end 10(2) - 10(3) fewer. Bacteria were eliminated from the root canals of eight teeth during the treatment. In seven root canals bacteria persisted despite treatment on five successive occasions. There was no evidence that specific microorganisms were implicated in these persistent infections. Teeth where the infection persisted despite being treated five times were those with a high number of bacteria in the initial sample.

Bacteriologic evaluation of the efficacy of mechanical root canal instrumentation in endodontic therapy.

The bactericidal efficacy of calcium hydroxide, camphorated phenol and camphorated paramonochlorophenol as intracanal dressings was evaluated clinically when the root canals of 65 single-rooted teeth with periapical lesions were treated. A bacteriological technique that could detect even small numbers of anaerobic bacteria in the canals was used. After treatment, including intracanal dressing with calcium hydroxide paste (Calasept), bacteria were recovered from one of 35 treated root canals. After use of camphorated phenol or camphorated paramonochlorophenol as the dressing, bacteria were recovered from 10 of 30 treated root canals. The isolated bacteria were predominantly Gram-positive and anaerobic. There was no indication that specific bacteria were resistant to the treatment. The results indicate that the endodontic treatment of infected root canals can be completed in two appointments when calcium hydroxide paste is used as an intracanal dressing.

Göran Sundqvist

Papers

Factors affecting the long-term results of endodontic treatment

Microbiologic analysis of teeth with failed endodontic treatment and the outcome of conservative re-treatment

Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis

Bacteriologic evaluation of the efficacy of mechanical root canal instrumentation in endodontic therapy.

The antibacterial effect of camphorated paramonochlorophenol, camphorated phenol and calcium hydroxide in the treatment of infected root canals