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Free Full Text ArticleAntimicrobial efficiency of some antiseptic products on endodontic microflora...
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Antimicrobial efficiency of some antiseptic products on endodontic microflora isolated from gangrenous pulp tissue.

J Contemp Dent Pract. 2006 Sep 1;7(4):53-62

Authors: Shurrab MY

AIM: The aims of the study are to investigate the bactericidal effect of three antiseptics (chlorhexidine solution, povidone-iodine solution, and Walkhoff solution) and to determine the minimum inhibitory concentration and their effect on different microbial species. METHODS AND MATERIALS: The study was performed on microflora derived from root canals with simple and complicated pulp gangrene and on pure strains of Enterococcus and Candida albicans. RESULTS: Chlorhexidine and povidone-iodine proved to have antibacterial and antifungal effects if used in the treatment of pulp gangrene and in cases not responding to conventional therapy. CONCLUSION: According to the obtained results, the spectrum of antibacterial agents used in infected canal irrigation can be enlarged to include the agents tested.

PMID: 16957791 [PubMed - indexed for MEDLINE]

Free Full Text ArticleTreponema denticola in disseminating endodontic infections.
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Treponema denticola in disseminating endodontic infections.

J Dent Res. 2006 Aug;85(8):761-5

Authors: Foschi F, Izard J, Sasaki H, Sambri V, Prati C, Müller R, Stashenko P

Treponema denticola is a consensus periodontal pathogen that has recently been associated with endodontic pathology. In this study, the effect of mono-infection of the dental pulp with T. denticola and with polymicrobial "red-complex" organisms (RC) (Porphyromonas gingivalis, Tannerella forsythia, and T. denticola) in inducing disseminating infections in wild-type (WT) and severe-combined-immunodeficiency (SCID) mice was analyzed. After 21 days, a high incidence (5/10) of orofacial abscesses was observed in SCID mice mono-infected with T. denticola, whereas abscesses were rare in SCID mice infected with the red-complex organisms or in wild-type mice. Splenomegaly was present in all groups, but only mono-infected SCID mice had weight loss. T. denticola DNA was detected in the spleen, heart, and brain of mono-infected SCID mice and in the spleen from mono-infected wild-type mice, which also had more periapical bone resorption. The results indicate that T. denticola has high pathogenicity, including dissemination to distant organs, further substantiating its potential importance in oral and linked systemic conditions.

PMID: 16861296 [PubMed - indexed for MEDLINE]

Free Full Text ArticleEndodontic therapy.
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Endodontic therapy.

J Am Dent Assoc. 2006 Jun;137(6):722, 724; author reply 724, 726

Authors: Kolzet DJ

PMID: 16803799 [PubMed - indexed for MEDLINE]

Free Full Text ArticleThe importance of apical patency and cleaning of the apical foramen on root c...
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The importance of apical patency and cleaning of the apical foramen on root canal preparation.

Braz Dent J. 2006;17(1):6-9

Authors: Souza RA

The apical limit of root canal instrumentation has always been a matter of great controversy. Despite the large number of published studies on this subject, a consensus has not yet been reached. In fact, the recent discussion on apical patency and cleaning of the apical foramen, as well as the incorporation of these procedures to the endodontic treatment, seem to have raised even more polemics. It is likely that all this polemics has its roots in the lack of interrelation between the theoretical knowledge of pulp stump and periapical tissues and the real clinical practice. By addressing the most important aspects of this theme, this paper aims to present news concepts about the importance of apical patency and cleaning of the apical foramen during root canal preparation.

PMID: 16721456 [PubMed - indexed for MEDLINE]

Free Full Text ArticleIdentification and quantification of archaea involved in primary endodontic i...
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Identification and quantification of archaea involved in primary endodontic infections.

J Clin Microbiol. 2006 Apr;44(4):1274-82

Authors: Vianna ME, Conrads G, Gomes BP, Horz HP

Members of the domain Archaea, one of the three domains of life, are a highly diverse group of prokaryotes, distinct from bacteria and eukaryotes. Despite their abundance and ubiquity on earth, including their close association with humans, animals, and plants, so far no pathogenic archaea have been described. As some archaea live in close proximity to anaerobic bacteria, for instance, in the human gut system and in periodontal pockets, the aim of our study was to assess whether archaea might possibly be involved in human endodontic infections, which are commonly polymicrobial. We analyzed 20 necrotic uniradicular teeth with radiographic evidence of apical periodontitis and with no previous endodontic treatment. Using real-time quantitative PCR based on the functional gene mcrA (encoding the methyl coenzyme M reductase, specific to methanogenic archaea) and on archaeal 16S rRNA genes, we found five cases to be positive. Direct sequencing of PCR products from both genes showed that the archaeal community was dominated by a Methanobrevibacter oralis-like phylotype. The size of the archaeal population at the diseased sites ranged from 1.3 x 10(5) to 6.8 x 10(5) 16S rRNA gene target molecule numbers and accounted for up to 2.5% of the total prokaryotic community (i.e., bacteria plus archaea). Our findings show that archaea can be intimately connected with infectious diseases and thus support the hypothesis that members of the domain Archaea may have a role as human pathogens.

PMID: 16597851 [PubMed - indexed for MEDLINE]

Free Full Text ArticleInability of laser and rotary instrumentation to eliminate root canal infection.

Inability of laser and rotary instrumentation to eliminate root canal infection.

J Am Dent Assoc. 2006 Jan;137(1):67-70

Authors: Jha D, Guerrero A, Ngo T, Helfer A, Hasselgren G

BACKGROUND: The authors evaluated the antibacterial effectiveness of laser instrumentation and rotary instrumentation of anterior, single-rooted teeth infected with Enterococcus faecalis. METHODS: The authors divided 35 infected samples into five groups: Group A: inoculation, laser, 17 percent ethylene-diamine-tetra-acetate (EDTA), 2.5 percent sodium hypochlorite (NaOCl) (n=10); Group B: inoculation, laser, 17 percent EDTA, sterile saline (n = 10); Group C: inoculation, rotary, 17 percent EDTA, 2.5 percent NaOCl (n=10); Group D: inoculation, no instrumentation (positive control) (n=5); Group E: no inoculation, no instrumentation (negative control) (n=5). They sampled and incubated dentin shavings from each canal for bacterial growth. RESULTS: In Group A, eight tubes were positive for bacterial growth. In Group B, 10 tubes were positive for bacterial growth. In Group C, six tube were positive for bacterial growth. In Group D, all of the tubes were positive for bacterial growth. In Group E, no tubes showed bacterial growth. The Fisher exact test showed no significant differences among groups A, E and C. CONCLUSION: Neither the laser nor the rotary instrumentation was able to eliminate endodontic infection. CLINICAL IMPLICATIONS: Although lasers have been presented as high-tech tools for disinfecting root canals, the laser was ineffective in this study.

PMID: 16457001 [PubMed - indexed for MEDLINE]

Free Full Text ArticlePhenol/water extract of Treponema socranskii subsp. socranskii as an antagoni...
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Phenol/water extract of Treponema socranskii subsp. socranskii as an antagonist of Toll-like receptor 4 signalling.

Microbiology. 2006 Feb;152(Pt 2):535-46

Authors: Lee SH, Kim KK, Rhyu IC, Koh S, Lee DS, Choi BK

Treponema socranskii is one of the most frequently found oral spirochaetes in periodontitis and endodontic infections. LPS or glycolipids from bacteria are potent stimulators of innate immune and inflammatory systems. In this study the bioactivity of a phenol/water extract from T. socranskii subsp. socranskii (TSS-P) was analysed. TSS-P showed minimal endotoxicity and no inducing potential for proinflammatory cytokines (TNF-alpha and IL-8) or for intercellular adhesion molecule-1 (ICAM-1) in human monocyte cell line THP-1 cells and primary cultured human gingival fibroblasts. Rather, it inhibited ICAM-1 expression and IL-8 secretion from cells stimulated by the LPS of Escherichia coli and Actinobacillus actinomycetemcomitans, which are known to be Toll-like receptor 4 (TLR4) agonists. However, this antagonistic activity was not shown in cells stimulated by peptidoglycan or IL-1beta. As its antagonistic mechanism, TSS-P blocked the binding of E. coli LPS to LPS-binding protein (LBP) and CD14, which are molecules involved in the recruitment of LPS to the cell membrane receptor complex TLR4-MD-2 for the intracellular signalling of LPS. TSS-P itself did not bind to MD-2 or THP-1 cells, but inhibited the binding of E. coli LPS to MD-2 or to the cells in the presence of serum (which could be replaced by recombinant human LBP and recombinant human CD14). The results suggest that TSS-P acts as an antagonist of TLR4 signalling by interfering with the functioning of LBP/CD14.

PMID: 16436441 [PubMed - indexed for MEDLINE]

Free Full Text ArticleIdentification of bacteria in endodontic infections by sequence analysis of 1...
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Identification of bacteria in endodontic infections by sequence analysis of 16S rDNA clone libraries.

J Med Microbiol. 2006 Jan;55(Pt 1):101-7

Authors: Saito D, Leonardo Rde T, Rodrigues JL, Tsai SM, Höfling JF, Gonçalves RB

A significant proportion of oral bacteria are unable to undergo cultivation by existing techniques. In this regard, the microbiota from root canals still requires complementary characterization. The present study aimed at the identification of bacteria by sequence analysis of 16S rDNA clone libraries from seven endodontically infected teeth. Samples were collected from the root canals, subjected to the PCR with universal 16S rDNA primers, cloned and partially sequenced. Clones were clustered into groups of closely related sequences (phylotypes) and identification to the species level was performed by comparative analysis with the GenBank, EMBL and DDBJ databases, according to a 98% minimum identity. All samples were positive for bacteria and the number of phylotypes detected per subject varied from two to 14. The majority of taxa (65.2%) belonged to the phylum Firmicutes of the Gram-positive bacteria, followed by Proteobacteria (10.9%), Spirochaetes (4.3%), Bacteroidetes (6.5%), Actinobacteria (2.2%) and Deferribacteres (2.2%). A total of 46 distinct taxonomic units was identified. Four clones with low similarity to sequences previously deposited in the databases were sequenced to nearly full extent and were classified taxonomically as novel representatives of the order Clostridiales, including a putative novel species of Mogibacterium. The identification of novel phylotypes associated with endodontic infections suggests that the endodontium may still harbour a relevant proportion of uncharacterized taxa.

PMID: 16388037 [PubMed - indexed for MEDLINE]

Free Full Text ArticleIdentification and localization of extraradicular biofilm-forming bacteria as...
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Identification and localization of extraradicular biofilm-forming bacteria associated with refractory endodontic pathogens.

Appl Environ Microbiol. 2005 Dec;71(12):8738-43

Authors: Noguchi N, Noiri Y, Narimatsu M, Ebisu S

Bacterial biofilms have been found to develop on root surfaces outside the apical foramen and be associated with refractory periapical periodontitis. However, it is unknown which bacterial species form extraradicular biofilms. The present study aimed to investigate the identity and localization of bacteria in human extraradicular biofilms. Twenty extraradicular biofilms, used to identify bacteria using a PCR-based 16S rRNA gene assay, and seven root-tips, used to observe immunohistochemical localization of three selected bacterial species, were taken from 27 patients with refractory periapical periodontitis. Bacterial DNA was detected from 14 of the 20 samples, and 113 bacterial species were isolated. Fusobacterium nucleatum (14 of 14), Porphyromonas gingivalis (12 of 14), and Tannellera forsythensis (8 of 14) were frequently detected. Unidentified and uncultured bacterial DNA was also detected in 11 of the 14 samples in which DNA was detected. In the biofilms, P. gingivalis was immunohistochemically detected in all parts of the extraradicular biofilms. Positive reactions to anti-F. nucleatum and anti-T. forsythensis sera were found at specific portions of the biofilm. These findings suggested that P. gingivalis, T. forsythensis, and F. nucleatum were associated with extraradicular biofilm formation and refractory periapical periodontitis.

PMID: 16332869 [PubMed - indexed for MEDLINE]

Free Full Text ArticleEvaluation of universal probes and primer sets for assessing total bacterial ...
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Evaluation of universal probes and primer sets for assessing total bacterial load in clinical samples: general implications and practical use in endodontic antimicrobial therapy.

J Clin Microbiol. 2005 Oct;43(10):5332-7

Authors: Horz HP, Vianna ME, Gomes BP, Conrads G

By re-examining 10 previously published "universal" PCR assays using the ARB phylogenetic software package and database with 41,000 16S rRNA gene sequences, we found that they differed considerably in their coverage of the domain Bacteria. We evaluated the broadest-range real-time quantitative PCR protocol for its efficacy in measuring the antimicrobial effects of endodontic treatments.

PMID: 16208011 [PubMed - indexed for MEDLINE]

Free Full Text ArticleQuantification of endotoxins in necrotic root canals from symptomatic and asy...
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Quantification of endotoxins in necrotic root canals from symptomatic and asymptomatic teeth.

J Med Microbiol. 2005 Aug;54(Pt 8):777-83

Authors: Jacinto RC, Gomes BP, Shah HN, Ferraz CC, Zaia AA, Souza-Filho FJ

The purpose of this investigation was to quantify the concentration of endotoxin in necrotic root canals and investigate the possible relationship between the concentration of endotoxin and endodontic signs and symptoms. Samples were collected from root canals of 50 patients requiring endodontic treatment due to necrosis of the pulpal tissue. Anaerobic techniques were used to determine the number of c.f.u. in each sample. A quantitative chromogenic Limulus amoebocyte lysate assay was used to measure the concentration of endotoxin in each sample. The presence of c.f.u. was detected by culture in all samples (range 10(2)-5x10(6)). In samples from cases of patients with spontaneous pain, the mean c.f.u. was 1.43x10(6) while in asymptomatic cases it was 9.1x10(4). Endotoxin was present in all the samples studied [range 2390.0-22100.0 endotoxin units (EU) ml-1]. The mean concentration of endotoxin in samples from patients with spontaneous pain was 18540.0 EU ml-1 while in asymptomatic cases it was 12030.0 EU ml-1. Asymptomatic cases generally had lower levels of endotoxin (i.e. a negative association). A positive association was found between endotoxin and symptomatic cases (e.g. spontaneous pain, tenderness to percussion, pain on palpation, swelling and purulent exudates). This study showed that endotoxin is present in high concentrations in root canals of symptomatic teeth. There was a positive correlation between the concentration of endotoxin in the root canal and the presence of endodontic signs and symptoms.

PMID: 16014432 [PubMed - indexed for MEDLINE]

Free Full Text ArticleUncultivated phylotypes and newly named species associated with primary and p...
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Uncultivated phylotypes and newly named species associated with primary and persistent endodontic infections.

J Clin Microbiol. 2005 Jul;43(7):3314-9

Authors: Siqueira JF, Rôças IN

Endodontic infections have been traditionally studied by culture methods, but recent reports showing that over 50% of the oral microbiota is still uncultivable (B. J. Paster et al., J. Bacteriol. 183:3770-3783, 2001) raise the possibility that many endodontic pathogens remain unknown. This study intended to investigate the prevalence of several uncultivated oral phylotypes, as well as newly named species in primary or persistent endodontic infections associated with chronic periradicular diseases. Samples were taken from the root canals of 21 untreated teeth and 22 root-filled teeth, all of them with radiographic evidence of periradicular bone destruction. Genomic DNA was isolated directly from each sample, and 16S rRNA gene-based nested or heminested PCR assays were used to determine the presence of 13 species or phylotypes of bacteria. Species-specific primers had already been validated in the literature or were developed by aligning closely related 16S rRNA gene sequences. Species specificity for each primer pair was confirmed by running PCRs against a panel of several oral bacteria and by sequencing DNA from representative positive samples. All species or phylotypes were detected in at least one case of primary infections. The most prevalent species or phylotypes found in primary infections were Dialister invisus (81%), Synergistes oral clone BA121 (33%), and Olsenella uli (33%). Of the target bacteria, only these three species were detected in persistent infections. Detection of uncultivated phylotypes and newly named species in infected root canals suggests that there are previously unrecognized bacteria that may play a role in the pathogenesis of periradicular diseases.

PMID: 16000454 [PubMed - indexed for MEDLINE]

Free Full Text ArticleFiber optic fluorescence microprobe for endodontic diagnosis.
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Fiber optic fluorescence microprobe for endodontic diagnosis.

J Dent Educ. 2005 Jun;69(6):633-8

Authors: Sarkissian A, Le AN

Successful endodontic therapy requires total debridement as well as complete obturation of the root canal to the cemento-dentinal junction. The goal of this study was to investigate the feasibility of using quantitative fluorescence spectroscopy for the detection and localization of pathological dentin, pulpal remnants, and microorganisms within the root canal. Specific aims were to identify: 1) characteristic excitation/emission spectra for healthy dentin, decayed dentin, enamel, and pulp; 2) the potential of specific spectral data for differentiating between these tissues; and 3) the potential of spectral data for detecting the presence and identifying four common endodontic pathogens. Fluorescence spectra were determined in the tissues of permanent human teeth, extirpated healthy and necrotic pulps, and four endodontic pathogens. Excitation/emission spectra were collected at 366 nm, 405 nm, and 440 nm excitation. Marked differences in spectral signatures between the different tissues under investigation were observed. We postulate that the differences in fluorescence spectra of decayed vs. healthy dentin are due to the loss of mineralized tissue components and increased organic presence and water in these tissues. Pulpal tissue showed distinctly different fluorescence spectra from healthy and decayed dentin, providing a basis for differentiating between tissue categories. Each bacterial species demonstrated distinct spectral emission patterns.

PMID: 15947209 [PubMed - indexed for MEDLINE]

Free Full Text ArticleNovel bacterial phylotypes in endodontic infections.
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Novel bacterial phylotypes in endodontic infections.

J Dent Res. 2005 Jun;84(6):565-9

Authors: Siqueira JF, Rôças IN, Cunha CD, Rosado AS

Although molecular studies have revealed potential oral pathogens among the phyla Spirochaetes and Deferribacteres, their occurrence in endodontic infections has not been consistently investigated. In this study, we devised a nested PCR-DGGE approach to survey samples from infected root canals for the presence of members of these two phyla, and to examine their diversity. The primers used also amplified DNA from Atopobium species. Eight of 10 cases showed bands representative of the target bacterial groups. DGGE profiles revealed a mean number of 6.5 intense and faint bands. No single band occurred in all profiles. Sequences from intense bands excised from the gel showed similarities to species/phylotypes of all target groups--Flexistipes species (Deferribacteres phylum), uncharacterized spirochetes, and Atopobium species. Analysis of these data indicates that uncultivated Spirochaetes and Deferribacteres phylotypes are frequent members of the endodontic microbiota and may be potential pathogens involved with the etiology of periradicular diseases.

PMID: 15914596 [PubMed - indexed for MEDLINE]

Free Full Text ArticleUpregulation of intercellular adhesion molecule 1 and proinflammatory cytokin...
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Upregulation of intercellular adhesion molecule 1 and proinflammatory cytokines by the major surface proteins of Treponema maltophilum and Treponema lecithinolyticum, the phylogenetic group IV oral spirochetes associated with periodontitis and endodontic infections.

Infect Immun. 2005 Jan;73(1):268-76

Authors: Lee SH, Kim KK, Choi BK

Treponema maltophilum and Treponema lecithinolyticum belong to the group IV oral spirochetes and are associated with endodontic infections, as well as periodontitis. Recently, the genes encoding the major surface proteins (Msps) of these bacteria (MspA and MspTL, respectively) were cloned and sequenced. The amino acid sequences of these proteins showed significant similarity. In this study we analyzed the functional role of these homologous proteins in human monocytic THP-1 cells and primary cultured periodontal ligament (PDL) cells using recombinant proteins. The complete genes encoding MspA and MspTL without the signal sequence were cloned into Escherichia coli by using the expression vector pQE-30. Fusion proteins tagged with N-terminal hexahistidine (recombinant MspA [rMspA] and rMspTL) were obtained, and any possible contamination of the recombinant proteins with E. coli endotoxin was removed by using polymyxin B-agarose. Flow cytometry showed that rMspA and rMspTL upregulated the expression of intercellular adhesion molecule 1 (ICAM-1) in both THP-1 and PDL cells. Expression of proinflammatory cytokines, such as interleukin-6 (IL-6) and IL-8, was also induced significantly in both cell types by the Msps, as determined by reverse transcription-PCR and an enzyme-linked immunosorbent assay, whereas IL-1beta synthesis could be detected only in the THP-1 cells. The upregulation of ICAM-1, IL-6, and IL-8 was completely inhibited by pretreating the cells with an NF-kappaB activation inhibitor, l-1-tosylamido-2-phenylethyl chloromethyl ketone. This suggests involvement of NF-kappaB activation. The increased ICAM-1 and IL-8 expression in the THP-1 cells obtained with rMsps was not inhibited in the presence of the IL-1 receptor antagonist (IL-1ra), a natural inhibitor of IL-1. Our results show that the Msps of the group IV oral spirochetes may play an important role in amplifying the local immune response by continuous inflammatory cell recruitment and retention at an infection site by stimulation of expression of ICAM-1 and proinflammatory cytokines.

PMID: 15618163 [PubMed - indexed for MEDLINE]

Free Full Text ArticlePathogenesis of apical periodontitis and the causes of endodontic failures.
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Pathogenesis of apical periodontitis and the causes of endodontic failures.

Crit Rev Oral Biol Med. 2004;15(6):348-81

Authors: Nair PN

Apical periodontitis is a sequel to endodontic infection and manifests itself as the host defense response to microbial challenge emanating from the root canal system. It is viewed as a dynamic encounter between microbial factors and host defenses at the interface between infected radicular pulp and periodontal ligament that results in local inflammation, resorption of hard tissues, destruction of other periapical tissues, and eventual formation of various histopathological categories of apical periodontitis, commonly referred to as periapical lesions. The treatment of apical periodontitis, as a disease of root canal infection, consists of eradicating microbes or substantially reducing the microbial load from the root canal and preventing re-infection by orthograde root filling. The treatment has a remarkably high degree of success. Nevertheless, endodontic treatment can fail. Most failures occur when treatment procedures, mostly of a technical nature, have not reached a satisfactory standard for the control and elimination of infection. Even when the highest standards and the most careful procedures are followed, failures still occur. This is because there are root canal regions that cannot be cleaned and obturated with existing equipments, materials, and techniques, and thus, infection can persist. In very rare cases, there are also factors located within the inflamed periapical tissue that can interfere with post-treatment healing of the lesion. The data on the biological causes of endodontic failures are recent and scattered in various journals. This communication is meant to provide a comprehensive overview of the etio-pathogenesis of apical periodontitis and the causes of failed endodontic treatments that can be visualized in radiographs as asymptomatic post-treatment periapical radiolucencies.

PMID: 15574679 [PubMed - indexed for MEDLINE]

Free Full Text ArticleVirulence factors of Enterococcus faecalis: relationship to endodontic disease.
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Virulence factors of Enterococcus faecalis: relationship to endodontic disease.

Crit Rev Oral Biol Med. 2004;15(5):308-20

Authors: Kayaoglu G, Ørstavik D

Enterococcus faecalis is a micro-organism that can survive extreme challenges. Its pathogenicity ranges from life-threatening diseases in compromised individuals to less severe conditions, such as infection of obturated root canals with chronic apical periodontitis. In the latter situation, the infecting organisms are partly shielded from the defense mechanisms of the body. In this article, we review the virulence factors of E. faecalis that may be related to endodontic infection and the periradicular inflammatory response. The most-cited virulence factors are aggregation substance, surface adhesins, sex pheromones, lipoteichoic acid, extracellular superoxide production, the lytic enzymes gelatinase and hyaluronidase, and the toxin cytolysin. Each of them may be associated with various stages of an endodontic infection as well as with periapical inflammation. While some products of the bacterium may be directly linked to damage of the periradicular tissues, a large part of the tissue damage is probably mediated by the host response to the bacterium and its products.

PMID: 15470268 [PubMed - indexed for MEDLINE]

Free Full Text ArticleDialister invisus sp. nov., isolated from the human oral cavity.
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Dialister invisus sp. nov., isolated from the human oral cavity.

Int J Syst Evol Microbiol. 2003 Nov;53(Pt 6):1937-40

Authors: Downes J, Munson M, Wade WG

Six strains of anaerobic, Gram-negative coccobacilli isolated from the root canals of patients with endodontic infections (five strains) and from a deep periodontal pocket (one strain) were subjected to a comprehensive range of phenotypic and genetic tests and were found to comprise a homogeneous group. Following 16S rRNA gene sequence analysis, they were found to be most closely related to Dialister pneumosintes, with 93 % sequence similarity between the two taxa. A novel species, Dialister invisus sp. nov., is proposed. Biochemically, the species is largely unreactive and is asaccharolytic, with only traces of acetate and propionate detected as metabolic end-products. The G+C content of the DNA of D. invisus strains is 45-46 mol%. The type strain is E7.25(T) (=CCUG 47026(T)=DSM 15470(T)).

PMID: 14657126 [PubMed - indexed for MEDLINE]

Free Full Text ArticleDiabetes mellitus as a modulating factor of endodontic infections.
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Diabetes mellitus as a modulating factor of endodontic infections.

J Dent Educ. 2003 Apr;67(4):459-67

Authors: Fouad AF

Diabetes mellitus is a chronic disease with serious health consequences. The association between diabetes and periodontal disease is well documented. However, the progression and healing of endodontic infections in diabetic patients has not been adequately studied. In this review, diabetes mellitus is explored as a potential modulating factor of endodontic pathosis. Recent data on the relationship between the clinical presentation of pulpal and periradicular disease, as well as the outcome of endodontic treatment in diabetic and nondiabetic patients, are presented. Diabetics who present for endodontic treatment, particularly those with periradicular pathosis, may have increased perioperative symptoms. Cases with preoperative periradicular lesions are less likely to be determined successful two years or longer postoperatively if the patient reports a history of diabetes. Studies examining the pathogenesis of periradicular lesions in mouse models with uncontrolled type 1 diabetes suggest that the lesion size may be increased and the animals have increased serious sequelae. Preliminary findings suggest that some bacterial species may be more prevalent in necrotic pulp of diabetic than nondiabetic patients. More studies are needed to further explore the microbiology of endodontic infections and to determine effective treatment strategies in both diabetic and nondiabetic patients.

PMID: 12749575 [PubMed - indexed for MEDLINE]

Free Full Text ArticleFluorescence in situ hybridization (FISH) for direct visualization of bacteri...
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Fluorescence in situ hybridization (FISH) for direct visualization of bacteria in periapical lesions of asymptomatic root-filled teeth.

Microbiology. 2003 May;149(Pt 5):1095-102

Authors: Sunde PT, Olsen I, Göbel UB, Theegarten D, Winter S, Debelian GJ, Tronstad L, Moter A

Whether micro-organisms can live in periapical endodontic lesions of asymptomatic teeth is under debate. The aim of the present study was to visualize and identify micro-organisms within periapical lesions directly, using fluorescence in situ hybridization (FISH) in combination with epifluorescence and confocal laser scanning microscopy (CLSM). Thirty-nine periapical lesions were surgically removed, fixed, embedded in cold polymerizing resin and sectioned. The probe EUB 338, specific for the domain Bacteria, was used together with a number of species-specific 16S rRNA-directed oligonucleotide probes to identify bacteria. To control non-specific binding of EUB 338, probe NON 338 was used. Alternatively, DAPI (4',6'-diamidino-2-phenylindole) staining was applied to record prokaryotic and eukaryotic DNA in the specimens. Hybridization with NON 338 gave no signals despite background fluorescence of the tissue. The eubacterial probe showed bacteria of different morphotypes in 50 % of the lesions. Rods, spirochaetes and cocci were spread out in areas of the tissue while other parts seemed bacteria-free. Bacteria were also seen to co-aggregate inside the tissue, forming microcolonies. Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis and treponemes of phylogenetic Group I were detected with specific probes. In addition, colonies with Streptococcus spp. were seen in some lesions. A number of morphotypes occurred that could not be identified with the specific probes used, indicating the presence of additional bacterial species. CLSM confirmed that bacteria were located in different layers of the tissue. Accordingly, the FISH technique demonstrated mixed consortia of bacteria consisting of rods, spirochaetes and cocci in asymptomatic periapical lesions of root-filled teeth.

PMID: 12724371 [PubMed - indexed for MEDLINE]

Free Full Text ArticleComparison of 16S rDNA-based PCR and checkerboard DNA-DNA hybridisation for d...
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Comparison of 16S rDNA-based PCR and checkerboard DNA-DNA hybridisation for detection of selected endodontic pathogens.

J Med Microbiol. 2002 Dec;51(12):1090-6

Authors: Siqueira JF, Rôças IN, De Uzeda M, Colombo AP, Santos KR

Molecular methods have been used recently to investigate the bacteria encountered in human endodontic infections. The aim of the present study was to compare the ability of a 16S rDNA-based PCR assay and checkerboard DNA-DNA hybridisation in detecting Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Peptostreptococcus micros, Porphyromonas endodontalis, Por. gingivalis and Treponema denticola directly from clinical samples. Specimens were obtained from 50 cases of endodontic infections and the presence of the target species was investigated by whole genomic DNA probes and checkerboard DNA-DNA hybridisation or taxon-specific oligonucleotides with PCR assay. Prevalence of the target species was based on data obtained by each method. The sensitivity and specificity of each molecular method was compared with the data generated by the other method as the reference--a value of 1.0 representing total agreement with the chosen standard. The methods were also compared with regard to the prevalence values for each target species. Regardless of the detection method used, T. denticola, Por. gingivalis, Por. endodontalis and B. forsythus were the most prevalent species. If the checkerboard data for these four species were used as the reference, PCR detection sensitivities ranged from 0.53 to 1.0, and specificities from 0.5 to 0.88, depending on the target bacterial species. When PCR data for the same species were used as the reference, the detection sensitivities for the checkerboard method ranged from 0.17 to 0.73, and specificities from 0.75 to 1.0. Accuracy values ranged from 0.6 to 0.74. On the whole, matching results between the two molecular methods ranged from 60% to 97.5%, depending on the target species. The major discrepancies between the methods comprised a number of PCR-positive but checkerboard-negative results. Significantly higher prevalence figures for Por. endodontalis and T. denticola were observed after PCR assessment. There was no further significant difference between the methods with regard to detection of the other target species.

PMID: 12466407 [PubMed - indexed for MEDLINE]

Free Full Text ArticleMolecular and cultural analysis of the microflora associated with endodontic ...
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Molecular and cultural analysis of the microflora associated with endodontic infections.

J Dent Res. 2002 Nov;81(11):761-6

Authors: Munson MA, Pitt-Ford T, Chong B, Weightman A, Wade WG

Cultural studies have indicated that a subset of the oral microflora is responsible for endodontic infections. Approximately 50% of oral bacteria are unculturable, so it is likely that currently unknown bacteria are present in such infections. In this study, cultural and molecular analyses were performed on the microflora in aspirate samples collected from 5 infected root canals. 16S rDNA sequences from 261 isolates and 624 clones were identified by comparison with database sequences. Sixty-five taxa were identified, of which 26 were found by the molecular method alone. A mean of 20.2 taxa was found in each sample. A new species of Dialister was the only organism present in all 5 samples. Twenty-seven novel taxa were detected, 18 of which belonged to the phylum Firmicutes and 8 to Bacteroidetes. Culture-independent, molecular analysis has revealed a more diverse microflora associated with endodontic infections than that revealed by cultural methods alone.

PMID: 12407091 [PubMed - indexed for MEDLINE]

Free Full Text ArticlePCR-based identification of bacteria associated with endodontic infections.
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PCR-based identification of bacteria associated with endodontic infections.

J Clin Microbiol. 2002 Sep;40(9):3223-31

Authors: Fouad AF, Barry J, Caimano M, Clawson M, Zhu Q, Carver R, Hazlett K, Radolf JD

PCR primers that target the bacterial 16S rRNA genes (or the tuf gene for the genus Enterococcus) were used to identify 10 putative bacterial pathogens in root canals with necrotic pulp. In addition, the associations of these microorganisms with symptoms and a history of diabetes mellitus were investigated. Microbial samples from the root canals of 24 teeth with necrotic pulp were included in the study. PCR with universal bacterial primers identified bacterial DNA in 22 specimens; the remaining 2 specimens were from intact teeth that had been traumatized 6 months prior to treatment. PCR with specific primers showed that preoperative symptoms were significantly associated with the presence of Streptococcus spp. (P < 0.001 by chi-square analysis). There was also a nonsignificant trend for symptoms to be associated with Fusobacterium nucleatum and Porphyromonas gingivalis (odds ratio, >2) and for diabetes mellitus to be associated with P. gingivalis and Porphyromonas endodontalis (odds ratio, >2). Cloning and sequencing of the universal PCR product in one specimen revealed the presence of an organism related to the genus Olsenella, which has not previously been described in endodontic infections.

PMID: 12202557 [PubMed - indexed for MEDLINE]

Free Full Text ArticleQuantitative microbiological study of human carious dentine by culture and re...
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Quantitative microbiological study of human carious dentine by culture and real-time PCR: association of anaerobes with histopathological changes in chronic pulpitis.

J Clin Microbiol. 2002 May;40(5):1698-704

Authors: Martin FE, Nadkarni MA, Jacques NA, Hunter N

The bacteria found in carious dentine were correlated with the tissue response of the dental pulps of 65 teeth extracted from patients with advanced caries and pulpitis. Standardized homogenates of carious dentine were plated onto selective and nonselective media under anaerobic and microaerophilic conditions. In addition, real-time PCR was used to quantify the recovery of anaerobic bacteria. Primers and fluorogenic probes were designed to detect the total anaerobic microbial load, the genera Prevotella and Fusobacterium, and the species Prevotella melaninogenica, Porphyromonas endodontalis, Porphyromonas gingivalis, and Micromonas (formerly Peptostreptococcus) micros. The pulpal pathology was categorized according to the cellular response and degenerative changes. Analysis of cultured bacteria showed a predominance of gram-positive microorganisms, particularly lactobacilli. Gram-negative bacteria were also present in significant numbers with Prevotella spp., the most numerous anaerobic group cultured. Real-time PCR analysis indicated a greater microbial load than that determined by colony counting. The total number of anaerobes detected was 41-fold greater by real-time PCR than by colony counting, while the numbers of Prevotella and Fusobacterium spp. detected were 82- and 2.4-fold greater by real-time PCR than by colony counting, respectively. Real-time PCR also identified M. micros, P. endodontalis, and P. gingivalis in 71, 60, and 52% of carious samples, respectively. Correlation matrices of the real-time PCR data revealed significant positive associations between M. micros and P. endodontalis detection and inflammatory degeneration of pulpal tissues. These anaerobes have been strongly implicated in endodontic infections that occur as sequelae to carious pulpitis. Accordingly, the data suggest that the presence of high levels of these bacteria in carious lesions may be indicative of irreversible pulpal pathology.

PMID: 11980945 [PubMed - indexed for MEDLINE]

Free Full Text ArticleDisinfection/sterilization of extracted teeth for dental student use.
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Disinfection/sterilization of extracted teeth for dental student use.

J Dent Educ. 2001 Nov;65(11):1278-80

Authors: Dominici JT, Eleazer PD, Clark SJ, Staat RH, Scheetz JP

Extracted human teeth are used in many preclinical courses. While there has been no report of disease transmission with extracted teeth, sterilization of teeth used in the teaching laboratory should be a concern. The purpose of this study was to determine the effectiveness of different sterilization/disinfection methods of extracted human teeth using Bacillus stearothermophilus, a bacteria resistant to heat and frequently used to test sterilizers. In this study, 110 extracted molars with no carious lesions were collected and stored in buffered saline. An endodontic occlusal access preparation was cut into the pulp chamber of each tooth. Pulp tissue in the chamber was removed with a broach. Approximately 1 x 10(5) B. stearothermophilus endospores in culture medium were injected into the pulp chamber, sealed with Cavit G, and then placed in sterile saline for twelve hours. Ten teeth were placed into each of eleven groups. Seven groups were immersed for one week in one of the following solutions: a) sterile saline (control group), b) 5.25% NaOCl, c) 2.6% NaOCl, d) 1% NaOCl, e) 10% buffered formalin, f) 2% gluteraldehyde, g) 0.28% quaternary ammonium. Four additional groups were treated by h) 10% formalin for two days, i) 10% formalin for four days, j) autoclaving at 240 degrees F and 20 psi for twenty minutes, and k) autoclaving at 240 degrees F and twenty psi for forty minutes. Each tooth was then aseptically split and placed in an individual test tube with growth medium. Samples were examined for evidence of growth (turbidity) at forty-eight hours. Only autoclaving for forty minutes at 240 degrees F and 20 psi or soaking in 10 percent formalin for one week were 100 percent effective in preventing growth. A chi-square analysis of the data indicates these two methods were significantly better than all other methods (p<0.001).

PMID: 11765875 [PubMed - indexed for MEDLINE]

Free Full Text ArticleTumor necrosis factor modulates fibroblast apoptosis, PMN recruitment, and os...
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Tumor necrosis factor modulates fibroblast apoptosis, PMN recruitment, and osteoclast formation in response to P. gingivalis infection.

J Dent Res. 2001 Oct;80(10):1875-9

Authors: Graves DT, Oskoui M, Volejnikova S, Naguib G, Cai S, Desta T, Kakouras A, Jiang Y

P. gingivalis is an important oral pathogen, which has been closely linked to periodontal disease as well as lesions of endodontic origin. Both infections are associated with a decrease in fibroblast numbers, formation of an inflammatory infiltrate, and bone resorption. The goal of this study was to investigate the role that the host response plays in the capacity of P. gingivalis to stimulate fibroblast apoptosis, PMN recruitment, and osteoclastogenesis. This was accomplished by the use of an in vivo calvarial model in mice with targeted deletion of TNF receptors p55 and p75 and matched wild-type mice. The results indicate that P. gingivalis induces fibroblast apoptosis in vivo and establish for the first time that this involves the stimulation of a host response. Moreover, bacteria-stimulated PMN recruitment and osteoclastogenesis were also dependent upon the host response. The results suggest that much of the damage caused by P. gingivalis infection, including fibroblast apoptosis, at least under some circumstances, results from stimulation of the host response rather than the direct effect of bacterial products. Furthermore, this may represent a more general mechanism by which bacterial challenge induces apoptosis of matrix-producing cells through the induction of TNF.

PMID: 11706944 [PubMed - indexed for MEDLINE]

Free Full Text ArticleMolecular identification of microorganisms from endodontic infections.
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Molecular identification of microorganisms from endodontic infections.

J Clin Microbiol. 2001 Sep;39(9):3282-9

Authors: Rolph HJ, Lennon A, Riggio MP, Saunders WP, MacKenzie D, Coldero L, Bagg J

A relatively wide range of bacteria have been isolated from root canals using standard culture techniques. However, only 50% of the bacteria in the oral cavity are cultivable (S. S. Socransky et al., Arch. Oral Biol. 8:278-280, 1963); hence, bacterial diversity in endodontic infections is underestimated. This study used a PCR-based 16S rRNA gene assay, followed by cloning and sequencing of 16S rRNA amplicons from a small subset of samples to assess the diversity of bacteria present in infected root canals. A total of 41 clinical samples from 15 de novo and 26 refractory cases of endodontic infections were assessed. Of these samples, 44% were positive by culture and 68% were positive by PCR. Eight samples were selected for further analysis. Of these, the two de novo cases yielded sequences related to those of the genera Enterococcus, Lactobacillus, Propionibacterium, and Streptococcus and two clones were related to previously uncultivated bacteria, while the sinus-associated, de novo case yielded sequences related to those of the genera Lactobacillus, Pantoea, Prevotella, and Selenomonas. The five refractory cases produced clones which were related to the genera Capnocytophaga, Cytophaga, Dialister, Eubacterium, Fusobacterium, Gemella, Mogibacterium, Peptostreptococcus, Prevotella, Propionibacterium, Selenomonas, Solobacterium, Streptococcus, and Veillonella and two clones representing previously uncultivated bacteria. The phylogenetic positions of several clones associated with the Clostridiaceae and Sporomusa subgroups of the Firmicutes grouping are also shown. This study demonstrates that molecular techniques can detect the presence of bacteria in endodontic infections when culture techniques yield a negative result and can be used to identify a wider range of endodontic-infection-related bacteria including the presence of previously unidentified or unculturable bacteria.

PMID: 11526164 [PubMed - indexed for MEDLINE]

Free Full Text ArticleIL-10, but not IL-4, suppresses infection-stimulated bone resorption in vivo.
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IL-10, but not IL-4, suppresses infection-stimulated bone resorption in vivo.

J Immunol. 2000 Oct 1;165(7):3626-30

Authors: Sasaki H, Hou L, Belani A, Wang CY, Uchiyama T, M&#xFC;ller R, Stashenko P

Periapical bone resorption occurs following infection of the dental pulp and is mediated mainly by IL-1alpha in the murine model. The production and activity of IL-1alpha is modulated by a network of regulatory cytokines, including those produced by Th1 (pro-inflammatory) and Th2 (anti-inflammatory) subset T cells. This study was designed to assess the functional role of the Th2-type cytokines IL-4 and IL-10 in infection-stimulated bone resorption in vivo. The dental pulps of the first molars were exposed and infected with a mixture of four common endodontic pathogens, and bone destruction was determined by micro-computed tomography at sacrifice on day 21. The results demonstrate that IL-10(-/-) mice had significantly greater infection-stimulated bone resorption in vivo compared with wild-type mice (p < 0.001), whereas IL-4(-/-) exhibited no increased resorption. IL-10(-/-) had markedly elevated IL-1alpha production within periapical inflammatory tissues (>10-fold) compared with wild type (p < 0.01), whereas IL-4(-/-) exhibited decreased IL-1alpha production (p < 0.05). IL-10 also suppressed IL-1alpha production by macrophages in a dose-dependent fashion in vitro, whereas IL-4 had weak and variable effects. We conclude that IL-10, but not IL-4, is an important endogenous suppressor of infection-stimulated bone resorption in vivo, likely acting via inhibition of IL-1alpha expression.

PMID: 11034365 [PubMed - indexed for MEDLINE]

Free Full Text ArticleCoinvasion of dentinal tubules by Porphyromonas gingivalis and Streptococcus ...
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Coinvasion of dentinal tubules by Porphyromonas gingivalis and Streptococcus gordonii depends upon binding specificity of streptococcal antigen I/II adhesin.

Infect Immun. 2000 Mar;68(3):1359-65

Authors: Love RM, McMillan MD, Park Y, Jenkinson HF

Cell wall-anchored polypeptides of the antigen I/II family are produced by many species of oral streptococci. These proteins mediate adhesion of streptococci to salivary glycoproteins and to other oral microorganisms and promote binding of cells to collagen type I and invasion of dentinal tubules. Since infections of the root canal system have a mixed anaerobic bacterial etiology, we investigated the hypothesis that coadhesion of anaerobic bacteria with streptococci may facilitate invasive endodontic disease. Porphyromonas gingivalis ATCC 33277 cells were able to invade dentinal tubules when cocultured with Streptococcus gordonii DL1 (Challis) but not when cocultured with Streptococcus mutans NG8. An isogenic noninvasive mutant of S. gordonii, with production of SspA and SspB (antigen I/II family) polypeptides abrogated, was deficient in binding to collagen and had a 40% reduced ability to support adhesion of P. gingivalis. Heterologous expression of the S. mutans SpaP (antigen I/II) protein in this mutant restored collagen binding and tubule invasion but not adhesion to P. gingivalis or the ability to promote P. gingivalis coinvasion of dentin. An isogenic afimbrial mutant of P. gingivalis had 50% reduced binding to S. gordonii cells but was unaffected in the ability to coinvade dentinal tubules with S. gordonii wild-type cells. Expression of the S. gordonii SspA or SspB polypeptide on the surface of Lactococcus lactis cells endowed these bacteria with the abilities to bind P. gingivalis, penetrate dentinal tubules, and promote P. gingivalis coinvasion of dentin. The results demonstrate that collagen-binding and P. gingivalis-binding properties of antigen I/II polypeptides are discrete functions. Specificity of antigen I/II polypeptide recognition accounts for the ability of P. gingivalis to coinvade dentinal tubules with S. gordonii but not with S. mutans. This provides evidence that the specificity of interbacterial coadhesion may influence directly the etiology of pulpal and periapical diseases.

PMID: 10678948 [PubMed - indexed for MEDLINE]

Free Full Text ArticleBacterium-dependent induction of cytokines in mononuclear cells and their pat...
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Bacterium-dependent induction of cytokines in mononuclear cells and their pathologic consequences in vivo.

Infect Immun. 1999 May;67(5):2125-30

Authors: Jiang Y, Magli L, Russo M

Viridans streptococci are a heterogeneous group of gram-positive bacteria that are normal inhabitants of the mouth. These organisms are thought to contribute significantly to the etiology of infective endocarditis, although recently they have been implicated in serious infections in other settings. Another group of oral bacteria, gram-negative anaerobes, is associated with chronic dental infections, such as periodontal diseases or endodontic lesion formation. We evaluated the ability of the oral pathogens Streptococcus mutans and Porphyromonas endodontalis to induce a pathogenic response in vivo, with the goal of quantifying the inflammatory response in soft tissue by measuring leukocyte recruitment and hard tissues by measuring osteoclastogenesis. S. mutans induced a strong inflammatory response and was a potent inducer of osteoclast formation, while P. endodontalis was not. To further study the mechanisms by which P. endodontalis and S. mutans elicit significantly different levels of inflammatory responses in vivo, we tested the capacity of each to induce production of cytokines by mononuclear cells in vitro. S. mutans stimulated high levels of interleukin-12 (IL-12), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha), all of which are associated with inflammation, enhanced monocyte function, and generation of a Th1 response. In contrast, P. endodontalis stimulated production of IL-10 but not of TNF-alpha, IL-12, or IFN-gamma. These results demonstrate that oral pathogens differ dramatically in their abilities to induce inflammatory and immunoregulatory cytokines. Moreover, there is a high degree of correlation between the cytokine profile induced by these bacteria in vitro and their pathogenic capacity in vivo.

PMID: 10225864 [PubMed - indexed for MEDLINE]

Free Full Text ArticleSurface structure, hydrophobicity, phagocytosis, and adherence to matrix prot...
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Surface structure, hydrophobicity, phagocytosis, and adherence to matrix proteins of Bacillus cereus cells with and without the crystalline surface protein layer.

Infect Immun. 1998 Oct;66(10):4895-902

Authors: Kotiranta A, Haapasalo M, Kari K, Kerosuo E, Olsen I, Sorsa T, Meurman JH, Lounatmaa K

Nonopsonic phagocytosis of Bacillus cereus by human polymorphonuclear leukocytes (PMNs) with particular attention to bacterial surface properties and structure was studied. Two reference strains (ATCC 14579(T) and ATCC 4342) and two clinical isolates (OH599 and OH600) from periodontal and endodontic infections were assessed for adherence to matrix proteins, such as type I collagen, fibronectin, laminin, and fibrinogen. One-day-old cultures of strains OH599 and OH600 were readily ingested by PMNs in the absence of opsonins, while cells from 6-day-old cultures were resistant. Both young and old cultures of the reference strains of B. cereus were resistant to PMN ingestion. Preincubation of PMNs with the phagocytosis-resistant strains of B. cereus did not affect the phagocytosis of the sensitive strain. Negatively stained cells of OH599 and OH600 studied by electron microscopy had a crystalline protein layer on the cell surface. In thin-sectioned cells of older cultures (3 to 6 days old), the S-layer was observed to peel off from the cells. No S-layer was detected on the reference strains. Extraction of cells with detergent followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a major 97-kDa protein from the strains OH599 and OH600 but only a weak 97-kDa band from the reference strain ATCC 4342. One-day-old cultures of the clinical strains (hydrophobicity, 5.9 to 6.0%) showed strong binding to type I collagen, laminin, and fibronectin. In contrast, reference strains (hydrophobicity, -1.0 to 4.2%) as well as 6-day-old cultures of clinical strains (hydrophobicity, 19.0 to 53.0%) bound in only low numbers to the proteins. Gold-labelled biotinylated fibronectin was localized on the S-layer on the cell surface as well as on fragments of S-layer peeling off the cells of a 6-day-old culture of B. cereus OH599. Lactose, fibronectin, laminin, and antibodies against the S-protein reduced binding to laminin but not to fibronectin. Heating the cells at 84 degreesC totally abolished binding to both proteins. Benzamidine, a noncompetitive serine protease inhibitor, strongly inhibited binding to fibronectin whereas binding to laminin was increased. Overall, the results indicate that changes in the surface structure, evidently involving the S-layer, during growth of the clinical strains of B. cereus cause a shift from susceptibility to PMN ingestion and strong binding to matrix and basement membrane proteins. Furthermore, it seems that binding to laminin is mediated by the S-protein while binding to fibronectin is dependent on active protease evidently attached to the S-layer.

PMID: 9746594 [PubMed - indexed for MEDLINE]

Free Full Text ArticleInvasion of dentinal tubules by oral streptococci is associated with collagen...
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Invasion of dentinal tubules by oral streptococci is associated with collagen recognition mediated by the antigen I/II family of polypeptides.

Infect Immun. 1997 Dec;65(12):5157-64

Authors: Love RM, McMillan MD, Jenkinson HF

Cell surface proteins SspA and SspB in Streptococcus gordonii and SpaP in Streptococcus mutans are members of the antigen I/II family of polypeptides produced by oral streptococci. These proteins are adhesins and mediate species-specific binding of cells to a variety of host and bacterial receptors. Here we show that antigen I/II polypeptides are involved in the attachment of oral streptococci to collagen and that they also determine the ability of these bacteria to invade human root dentinal tubules. Wild-type S. gordonii DL1 (Challis) cells showed heavy invasion of tubules to a depth of approximately 200 microm, whereas the abilities of cells of isogenic mutant strains OB220 (sspA) and OB219 (sspA sspB) to invade were 50 and >90% reduced, respectively. Likewise, wild-type S. mutans NG8 cells invaded dentinal tubules, whereas cells of isogenic mutant strain 834 (spaP) did not. The invasive abilities of strains OB220 and OB219 were restored by heterologous expression of S. mutans SpaP polypeptide in these strains. The extents of tubule invasion by various wild-type and mutant strains correlated with their levels of adhesion to type I collagen, a major component of dentin. Furthermore, S. gordonii DL1 cells exhibited a growth response to collagen by forming long chains. This was not shown by ssp mutants but was restored by the expression of SpaP in these cells. The production of SspA polypeptide by S. gordonii DL1, but not production of SspB polypeptide by strain OB220 (sspA), was enhanced in the presence of collagen. These results are the first to demonstrate that antigen I/II family polypeptides bind collagen and mediate a morphological growth response of streptococci to collagen. These antigen I/II polypeptide activities are critical for intratubular growth of streptococci and thus for establishment of endodontic infections.

PMID: 9393810 [PubMed - indexed for MEDLINE]

Free Full Text ArticleIncreased susceptibility of RAG-2 SCID mice to dissemination of endodontic in...
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Increased susceptibility of RAG-2 SCID mice to dissemination of endodontic infections.

Infect Immun. 1997 Sep;65(9):3781-7

Authors: Teles R, Wang CY, Stashenko P

Specific immunity has been implicated in the pathogenesis of periapical lesions, although the extent to which these mechanisms are actually involved in either protection or destruction of the pulp-periapex complex is yet to be established. To investigate this question we compared periapical-lesion pathogenesis in RAG-2 severe combined immunodeficient (SCID) mice with immunocompetent control mice following surgical pulp exposure. In order to equalize the bacterial challenge, an infection protocol using Prevotella intermedia, Fusobacterium nucleatum, Peptostreptococcus micros, and Streptococcus intermedius was devised. The results demonstrated that after infection, the proportion of the root canal flora represented by the four pathogens was almost identical in both groups (39.9 and 42.2% for RAG-2 and immunocompetent control mice, respectively). The effects of abrogation of T- and B-cell mechanisms on periapical pathogenesis were then assessed. Approximately one-third of the RAG-2 mice developed endodontic abscesses, while no immunocompetent controls had abscesses, results which indicated regional dissemination of the infection. A similar incidence of abscesses was found in two additional experiments. Abscessed RAG-2 teeth had significantly larger periapical lesions than did nonabscessed RAG-2 teeth (P < or = 0.05) and exposed immunocompetent controls (P < or = 0.01), whereas nonabscessed RAG-2 teeth were not significantly different from those of exposed immunocompetent controls in periapical-lesion size. We conclude that B- and T-cell-mediated immunity protects the host from the dissemination of endodontic infections and that RAG-2 mice are more susceptible to infection-induced pulp-periapex destruction.

PMID: 9284152 [PubMed - indexed for MEDLINE]

Free Full Text ArticleEvaluating chemical inactivation of viral agents in handpiece splatter.
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Evaluating chemical inactivation of viral agents in handpiece splatter.

J Am Dent Assoc. 1995 Feb;126(2):197-202

Authors: Ceisel RJ, Osetek EM, Turner DW, Spear PG

The water spray used with a modern high-speed dental drill is a significant vehicle for dispersion of infectious agents into the environment, putting patients and the dental staff at risk of infection. This study examines whether disinfectants added to the handpiece water supply could inactivate viral contaminants in splatter. Results supporting use of ethanol or sodium hypochlorite are presented.

PMID: 7860888 [PubMed - indexed for MEDLINE]

Free Full Text ArticleDetection and quantitation by lysis-filtration of bacteremia after different ...
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Detection and quantitation by lysis-filtration of bacteremia after different oral surgical procedures.

J Clin Microbiol. 1990 Oct;28(10):2205-9

Authors: Heimdahl A, Hall G, Hedberg M, Sandberg H, S&#xF6;der PO, Tunér K, Nord CE

Patients with bacteremia after dental extraction, third-molar surgery, dental scaling, endodontic treatment, and bilateral tonsillectomy were studied by means of lysis-filtration of blood samples with subsequent aerobic and anaerobic incubation. Samples were obtained before, during, and 10 min after treatment. Bacteremia was observed in 100% of patients after dental extraction, 55% of patients after third-molar surgery, 70% of patients after dental scaling, 20% of patients after endodontic treatment, and 55% of patients after bilateral tonsillectomy. Anaerobic microorganisms were isolated more frequently than aerobic microorganisms were, and viridans group streptococci were the most commonly isolated bacteria. Ten minutes after treatment, the frequency as well as the magnitude of bacteremia showed pronounced reduction.

PMID: 2229342 [PubMed - indexed for MEDLINE]

Free Full Text ArticleBlack-pigmented Bacteroides spp. in human apical periodontitis.
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Black-pigmented Bacteroides spp. in human apical periodontitis.

Infect Immun. 1986 Jul;53(1):149-53

Authors: Haapasalo M, Ranta H, Ranta K, Shah H

The incidence of black-pigmented (BP) Bacteroides spp. in 62 human dental root canal infections (35 acute and 27 clinically asymptomatic cases of apical periodontitis) in 57 adults was studied. Altogether 37 strains of BP Bacteroides were found in 31 infections, always in mixed anaerobic infections. Two different BP Bacteroides species were present in six infections. B. intermedius was most frequently isolated (15 of 62 canals; 24%) followed by B. denticola which was present in 12 cases. Asaccharolytic BP Bacteroides species, B. gingivalis and B. endodontalis, were found in eight cases. BP Bacteroides species were found both from symptomatic and asymptomatic infections, but there were also several symptomatic cases from which BP Bacteroides species were not isolated. B. gingivalis and B. endodontalis were present only in acute infections, B. intermedius was found both in symptomatic and asymptomatic infections, and B. denticola occurred mostly in asymptomatic infections. BP Bacteroides species were isolated initially from 9 of the 11 teeth with symptoms at 1 week, but only from 22 of the 51 teeth that were symptomless at 1 week. Two strains of B. denticola were resistant to penicillin G at a concentration of 2.4 micrograms/ml, but the MIC of penicillin G for all other strains was 0.6 micrograms/ml or lower. Forty-two randomly selected patients received penicillin V (oral administration, 650 mg, three times daily) during the first week of endodontic therapy. Penicillin had no effect on the occurrence of symptoms after 1 week compared with the control group (20 patients).

PMID: 3721577 [PubMed - indexed for MEDLINE]

Free Full Text ArticleBacteriology of dental abscesses of endodontic origin.
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Bacteriology of dental abscesses of endodontic origin.

J Clin Microbiol. 1983 Oct;18(4):770-4

Authors: Williams BL, McCann GF, Schoenknecht FD

Aspirates have been cultured from 10 dental abscesses of endodontic origin, all of which had penetrated beyond the bony alveolus to produce fluctuant swelling. Sampling was by syringe aspiration. Strict anaerobic techniques, including the use of an anaerobic chamber, were used for serial dilution and plating. Randomly selected colonies (100) from each culture were purified, characterized, and identified. Seventy percent of the bacterial isolates were either strict anaerobes or microaerophilic. One abscess yielded a pure culture of a viridans streptococcus, Streptococcus milleri. Streptococcus intermedius dominated the flora in a second abscess. The common oral streptococcus, Streptococcus sanguis, constituted only 2% of the isolates from one additional infection. Fusobacterium nucleatum, Bacteroides melaninogenicus, other Bacteroides including B. oralis and B. ruminicola, anaerobic diphtheroids, Peptostreptococcus micros, and Staphylococcus epidermis were other predominant isolates.

PMID: 6630460 [PubMed - indexed for MEDLINE]

Free Full Text ArticleRationalized endodontic treatment by a bacteriologic direct sampling technique.
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Rationalized endodontic treatment by a bacteriologic direct sampling technique.

J Dent Res. 1970 Nov-Dec;49(6):Suppl:1427-30

Authors: Olgart LG

PMID: 5274368 [PubMed - indexed for MEDLINE]

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