Microbiological analysis of infected root canals from symptomatic and asymptomatic teeth with periapical periodontitis and the antimicrobial susceptibility of some isolated anaerobic bacteria

Microbiological profile and antimicrobial susceptibility pattern of infected root canals associated with periapical abscesses

The aim of this investigation was to identify microorganisms from root canals with periapical abscesses and assess the susceptibility of specific anaerobic bacteria to selected antimicrobials and their β-lactamase production. Sixty root canals were microbiologically investigated. The susceptibility of Anaerococcus prevotii, Fusobacterium necrophorum, F. nucleatum, Parvimonas micra, and Prevotella intermedia/nigrescens to antimicrobials was evaluated with the Etest, whereas β-lactamase production was assessed with nitrocefin. A total of 287 different bacterial strains were recovered, including 201 strict anaerobes. The most frequently strict isolated anaerobes were A. prevotii, P. micra, and F. necrophorum. The selected bacteria were susceptible to all the tested antibiotics, except A. prevotii and Fusobacterium species to azithromycin and erythromycin, as well as A. prevotii and F. necrophorum to metronidazole. None of the microorganisms produced β-lactamase. Gram-positive anaerobic bacteria predominated in the root canals with periapical abscesses. All microorganisms tested were susceptible to benzylpenicillin, amoxicillin, amoxicillin + clavulanate, cefaclor, and clindamycin, producing no β-lactamase.

Clinical and pharmacological management of endodontic flare-up

Knowledge of the causes of and mechanisms behind interappointment pain in endodontics is of utmost importance for the clinician to properly prevent or manage this undesirable condition. The causative factors of interappointment pain encompass mechanical, chemical, and microbial injuries to the pulp or periradicular tissues, which are induced or exacerbated during root canal treatment. This review article underlines the various treatment modalities for relief of pain and swelling in such situations, including premedication, drainage establishment, relief of occlusion, and intracanal and systemic medication.

Analysis of the antimicrobial susceptibility of anaerobic bacteria isolated from endodontic infections in Brazil during a period of nine years

INTRODUCTION

The purpose of this study was to analyze the susceptibility of some anaerobic species isolated from a Brazilian population at different periods of time by determining a pattern of development of resistance to frequently prescribed antibiotics in endodontics.

METHODS

Root canal samples were collected from infected teeth at different periods of time (2000-2002, 2003-2005, and 2007-2008) and microbiologically identified with conventional culture techniques. The susceptibility of Prevotella intermedia/nigrescens, P. oralis, Fusobacterium nucleatum, and P. micra isolated strains was determined by the minimum inhibitory concentration (MIC) of amoxicillin, amoxicillin + clavulanate, benzylpenicillin, clindamycin, erythromycin, and metronidazole by using the E-test method.

RESULTS

Amoxicillin and amoxicillin + clavulanate were effective against the majority of species at the different periods of study. Overall, there were low statistical differences regarding the microbial susceptibility between the experimental periods. However, an increase in the anaerobic resistance to penicillin G and clindamycin was observed. Resistance to erythromycin was observed in all species, and there were statistically significant differences between 2000-2002 and 2003-2005 periods for F. nucleatum (P < .05) and between 2003-2005 and 2007-2008 periods for P. intermedia/nigrescens and P. oralis (P < .05).

CONCLUSIONS

The antimicrobial resistance of anaerobes isolated from primary endodontic infections showed an increase throughout a period of time regarding a specific Brazilian population.

Synergistic growth effect among bacteria recovered from root canal infections

The objective of this study was to determine the ecological relationships between bacterial species that colonize infected root canals. Root canal bacteria recovered from one patient with pulp canal necrosis were evaluated in vitro for synergistic and antagonistic activities determined by mono and co-culture growth kinetics and the production of bacteriocin-like substances using the double layer diffusion method. Peptostreptococcus prevotii triggered a significant increase of Fusobacterium nucleatum growth, while the former bacteria did not affect the growth of P. prevotii. The bacterial species did not produce antagonism activity against itself or against any of the other two species. Despite many studies have demonstrated the capability of root canal microorganisms to produce antagonistic substances, these in vitro experimental tests show the synergistic effect of P. prevotii on the growth of F. nucleatum.

Prevalence of apical periodontitis of root canal-treated teeth and retrospective evaluation of symptom-related prognostic factors in an urban South Korean population

OBJECTIVES

This study aimed to investigate the prevalence of apical periodontitis among root canal-treated teeth in an urban South Korean population and evaluate prognostic factors for periapical radiolucency and its symptoms.

STUDY DESIGN

The periapical status of 896 root canal-treated teeth was evaluated by using digital panoramic radiography. Five prognostic factors were analyzed: length and density of the root filling, presence of crown restoration, probability of unilateral bite, and presence of missing canals.

RESULTS

The prevalence of apical periodontitis among root canal-treated teeth in the study population was 22.8%, and 29.3% of these teeth had received dental treatment for pain relief. Evaluation of the prognostic factors indicated that inadequacy of endodontic treatment was more predictive of apical periodontitis than the absence of a crown restoration.

CONCLUSION

Inadequate root filling length appeared to be the most important prognostic factor related to apical periodontitis and its acute symptoms among root canal-treated teeth.

Susceptibility of strict and facultative anaerobes Isolated from endodontic infections to metronidazole and beta-lactams

Endodontic infections are mixed aerobic-anaerobic infections and several microbial groups associated to these pathologies are also involved in orofacial infections. The goal of this study was to evaluate the susceptibility of microorganisms isolated from endodontic infections to beta-lactams and metronidazole and verify the production of beta-lactamases. Clinical specimens were collected from 58 endodontic infections of 52 patients. The microorganisms were isolated in selective and non-selective culture media, under anaerobiosis and aerobiosis, and identified using biochemical methods. In the susceptibility tests, it was used an agar dilution method, and Wilkins-Chalgren agar enriched with blood, hemin and menadione for the anaerobes, while Mueller-Hinton agar was employed for the facultative anaerobes. The production of beta-lactamases was evaluated through the biological and chromogenic cephalosporin methods. All tested isolates were sensitive to imipenem and 99.3% to amoxicillin/clavulanate association, while 16.1% showed resistance to amoxicillin and penicillin G, and 4.89% to cefoxitin. Resistance to metronidazole was just found in facultative anaerobes. Production of beta-lactamases was detected in 18.2% of the isolates and presented a correlation with resistance to beta-lactams.

[Identification of periodontopathogen microorganisms by PCR technique]

INTRODUCTION

Periodontitis is an inflammatory disease of the supporting tissues of teeth and is a major cause of tooth loss in adults. The onset and progression of periodontal disease is attributed to the presence of elevated levels of a consortium of pathogenic bacteria. Gram negative bacteria, mainly strict anaerobes, play the major role.

OBJECTIVE

The present study aimed to assess the presence of the main types of microorganisms involved in the aetiopathogenesis of periodontal disease: Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Eikenella corrodens, Treponema denticola, Tanerella forsythia and Prevotella intermedia in different samples collected from the oral cavity of 90 patients diagnosed with periodontitis.

METHOD

Bacterial DNA detection was performed in diverse biological materials, namely in dental plaque, gingival tissue and saliva, by means of multiplex PCR, a technique that allows simultaneous identification of two different bacterial genomes.

RESULTS

In the dental plaque of the periodontitis patients, Treponema denticola dominated. In the gingival tissue, Tannerella forsythia and Treponema denticola were the microbiota most frequently detected, whilst in saliva Treponema denticola and Eikenella corrodens were found with the highest percentage.

CONCLUSION

The identification of microorganisms by multiplex PCR is specific and sensitive. Rapid and precise assessment of different types of periodontopathogens is extremely important for early detection of the infection and consequently for the prevention and treatment of periodontal disease. In everyday clinical practice, for routine bacterial evaluation in patients with periodontal disease, the dental plaque is the most suitable biological material, because it is the richest in periodontal bacteria.

PCR-based identification of selected pathogens associated with endodontic infections in deciduous and permanent teeth

OBJECTIVE

The aim of the present study was to evaluate the presence of the selected pathogens in samples from deciduous and permanent tooth root canals by using PCR method and to determine the association of these organisms with clinical symptoms.

STUDY DESIGN

A total of 145 children, 5 to 13 years old, were involved in this study. The presence of selected pathogens (Actinomyces israelii, Candida albicans, Enterococcus faecalis, Fusobacterium nucleatum, Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Streptococcus intermedius, Treponema denticola, Parvimonas micra, Tannerella forsythensis, Enterococcus faecium, Prevotella melaninogenica) in infected root canals was studied using PCR.

RESULTS

T. denticola (P = .012, .02) and E. faecalis (P = .012, .04) were highly associated with periapical radiolucency and previous pain, while P. gingivalis was associated with tenderness to percussion in both deciduous and permanent teeth (P = .01, .015).

CONCLUSION

The results of the present study confirm that certain species of microorganisms are associated with clinical signs and symptoms of endodontic disease in both deciduous and permanent teeth.

Gemella morbillorum in primary and secondary/persistent endodontic infections

OBJECTIVE

To investigate the presence of Gemella morbillorum by culture or nested PCR in primary and secondary/persistent endodontic infections.

STUDY DESIGN

Microbial samples were taken from 50 cases with primary and 50 cases with secondary/persistent endodontic infections. Microbiologic techniques were used for culture and identification. The DNA extracted from the samples was analyzed for the presence of the target species using species-specific primers.

RESULTS

Culture and polymerase chain reaction (PCR) identified the species in 23 and 77, respectively, of 100 root canals. Culture yielded the test organism in 19 of 50 (38%) of root canal samples from primary and in 4 of 50 (8%) from secondary/persistent infections. PCR yielded the test organisms in 41 of 50 (82%) and 36 of 50 (72%) of the, respectively, primary and secondary/persistent root canal infections studied.

CONCLUSION

Gemella morbillorum was identified more frequently in primary endodontic infections than in secondary/persistent ones. A higher frequency of the target species was detected by PCR than by culture.

Doxycycline sustained release from brushite cements for the treatment of periodontal diseases

Doxycycline (DOXY) is a wide spectrum antibiotic used in the treatment of dental, periodontal, and bone infections. Brushite cements are calcium phosphate biomaterials especially interesting for bone regeneration processes. In this work, we describe the preparation of a brushite cement containing DOXY and the drug release from the cement. DOXY solutions were mixed with the cement powder and after a 50% burst release in the first 12 h, a slow and controlled release was achieved over 3.5 days. The release of DOXY hyclate was controlled by both, diffusion and Ca(2+) interaction. Formation of DOXY-Ca(2+) chelates was detected in the cement structure using solid state fluorescence. The brushite cement loaded with DOXY hyclate had antibacterial activity against periodontal pathogens: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides frosthytus. This new biomaterial may be helpful for the treatment of periodontal diseases.

Bacterial examination of endodontic infections by clonal analysis in concert with denaturing high-performance liquid chromatography

BACKGROUND/AIMS

The aim of this study was to examine the diversity of bacterial species in the infected root canals of teeth associated with endodontic abscesses by cloning and sequencing techniques in concert with denaturing high-performance liquid chromatography.

METHODS

Samples collected from five infected root canals were subjected to polymerase chain reaction (PCR) with universal 16S ribosomal DNA primers. Products of these PCRs were cloned and sequenced. Denaturing high-performance liquid chromatography (DHPLC) was used as a screening method to reduce the number of clones necessary for DNA sequencing.

RESULTS

All samples were positive for the presence of bacteria and a range of 7-13 different bacteria were found per root canal sample. In total, 48 different oral clones were detected among the five root canal samples. Olsenella profusa was the only species present in all samples. Porphyromonas gingivalis, Dialister pneumosintes, Dialister invisus, Lachnospiraceae oral clone, Staphylococcus aureus, Pseudoramibacter alactolyticus, Peptostreptococcus micros and Enterococcus faecalis were found in two of the five samples. The majority of the taxa were present in only one sample, for example Tannerella forsythia, Shuttleworthia satelles and Filifactor alocis. Some facultative anaerobes that are frequently isolated from endodontic infections such as E. faecalis, Streptococcus anginosus and Lactobacillus spp. were also found in this study.

CONCLUSION

Clonal analysis of the microflora associated with endodontic infections revealed a wide diversity of oral species.

Susceptibility of oral obligate anaerobes to telithromycin, moxifloxacin and a number of commonly used antibacterials

INTRODUCTION

Obligate anaerobes are closely involved in the pathogenesis of oral and focal infections. The objective of this study was to evaluate the susceptibility profiles of obligate anaerobes of oral origin to telithromycin (TLM), moxifloxacin (MXF), and other antibiotics that are commonly used in dentistry.

METHODS

The study sample comprised 172 obligate anaerobes isolated from the saliva of 43 adult volunteers. The minimum inhibitory concentrations (MICs) were determined by the agar dilution technique in Brucella agar medium supplemented with vitamin K, haemin and 5% (volume/volume) laked sheep blood, and incubated under anaerobic conditions. The Clinical and Laboratory Standards Institute methodology was followed and its criteria were used for the qualitative interpretation of the results. The antibiotics evaluated were: amoxicillin (AMX), amoxicillin-clavulanic acid (AMX-CLA), clindamycin (CM), metronidazole (MTZ), azithromycin (AZM), TLM and MXF.

RESULTS

Resistance to AMX (MIC(90) > or = 16 mg/l) was observed in 45.3% of the obligate anaerobes and resistance to CM (MIC(90) > or = 16 mg/l) was found in 18.6%. All the isolates were sensitive to MTZ (MIC(90) = 1 mg/l) and 98.8% were sensitive to AMX-CLA (MIC(90) = 2 mg/l). The MIC(90) values for AZM, TLM and MXF were > or =16, > or =8 and > or =2 mg/l, respectively.

CONCLUSION

Pathogenic, opportunistic and non-pathogenic obligate anaerobes showed high percentages of resistance to AMX and CM, and high MIC values for AZM in the absence of recently administered antibiotics. MXF showed a higher activity than TLM, similar to that detected for AMX-CLA and MTZ. In consequence, MXF could represent a possible alternative antimicrobial against obligate anaerobes of oral origin, particularly in those patients with allergy, intolerance or lack of response to AMX-CLA or MTZ.

Cultivable bacteria in infected root canals as identified by 16S rRNA gene sequencing

INTRODUCTION

Traditionally, cultivable bacteria isolated from infected root canals have been identified by phenotype-based methods. Because 16S ribosomal RNA (rRNA) gene sequencing has emerged as a more accurate and reliable tool for bacterial identification, the present study applied this approach to identify bacterial isolates recovered from the root canals of teeth with chronic apical periodontitis.

METHODS

Anaerobic techniques were used for culturing; identification of the isolates was carried out by polymerase chain reaction amplification and sequencing of the V5-V8 region of the 16S rRNA gene. Bacteria were found in all samples. The mean number of taxa per canal was 3.1, ranging from 2 to 8. The median number of cultivable bacterial cells in the root canals was 4.2 x 10(5), ranging from 2.8 x 10(3) to 3.3 x 10(7). Eighty-seven strains belonging to 52 bacterial taxa were identified. The most prevalent taxa were Fusobacterium nucleatum, Porphyromonas gingivalis, Pseudoramibacter alactolyticus, Micromonas micros and streptococci. The following bacterial phyla were represented in this study: Firmicutes (22 taxa, 46% of the identified isolates), Actinobacteria (14 taxa, 25.3% of the isolates), Bacteroidetes (eight taxa, 13.8% of the isolates), Fusobacteria (three taxa, 9.2% of the isolates) and Proteobacteria (five taxa, 5.7% of the isolates). Some of the isolates represented unnamed species not previously cultivated and characterized. In conclusion, our findings using a combined anaerobic culture-molecular identification approach confirmed the polymicrobial nature of primary endodontic infections with dominance of anaerobic bacteria. Notably several bacteria that are difficult or impossible to identify by phenotypic means were identified, including previously uncultivated taxa, cultivated-but-not-yet-characterized taxa and newly named species.

Phylogenetic analysis of bacterial and archaeal species in symptomatic and asymptomatic endodontic infections

Phylogenetic analysis of bacterial and archaeal 16S rRNA was used to examine polymicrobial communities within infected root canals of 20 symptomatic and 14 asymptomatic patients. Nucleotide sequences from approximately 750 clones amplified from each patient group with universal bacterial primers were matched to the Ribosomal Database Project II database. Phylotypes from 37 genera representing Actinobacteria, Bacteroidetes, Firmicutes, Fusobacteria and Proteobacteria were identified. Results were compared to those obtained with species-specific primers designed to detect Prevotella intermedia, Porphyromonas gingivalis, Porphyromonas endodontalis, Peptostreptococcus micros, Enterococcus sp., Streptococcus sp., Fusobacterium nucleatum, Tannerella forsythensis and Treponema denticola. Since members of the domain Archaea have been implicated in the severity of periodontal disease, and a recent report confirms that archaea are present in endodontic infections, 16S archaeal primers were also used to detect which patients carried these prokaryotes, to determine if their presence correlated with severity of the clinical symptoms. A Methanobrevibacter oralis-like species was detected in one asymptomatic and one symptomatic patient. DNA from root canals of these two patients was further analysed using species-specific primers to determine bacterial cohabitants. Trep. denticola was detected in the asymptomatic but not the symptomatic patient. Conversely, Porph. endodontalis was found in the symptomatic but not the asymptomatic patient. All other species except enterococci were detected with the species-specific primers in both patients. These results confirm the presence of archaea in root canals and provide additional insights into the polymicrobial communities in endodontic infections associated with clinical symptoms.

Incidence and behaviour of Tn916-like elements within tetracycline-resistant bacteria isolated from root canals

INTRODUCTION

Tetracycline resistance is commonly found in endodontic bacteria. One of the most common tetracycline-resistance genes is tet(M), which is often encoded on the broad-host-range conjugative transposon Tn916. This study aimed to determine whether tet(M) was present in bacteria isolated from endodontic patients at the Eastman Dental Institute and whether this gene was carried on the transferable conjugative transposon Tn916.

METHODS

The cultivable microflora isolated from 15 endodontic patients was screened for resistance to tetracycline. Polymerase chain reactions for tet(M) and for unique regions of Tn916 were carried out on the DNA of all tetracycline-resistant bacteria. Filter-mating experiments were used to see if transfer of any Tn916-like elements could occur.

RESULTS

Eight out of 15 tetracycline-resistant bacteria isolated were shown to possess tet(M). Furthermore, four of these eight were shown to possess the Tn916-unique regions linked to the tet(M) gene. Transfer experiments demonstrated that a Neisseria sp. donor could transfer an extremely unstable Tn916-like element to Enterococcus faecalis.

CONCLUSIONS

The tet(M) gene is present in the majority of tetracycline-resistant bacteria isolated in this study and the conjugative transposon Tn916 has been shown to be responsible for the support and transfer of this gene in some of the bacteria isolated.

Molecular analysis of Filifactor alocis, Tannerella forsythia, and treponema denticola associated with primary endodontic infections and failed endodontic treatment

The aim of this study was to investigate the presence of strict anaerobes such as Filifactor alocis, Tannerella forsythia, and Treponema denticola in primary and secondary root-infected canals with periapical lesions by molecular analysis and the association of these species with specific endodontic signs and symptoms. Microbial samples were taken from 100 root canals, 50 with necrotic pulp tissues (NPT, primary infection), and 50 with failed endodontic treatment (FET, secondary infection). DNA was extracted from the samples, which were analyzed for the presence of three endodontic pathogens using species-specific primers and PCR. F. alocis were isolated from 23 canals with NPT and 12 canals with FET; T. forsythia from 12 canals with NPT and three canals with FET; T. denticola from 19 canals with NPT and 12 canals with TEP. Suggested associations were found between primary infection and the presence of F. alocis and T. forsythia (both p < 0.05). In particular, associations were found between: pain and F. alocis; swelling and F. alocis; tenderness to percussion and T. forsythia; mobility and T. forsythia and T. denticola; wet canals and F. alocis, T. forsythia, and T. denticola; purulent exsudate and F. alocis, T. forsythia and T. denticola; abscess and F. alocis, T. forsythia, and T. denticola (all p < 0.05). The findings of this study indicated that F. alocis, T. forsythia, and T. denticola seem to be associated with endodontic signs and symptoms. Additionally, F. alocis and T. forsythia were detected more frequently in teeth with necrotic pulp than in teeth with failing endodontic treatment.

Incidence and antimicrobial susceptibility of Porphyromonas gingivalis isolated from mixed endodontic infections

AIM

To investigate the prevalence of Porphyromonas gingivalis in root canals of infected teeth with periapical abscesses and to investigate the antimicrobial susceptibility of this species to some frequently prescribed antibiotics.

METHODOLOGY

Samples were obtained from 70 root canals of abscessed teeth. Microbial sampling, isolation and bacterial identification were accomplished using appropriate culture methods for anaerobic species. The antimicrobial susceptibility of the 20 strains of P. gingivalis isolated was determined by using the E-test. The antimicrobial agents tested were amoxicillin, amoxicillin + clavulanate, azythromycin, benzylpenicillin, cephaclor, clindamycin, erythromycin, metronidazole and tetracycline.

RESULTS

A total of 352 individual strains, belonging to 69 different species, were isolated. Eighty three percent of the strains were strict anaerobes and 47.5% of the isolated bacteria were Gram-negative. Porphyromonas gingivalis was found in 20 root canals and was most frequently found in symptomatic cases. Statistically, the presence of P. gingivalis was related to purulent exudates and pain on palpation (both P < 0.05). All P. gingivalis strains were sensitive to amoxicillin, amoxicillin + clavulanate, cephaclor, clindamycin, benzylpenicyllin, metronidazole and tetracycline. The lowest range of minimum inhibitory concentration (MIC) (0.026-0.125 microg mL(-1)) was observed against amoxicillin + clavulanate and clindamycin. The lowest MIC 90 was observed against clindamycin (0.064 microg mL(-1)). One strain was resistant to erythromycin and eight strains were resistant to azythromycin.

CONCLUSION

Porphyromonas gingivalis pathogen is isolated with frequency from root canals of infected teeth with periapical abscesses. Amoxicillin, as well as amoxicillin-clavulanic acid and benzylpenicillin were effective against P. gingivalis.

Clinical and microbiological characterization of periodontal abscesses

BACKGROUND/AIM

The knowledge of clinical features, microbial composition and susceptibility to antimicrobials of periodontal abscesses has recently improved. This descriptive clinical and microbiological study provides more information on the characteristics of periodontal abscesses.

MATERIALS AND METHODS

Clinical parameters and subgingival samples were examined from 54 subjects presenting 60 periodontal abscesses. Samples were cultured for anaerobic and facultative bacteria, and data were expressed as frequency detection and mean proportion of isolation for microorganisms. Selected isolates of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia/nigrescens were used to test susceptibility to amoxicillin, azithromycin, tetracycline and metronidazole. Statistical descriptive analysis was conducted.

RESULTS

Most periodontal abscesses were present in patients with ongoing Chronic Periodontitis. Bleeding on probing, tumefaction and suppuration were present in almost all abscesses. Affected teeth were lower anterior teeth, upper anterior teeth and lower molars. The subgingival microbiota was composed of periodontal pathogens such as Fusobacterium spp. (75%), P. intermedia/nigrescens (60%), P. gingivalis (51%) and A. actinomycetemcomitans (30%). Some periodontopathogens showed antimicrobial resistance to tetracycline, metronidazole and amoxicillin, but not to azithromycin.

CONCLUSIONS

Periodontal abscesses showed typical clinical features associated with untreated periodontitis, and the organisms identified were important periodontopathic bacteria. Rationale use of antibiotic adjunctive therapy in abscess treatment should be taken into account.

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

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.

Detection of bacteria in endodontic samples by polymerase chain reaction assays and association with defined clinical signs in Italian patients

BACKGROUND/AIMS

The presence of selected bacteria (Enterococcus faecalis, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, Treponema denticola) in infected root canals was studied using polymerase chain reaction (PCR) assays, and the association of bacteria with clinical signs of endodontic disease was assessed. The null hypothesis, that no difference could be observed between clinical signs of apical periodontitis and a specific bacterial strain, was tested.

METHODS

Microbial samples were obtained from 62 teeth in 54 patients with endodontic disease. For each tooth, clinical data including patient symptoms were collected. Teeth were categorized by diagnosis as having acute apical periodontitis (AAP, teeth with clinical symptoms but no periapical radiolucency, n=22), chronic apical periodontitis (CAP, teeth with radiolucency but no clinical symptoms, n=15) or exacerbated apical periodontitis (EAP, teeth with symptoms and radiolucency, n=25). Seventy-one percent of cases were primary endodontic infections, and 29% were recurrent ('secondary') endodontic infections (failing cases). PCR assays were used to detect the presence of the selected bacteria.

RESULTS

T. denticola and E. faecalis were each detected in 15 of 62 samples (24%), P. gingivalis in 8 samples (13%), P. intermedia in 5 samples (8%), and T. forsythensis in 4 samples (7%). T. denticola was detected in 56% of teeth with EAP. E. faecalis was found in 60% of teeth with CAP and in 72% of teeth with secondary infection. Statistical analysis demonstrated an association of CAP and secondary endodontic infection with the presence of E. faecalis. (P<0.01). EAP was associated with the presence of T. denticola (P<0.01).

CONCLUSION

T. denticola was associated with symptomatic endodontic disease in the presence of apical bone resorption. E. faecalis was associated with treatment failures. We suggest that these species may play critical roles in endodontic pathology.

Quantification of endotoxins in necrotic root canals from symptomatic and asymptomatic teeth

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.

Microarrays complement culture methods for identification of bacteria in endodontic infections

The aim of this study was to investigate the microbial composition of necrotic root canals using culture methods and microarray technology. Twenty uniradicular teeth with radiographic evidence of periapical bone loss and with no previous endodontic treatment were selected for this study. For molecular diagnosis a DNA chip with 20 different species-specific, 16S-rDNA-directed catcher probes was used. The microorganisms most frequently detected by the DNA chip were: Micromonas micros, Fusobacterium nucleatum ssp., Tannerella forsythia, Treponema denticola, Veillonella parvula, Eubacterium nodatum, Porphyromonas gingivalis, Actinomyces odontolyticus, and Streptococcus constellatus. As expected, additional important bacterial taxa were found by culture analysis, but microorganisms such as T. forsythia and T. denticola could not be identified. In conclusion, microarrays may provide significant additional information regarding the endodontic microbiota by detecting bacterial species that are otherwise difficult or impossible to culture.

Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia and Prevotella nigrescens in endodontic lesions detected by culture and by PCR

he aim of this study was to investigate the presence of four black-pigmented bacteria, Porphyromonas gingivalis, Porphyromonas endodontalis, Prevotella intermedia and Prevotella nigrescens, in endodontic infections by culture and polymerase chain reaction (PCR) analyses. Microbial samples were obtained from 50 teeth with untreated necrotic pulps (primary infection) and from 50 teeth with failing endodontic treatment (secondary infection). Microbiological strict anaerobic techniques were used for serial dilution, plating, incubation, and identification. For PCR detection, the samples were analyzed using species-specific primers of 16S rDNA and the downstream intergenic spacer region. Culture and PCR detected the test species in 13/100 and 50/100 of the study teeth, respectively. The organisms were cultured from 11/50 (22%) of primarily infected root canal samples and from 2/50 (4%) of secondary root canal samples. PCR detection identified the target species in 32/50 (64%) and 18/50 (36%) of primary and secondary infections, respectively. P. gingivalis was rarely isolated by culture methods (1%), but was the most frequently identified test species by PCR (38%). Similarly, P. endodontalis was not recovered by culture from any tooth studied, but was detected by PCR in 25% of the sampled teeth. PCR-based identification also showed higher detection rates of P. intermedia (33%) and P. nigrescens (22%) than culture (13%). In conclusion, P. gingivalis, P. endodontalis, P. intermedia, and P. nigrescens were identified more frequently in teeth with necrotic pulp than in teeth with failing endodontic treatment. Also, a higher frequency of black-pigmented species was detected by PCR than by culture.

Identification of Cultivable Microorganisms from Primary Endodontic Infections with Exposed and Unexposed Pulp Space

This study was aimed at comparing the cultivable microorganisms in canals with periapical radiolucencies with exposed and unexposed pulp space. Microbiological samples were taken and analyzed from 45 canals with exposed pulp space, and 43 canals with unexposed pulp space. The canal contents were analyzed by aerobic/anaerobic culture, and conventional identification techniques. There were 211 isolates of bacteria belonging to 28 genera and 55 species recovered from exposed canals. In the unexposed group, 185 isolates of bacteria were recovered, of which 54 species of 28 genera were identified. Among the four most common genera, Prevotella was significantly more common in the exposed group (51/211 in the exposed group versus 30/185 in the unexposed group) (p = 0.049), while there were no differences in prevalence of Actinomyces, Peptostreptococcus, and Campylobacter between two groups of canals. In addition, Fusobacterium nucleatum and Propionibacterium acne were significantly more common in the unexposed canals (p = 0.047 and p = 0.0051, respectively). Similarity in bacterial species in these two groups suggests that pulp space exposure may not be a significant factor in determining the type of bacteria present in infected canals.

Microbiological examination of infected dental root canals

OBJECTIVES

The aim of this study was to investigate the root canal microbiota of primary and secondary root-infected canals and the association of constituent species with specific endodontic signs and symptoms.

METHODS

Microbial samples were taken from 60 root canals, 41 with necrotic pulp tissues (primary infection) and 19 with failed endodontic treatment (secondary infection). Strict anaerobic techniques were used for serial dilution, plating, incubation and identification.

RESULTS

A total of 224 cultivable isolates were recovered belonging to 56 different bacterial species. Individual root canals yielded a maximum of 10 bacterial species. Of the bacterial isolates, 70% were either strict anaerobes or microphilic. The anaerobes most frequently isolated were: Peptostreptococcus micros (35%), Fusobacterium necrophorum (23.3%), Fusobacterium nucleatum (11.7%), Prevotella intermedia/nigrescens (16.7%), Porphyromonas gingivalis (6.7%) and Porphyromonas endodontalis (5%). The root canal microflora of untreated teeth with apical periodontitis was found to be mixed, comprising gram-negative and gram-positive and mostly anaerobic microorganisms and usually containing more than 3 species per canal. On the other hand, facultative anaerobic and gram-positive bacteria predominated in canals with failed endodontic treatment, which harbored 1-2 species per canal. Suggested relationships were found between anaerobes, especially gram-negatives, and the presence or history of pain, tenderness to percussion and swelling (P<0.05). In particular, associations were found between: a) pain (n=29) and P. micros (P<0.01), P. intermedia/nigrescens and Eubacterium spp. (both P<0.05); b) history of pain (n=31) and P. micros (P<0.01) Porphyromonas and Fusobacterium spp. (P<0.05); c) tenderness to percussion (n=29) and Porphyromonas spp. (P<0.01), Peptostreptococcus and Fusobacterium spp. (P<0.001); d) swelling (n=20) and Peptostreptococcus spp. (P<0.01), Porphyromonas and Enterococcus spp. (P<0.05); e) wet canals (n=33) and Porphyromonas and Fusobacterium spp. (P<0.05); f) purulent exudate (n=20) and Porphyromonas, Peptostreptococcus and Fusobacterium spp. (P<0.05); previous endodontic treatment and Enterococcus faecalis, Streptococcus spp., P. micros, F. necrophorum (P<0.05).

CONCLUSIONS

Our findings indicate potential complex interactions of species resulting in characteristic clinical pictures which cannot be achieved by individual species alone. They also indicate that the microbiota of primary infected canals with apical periodontitis differs in number and in species from the secondary infected canals by using the culture technique.