Bacteria isolated after unsuccessful endodontic treatment in a North American population

Enterococcus faecalis lipoteichoic acid suppresses Aggregatibacter actinomycetemcomitans lipopolysaccharide-induced IL-8 expression in human periodontal ligament cells

Periodontitis is caused by multi-bacterial infection and Aggregatibacter actinomycetemcomitans and Enterococcus faecalis are closely associated with inflammatory periodontal diseases. Although lipopolysaccharide (LPS) of A. actinomycetemcomitans (Aa.LPS) and lipoteichoic acid of E. faecalis (Ef.LTA) are considered to be major virulence factors evoking inflammatory responses, their combinatorial effect on the induction of chemokines has not been investigated. In this study, we investigated the interaction between Aa.LPS and Ef.LTA on IL-8 expression in human periodontal ligament (PDL) cells. Aa.LPS, but not Ef.LTA, substantially induced IL-8 expression at the protein and mRNA levels. Interestingly, Ef.LTA suppressed Aa.LPS-induced IL-8 expression without affecting the binding of Aa.LPS to Toll-like receptor (TLR) 4. Ef.LTA reduced Aa.LPS-induced phosphorylation of mitogen-activated protein kinases, including ERK, JNK and p38 kinase. Furthermore, Ef.LTA inhibited the Aa.LPS-induced transcriptional activities of the activating protein 1, CCAAT/enhancer-binding protein and nuclear factor-kappa B transcription factors, all of which are known to regulate IL-8 gene expression. Ef.LTA augmented the expression of IL-1 receptor-associated kinase-M (IRAK-M), a negative regulator of TLR intracellular signaling pathways, in the presence of Aa.LPS at both the mRNA and protein levels. Small interfering RNA silencing IRAK-M reversed the attenuation of Aa.LPS-induced IL-8 expression by Ef.LTA. Collectively, these results suggest that Ef.LTA down-regulates Aa.LPS-induced IL-8 expression in human PDL cells through up-regulation of the negative regulator IRAK-M.

Evaluation of minimal inhibitory concentration of two new materials using tube dilution method: An in vitro study

Aim:

The aim of the study is to evaluate and compare the antimicrobial efficacy of two new materials MTA Plus and Biodentine with ProRoot MTA using tube dilution method.

Materials and Methods:

The materials used were ProRoot MTA (Dentsply), MTA Plus (compounded by Prevest Denpro, Jammu, India for Avalon Biomed Inc, USA) and a calcium silicate based material Biodentine (Septodont, Saint-Maur-des-Fosses, France). Doubling dilutions of the material were prepared in Sabouraud's dextrose broth (SDB) and Brain Heart Infusion (BHI) broth for Candida albicans and Enterococcus faecalis, respectively. The minimal concentration at which inhibition of microorganism occurred was measured and noted as minimal inhibitory concentration (MIC) of the material.

Results:

There was no statistically significant difference between the materials against C. albicans. Biodentine was statistically significant than MTA Plus against E. faecalis (P-value-0.022). ProRoot MTA was statistically significant at different time intervals against E. faecalis (P-value-0.001).

Conclusion:

ProRoot MTA and Biodentine proved to have antimicrobial property. MTA Plusproved as a good antifungal agent.

Ultrasonic activation and chemical modification of photosensitizers enhances the effects of photodynamic therapy against Enterococcus faecalis root-canal isolates

BACKGROUND

The aim of this study was to evaluate the effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilms in artificially infected root canals using modified photosensitizers and passive ultrasonic activation.

METHODS

Two hundred and seventy extracted human teeth with one root canal were instrumented utilizing ProTaper files, autoclaved, infected with E. faecalis T9 for 72 h and divided into different groups: irrigation with 3% sodium hypochlorite (NaOCl), 20% ethylenediaminetetraacetic acid (EDTA), or 20% citric acid, PDT without irrigation, PDT accompanied by irrigation with NaOCl, EDTA, or citric acid, PDT using an EDTA-based photosensitizer or a citric-acid-based photosensitizer and PDT with ultrasonic activation of the photosensitizer. A 15 mg/ml toluidine blue served as the photosensitizer, activated by a 100 mW LED light source. Sterile paper points were used for sampling the root canals and dentin chips were collected to assess the remaining contamination after treatment. Samples were cultured on blood agar plates and colony forming units were quantified.

RESULTS

PDT alone achieved a reduction in E. faecalis counts by 92.7%, NaOCl irrigation alone and combined with PDT by 99.9%. The antibacterial effects increased by the combination of irrigation using EDTA or citric acid and PDT compared to irrigation alone. More than 99% of E. faecalis were killed using PDT with the modified photosensitizers and ultrasonic activation.

CONCLUSIONS

NaOCl based disinfection achieved the highest antimicrobial effect. Using PDT with an EDTA-based or citric-acid-based phozosensitizer or activating the photosensitizer with ultrasound resulted in a significantly higher reduction in E. faecalis counts compared to conventional PDT.

Effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilm in experimental primary and secondary endodontic infections

BACKGROUND

To determine the antibacterial effect of photodynamic Therapy on Enterococcus faecalis (E. faecalis) biofilms in experimentally infected human root canals in primary infections and endodontic retreatments.

METHODS

One hundred and sixty single-rooted extracted teeth with one root canal were prepared using ProTaper instruments. Seventy specimens were left without root canal filling and autoclaved. The root canals of another 70 specimens were filled with Thermafil and AH Plus and the root canal fillings were removed after 24 hours using ProTaper D files and plasma sterilized. The specimens were infected with a clinical isolate of E. faecalis for 72 hours. Samples were taken using sterile paper points to determine the presence of E. faecalis in the root canals. The specimens were randomly divided into groups according to their treatment with 20 teeth each and a control. In the PDT group the teeth were treated using PDT, consisting of the photosensitizer toluidine blue and the PDT light source at 635 nm. In the NaOCl (sodium hypochlorite) group the root canals were rinsed with 10 mL of 3% NaOCl. In the NaOCl-PDT group the root canals were rinsed with 10 mL of 3% of sodium hypochlorite and then treated with PDT. Samples were taken after treatments using sterile paper points. Additionally, remaining root canal filling material was recovered from the root canal walls. Survival fractions of the samples were calculated by counting colony-forming units. A one-way analysis of variance (ANOVA) was applied to the data to assess the effect of different treatment techniques.

RESULTS

Antimicrobial treatment of root canals caused a significant reduction of bacterial load in all groups. NaOCl irrigation eliminated E. faecalis most effectively. PDT alone was less effective compared to NaOCl irrigation and the combination of NaOCl irrigation and PDT. CFU levels recovered from the filling material after NaOCl irrigation of the root canals were 10fold higher compared to PDT and the combination of NaOCl irrigation and PDT.

CONCLUSIONS

Photodynamic therapy killed E. faecalis in experimental primary endodontic infections and retreated human root canals. PDT is an effective supplement in root canal disinfection, especially in endodontic retreatments.

In vitro activity of Amazon plant extracts against Enterococcus faecalis

Previous studies analyzing 2,200 plant extracts indicated anti-enterococcal activity in 25 extracts obtained from Brazilian forests’ plants. In the present study, these extracts were subjected to microdilution broth assay (MDBA) and disk diffusion assay (DDA) using planktonic Enterococcus faecalis ATCC^® 29212™ and were submitted to phytochemical analysis in TLC and HPLC. Three extracts obtained from Ipomoea alba (MIC < 40 μg/mL), Diclinanona calycina (MIC ≤ 40 μg/mL) and Moronobea coccinea (40 < MIC < 80 μg/mL; MBC = 80 μg/mL) showed significant bactericidal activity in the MDBA and four extracts obtained from I. alba (14.04 ± 0.55 mm diameter) S. globulifera (14.43 ± 0.33 mm and 12.18 ± 0.28 mm diameter) and Connarus ruber var. ruber (13.13 ± 0.18 mm diameter) were active in DDA. Residues H₂O obtained from Psidium densicomum (mean of 16.78 mm diameter) and from Stryphnodendron pulcherrimum (mean of 15.97 mm diameter) have shown an improved antibacterial activity after fractionation if compared to that obtained from the respective crude extracts. Antioxidant activity was observed in some residues of the active extracts. TLC analysis showed that phenolic compounds are likely to be found in active extracts. Three molecules were isolated from S. globulifera and were identified by ¹³C NMR lupeol, α-amyrin and 3β-hydroxyglutin-5-ene. The present chemical and biological findings suggest that these extracts are a potential source of new anti-Enterococcus compounds to be introduced in endodontic therapy.

Cytotoxicity evaluation of Iranian propolis and calcium hydroxide on dental pulp fibroblasts

Background and aims. Since intracanal medicaments can affect the cell viability in periapical tissues, the aim of this study was to evaluate the effect of calcium hydroxide and propolis on pulp fibroblasts.

Materials and methods. Two healthy third molars were used as a source to obtain fibroblasts. The fibroblasts were cultured and subjected to 1 mg/mL of propolis and calcium hydroxide. This experiment was performed in six replicates and cell viability was evaluated with MTT assay. Statistical analysis was performed by t-test.

Results. Comparison of cell viability with the use of 1 mg/mL of calcium hydroxide and propolis showed that cells subjected to propolis were more viable when compared to calcium hydroxide (P < 0.05).

Conclusion. In this study, calcium hydroxide reduced fibroblast viability, significantly more than Iranian propolis. Other properties should be evaluated before Iranian propolis could be indicated for use as intracanal medicament.

Survey of root canal irrigating solutions used in dental practices within Germany

AIM

Irrigant usage information in relation to years of professional experience was collected from general dentists in different German federal states by means of a questionnaire.

METHODOLOGY

A short survey concerning endodontic treatment and use of irrigants was mailed to 4240 dentists or delivered to 3720 dental offices as an extra page in a journal in eight German states. Detailed information concerning the most frequently used irrigants, their concentrations, the spectrum of disinfectants used in root canal treatment concepts for vital and nonvital pulps, main topics of continuing education as well as years of professional experience was collected. The statistical analysis of differences found amongst the dentists in relation to professional experience or federal state was performed using the chi-square test.

RESULTS

Of a total of 7960 invitations, 1630 replies were evaluated (response rate 20.5%). The majority of the dentists (57.3%) had >20 years of professional experience, 23% had >30 years. Dentists with long-standing professional experience (20-30 years) used H2 O2 significantly more often than dentists with less experience (P < 0.001), and of the older colleagues (>30 years of professional experience), 14.6% never used NaOCl, whilst the younger colleagues almost always used it (P < 0.001). Differences were also found for the usage of irrigants amongst dentists from the various German states.

CONCLUSIONS

Whilst NaOCl was used in almost all states, regional differences were found regarding the choice of additional irrigants, which were mainly determined by the irrigation protocols taught at different universities.

Quantitative and qualitative analysis of microorganisms in root-filled teeth with persistent infection: Monitoring of the endodontic retreatment

Objective:

The aim of this study was to investigate in vivo microorganisms detected in root-filled teeth with post-treatment apical periodontitis and quantify colony-forming units (CFU) during endodontic retreatment.

Materials and Methods:

Fifteen root-filled teeth had their previous gutta-percha removed and were randomly instrumented before being divided into three groups and medicated with either [Ca(OH)₂ + 2% CHX gel], [Ca(OH)₂ + 0.9% NaCl] or 2% CHX gel. Samples were taken after removal of gutta-percha (S1), after chemomechanical preparation using 2% CHX gel (S2), and after inter-appointment dressing (S3) for 7 or 14 days later. Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of culture and PCR assay (16S rDNA). Quantitative data were statistically analyzed by using Mann-Whitney test in which pairs of groups were compared (P < 0.05).

Results:

CFU counts decreased significantly from S1 to S2 (P < 0.05). No significant difference was found between S2 and S3 (P = 0.3093) for all three experimental groups. Chemomechanical preparation and intra-canal dressing promoted significant median reductions of 99.61% and 99.57%, respectively, in the number of bacteria compared to S1 samples. A total of 110 cultivable isolates were recovered by culture technique from 32 different species and 7 different genera. Out of the 13 target species-specific primer of bacteria analyzed, 11 were detected during endodontic retreatment.

Conclusion:

The great majority of taxa found in post-treatment samples were Gram-positive bacteria, although Gram-negative bacteria were found by molecular methods. Moreover, our results showed that gutta-percha removal and chemomechanical preparation are effective for root canal disinfection, whereas additional intra-canal dressing did not improve disinfection.

Bactericidal effect of hydroxyl radicals generated from a low concentration hydrogen peroxide with ultrasound in endodontic treatment

One approach to enhance the disinfection of root canals in endodontic treatment is ultrasonic irrigation with sodium hypochlorite. Reactive oxygen species, such as hydroxyl radical, are generated by biological defense systems to kill invading bacteria. Ultrasonic irrigation with hydrogen peroxide may be a promising option to increase hydroxyl radical generation. We examined the bactericidal effects of hydroxyl radical generated from low concentration hydrogen peroxide with ultrasound in vitro. An ultrasonic tip was submerged in 0.5 or 1.0 M hydrogen peroxide in a microfuge tube. hydrogen peroxide was irradiated with the ultrasound, the tip of which was maintained centered in the tube to mimic ultrasonic irrigation. Hydroxyl radical generation was assessed by electron spin resonance spectroscopy. Subsequently, Enterococcus faecalis suspension in hydrogen peroxide was prepared and irradiated as described above. Bactericidal effects were assessed by viable counting. Electron spin resonance measurements showed that hydroxyl radical generation increased significantly in a time- and dose-dependent manner (two-way analysis of variance and Tukey's test, p<0.05). Moreover, the bactericidal effects of hydrogen peroxide against Enterococcus faecalis were enhanced by ultrasonic irradiation in a time- and dose-dependent manner. These results suggest that ultrasonic irrigation in the presence of low concentration hydrogen peroxide can serve as a disinfection strategy in endodontic treatment.

Photoactivated rose bengal functionalized chitosan nanoparticles produce antibacterial/biofilm activity and stabilize dentin-collagen

Treatment of infected teeth presents two major challenges: persistence of the bacterial-biofilm within root canals after treatment and compromised structural integrity of the dentin hard-tissue. In this study bioactive polymeric chitosan nanoparticles functionalized with rose-bengal, CSRBnp were developed to produce antibiofilm effects as well as stabilize structural-integrity by photocrosslinking dentin-collagen. CSRBnp were less toxic to fibroblasts and had significant antibacterial activity even in the presence of bovine serum albumin. CSRBnp exerted antibacterial mechanism by adhering to bacterial cell surface, permeabilizing the membrane and lysing the cells subsequent to photodynamic treatment. Photoactivated CSRBnp resulted in reduced viability of Enterococcus faecalis biofilms and disruption of biofilm structure. Incorporation of CSRBnp and photocrosslinking significantly improved resistance to degradation and mechanical strength of dentin-collagen (P<0.05). The functionalized chitosan nanoparticles provided a single-step treatment of infected root dentin by combining the properties of chitosan and that of photosensitizer to eliminate bacterial-biofilms and stabilize dentin-matrix.

FROM THE CLINICAL EDITOR

In this study, bioactive polymeric chitosan nanoparticles functionalized with rose-bengal (a photosensitizer), CSRBnp were developed to produce antibiofilm effects as well as stabilize structural-integrity of dental root dentin by photocrosslinking dentin-collagen, leading to efficient elimination of bacterial-biofilms and stabilization of dentin-matrix.

Preservation of Fusobacterium nucleatum and Peptostreptococcus anaerobius DNA after loss of cell viability

AIM

To investigate whether DNA from two obligate anaerobes, Fusobacterium nucleatum and Peptostreptococcus anaerobius, is recoverable after loss of cell viability induced by air exposure.

METHODOLOGY

Harvested cultures of F. nucleatum and P. anaerobius were killed by exposure to air and stored in phosphate-buffered saline. Dead cells were incubated aerobically for up to 6 months. Every month, the presence of detectable DNA in the cell pellet and supernatant was assessed by conventional and quantitative PCR. Cell staining techniques were used to characterize the cell wall permeability of air-killed cells. Scanning electron microscopy was used to examine viable, freshly killed and stored cells.

RESULTS

With conventional PCR, amplifiable DNA was detectable over 6 months in all samples. Quantitative PCR showed a progressive fall in DNA concentration in nonviable cell pellets and a concomitant rise in DNA concentration in the supernatant. DNA staining showed that some air-killed cells retained an intact cell wall. After storage, SEM of both air-killed species revealed shrivelling of the cells, but some cells of P. anaerobius retained their initial form.

CONCLUSION

Amplifiable DNA from F. nucleatum and P. anaerobius was detectable 6 months after loss of viability. Air-killed anaerobes initially retained their cell form, but cells gradually shriveled over time. The morphological changes were more pronounced with the gram-negative F. nucleatum than the gram-positive P. anaerobius. Over 6 months, there was a gradual increase in cell wall permeability with progressive leakage of DNA. Bacterial DNA was recoverable long after loss of cell viability.

Comparison of the Antifungal Efficacy of 1.3% NaOCl/MTAD with Other Routine Irrigants: An Ex-Vivo Study

Objectives. To evaluate and compare the antifungal efficacy of 1.3% NaOCl/MTAD with 2.5% sodium hypochlorite (NaOCl), 2% chlorhexidine gluconate (CHX), and iodine potassium iodide (IKI). Materials and Methods. Fifty-two single rooted teeth were used which were divided into four groups with 10 teeth in each group: 2.5% NaOCl, 2% CHX, IKI, 1.3% NaOCl/MTAD, and physiologic saline. Two teeth served as negative controls and were placed in fresh brain-heart infusion broth (BHI) after autoclaving. The teeth were inoculated and incubated with Candida albicans after which the teeth were instrumented and irrigated with the test irrigants. The first microbial sampling was then performed and colony forming unit/mL (cfu/mL) was counted. The second microbial sampling was performed 1 week after instrumentation and irrigation. Results. The test irrigants were effective against C. albicans in both the first and second microbial samplings. When the irrigants were compared, there was no statistical difference in their activity in the 1st and 2nd microbial sampling. On comparison of the change in mean cfu/mL between the 1st and 2nd microbial samplings, the antifungal activity of the test irrigants was in the order 2.5% NaOCl > 2% CHX > 1.3% NaOCl/MTAD > IKI.

Comparison of the bacterial composition and structure in symptomatic and asymptomatic endodontic infections associated with root-filled teeth using pyrosequencing

Residual microorganisms and/or re-infections are a major cause for root canal therapy failure. Understanding of the bacterial content could improve treatment protocols. Fifty samples from 25 symptomatic and 25 asymptomatic previously root-filled teeth were collected from Sudanese patients with periradicular lesions. Amplified 16S rRNA gene (V1-V2) variable regions were subjected to pyrosequencing (FLX 454) to determine the bacterial profile. Obtained quality-controlled sequences from forty samples were classified into 741 operational taxonomic units (OTUs) at 3% dissimilarity, 525 at 5% dissimilarity and 297 at 10% dissimilarity, approximately corresponding to species-, genus- and class levels. The most abundant phyla were: Firmicutes (29.9%), Proteobacteria (26.1%), Actinobacteria (22.72%), Bacteroidetes (13.31%) and Fusobacteria (4.55%). Symptomatic patients had more Firmicutes and Fusobacteria than asymptomatic patients, while asymptomatic patients showed more Proteobacteria and Actinobacteria. Interaction of disease status and age was observed by two-way ANOSIM. Canonical correspondence analysis for age, tooth restoration and disease status showed a correlation of disease status with the composition and prevalence of different members of the microbial community. The pyrosequencing analysis revealed a distinctly higher diversity of the microbiota compared to earlier reports. The comparison of symptomatic and asymptomatic patients showed a clear association of the composition of the bacterial community with the presence and absence of symptoms in conjunction with the patients’ age.

Rapid kill-novel endodontic sealer and Enterococcus faecalis

With growing concern over bacterial resistance, the identification of new antimicrobial means is paramount. In the oral cavity microorganisms are essential to the development of periradicular diseases and are the major causative factors associated with endodontic treatment failure. As quaternary ammonium compounds have the ability to kill a wide array of bacteria through electrostatic interactions with multiple anionic targets on the bacterial surface, it is likely that they can overcome bacterial resistance. Melding these ideas, we investigated the potency of a novel endodontic sealer in limiting Enterococcus faecalis growth. We used a polyethyleneimine scaffold to synthesize nano-sized particles, optimized for incorporation into an epoxy-based endodontic sealer. The novel endodontic sealer was tested for its antimicrobial efficacy and evaluated for biocompatibility and physical eligibility. Our results show that the novel sealer foundation affixes the nanoparticles, achieving surface bactericidal properties, but at the same time impeding nanoparticle penetration into eukaryotic cells and thereby mitigating a possible toxic effect. Moreover, adequate physical properties are maintained. The nanosized quaternary amine particles interact within minutes with bacteria, triggering cell death across wide pH values. Throughout this study we demonstrate a new antibacterial perspective for endodontic sealers; a novel antibacterial, effective and safe antimicrobial means.

Antibacterial efficacy of photosensitizer functionalized biopolymeric nanoparticles in the presence of tissue inhibitors in root canal

INTRODUCTION

Application of antibacterial nanoparticles to improve root canal disinfection has received strong interest recently. The current study aims to assess the antibacterial effect of a novel photosensitizer (rose bengal functionalized chitosan nanoparticles [CSRBnp]) to eliminate bacteria in the presence of various root canal constituents that are known to inhibit the antibacterial efficacy of root canal disinfectants.

METHODS

The synthesized CSRBnp were evaluated for size, charge, and singlet oxygen release. The antibacterial effect of CSRBnp was tested on planktonic Enterococcus faecalis with or without pretreatment by using different inhibiting agents such as dentin, dentin-matrix, pulp tissue, bacterial lipopolysaccharides, and bovine serum albumin (BSA). Bacterial survival was assessed in a time-dependent manner. The antibacterial effects after photodynamic activation on CSRBnp, a cationic photosensitizer (methylene blue), and an anionic photosensitizer (rose bengal [RB]) in the presence of inhibitors were also evaluated.

RESULTS

CSRBnp were 60 ± 20 nm in size and showed reduced rate of singlet oxygen release as compared with methylene blue and RB. Pulp and BSA inhibited the antibacterial effect of CSRBnp (without photoactivation) significantly (P < .05) even after 24 hours of interaction. In case of photodynamic therapy, the pulp and BSA significantly inhibited the antibacterial activity of all 3 photosensitizers. CSRBnp showed residual effect and completely eliminated the bacteria after 24 hours of interaction after photodynamic therapy.

CONCLUSIONS

The inherent antibacterial activity of polycationic chitosan nanoparticles and the singlet oxygen released after photoactivation of RB synergistically provided CSRBnp the potential to achieve significant antibacterial efficacy even in the presence of tissue inhibitors within root canals.

Antibacterial efficacy of Mangifera indica L. kernel and Ocimum sanctum L. leaves against Enterococcus faecalis dentinal biofilm

Introduction:

The Enterococcus faecalis biofilm in the root canal makes it difficult to be eradicated by the conventional irrigants with no toxicity to the tissues. Hence, plant products with least side effects are explored for their use as irrigants in the root canal therapy.

Aim:

To evaluate and compare the antibacterial efficacy of Mangifera indica L. kernel (mango kernel) and Ocimum sanctum L. leaves (tulsi) extracts with conventional irrigants (5% sodium hypochlorite (NaOCl) and 2% chlorhexidine) against E. faecalis dentinal biofilm.

Materials and Methods:

Agar diffusion and broth microdilution assay was performed with the herbal extracts and conventional irrigants (2% chlorhexidine and 5% NaOCl) against E. faecalis planktonic cells. The assay was extended onto 3 week E. faecalis dentinal biofilm.

Results:

Significant reduction of colony forming units (CFU)/mL was observed for the herbal groups and the antibacterial activity of the herbal groups was at par with 5% NaOCl.

Conclusions:

The antibacterial activity of these herbal extracts is found to be comparable with that of conventional irrigants both on the biofilm and planktonic counterparts.

Detection of Enterococcus faecalis and Candida albicans in previously root-filled teeth in a population of Gujarat with polymerase chain reaction

BACKGROUND

Micro-organisms are the primary causative agents of endodontic infections. Phenotype based procedures for bacterial identification has certain drawbacks especially, when investigating the microbiota of root-filled teeth. Thus, more sensitive methods like Polymerase chain reaction (PCR) can provide results that are more accurate and reliable for the microbial prevalence in the root filled teeth.

AIM

In this study, we have investigated twenty symptomatic root-filled teeth with chronic apical periodontitis for the prevalence of Enterococcus faecalis and Candida albicans in the root filled teeth associated with symptomatic cases with or without periradicular lesions.

MATERIALS AND METHODS

Microbiological samples were taken from the canals immediately after removal of previous gutta percha cones using aseptic techniques. After removal of root canal filling, samples were obtained with paper points placed in the canal. Paper points were transferred to a cryotube containing "Tris EDTA" buffer and immediately frozen at -20°C.

RESULTS

By PCR amplification of the samples using taxon specific primers, E. faecalis was found to be prevalent species, detected in 65% of the cases and C. albicans was detected in 35% of cases.

CONCLUSION

The results of the study shows that geographical influence and dietary factors might have some role to play in the prevalence of the species like C. albicans and presence of E. faecalis confirming the assertion of previous culture-dependent and independent approaches for the microbiological survey of root filled teeth.

Analysis of the secondary endodontic lesions focusing on the extraradicular microorganisms: an overview

The present study aimed at reviewing the literature on extraradicular infections of endodontically treated teeth, summarizing the main hypotheses on etiopathogenesis and describing the most suitable techniques to identify the composition of pathogenic extraradicular microorganisms. Medline database was searched using the keywords "Apical biofilm," "extraradicular infection," "secondary endodontic lesion," "endodontic retreatment," "biofilm" either alone or combined with AND. A further hand search was performed on the main endodontic journals. The most frequent bacterial species identified in different studies and with different techniques may vary considerably. Although the presence of some species of microorganisms seems to be determinant, the true origin of extraradicular infection is still undetermined. The literature analysis showed marked differences in methodology, materials, aims, and techniques adopted, which led to highly heterogeneous outcomes. The picture emerging from this review is that extraradicular infection is likely a multifactorial disease that requires further systematic investigation using standardized techniques.

New trends in dentistry: plant extracts against Enterococcus faecalis. The efficacy compared to chlorhexidine

Enterococcus faecalis is an important pathogen associated with endodontic diseases, and its elimination and control are of paramount importance, as it represents one of the major causes of failure in the treatment of endodontic disease. Twenty-five plant extracts obtained from Brazilian forests were found to be effective against planktonic E. faecalis and were subjected to two traditional antibacterial assays, the microdilution broth assay (MDBA) and the disk diffusion assay (DDA), using chlorhexidine (CHX) as a control. Seven out of 25 extracts showed significant antibacterial activity and were tested in a biofilm assay, and three of these extracts were subjected to chemical fractionation. Residues were tested for their antibacterial activity, and the first chemical findings were described based on thin layer chromatography (TLC). Extracts obtained from Ipomoea alba, Symphonia globulifera and Moronobea coccinea showed significant bactericidal activity in the MDBA. The same I. alba and S. globulifera extracts, as well as the extract obtained from Connarus ruber var. ruber, showed significant activity in the DDA. RH2O obtained from Psidium densicomum and Stryphnodendron pulcherrimum showed better antibacterial activity compared to the respective crude extracts and CHX. TLC analysis showed that phenolic compounds and triterpenes represent the first findings of chemical groups that may occur in all species. The results of the present study include the discovery of six active extracts against planktonic E. faecalis and support further testing via assays involving biofilm formation, as well as the determination of the compounds' chemical profiles, as their activity was significantly better than that observed for CHX.

An in vitro evaluation of the antimicrobial efficacy of Curcuma longa, Tachyspermum ammi, chlorhexidine gluconate, and calcium hydroxide on Enterococcus faecalis

Aim and Objectives:

This in vitro study was designed to comparatively evaluate the antimicrobial efficacy of Curcuma longa (turmeric – T₁-10%, T₂-20%); Tachyspermum ammi (ajwain – A₁-10%, A₂-20%); chlorhexidine (CHX) gluconate gel (hexigel – 1%); and calcium hydroxide (10%) as intracanal medicaments against Enterococcus faecalis.

Materials and Methods:

Agar plates were prepared using brain-heart infusion (BHI) agar. Cultures of E. faecalis were grown in BHI broth at 37°C. Well diffusion method was used to derive results. Plates were inoculated for 72 h at 37°C and microbial zones of inhibition were recorded. Statistical analysis was performed with repeated measures analysis of variance.

Results:

C. longa (T₂-20%) and CHX gluconate gel (hexigel – CHX-1%) showed larger zones of microbial inhibition than C. longa (T₁-10%) that were statistically significant (P < 0.05) and were highly significant when compared to T. ammi (ajwain – A₁ and A₂) and calcium hydroxide.

Conclusion:

C. longa can be used as intracanal medicament in endodontic failure cases.

Effect of high-intensity focused ultrasound on Enterococcus faecalis planktonic suspensions and biofilms

In this study, the effect of high-intensity focused ultrasound (HIFU) on Enterococcus faecalis on both planktonic suspensions and biofilms was investigated. E. faecalis persist in secondary dental infections as biofilms. Glass-bottom Petri dishes with biofilms were centered at the focal point of the HIFU wave generated by a 250-kHz transducer. Specimens were subjected to HIFU exposure at different periods of 30, 60 and 120 s. The viable bacteria, removal effect and bacterial viability of biofilms attached to the Petri dish surface were studied by colony-forming units (CFUs), scanning electron microscopy and confocal microscopy, respectively. The removal and bactericidal effects of HIFU are dependent on the exposure time. A significant reduction in biofilm thickness and CFU was found with the increase in HIFU exposure. The removal or bactericidal effect of HIFU was more significant starting from 60 s of exposure. This study highlighted the potential application of HIFU as a novel method for root canal disinfection.

Antimicrobial activity of essential oils and chloroform alone and combinated with cetrimide against Enterococcus faecalis biofilm

The Enterococcus faecalis bacteria have been identified as the most commonly recovered species from teeth with persistent endodontic infections. The antimicrobial activity of essential oils and chloroform (CHL), alone and in association with various concentrations of cetrimide (CTR), against biofilm of Enterococcus faecalis was investigated. Solutions of CHL, eucalyptus oil (EO) and orange oil (OO) associated with CTR at 0.3%, 0.2%, 0.1%, and 0.05% were used to determine antimicrobial activity by exposing treated bovine dentine blocks to E. faecalis. Biofilms grown in the dentine blocks for 7 days were exposed to solutions for 2 and 5 min. Biofilm reduction between OO and EO at 2 min did not show any significant differences; however, OO had a higher kill percentage of biofilms than did the eucalyptus oil at 5 min (p < 0.01). Combinations with CTR at all concentrations achieved a 100% kill rate at 2 and 5 min. The association of CTR with solvent agents achieved the maximum antimicrobial activity against E. faecalis biofilms in dentine.

Towards antibacterial endodontic sealers using quaternary ammonium nanoparticles

AIM

To change and characterize the antibacterial properties of endodontic sealers by incorporating low concentrations of insoluble antibacterial nanoparticles (IABN).

METHODOLOGY

The antibacterial effect against Enterococcus faecalis was evaluated by (i) agar diffusion test (ADT), (ii) direct contact test (DCT) and (iii) scanning electron microscopy (SEM). IABN were incorporated into AH Plus (Dentsply, DeTrey Konstanz, Germany) and GuttaFlow (Coltène Whaledent, Langenau, Germany) at concentrations of 0.5%, 1% or 2% weight/weight. Bacterial growth rates were analysed using ANOVA followed by Tukey's test.

RESULTS

The antibacterial tests demonstrated total bacterial growth inhibition using AH Plus samples incorporating 2% weight/weight IABN after 4 weeks (P < 0.005). DCT showed total growth inhibition of up to 6 logs in viable count in AH Plus samples incorporating IABN and up to 4 log in count in GuttaFlow incorporating IABN (P < 0.005). Significant differences were found between the unmodified sealers and the experimental groups. No antibacterial effect was observed in the ADT, indicating IABN were not diffusing into the agar. Furthermore, SEM indicated bacterial cell wall damage and lysis.

CONCLUSIONS

AH Plus and GuttaFlow incorporating low concentrations of IABN exhibited significant and stable antimicrobial properties.

Comprehensive analysis of secondary dental root canal infections: a combination of culture and culture-independent approaches reveals new insights

Persistence of microorganisms or reinfections are the main reasons for failure of root canal therapy. Very few studies to date have included culture-independent methods to assess the microbiota, including non-cultivable microorganisms. The aim of this study was to combine culture methods with culture-independent cloning methods to analyze the microbial flora of root-filled teeth with periradicular lesions. Twenty-one samples from previously root-filled teeth were collected from patients with periradicular lesions. Microorganisms were cultivated, isolated and biochemically identified. In addition, ribosomal DNA of bacteria, fungi and archaea derived from the same samples was amplified and the PCR products were used to construct clone libraries. DNA of selected clones was sequenced and microbial species were identified, comparing the sequences with public databases. Microorganisms were found in 12 samples with culture-dependent and -independent methods combined. The number of bacterial species ranged from 1 to 12 in one sample. The majority of the 26 taxa belonged to the phylum Firmicutes (14 taxa), followed by Actinobacteria, Proteobacteria and Bacteroidetes. One sample was positive for fungi, and archaea could not be detected. The results obtained with both methods differed. The cloning technique detected several as-yet-uncultivated taxa. Using a combination of both methods 13 taxa were detected that had not been found in root-filled teeth so far. Enterococcus faecalis was only detected in two samples using culture methods. Combining the culture-dependent and –independent approaches revealed new candidate endodontic pathogens and a high diversity of the microbial flora in root-filled teeth with periradicular lesions. Both methods yielded differing results, emphasizing the benefit of combined methods for the detection of the actual microbial diversity in apical periodontitis.

The Antibacterial Efficacy of Biopure MTAD in Root Canal Contaminated with Enterococcus faecalis

Aim. The purpose of this in vitro study was to assess the antimicrobial efficacy of Biopure MTAD against E. faecalis in contaminated root canals. Materials and Methods. Forty-two single rooted extracted human teeth were inoculated with E. faecalis and incubated for four weeks. The samples were divided in two control and five experimental groups irrigated with 1.5% sodium hypochlorite solution (NaOCl); 3% NaOCl; BioPure MTAD; 1.5% NaOCl/17% EDTA; or 3% NaOCl/17% EDTA. After a one-week incubation, complete disinfection was confirmed by the absence of turbidity in the incubation media. Dentin shavings were taken from samples with no turbidity to verify whether E. faecalis was present in dentin tubules. Results were analyzed statistically using Fisher's exact test, with the level of significance set at P < 0.05. Results. Statistical analysis of the data obtained at Day 7 and after dentin shaving analysis showed that BioPure MTAD had significantly greater antibacterial activity than 1.5% NaOCl, 1.5% NaOCl/17% EDTA and 3% NaOCl/17% EDTA. No significant difference was detected between MTAD and 3% NaOCl. Conclusions. These findings suggest that BioPure MTAD possesses superior bactericidal activity compared with NaOCl and EDTA against E. faecalis.

Characterization of microbiota of root canal-treated teeth with posttreatment disease

This study evaluated the microbiota of root canals undergoing retreatment. The most prevalent taxa detected by checkerboard included Propionibacterium species, Fusobacterium nucleatum, streptococci, and Pseudoramibacter alactolyticus. Quantitative real-time PCR detected Enterococcus faecalis and streptococci in 38% and 41% of the cases, comprising 9.76% and 65.78% of the total bacterial counts, respectively. The findings call into question the status of E. faecalis as the main pathogen and suggest that other species can be candidate pathogens associated with persistent/secondary endodontic infections.

Polymerase chain reaction of enterococcus faecalis and candida albicans in apical periodontitis from Turkish patients

Aim: The aim of this study was to determine the frequency of two important pathogenic microorganisms associated with endodontic infections, Enterococcus faecalis and Candida albicans, in root canal samples from patients with necrotic pulps or failed canal therapy by polymerase chain reaction method. Method: Microbial samples were obtained from 117 teeth with necrotic pulp tissues and 114 teeth with failed endodontic treatment. Results: E.faecalis were identified in 16% of the necrotic and 10% of the retreated root canal infections by PCR. C.albicans genome were identified in 20% and 11% of the necrotic and retreated root canal infections, respectively, by PCR. The frequencies of microbiota were not statistically different between necrotic and retreatment groups (p > 0.05, chi squared test). Conclusions: PCR analysis of teeth with periapical lesions revealed that E.faecalis was found in fewer patients than in previous studies. The C.albicans prevelance was consistent with previous reports. No statistical difference was found between primary and secondary root canal infections for C.albicans or E.faecalis.

Key words:Primary root canal infection, secondary root canal infection, E.faecalis, C.albicans.

Antibacterial and neutralizing effect of human β-defensins on Enterococcus faecalis and Enterococcus faecalis lipoteichoic acid

INTRODUCTION

Enterococcus faecalis is frequently found in the root canal of teeth, is a major microorganism of endodontic therapy failure, and is associated with chronic apical periodontitis. Human β-defensins (HBDs) are known to play critical roles in defending the host against infectious microbes and producing dental pulp in healthy and patients. The purpose of the present study was to investigate the bactericidal and neutralizing effects of HBDs on E. faecalis and E. faecalis lipoteichoic acid (Ef LTA) as a major virulence factor of E. faecalis.

METHODS

HBD-1, -2, -3, and -4 were synthesized and investigated the susceptibility against E. faecalis. Also, the neutralizing effects of HBDs on cytokine and intercellular adhesion molecule 1 (ICAM-1) expression by activity of E. faecalis and Ef LTA were analyzed using enzyme-linked immunosorbent assay and flow cytometry.

RESULTS

HBD-1 and -2 were weakly susceptible, and HBD-3 and HBD-4 were strongly susceptible to E. faecalis. All of the HBDs exhibited neutralizing effects on the activity of Ef LTA, and HBD-3 strongly neutralized the activity of E. faecalis in tumor necrosis factor-α, interleukin-8, and ICAM-1 expression. The neutralizing effects of HBDs were to inhibit E. faecalis or Ef LTA binding to the host cells.

CONCLUSIONS

These results suggest that the induction of HBDs might have great potential as endodontic therapeutic agents.

Antibacterial Effects of Six Endodontic Sealers

Purpose

The objective of this study was to perform an in vitro evaluation of the antibacterial properties of 6 endodontic sealers (Endomethasone C, Argoseal, Bioseal Normal, Acroseal, AH Plus, Sicura Seal).

Methods

The agar diffusion test (well and paper disc methods) with Enterococcus faecalis, Staphylococcus aureus and Streptococcus mutans was used. For the well method, Petri dishes were inoculated with bacterial suspensions. Each well was completely filled with freshly mixed endodontic sealer. For the paper disc method, sterile paper discs were immersed in freshly mixed sealers and put on agar plates. Diameters of halos formed around the sealers were measured after 24 h and 48 h. Statistical analysis: The effects of well method and of paper disc method were analyzed by 1-way ANOVA.

Results

Endomethasone C, Argoseal and Bioseal showed the largest inhibition halos for all the tested microorganisms, while Sicura Seal and AH Plus showed low antibacterial effects. Moreover, the comparison of well method and paper disc methods showed significant statistical differences (P<0,01) for all sealers and indicated a dose-dependent antimicrobial effect.

Bacterial and Candida albicans adhesion on different root canal filling materials and sealers

INTRODUCTION

Microbial adhesion and subsequent biofilm formation on endodontic root canal filling materials and sealers lead to survival of microorganisms in treated root canals and subsequently to endodontic treatment failures. The present study focused on initial microbial adhesion to different endodontic filling materials.

METHODS

The following endodontic biomaterials were tested: AH-Plus, Tubli Seal, gutta-percha, Real Seal SE, EndoREZ, Apexit Plus, GuttaFlow, and dentin. Samples of each material were prepared. Bovine dentin samples were used as a control. The initial adhesions of salivary bacteria as well as the subsequent single species were quantified by determination of colony-forming units (CFUs) and visualized by scanning electron microscopy and confocal microscopy (CLSM): Enterococcus faecalis, Streptococcus mutans, Streptococcus sanguis, Candida albicans, and Prevotella nigrescens.

RESULTS

Initially adherent microorganisms could be detected and microscopically visualized on each of the materials tested. Considering the values of the CFUs and the covering grade as detected by CLSM, there were significant differences among the materials. Fewer bacteria tended to adhere to Apexit Plus, whereas Real Seal SE and the widely used gutta-percha showed the highest number of adherent bacteria. This tendency was not detected for C. albicans.

CONCLUSIONS

Endodontic microorganisms have a high affinity to root canal filling materials and sealers, especially to gutta-percha. Because of this high level of bacterial adhesion, subsequent biofilm formation on these materials could be suggested as leading to the persistence of microorganisms in root canals.

Antibiotic resistance and adhesion properties of oral Enterococci associated to dental caries

BACKGROUND

Enterococci are increasingly associated with opportunistic infections in Humans but the role of the oral cavity as a reservoir for this species is unclear. This study aimed to explore the carriage rate of Enterococci in the oral cavity of Tunisian children and their antimicrobial susceptibility to a broad range of antibiotics together with their adherence ability to abiotic and biotic surfaces.

RESULTS

In this study, 17 E. faecalis (27.5%) and 4 E. faecium (6.5%) were detected. The identified strains showed resistance to commonly used antibiotics. Among the 17 isolated E. faecalis, 12 strains (71%) were slime producers and 5 strains were non-producers. Among the 4 E. faecium, 2 strains were slime producers. All the tested strains were able to adhere to at least one of the two tested cell lines. Our result showed that 11 E. faecalis and 2 E. faecium strains adhered strongly to Hep-2 as well as to A549 cells.

CONCLUSIONS

Drugs resistance and strong biofilm production abilities together with a high phenotypic adhesion to host cells are important equipment in E. faecalis and E. faecium which lead to their oral cavity colonization and focal infections.

Bacterial localization and viability assessment in human ex vivo dentinal tubules by fluorescence confocal laser scanning microscopy

AIM

To develop a convenient method for the localization and quantification of live and dead bacteria in human ex vivo mineralized dentinal tubules.

METHODOLOGY

The roots from human single-rooted teeth (n = 12) were infected with Enterococcus faecalis V583 and either treated with calcium hydroxide paste or left untreated; six control roots were uninoculated and untreated. Following further incubation, roots were stained with fluorescent DNA-binding reagents, washed thoroughly, sectioned and examined by confocal laser scanning microscopy. Computer-assisted determinations of fluorescence (bacterial viability) were compared statistically.

RESULTS

Bacteria were distributed in the tubules throughout the length of the roots but tubule penetration distance was slightly reduced in the apical sections. There was no significant difference in bacterial tubule penetration between roots from different teeth and small standard deviations indicated reproducibility appropriate for experimental application. Following treatment with calcium hydroxide paste, live and dead bacteria were readily distinguishable by contrasting green and red fluorescence. Bacterial viability determinations amongst roots treated in the same way were not significantly different, and the small standard deviation is commensurate with experimental application.

CONCLUSIONS

Fluorescent viability staining is a convenient, accurate and reproducible method for localizing and quantifying live and dead bacteria in human ex vivo mineralized dentinal tubules.