New Bacterial Composition in Primary and Persistent/Secondary Endodontic Infections with Respect to Clinical and Radiographic Findings

Identification and antimicrobial susceptibility profile of bacteria isolated from primary endodontic infections

This study aimed to identify and characterize the antimicrobial susceptibility profile of bacteria found in primary endodontic infections in the teeth of patients treated at the Dental Clinic of the University of Ribeirão Preto, São Paulo, Brazil. From September to December 2019, samples were obtained from 21 patients with primary endodontic infections. The collections were carried out in triplicate using paper cones placed close to the total length of the root canal. Bacterial isolation was performed in Brain Heart Infusion agar, Blood agar, and other selective culture media cultured at 37°C for up to 48 h under aerobiosis and microaerophilic conditions. The bacterial species were identified using the Vitek 2 automated system. The disk diffusion method on agar Müeller-Hinton was used to assess antimicrobial susceptibility with the recommended antimicrobials for each identified bacterial species. A total of 49 antibiotics were evaluated. Fifteen of the 21 samples collected showed bacterial growth, and 17 bacterial isolates were found. There were 10 different bacterial species identified: Enterococcus faecalis (four isolates), Streptococcus mitis/oralis (three isolates), Streptococcus anginosus (three isolates) being the most common, followed by Staphylococcus epidermidis, Enterococcus faecium, Streptococcus constellatus, Streptococcus alactolyticus, Enterobacter cloacae, Klebsiella variicola, and Providencia rettgeri (one isolate of each species). The analysis demonstrated significant susceptibility to most of the tested antibiotics. However, some Enterococcus isolates resisted the antibiotic's erythromycin, ciprofloxacin, and tetracycline. A Staphylococcus epidermidis isolate was characterized as multidrug-resistant. Five Streptococcus isolates were non-susceptible to all antibiotics tested.

Comparative evaluation of the antibacterial activity of curcumin-coated gutta-percha versus nanocurcumin-coated gutta-percha against Escherichia coli: An in vitro study

Introduction

Due to its biological and antibacterial qualities, many plants, including curcumin, are used as phytomedicines in dentistry. They are primarily used as intracanal medication in endodontics to prevent probable chemical side effects and also to address antimicrobial resistance. Curcumin nanoformulations have improved antibacterial activity and improved dispersion, making them the superior form of curcumin. The purpose of this study was to assess curcumin and nanocurcumin's antibacterial properties. As a gutta-percha coating, they are to be tested against Escherichia coli.

Materials and Methods

The study employs the standard strain of E. coli, ATCC 25922. The antibacterial activity of gutta-percha cones against E. coli is assessed after coating them with suspensions of curcumin and nanocurcumin. Scanning electron microscopy is utilized to evaluate the coatings' continuity.

Results

The gutta-percha cones that are untreated, coated with curcumin, and coated with nanocurcumin exhibit significantly different levels of antibacterial activity. There is statistically significant variation in their antibacterial activity.

Conclusion

(1) Compared to curcumin-coated and untreated gutta-percha cones, those coated with nanocurcumin exhibit a stronger antibacterial activity. (2) Compared to uncoated gutta-percha cones, gutta-percha cones coated with curcumin exhibit more antibacterial action.

Increased IL-12p70 and IL-8 Produced by Monocytes in Response to Streptococcus spp. and Actinomyces spp. Causals of Endodontic Primary Infections

We sought to evaluate the effect of endodontic-causative microorganisms of primary infections on mononuclear cells such as CD14+, CD4+, CD8+, CD19+ and Tregs Foxp3+. Facultative anaerobic microorganisms were isolated from radicular conducts and peripheral blood samples, which were taken from patients with primary infections. Cellular cultures were performed with peripheral blood mononuclear cells (PBMC) with and without Actinomyces spp. and Streptococcus spp. during 48, 72, and 96 h of contact in culture (concentration 5 × 105 cells/well) in a round plate bound with 48 wells. Later, PBMC was collected for analysis by flow cytometry, with the monoclonal antibodies αCD14, αCD4, αCD8, αCD19 and αFoxp3, and acquired using an FACSCanto II cytometer. The supernatant of cellular cultures was analyzed for the quantification of inflammatory cytokines. Data analysis was performed in FlowJo v10.8.2 and FCAPArray software, and statistical analysis was performed using GraphPad v5.0. software. We observed an increase in the percentage of CD14+ cells in patients at different hours of cellular culture in the presence of both Actinomyces spp. and Streptococcus spp. microorganisms, compared to healthy controls. This study demonstrates the role played by the innate immune system in the pathogeny of endodontic primary infections, explaining the effects that generate the more common microorganisms in this oral pathology.

In Vitro Assessment of SWEEPS and Antimicrobial Photodynamic Therapy Alone or in Combination for Eradicating Enterococcus faecalis Biofilm in Root Canals

OBJECTIVES

This study investigates the efficacy of antimicrobial photodynamic therapy (aPDT) using riboflavin and a blue diode laser (BDL), combined with shock wave-enhanced emission photoacoustic streaming (SWEEPS), against Enterococcus faecalis.

MATERIALS AND METHODS

A total of 48 extracted single-rooted human teeth were used. The root canals were instrumented, sealed at their apices, had the smear layer removed, and then underwent autoclave sterilization. Subsequently, each canal was inoculated with E. faecalis bacterial suspension and allowed to incubate for ten days. After confirming the presence of biofilms through scanning electron microscopy (SEM) in three teeth, the remaining teeth were randomly allocated into nine groups, each containing five teeth: control, 5.25% sodium hypochlorite (NaOCl), BDL, SWEEPS + normal saline, SWEEPS + NaOCl, riboflavin, riboflavin + SWEEPS, riboflavin + BDL, and riboflavin + BDL + SWEEPS. After the treatment, the numbers of colony-forming units (CFUs)/mL were calculated. The data were analysed using one-way ANOVA followed by Tukey's test for comparisons.

RESULTS

All groups, with the exception of the BDL group, exhibited a significant reduction in E. faecalis CFU/mL when compared to the control group (p < 0.001). The difference in CFU/mL value between riboflavin + BDL + SWEEPS and riboflavin + SWEEPS was significant (p = 0.029), whereas there was no significant difference between riboflavin + BDL + SWEEPS and riboflavin + BDL (p = 0.397). Moreover, there was no statistically significant difference between the riboflavin + SWEEPS group and the riboflavin + BDL group (p = 0.893).

CONCLUSIONS

The results demonstrated that combining the SWEEPS technique with riboflavin as a photosensitizer activated by BDL in aPDT effectively reduced the presence of E. faecalis in root canals.

Enterococcus faecalis in secondary apical periodontitis: Mechanisms of bacterial survival and disease persistence

Enterococcus faecalis is a commensal bacterium commonly found in the human gastrointestinal tract. However, in individuals with compromised immune systems, the pathogen can lead to severe illness. This opportunistic pathogen is associated with secondary apical diseases and is adept at resisting antibiotics and other forms of treatment because of its numerous virulence factors. Enterococcus faecalis is capable of disrupting the normal functions of immune cells, thereby hindering the body's ability to eradicate the infection. However, intensive research is needed in further understanding the adverse immunomodulatory effects of E. faecalis. Potential strategies specific for eradicating E. faecalis have proven beneficial in the treatment of persistent secondary apical periodontitis.

Prevalence of Fusobacterium Species in Endodontic Infections Detected With Molecular Methods: Systematic Review and Meta-Analysis

INTRODUCTION

Endodontic infections are polymicrobial; however, investigating the role of bacterial species is critical because they may influence pathogenesis, the development of symptoms, or the persistence of disease. This systematic review aimed to determine the prevalence of Fusobacterium species and its association with different types of endodontic infections.

METHODS

MEDLINE (Ovid), PubMed, Scopus, Web of Science, and Cochrane Library databases were used as electronic databases to retrieve relevant studies. The studies were evaluated for eligibility criteria, and the certainty in evidence and risk of bias were evaluated using critical appraisal tools for prevalence studies from the Joanna Briggs Institute. Forty studies were selected for meta-analysis and statistically analyzed for the relationship between the prevalence of Fusobacterium species and both the presence of symptoms and the type of infections (primary vs secondary/persistent) using meta-regression analysis.

RESULTS

The prevalence of Fusobacterium spp. in endodontic infections ranged from 3%-100% (mean = 42.51%) in the 40 included studies. Calculated confidence intervals indicated that the presence of Fusobacterium spp. was not statistically associated with the presence of symptoms or with the type of infections (the set of 2 predictors was not significant; P < .05).

CONCLUSIONS

The prevalence of Fusobacterium infection, which was identified with molecular methods, was not significant for overall regression using both predictors (ie, symptoms [symptomatic vs asymptomatic] and types of infections [primary vs secondary/persistent]).

Study of the Antibacterial Capacity of a Biomaterial of Zeolites Saturated with Copper Ions (Cu2+) and Supported with Copper Oxide (CuO) Nanoparticles

In this work, copper (II) ions were saturated and copper oxide nanoparticles (CuO NPs) were supported in natural zeolite from Chile; this was achieved by making the adsorbent material come into contact with a copper ion precursor solution and using mechanical agitation, respectively. The kinetic and physicochemical process of the adsorption of copper ions in the zeolite was studied, as well as the effect of the addition of CuO NPs on the antibacterial properties. The results showed that the saturation of copper (II) ions in the zeolite is an efficient process, obtaining a 27 g L^-1 concentration of copper ions in a time of 30 min. The TEM images showed that a good dispersion of the CuO NPs was obtained via mechanical stirring. The material effectively inhibited the growth of Gram-negative and Gram-positive bacteria that have shown resistance to methicillin and carbapenem. Furthermore, the zeolite saturated with copper at the same concentration had a better bactericidal effect than the zeolite supported with CuO NPs. The results suggested that the ease of processing and low cost of copper (II) ion-saturated zeolitic material could potentially be used for dental biomedical applications, either directly or as a bactericidal additive for 3D printing filaments.

Microbiome in paired root apices and periapical lesions and its association with clinical signs in persistent apical periodontitis using next-generation sequencing

AIM

To assess and compare the microbiome of paired root apices and periapical lesions from cases with failed endodontic treatment and to associate the microbiome and bacterial metabolic pathways in both sites with asymptomatic apical periodontitis (AAP) and symptomatic apical periodontitis (SAP), using next-generation sequencing (NGS).

METHODOLOGY

Matched root apices and periapical lesions of patients with failed root canal treatments were surgically extracted. Specimens were cryopulverized, bacterial DNA was extracted and the V3-V4 hypervariable regions of the 16 S rRNA gene were amplified and sequenced using the Illumina Miseq platform. Diversity and community composition were studied in the paired samples, as well as in AAP and SAP cases. Diversity indices were compared in each case by means of the Wilcoxon matched-pairs signed rank and Mann-Whitney U tests. Differences in the community composition were explored with multivariate statistical analysis and Linear discriminant analysis Effect Size (LEfSe). Bacterial functional study was performed through the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis.

RESULTS

Twenty-one paired apices and lesions were successfully sequenced and analysed, identifying a total of 21 phyla and 600 genera. A higher alpha-diversity was observed in the periapical lesions, although no global differences in the community composition between the two sites were found (p = .87), the most prevalent genera being Fusobacterium, Porphyromonas and Streptococcus. Prevotella, Clostridiales_vadinBB60_group, Bosea, Phreatobacter, Afipia and Xanthobacteriaceae_unclassified were enriched in SAP samples, while Pseudopropionibacterium, Campylobacter and Peptoniphilus were significantly more abundant in AAP cases (p < .05). Metabolic pathways involved in the amino acid metabolism or degradation and flagellum assembly were more abundant in SAP samples, whereas glucose metabolism-related pathways were associated with AAP.

CONCLUSIONS

The bacterial community composition was similar in the apices and periapical lesions. The microbiome was different in AAP and SAP samples, gram-negative bacteria showing higher relative abundances in SAP cases. An association was observed between amino acid degradation and flagellum assembly pathways, and the development of tenderness to percussion or palpation.

Biodentine Inhibits the Initial Microbial Adhesion of Oral Microbiota In Vivo

This study aimed to evaluate the in vivo initial microbial adhesion of oral microorganisms on the biomaterial Biodentine compared to MTA and AH Plus. Cylindrical samples of the materials were prepared, and dentin slabs served as a control. An individual intraoral lower jaw splint served as a carrier for the samples and was worn by six volunteers. The specimens were worn for 120 min. Adherent bacteria were quantified by determining the colony-forming units (CFUs), while the visualization and quantification of total adherent microorganisms were facilitated by using DAPI and live/dead staining combined with fluorescence microscopy. Bovine dentin had a significantly higher number of aerobic CFUs compared to Biodentine (p = 0.017) and MTA (p = 0.013). The lowest amounts of DAPI-stained adherent microorganisms were quantified for Biodentine (15% ± 9%) and the control (18% ± 9%), while MTA showed the highest counts of initially adherent microorganisms (38% ± 10%). Significant differences were found for MTA and Biodentine (p = 0.004) as well as for MTA and the control (p = 0.021) and for AH Plus and the control (p = 0.025). Biodentine inhibited microbial adherence, thereby yielding an antimicrobial effectivity similar to that of MTA.

Comparative effects of SWEEPS technique and antimicrobial photodynamic therapy by using curcumin and nano-curcumin on Enterococcus faecalis biofilm in root canal treatment

OBJECTIVES

This study aimed to compare the antimicrobial effects of the shock wave enhanced emission photoacoustic streaming (SWEEPS) technique and Antimicrobial photodynamic therapy (aPDT) with curcumin and nano-curcumin photosensitizers on Enterococcus faecalis (E. faecalis) biofilm in root canals of extracted teeth.

MATERIALS AND METHODS

This experimental study was conducted on extracted single-rooted human teeth. The teeth were decoronated at the cementoenamel junction, the root canals were instrumented with BioRace system, and their apices were sealed. Smear layer was removed, and the teeth were autoclave-sterilized. E. faecalis strains were cultured in sterile brain heart infusion (BHI) and a bacterial suspension with 0.5 McFarland standard concentration was prepared. The root canals were inoculated with the bacterial suspension and incubated at 37 °C for 4 weeks. The teeth were then divided into 12 groups (curcumin, nano-curcumin, curcumin + LED, nano-curcumin + LED, curcumin + SWEEPS, nano-curcumin + SWEEPS, curcumin + LED + SWEEPS, nano-curcumin + LED + SWEEPS, SWEEPS, positive control and negative control). The number of colony forming units (CFUs) was counted and analyzed by one-way ANOVA and Tukey's test.

RESULTS

A significant difference was noted in colony count among the groups (P<0.001). LED alone had the lowest and nano-curcumin + LED + SWEEPS had the highest root canal cleaning efficacy. SWEEPS along with curcumin, nano-curcumin, and LED significantly decreased the bacterial count compared with other groups (P<0.05).

CONCLUSION

Application of the SWEEPS technique with curcumin and nano-curcumin as photosensitizer activated by LED in aPDT improved the reduction of E. faecalis in root canals.

Biocompatibility and Antibacterial Action of Salvadora persica Extract as Intracanal Medication (In Vitro and Ex Vivo Experiment)

This study aimed to test the biocompatibility and antibacterial properties of Salvadora persica (S. persica) extract, a natural product, as an intracanal medication in comparison with calcium hydroxide (Metapaste, META BIOMED, Cheongju, Korea). The pH values of both materials were tested. The biocompatibility of S. persica extract and Metapaste was determined using light microscopy and MTT assays. The antibacterial action was tested using the zone of bacterial inhibition on four common bacterial species. In addition, intracanal medication was administered using 68 extracted single-rooted teeth contaminated with Enterococcus faecalis (E. faecalis), and the percentage reduction in colony count (% RCC) at 1, 3, and 7 days was measured. The extension of activity for both materials was assessed using histological sections and scanning electron microscopy. S. persica was found to be acidic in nature. Both materials showed significantly lower cell viability than the positive control cells on days 1 and 3 but not on day 7. S. persica showed better antibacterial effects against E. faecalis and S. mutans. S. persica extract showed 97.6%, 98.9%, and 99.3% RCC values at 1, 3, and 7 days, respectively, which are comparable to those of Metapaste. S. persica herbal extract is a promising material that can be utilized as an intracanal medication, but its use requires further research.

Prevalence of Fungi in Primary Endodontic Infections of a Greek-living Population Through Real-time Polymerase Chain Reaction and Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

INTRODUCTION

Fungi are considered to be opportunistic pathogens that may play a significant role in the pathogenesis of endodontic infections. The main purpose of this study was to assess the prevalence of 2 selected genera of fungi, Candida albicans and Aspergillus spp., using real-time polymerase chain reaction (RT-PCR) and to compare the findings with the respective ones obtained by a culture-dependent approach, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS). A secondary aim was to assess the presence of other bacteria growing under aerobic conditions.

METHODS

Microbial samples were obtained from the root canals of 60 teeth associated with pulp necrosis and apical periodontitis. DNA was extracted, and RT-PCR was applied for the detection of C. albicans and Aspergillus spp. pathogenic subtypes. In addition, MALDI-ToF MS was performed to identify microorganisms grown under aerobic conditions.

RESULTS

Based on RT-PCR, Aspergillus was detected in 8 cases, whereas C. albicans was detected in 4 cases. Using MALDI-ToF MS, no trace of Aspergillus was detected, whereas C. albicans was identified in 2 cases. Significant differences were revealed in the detection potential for Aspergillus spp. between MALDI-ToF MS and RT-PCR (P = .01); conversely, this was not the case for C. albicans (P = .50). After MALDI-ToF MS, 35 samples showed evidence of bacterial growth. The vast majority was colonized by Achromobacter xylosoxidans followed by Lactobacillus spp., Methylobacterium spp., and Enterococcus faecalis.

CONCLUSIONS

The findings confirm the presence of fungi in primarily infected canals with apical periodontitis as well as some rarely inspected aerobic bacterial species. A. xylosoxidans was prevalent; however, the clinical relevance of its presence needs to be investigated further.

A small molecule II-6s inhibits Enterococcus faecalis biofilms

Background

Limitations of current intracanal irrigants such as sodium hypochlorite (NaOCl) and chlorhexidine (CHX) necessitate the development of novel antimicrobial agents to control endodontic infection.

Aim

This study investigated the antimicrobial activities of a small molecule II-6s against Enterococcus faecalis associated with endodontic diseases.

Methods

The susceptibility of E. faecalis to II-6s was evaluated by the microdilution method and time-kill assay. Microbial resistance was assessed by repeated exposure of E. faecalis to II-6s. Cytotoxicity of II-6s was evaluated by CCK-8 assay. Virulence gene expression of the II-6s-treated E. faecalis cells was measured by RT-qPCR. Bacterial reductions in the dentinal tubules were further assessed by confocal laser scanning microscopy.

Results

II-6s exhibited potent antimicrobial activity against E. faecalis and down-regulated virulence-associated genes in E. faecalis. II-6s induced no drug resistance in E. faecalis with lower cytotoxicity as compared to NaOCl and CHX. More importantly, 0.003125% II-6s exhibited significant bactericidal effect against E. faecalis residing in the dentinal tubules, which was comparable to 5.25% NaOCl and 2% CHX.

Conclusions

II-6s has excellent antimicrobial activity, moderate cytotoxicity and induces no drug resistance, and thus is a promising agent for the treatment of endodontic infection.

Antibacterial Activity of Copper Nanoparticles (CuNPs) against a Resistant Calcium Hydroxide Multispecies Endodontic Biofilm

Endodontic treatment reduces the amount of bacteria by using antimicrobial agents to favor healing. However, disinfecting all of the canal system is difficult due to its anatomical complexity and may result in endodontic failure. Copper nanoparticles have antimicrobial activity against diverse microorganisms, especially to resistant strains, and offer a potential alternative for disinfection during endodontic therapy. This study evaluated the antibacterial action of copper nanoparticles (CuNPs) on an ex vivo multispecies biofilm using plaque count compared to the antibacterial activity of calcium hydroxide Ca(OH)₂. There were significant differences between the Ca(OH)₂ and CuNPs groups as an intracanal dressing compared with the CuNPs groups as an irrigation solution (p < 0.0001). An increase in the count of the group exposed to 7 days of Ca(OH)₂ was observed compared to the group exposed to Ca(OH)₂ for 1 day. These findings differ from what was observed with CuNPs in the same period of time. Antibacterial activity of CuNPs was observed on a multispecies biofilm, detecting an immediate action and over-time effect, gradually reaching their highest efficacy on day 7 after application. The latter raises the possibility of the emergence of Ca(OH)₂-resistant strains and supports the use of CuNPs as alternative intracanal medication.

Complete Obturation-Cold Lateral Condensation vs. Thermoplastic Techniques: A Systematic Review of Micro-CT Studies

To prevent re-infection and provide a hermetic seal of the root canal system, an endodontist must aim to produce a void-free obturation. This review aimed to compare the completeness of root canal obturation between the two most prevalent methods-cold lateral condensation and warm gutta-percha techniques-using micro-CT (PROSPERO reg no. 249815).

MATERIALS AND METHODS

A search of Scopus, Embase, PubMed (Medline via PubMed), and Web of Science databases was done without any time restriction according to the PRISMA protocol. Articles that compared both techniques and were published in English were included. Data was extracted and the risk of bias was assessed using an adapted tool based on previous studies.

RESULTS

A total of 141 studies were identified by the search. Following the screening and selection of articles, 9 studies were included for review. Data was extracted manually and tabulated. Most studies had a moderate risk of bias. None determined operator skill in both methods before comparison. The data extracted from the included studies suggests that both techniques produce voids in the obturation. The thermoplasticized gutta-percha techniques may result in fewer voids compared to cold lateral condensation.

CONCLUSION

Considering the limitations of the included studies, it was concluded that neither technique could completely obturate the root canal. Thermoplasticized gutta-percha techniques showed better outcomes despite a possible learning bias in favor of cold lateral condensation. Establishing operator skills before comparison may help reduce this bias.

Diverse bacterial profile in extraradicular biofilms and periradicular lesions associated with persistent apical periodontitis

AIM

To characterize the bacterial community present in the extraradicular biofilm and periradicular lesions associated with persistent apical periodontitis.

METHODOLOGY

Eighteen adult patients who presented with persistent periradicular lesions after root canal treatment and scheduled for endodontic surgery were selected. During surgery, extraradicular samples of biofilms and periradicular lesions were collected. Ten pairs of periradicular lesions and extraradicular biofilm samples were randomly selected for ribosomal 16S rRNA cloning and sequencing. A Wilcoxon's rank-sum test was used to compare total bacterial counts and the levels of individual genera and species between the two groups (P < 0.05).

RESULTS

Overall, seventy-three phylotypes belonging to six different phyla were identified from 1000 sequenced clones. Mogibacterium timidum, Streptococcus intermedius and Enterococcus faecalis predominated in both extraradicular biofilm and periapical lesions. Propionibacterium propionicus, Abiotrophia adiacens, Peptostreptococcus prevotii, Campylobacter gracilis and Pseudomonas aeruginosa were found in significantly higher levels in the extraradicular biofilm than periapical lesions, whilst Parvimonas micra and Atopobium rimae were more abundant in periapical lesions (P < 0.05).

CONCLUSIONS

The microbial profile of extraradicular biofilms differed from periapical lesions, indicating the presence of diverse bacterial populations in these regions. Several genera and species were significantly associated with the formation of extraradicular biofilms.

Radiographic and antimicrobial evaluation of enterococcus Faecalis and Actinomyces Israelii micro-organisms after photodynamic therapy (aPDT)

This study evaluated the action of Antimicrobial Photodynamic Therapy (aPDT) on Enterococcus faecalis and Actinomyces israelii. Samples were taken from the root canal system, at different stages of treatment and bacteria were identified through qPCR. Fifty teeth (incisors, canines, and premolars) with pulp necrosis and periapical lesion diagnosis were randomly selected and divided into 2 groups: Group 1 (G1) - Endodontic Therapy with Mechanical Chemical Preparation (MPQ) and intracanal medication; Group 2 (G2) - Endodontic therapy with MPQ, intracanal medication, and 2 applications of aPDT. APDT was performed with application of 0.005% methylene blue, wavelength of 660 nm, and 90 seconds. Follow-up was performed with an initial x-ray and an x-ray 60 days after the end of treatment. The radiographs were scored evaluated by two examiners to classify periapical repair: total repair, partial repair, doubtful repair, or no repair. Enterococcus faecalis was found more frequently in G1 than G2. Actinomyces israelii was found equally in G1 and G2. Evaluation of the two bacteria between collections 1, 2 and 3, showed that there was no difference, both in G1 and in G2. There was association between the variables group and repair classification in radiographs evaluation. APDT did not promote better results in endodontic treatment, being similar to conventional treatment. However, this study pointed out that molecular methods may not be efficient in detecting bacteria after treatment, and colony-forming units may complement, being an effective quantifying method. Therefore, new studies must be carried out to show the possible effectiveness of aPDT.

Enhanced Eradication of Bacterial/Fungi Biofilms by Glucose Oxidase-Modified Magnetic Nanoparticles as a Potential Treatment for Persistent Endodontic Infections

Bacterial/fungal biofilm-mediated persistent endodontic infections (PEIs) are one of the most frequent clinical lesions in the oral cavity, resulting in apical periodontitis and tooth damage caused by loss of minerals. The conventional root canal disinfectants are poorly bio-safe and harmful to teeth and tissues, making them ineffective in treating PEIs. The development of nanomaterials is emerging as a promising strategy to eradicate disease-related bacteria/fungi. Herein, glucose oxidase (GOx)-modified magnetic nanoparticles (MNPs) were synthesized via a facile and versatile route for investigating their effects on removing PEI-related bacterial/fungal biofilms. It is found that GOx was successfully immobilized on the MNPs by detecting the changes in the diameter, chemical functional group, charge, and magnetic response. Further, we demonstrate that GOx-modified MNPs (GMNPs) exhibit highly effective antibacterial activity against Enterococcus faecalis and Candida albicans. Moreover, the antibacterial/fungal activity of GMNPs is greatly dependent on their concentrations. Importantly, when placed in contact with bacterial/fungal biofilms, the dense biofilm matrix is destructed due to the movement of GMNPs induced by the magnetic field, the formation of reactive oxygen species, and nutrient starvation induced by GOx. Also, the in vitro experiment shows that the as-prepared GMNPs have excellent cytocompatibility and blood compatibility. Thus, GMNPs offer a novel strategy to treat bacteria/fungi-associated PEIs for potential clinical applications.

Starvation Survival and Biofilm Formation under Subminimum Inhibitory Concentration of QAMs

Quaternary ammonium methacrylates (QAMs) are useful antimicrobial compounds against oral bacteria. Here, we investigated the effects of two QAMs, dimethylaminododecyl methacrylate (DMADDM) and dimethylaminohexadecyl methacrylate (DMAHDM), on biofilm formation, survival and development of tolerance by biofilm, and survival and development of tolerance against QAMs after prolonged starvation. Enterococcus faecalis (E. faecalis), Streptococcus gordonii (S. gordonii), Lactobacillus acidophilus (L. acidophilus), and Actinomyces naeslundii (A. naeslundii) were used. Minimum inhibitory concentration (MIC) of QAMs against multispecies biofilm was determined. Biofilm formed under sub-MIC was observed by crystal violet staining and confocal laser scanning microscopy (CLSM). Metabolic activity was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactic acid production measurement. Development of tolerance was determined by MIC values before and after exposure to QAMs or after prolonged starvation. It was found that E. faecalis and S. gordonii could survive and form biofilm under sub-MIC of QAMs. Lactic acid production from biofilms formed under sub-MIC was significantly higher than control specimens (p < 0.05). The exposure to sub-MIC of QAMs promoted biofilm formation, and prolonged starvation or prolonged contact with sub-MIC helped bacteria develop tolerance against killing by QAMs.

Root canal microorganisms and their antibiotic susceptibility in patients with persistent endodontic infections, with and without clinical symptoms

Secondary/persistent infections are present in teeth with previous root canal treatment, and a great variety of anaerobic microorganisms has been observed in these infections. The antibiotics prescription is occasional; however, in some cases, it is essential, particularly when the general health condition of the patient is compromised. The aims of this study were to identify the associated microorganisms in diagnosis of persistent or secondary apical periodontitis and to evaluate the susceptibility level to the antibiotics most used. Fifteen patients with persistent or secondary apical periodontitis requiring endodontic re-treatment were included. Microbiological samples were taken from the root canals and incubated in thioglycollate under anaerobic conditions. Anaerobic CDC agar (formulated by the Center for Disease Control and Prevention) was employed as a culture medium and the microorganisms were identified using the API system. The microorganisms were subjected to antibiograms with three different antibiotics. Twenty-six microorganisms were identified, the most common genus was Enterococcus (26.8%), Streptococcus (19.22%), Aerococcus (19.1%), and Clostridium (11.4%). 48% of them were susceptible to amoxicillin, with 28% of resistance. For clavulanic acid/amoxicillin, the susceptibility occurred in 32%, with 28% of resistance; and for clindamycin, the susceptibility was present in 40%, with 52% of resistance. The most frequently detected associated microorganism for secondary infections was genus Enterococcus, which exhibited high resistance to the studied antibiotics.

Bacteria and virulence factors in periapical lesions associated with teeth following primary and secondary root canal treatment

AIM

This cross-sectional study aimed to investigate the microbial profile and to quantify the levels of endotoxins (LPS) and lipoteichoic acid (LTA) present in periapical lesions associated with root filled teeth and those that had received root canal retreatment. It also aimed to investigate the association between microorganisms and their virulence factors with clinical and radiographic features.

METHODOLOGY

Patients with periapical lesions in teeth with post-treatment endodontic disease following primary root canal treatment (n = 19) and unsuccessful root canal retreatment (n = 13) were treatment planned for endodontic microsurgery, where the periapical lesions were collected. Clinical and radiographic data were also collected. For microbiological analysis, nested polymerase chain reaction was used to detect 17 bacterial species. Levels of LPS and LTA were determined using limulus amebocyte lysate and enzyme-linked immunosorbent assays, respectively. The Student t-test or Wilcoxon-Mann-Whitney tests were applied to compare the data on LPS and LTA with clinical and radiographic features. The associations between the clinical and radiographic features and the bacterial species were analysed using the Fisher's exact test. A significance level of 5% was adopted.

RESULTS

Bacterial DNA, LPS and LTA were detected in all samples. Parvimonas micra was the most commonly detected species in all groups, followed by Enterococcus faecalis, Fusobacterium nucleatum and Porphyromonas endodontalis. The type of endodontic treatment, whether a primary root canal treatment or retreatment, was not associated with the presence of any bacterial species in periapical lesions. The levels of LPS and LTA in periapical lesions of root filled teeth were not significantly different from those that had been retreated. Associations between the levels of LPS and LTA with clinical signs and symptoms were found. No association was found between specific bacteria and clinical features.

CONCLUSION

Periapical lesions associated with teeth after primary root canal treatment and retreatment had similar polymicrobial composition. The levels of LPS and LTA in periapical lesions associated with teeth after primary root canal treatment and retreatment were similar, and both were associated with the same symptomatology.

Microbiological Analysis of Primary Infected Root Canals with Symptomatic and Asymptomatic Apical Periodontitis of Young Permanent Teeth

Background/Aim: Understanding the composition of bacteria in infected root canals is important for ameliorating the treatment strategies that lead to the elimination of pathogens and infection control, but also prevent reinfection. Aim of this study was to investigate microbial composition of primary infected root canals with apical periodontitis of young permanent teeth, originating form school children in Serbia, and its association with clinical symptoms.

Material and Methods: To determine the bacterial composition of infected root canals in children, 35 endodontic samples were obtained. The identification of cultured bacteria was performed by MALDI-TOF MS analysis. The presence or absence of clinical symtoms were recorded.

Results: Facultative anaerobes were 2,2 times more frequent than obligate anaerobes. The most common facultative anaerobes belonged to following genera, Streptococcus (58 isolates), Actinomyces (10) and Enterococcus (8), while predominant obligate anaerobes, belonged to genera Veillonella (15), Prevotella (9) and Fusobacterium (8). The most common clinical isolates recovered from infected root canals with symptomatic apical periodontitis were Veillonella parvula (10) and Fusobacterium nucleatum (7), while from the asymptomatic ones, they were Streptococcus mitis/Streptococcus oralis (5). Prevalence of Parvimonas micra, Prevotella buccae and Streptococcus constellatus within the root canals might be associated to clinical symptoms.

Conclusions: Species of genera Streptococcus and Veillonella were the most common isolates from primary infected root canals with apical periodontitis in Serbian school children. Facultative anaerobes were predominant over obligate anaerobes. The prevalence of obligate anaerobes was much higher in symptomatic compared to asymptomatic root canal infections. No specific bacterial strain might be associated to a single examined clinical symptom (pain, tenderness to percussion or swelling), but majority of the strains are associated to all of the examined three symptoms.

The benefit of culture-independent methods to detect bacteria and fungi in re-infected root filled teeth: a pilot study

AIM

To identify dominant microorganisms in root filled teeth with apical periodontitis by Pan-PCRs in comparison with a culture-dependent approach, focusing on fungal species profiling.

METHODOLOGY

The root filling material (gutta-percha) removed from 42 teeth with periapical radiolucencies undergoing root canal retreatments was analysed by molecular genetics techniques. Real-Time Pan-PCRs were conducted for the diagnosis of predominant bacteria (targeting 16S rDNA) and fungi (targeting ITS1-2 region). Identification of microorganisms was performed by Sanger sequencing of the PCR products and BLAST analysis. Additionally, subgingival plaque samples were collected and cultured to review the composition of the microbial flora. The McNemar test and the repeated measures anova were used for statistical analyses (significance level was set at P < 0.05).

RESULTS

Overall, 42/42 plaque samples had bacterial growth, whereas 32/42 gutta-percha samples had bacterial growth with a dominance of Streptococcus spp. (12/42) and Enterococcus faecalis (9/42). The mean number of bacterial taxa per gutta-percha sample was 1.6 cultivatable taxa, significantly lower than in the plaque sample that had six taxa/sample (P < 0.001). Fungus-specific cultures were negative for gutta-percha samples, and only one plaque sample had growth of a fungus. In total, 36/42 plaque samples were positive in bacterial Pan-PCRs. In bacterial Pan-PCRs of 31/42 gutta-percha samples, dominant microorganisms were identified including Streptococcus spp. (5/42) and E. faecalis (4/42). Moreover, in 7/42 gutta-percha samples, DNA of bacteria which are difficult-to-cultivate in microbiology routine culture (Acinetobacter,Pyramidobacter,Bacteroidetes,Synergistes,Atopobium and Pseudoramibacter) was found. DNA of Candida spp. was detected in 5/42 root canals by fungal Pan-PCR (1/5) and genus-specific Candida-PCR (5/5).

CONCLUSIONS

Pan-PCR assays remain appropriate as a broad-range approach for the detection of a dominant pathogen in gutta-percha samples which have less diverse microbial composition. The molecular genetic Pan-PCR approach has the advantage of detecting microorganisms that are as-yet-uncultivable or difficult-to-cultivate and should be therefore complement conventional microbiological diagnostics.

The enterococcal PASTA kinase: A sentinel for cell envelope stress

Enterococci are Gram-positive, opportunistic pathogens that reside throughout the gastrointestinal tracts of most terrestrial organisms. Enterococci are resistant to many antibiotics, which makes enterococcal infections difficult to treat. Enterococci are also particularly hardy bacteria that can tolerate a variety of environmental stressors. Understanding how enterococci sense and respond to the extracellular environment to enact adaptive biological responses may identify new targets that can be exploited for development of treatments for enterococcal infections. Bacterial eukaryotic-like serine/threonine kinases (eSTKs) and cognate phosphatases (STPs) are important signaling systems that mediate biological responses to extracellular stimuli. Some bacterial eSTKs are transmembrane proteins that contain a series of extracellular repeats of the penicillin-binding and Ser/Thr kinase-associated (PASTA) domain, leading to their designation as "PASTA kinases." Enterococcal genomes encode a single PASTA kinase and its cognate phosphatase. Investigations of the enterococcal PASTA kinase revealed its importance in resistance to antibiotics and other cell wall stresses, in enterococcal colonization of the mammalian gut, clues about its mechanism of signal transduction, and its integration with other enterococcal signal transduction systems. In this review, we describe the current state of knowledge of PASTA kinase signaling in enterococci and describe important gaps that still need to be addressed to provide a better understanding of this important signaling system.

Evaluation of in vitro biofilm elimination of Enterococcus faecalis using a continuous ultrasonic irrigation device

This study sought to evaluate biofilm elimination using the HBW Ultrasonic Ring based on continuous ultrasonic irrigation. Forty-five premolars and molars with complex curvatures were included. An Enterococcus faecalis biofilm was established for 30 days on the extracted teeth. The teeth were then stratified into three experimental groups for instrumentation and irrigation (i.e. HBW Ultrasonic Ring, conventional irrigation, and passive ultrasonic irrigation). Pre- and post-instrumentation samples were collected, and reductions of bacterial load were evaluated by McFarland's scale, counting of colony-forming units, and scanning electronic microscopy. The HBW Ultrasonic Ring promoted a higher reduction in bacterial load relative to conventional irrigation (P < 0.05) and a similar reduction compared with passive ultrasonic irrigation (P > 0.05). These results suggest the HBW Ultrasonic Ring is a promising alternative modality for simultaneous instrumentation and irrigation during root canal treatment, achieving an appropriate level of bacterial reduction and allowing the passage of the irrigating solution throughout the entire working length.

The Effectiveness of Three Irrigation Systems in the Enterococcus faecalis Reduction after Instrumentation with a Reciprocating Instrument

OBJECTIVE

 This study aimed to analyze the effectiveness of three irrigation systems: EndoActivator, passive ultrasonic irrigation (PUI), and Easy Clean in the reduction of Enterococcus faecalis, after instrumentation with the reciprocating system, through microbiological collection and culture method.

MATERIALS AND METHODS

 A total of 60 extracted human lower premolars were used and standardized at 16 mm in length. The teeth were accessed, contaminated with E. faecalis, and incubated for 21 days at 37°C. Initial collections (S1) were made with an absorbent paper cone to confirm the contamination; subsequently, instrumentation was performed with WaveOne Primary. The teeth were divided into four groups according to the final irrigation protocol (n = 15): group 1. EndoActivator; group 2, PUI; group 3, Easy Clean; and group 4, control group irrigated with saline solution sterile and without agitation. In the final irrigation, the agitation of the 17% ethylene amine tetra-acetic acid (EDTA) solutions was used, then 2.5% sodium hypochlorite (NaOCl); in both for this, three cycles of 20 seconds each. After the chemical-mechanical preparation and agitation of the irrigating solutions, the final collections (S2) for counting the colony-forming units (CFU/mL) occurred.

RESULTS

 The Kruskal-Wallis test revealed that all the agitation systems reduced by 100% and the control group by 65.7%.

CONCLUSION

 The control group presented a significantly higher amount of CFU/mL after the chemical-mechanical preparation than the other groups, which were similar to each other (p > 0.05).

Improving the Efficiency of Photodynamic Chemotherapy in Root Canals against Enterococcus faecalis In Vitro

The aim of this study was to evaluate the effect of photoactivated chemotherapy (PACT) on Enterococcus faecalis (E. faecalis) biofilms in root canals using an 90% isopropanol (IPA)-based photosensitizer and removing excess photosensitizer before light incubation. Three hundred and seven extracted human teeth with one root canal were infected with E. faecalis for 72 h and treated in groups: IPA irrigation; PACT; PACT and final rinse with IPA; PACT with photosensitizer removal using either 0.9% NaCl solution or sterile paper points or both; PACT using IPA-based photosensitizer with and without a final rinse of IPA. Root canals were sampled using sterile paper points and dentin chips collected from the root canal walls. Additionally, SEM (Scanning Electron Microscopy) images of the specimens were taken to evaluate the root canal walls for residue bacterial contamination. In all antimicrobial treatment groups treatments E. faecalis counts were significantly reduced in the root canals. Using IPA-based photosensitizer the antimicrobial effect of PACT was significantly enhanced. Irrigation with IPA alone or after PACT significantly increased the antimicrobial effect compared to PACT alone. The collected dentin chips revealed the highest amount of culture negative root canals (10%) after PACT using IPA-based photosensitizer. In the other groups, the culture negative samples ranged from only 0–2 specimens of 30 specimens. REM images show remaining E. faecalis cells on the root canal wall and inside dentin tubules. Using IPA-based photosensitizer significantly enhanced the antimicrobial effect of PACT against E. faecalis in the root canals.

Identification of microorganisms in irreversible pulpitis and primary endodontic infections with respect to clinical and radiographic findings

OBJECTIVES

The aim of this study was to evaluate the composition of microbiota of irreversible pulpitis and primary endodontic infections with respect to clinical and radiographic findings by performing cultures and 16s rDNA sequencing in Iranian patients.

MATERIAL AND METHODS

In this prospective cross-sectional study, samples were collected from 41 root canals for 4 main groups of patients. Bacterial identification was performed by the polymerase chain reaction (PCR) and 16s rDNA sequencing of aerobic and anaerobic cultivable colonies taken from patients' culture plates. Additionally, the presence of 13 bacterial species and 3 nonbacterial species was also explored using PCR and species-specific primers.

RESULTS

Sixteen microbial species, 1 fungus (Candida albicans), and 1 virus (Herpes simplex virus) were discovered and isolated. Species with the highest prevalence were Dialister invisus (68.3%), Porphyromonas gingivalis (58.8%), Streptococcus salivarius (58.5%), and Treponema denticola (56.1%). Lysinibacillus fusiformis (19.1%) was detected in the root canals for the first time. Candida albicans was seen in 11 cases (26.8%). Herpes simplex virus (HSV) was seen in 4 patients (9.8%).

CONCLUSIONS

Our results suggest that Gram-negative anaerobic oral bacteria are the majority of the microbes in primary endodontic infections. Various combinations of bacterial species were related to different clinical and radiographic conditions. Lysinibacillus fusiformis was detected for the first time in primary endodontic infections.

CLINICAL RELEVANCE

The results of this investigation might help clinicians choose to identify suspected endodontic pathogens in the etiology of each form of pulpal and periradicular diseases to determine the best therapeutic measures.

Prevalence of the Genus Propionibacterium in Primary and Persistent Endodontic Lesions: A Systematic Review

Propionibacterium are anaerobic/aero-tolerant rod Gram-positive bacteria, and numerous studies are associated with primary and secondary endodontic infections. The data in the literature on the prevalence of Propionibacterium are conflicting, and there are studies that report conflicting data on the prevalence in primary and secondary endodontic infections. This review aims to clarify the prevalence of bacteria of the genus Propionibacterium in endodontic lesions. The present systematic review work was performed on the basis of the Prisma protocol. A search was carried out on the PubMed and Scopus databases with the use of keywords. The research produced 410 records, which, after the elimination of the overlaps and the application of the inclusion and exclusion criteria, led to a number of 36 included articles divided by the three outcomes. The first outcome concerns prevalence of bacteria of the genus Propionibacterium in primary and secondary endodontic lesions. The secondary outcome, differences in the prevalence of bacteria of the genus Propionibacterium between primary endodontic infections and secondary endodontic infections. The tertiary outcome, differences in the prevalence of Propionibacterium Acnes compared to Propionibacterium propionicum in endodontic infections. The results of the meta-analysis show that the genus Propionibacterium bacteria are more prevalent in secondary endodontic infections and that P. Acnes has a higher prevalence than P. propionicum.

Prevalence of Bacteria of Genus Actinomyces in Persistent Extraradicular Lesions-Systematic Review

Actinomyces are anaerobic, rod-shaped, Gram-positive bacteria. They are associated with persistent extraradicular endodontic infections, with possible involvement of the soft tissues of the maxillofacial district. Many studies reported conflicting data on the presence of bacteria of the genus Actinomyces in endodontic infections. The aim of this systematic review of the literature was to determine the real prevalence of such bacteria in primary and/or secondary endodontic infections and in cases of persistence with extraradicular involvement. This systematic review was performed according to the PRISMA protocol. A search was carried out through the Scopus and PubMed databases of potentially eligible articles through the use of appropriate keywords. The literature research resulted in preliminary 2240 records which, after the elimination of overlaps and the application of inclusion and exclusion criteria, led to the inclusion of 46 articles focusing on three outcomes (primary outcome: number of teeth with the presence of a persistent extraradicular infection in which the presence of Actinomyces was ascertained; secondary outcome: number of teeth with endodontic infection in which the presence of Actinomyces was assessed; tertiary outcome: difference in the prevalence of bacteria of the genus Actinomyces between primary endodontic infections and secondary endodontic infections). Results of the meta-analysis show how bacteria of the genus Actinomyces are present in primary and secondary intraradicular infections and in those with persistence with a prevalence (ratio between teeth with actinomyces and teeth with infection) ranging from 0.091 up to 0.130 depending on the subgroups analyzed.

Identification of bacteria associated with periapical abscesses of primary teeth by sequence analysis of 16S rDNA clone libraries

OBJECTIVE

This study aims to detect the predominant bacteria in acute periapical abscesses of primary teeth using culture-independent molecular methods based on 16S ribosomal DNA cloning.

METHODS

Purulent material was collected from nine children diagnosed with abscesses of endodontic origin. DNA was extracted and the 16S rRNA gene amplified with universal primer pairs 27F and 1492R. Amplified genes were cloned, sequenced by Applied Biosystems, and identified by comparison with known 16S rRNA gene sequences.

RESULTS

Bacterial DNA was present in all nine purulence samples. A total of 681 clones were classified into 8 phyla, 78 genera, and 125 species/phylotypes. The phyla were Firmicutes, Proteobacteria, Fusobacteria, Bacteroidetes, Actinobacteria, Tenericutes, Deinococcus-Thermus, and Spirochaetes. The most dominant genera were Streptococcus (13.3%), Fusobacterium (11.8%), Parvimonas (7.8%), Prevotella (6.7%), Sphingomonas (5.8%), and Hafnia (5.2%). Fusobacterium nucleatum (11.5%), Parvimonas micra (7.8%), Streptococcus intermedius (6.6%), Sphingomonas echinoides (5.3%), Hafnia alvei (5.2%), and Citrobacter freundii (4.9%) were the most common species/phylotypes. Among these species/phylotypes, F.nucleatum was the most prevalent (7/9). C. freundii, Carnobacterium maltaromaticum, and H. alvei were seldom detected species in acute periapical abscesses but had relatively high abundance and prevalence.

CONCLUSION

Acute periapical abscesses are polymicrobial with certain prevalent bacteria, especially anaerobic bacterium. The most predominant and prevalent bacteria of acute periapical abscesses in children was F. nucleatum.

Epstein-Barr virus reactivation by persistent apical periodontal pathogens

AIM

To assess whether Epstein-Barr virus (EBV) reactivation is triggered by persistent apical periodontitis-related microbes using in vitro and ex vivo methodologies.

METHODOLOGY

Surgically removed human periapical granulomas (n = 50) and healthy gingival tissues (n = 10) were analysed to determine the presence of EBV and seven persistent apical periodontitis-related microbes. In addition, real-time polymerase chain reaction was used to detect the mRNA expression of BZLF-1, an immediate-early gene of EBV. Expression of latent membrane protein (LMP)-1 and ZEBRA, an early lytic protein of EBV encoded by BZLF-1, was also examined using triple-colour immunofluorescence staining. n-Butyric acid produced by the microbes was quantified, and luciferase assays were performed in association with bacterial lysates. In addition, Daudi cells were cultured with bacterial lysates, and the expression levels of BZLF-1 mRNA and ZEBRA protein were determined.

RESULTS

EBV DNA and BZLF-1 mRNA were detected in 47 out of 50 periapical granulomas, but not in healthy gingival tissues. The EBV DNA copy number and the number of Fusobacterium nucleatum were significantly positively correlated with BZLF-1 expression in periapical granulomas. The number of Prevotella intermedia was slightly correlated with BZLF-1 expression; however, the other microbes were not. CD79a-positive B cells in periapical granulomas, but not those in healthy gingival tissues, expressed both LMP-1 and ZEBRA. n-Butyric acid production was the highest in F. nucleatum and the lowest in P. intermedia. Enterococcus faecalis, Candida albicans and the other tested microbes did not produce n-butyric acid. An F. nucleatum lysate exhibited significantly increased BZLF-1-luciferase activity in the same manner of commercial butyric acid, whereas P. intermedia did not. F. nucleatum also induced the expression of BZLF-1 mRNA and ZEBRA protein by Daudi cells, indicating that EBV reactivation was induced.

CONCLUSION

Among the persistent apical periodontitis-related bacteria that were tested, F. nucleatum most strongly reactivated latent EBV, whereas E. faecalis and C. albicans as well as the other microbes did not.

Microbiota in Human Periodontal Abscess Revealed by 16S rDNA Sequencing

Periodontal abscess is an oral infective disease caused by various kinds of bacteria. We aimed to characterize the microbiota composition of periodontal abscesses by metagenomic methods and compare it to that of the corresponding pocket and healthy gingival crevice to investigate the specific bacteria associated with this disease. Samples from abscess pus (AB), periodontal pocket coronally above the abscess (PO), and the gingival crevice of the periodontal healthy tooth were obtained from 20 periodontal abscess patients. Furthermore, healthy gingival crevice samples were obtained from 25 healthy individuals. Bacterial DNA was extracted and 16S rRNA gene fragments were sequenced to characterize the microbiota and determine taxonomic classification. The beta-diversity analysis results showed that the AB and PO groups had similar compositions. Porphyromonas gingivalis, Prevotella intermedia, and other Prevotella spp. were the predominant bacteria of human periodontal abscesses. The abundances of Filifactor alocis and Atopobium rimae were significantly higher in periodontal abscesses than in the periodontal pocket, suggesting their association with periodontal abscess formation. In conclusion, we characterized the microbiota in periodontal abscess and identified some species that are positively associated with this disease. This provides a better understanding of the components of periodontal abscesses, which will help facilitate the development of antibiotic therapy strategies.

In Vitro Effect of Er:YAG Laser on Different Single and Mixed Microorganisms Being Associated with Endodontic Infections

Objective: The purpose of this in vitro study was to evaluate the antimicrobial effect of activated irrigation with different modes of erbium-doped yttrium aluminum garnet (Er:YAG) laser application on microorganisms related to secondary endodontic infection. Background: Er:YAG laser has been recommended as an adjuvant tool for root canal disinfection during endodontic treatment. Materials and methods: Laser-activated irrigation (LAI) with 300 or 600 μm tips were tested with or without intermittent irrigation with 0.9% sodium chloride (NaCl) solution against different microorganisms (five single strains and dual species (Streptococcus gordonii combined with Actinomyces oris or Fusobacterium nucleatum) in root canals after 3 days of incubation. In a 21-day infection model, LAI was used together with intermittent rinsing with sodium hypochlorite (NaOCl) against the dual-species mixtures; here the incidence of microbial regrowth after up to 7 days was monitored. Results: In the 3-day root infection model, LAI protocols did not show any significant reduction of the microbial load when compared with manual irrigation with saline solution. In the 21-day infection, S. gordonii combined with A. oris were not detectable anymore after applying the LAI protocol with a 600 μm tip (30 mJ/10 pps) up to 7 days after treatment. Conclusions: Application of LAI with a 600 μm tip by using an Er:YAG laser might be advantageous in treatment of endodontic infections.

Apical periodontitis associated with a calculus-like deposit: A case report of a rare fan-shaped manifestation

Introduction

Bacterial biofilms can be calcified. Granulomas or cystic lesions are the most commonly found entities in endodontics. Surprisingly, this case report presents a rare radiopaque image, in a fan shape, of a calculus-like deposit in the periapical region of the maxillary left central incisor.

Case presentation

A 34-year-old male, with a history of trauma, presented with apical periodontitis associated with an uncommon image, similar to a calculus-like deposit adhered to the apical region of the maxillary left central incisor. Nonsurgical endodontic intervention was performed, followed by apicoectomy and histopathological analysis of the collected material. The results of the biopsy were not compatible with a cyst or granuloma but showed fibrous connective tissue with calcified areas.

Discussion

Correct diagnosis in endodontics is possible with a well-conducted anamnesis, complementary imaging exams and, in some cases, histopathological analysis. The periapical calculus-like deposit, associated with a periapical radiolucent lesion, was a result of the body's fight for healing, producing unusual radiopacity.

Conclusion

The presence of the calculus-like deposit in a fan shape at the root surface represented dystrophic calcification as a manifestation of the attempt to heal. In the present case, apicoectomy and tissue biopsy for histological evaluation were fundamental for the correct diagnosis.

•

Root canal is critical area for biofilm development.

•

Extraradicular biofilm on the surface of the root may cause persistent periapical lesions.

•

Uncommon radiopaque image association with endodontic periapical lesions was related.

•

Persistent periapical lesions associate with extraradicular biofilm represents a challenge for Endodontic treatment.

•

Only surgical resection was capable to repair the injury.

Compounds from Olea europaea and Pistacia lentiscus inhibit oral microbial growth

BACKGROUND

In view of the increasing antibiotic resistance, the introduction of natural anti-infective agents has brought a new era in the treatment of bacterially derived oral diseases.

METHODS

The aim of this study was to investigate the antimicrobial potential of five natural constituents of Olea europaea (oleuropein, maslinic acid, hydroxytyrosol, oleocanthal, oleacein) and three compounds of Pistacia lentiscus (24Z-isomasticadienolic acid, oleanolic acid, oleanonic aldehyde) against ten representative oral bacterial species and a Candida albicans strain. After the isolation and quality control of natural compounds, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assay were performed.

RESULTS

Among all O. europaea-derived constituents, maslinic acid was the most active (MIC = 4.9-312 μg mL^- 1, MBC = 9.8-25 μg mL^- 1) one against oral streptococci and anaerobic pathogenic bacteria (Porphyromonas gingivalis, Fusobacterium nucleatum, Parvimonas micra), while oleuropein, hydroxytyrosol, oleocanthal and oleacein showed milder, yet significant effects against P. gingivalis and F. nucleatum. Among all P. lentiscus compounds, oleanolic acid was the most effective one against almost all microorganisms with MIC values ranging from 9.8 μg mL^- 1 (P. gingivalis) to 625 μg mL^- 1 (F. nucleatum, P. micra). In the presence of 24Z-isomasticadienolic acid, a mean inhibitory concentration range of 2.4 μg mL^- 1 to 625 μg mL^- 1 was observed for strict anaerobia. The MIC value for 24Z-isomasticadienolic acid was estimated between 39 μg mL^- 1 (Streptococcus sobrinus, Streptococcus oralis) and 78 μg mL^- 1 (Streptococcus mutans). All tested compounds showed no effects against Prevotella intermedia.

CONCLUSIONS

Overall, maslinic acid and oleanolic acid exerted the most significant inhibitory activity against the tested oral pathogens, especially streptococci and anaerobic oral microorganisms.

Etiologic role of root canal infection in apical periodontitis and its relationship with clinical symptomatology

Evidence shows the polymicrobial etiology of endodontic infections, in which bacteria and their products are the main agents for the development, progression, and dissemination of apical periodontitis. Microbial factors in necrotic root canals (e.g., endotoxin) may spread into apical tissue, evoking and supporting a chronic inflammatory load. Thus, apical periodontitis is the result of the complex interplay between microbial factors and host defense against invasion of periradicular tissues. This review of the literature aims to discuss the complex network between endodontic infectious content and host immune response in apical periodontitis. A better understanding of the relationship of microbial factors with clinical symptomatology is important to establish appropriate therapeutic procedures for a more predictable outcome of endodontic treatment.

Molecular analysis of oral microflora in patients with primary Sjögren's syndrome by using high-throughput sequencing

Background

The objective of this study was to characterize the oral microflora profile of primary Sjögren's syndrome (pSS) patients, thereby revealing the connection between oral bacterial composition and dental caries, and to identify the "core microbiome" in the oral cavities of pSS patients and systemic healthy individuals by using a high-throughput sequencing technique.

Methods

Twenty-two pSS patients and 23 healthy controls were enrolled in this study. Their clinical data and oral rinse samples were collected. The V3-V4 hypervariable regions of the bacterial 16S rRNA gene of samples were amplified and analyzed by high-throughput sequencing on the Illumina Miseq PE300 platform.

Results

Both two groups were age- and sex-matched. There were significantly higher decayed, missing and filled teeth (DMFT) and decayed, missing and filled surfaces (DMFS) in the pSS group than in the control group (p < 0.01). Alpha diversity was depleted in pSS patients, compared with healthy controls (p < 0.01), while beta diversity between the two groups was not significantly different. Seven discriminative genera (LDA > 4) were found between the two groups in LEfSe (LDA Effect Size) analysis. The relative abundance of Veillonella in pSS patients was fourfold higher, while Actinomyces, Haemophilus, Neisseria, Rothia, Porphyromonas and Peptostreptococcus were significantly lower in pSS patients than in healthy controls. However, the correlation between Veillonella and DMFT/DMFS was not significant (p > 0.05). In Venn diagram analysis, nine genera shared by all samples of two groups, which comprised 71.88% and 67.64% in pSS patients and controls, respectively.

Discussion

These findings indicate a microbial dysbiosis in pSS patients; notably, Veillonella might be recognized as a biomarker in pSS patients. The core microbiome in pSS patients was similar to the systemic healthy population. These provide insight regarding advanced microbial prevention and treatment of severe dental caries in pSS patients. This study also provides basic data regarding microbiology in pSS.

Evaluation of the WaveOne Gold and One Shape New Generation in Reducing Enterococcus faecalis from Root Canal

The aim of this study was to evaluate the WaveOne Gold and One Shape New Generation systems regarding the bacterial removal from root canals infected with Enterococcus faecalis by comparing them to the conventional WaveOne and One Shape systems. Forty-eight distobuccal root canals of maxillary molars sterilized with ethylene oxide were infected with E. faecalis for 21 days, and then root canal initial bacterial sample was collected with paper cones and plated on M-enterococcus agar. The specimens were randomly divided into 4 groups according to the instrumentation: WaveOne Gold, One Shape New Generation, WaveOne and One Shape. After instrumentation, samples were collected with use of scraping and paper cones at immediate and 7 days after instrumentation. The bacterial reduction was calculated and then made intragroup analysis by Friedman test and intergroup analysis by Kruskal-Wallis with Dunn's post-hoc test, all at 5% significance. All techniques significantly reduced the number of bacteria in the root canal (p<0.05). WaveOne Gold and One Shape New Generation promoted higher bacterial reduction than WaveOne and One Shape systems (p<0.05), but no significant difference was found between WaveOne Gold and One Shape New Generation or between WaveOne and One Shape (p>0.05). Novel single-file systems promote better bacterial removal than the conventional single-file systems.

Efficacy of relacin combined with sodium hypochlorite against Enterococcus faecalis biofilms

Objective

Relacin is a synthetic molecule that targets RelA, an essential protein in a conserved bacterial stress response system. It was shown to inhibit bacterial growth. The aims of this study were to evaluate the antimicrobial effect of relacin combined with sodium hypochlorite (NaOCl) on Enterococcus faecalis biofilms and to evaluate the cytotoxicity of relacin.

Material and Methods

48-h E. faecalis OG1RF biofilms were treated by various concentrations of relacin in order to determine its inhibitory concentration. Then, the 48-h biofilms were treated either with 1-min NaOCl (0.01%, 0.05%) alone, or in combination of relacin. As a means of comparison, the biofilms of ΔrelA were also treated by 1-min NaOCl (0.01%, 0.05%, 0.25%). The treatment efficacy was determined by agar plate count assays. The cytotoxicity of relacin was examined on human gingival epithelial cells Ca9-22 and murine fibroblasts NIH-3T3 by a methyl thiazolyltetrazolium (MTT) assay and a lactate dehydrogenase assay. Statistical analysis was performed by one-way or two-way analysis of variance (ANOVA) with Bonferroni’s post-hoc test and an independent Student’s t-test. A significance level of p<0.05 was used.

Results

Relacin inhibited the growth of OG1RF biofilms partially at 8 mM and fully at 14 mM. The relacin (14 mM) and NaOCl combined treatment resulted in significantly higher treatment efficacy than NaOCl treatment alone. At 0.05% NaOCl, the combined treatment resulted in 5.65 (±0.19) log reduction in biofilm viability. The ΔrelA biofilms were more susceptible to NaOCl treatment than the wild type biofilms at 0.25% NaOCl. Relacin at 14 mM was not toxic to host epithelial cells and fibroblasts.

Conclusions

The combination of relacin with a low concentration of NaOCl was effective and not cytotoxic.

Metagenomic study of bacterial microbiota in persistent endodontic infections using Next-generation sequencing

AIM

To determine the bacterial microbiota in root canals associated with persistent apical periodontitis and their relationship with the clinical characteristics of patients using next-generation sequencing (NGS).

METHODOLOGY

Bacterial samples from root canals associated with teeth having persistent apical periodontitis were taken from 24 patients undergoing root canal retreatment. Bacterial DNA was extracted, and V3-V4 variable regions of the 16S rRNA gene were amplified. The amplification was deep sequenced by Illumina technology to establish the metagenetic relationships among the bacterial species identified. The composition and diversity of microbial communities in the root canal and their relationships with clinical features were analysed. Parametric and nonparametric tests were used to analyse differences between patient characteristics and microbial data.

RESULTS

A total of 86 different operational taxonomic units (OTUs) were identified and Good's nonparametric coverage estimator method indicated that 99.9 ± 0.00001% diversity was recovered per sample. The largest number of bacteria belonged to the phylum Proteobacteria. According to the medical history from the American Society of Anesthesiologists (ASA) Classification System, ASA II-III had higher richness estimates and distinct phylogenetic relationships compared to ASA I individuals (P < 0.05). Periapical index (PAI) score 5 was associated with increased microbiota diversity in comparison to PAI score 4, and this index was reduced in symptomatic patients.

CONCLUSIONS

Based on the findings of this study, it is possible to suggest a close relationship between several clinical features and greater microbiota diversity with persistent endodontic infections. This work provides a better understanding on how microbial communities interact with their host and vice versa.

Mechanism of bioactive molecular extraction from mineralized dentin by calcium hydroxide and tricalcium silicate cement

OBJECTIVES

The objective of the present study was to elucidate the mechanism of bioactive molecule extraction from mineralized dentin by calcium hydroxide (Ca(OH)₂) and tricalcium silicate cements (TSC).

METHODS AND RESULTS

Transmission electron microscopy was used to provide evidence for collagen degradation in dentin surfaces covered with Ca(OH)₂ or a set, hydrated TSC for 1-3 months. A one micron thick collagen degradation zone was observed on the dentin surface. Fourier transform-infrared spectroscopy was used to identify increases in apatite/collagen ratio in dentin exposed to Ca(OH)₂. Using three-point bending, dentin exposed to Ca(OH)₂ exhibited significant reduction in flexural strength. Using size exclusion chromatography, it was found that the small size of the hydroxyl ions derived from Ca(OH)₂ enabled those ions to infiltrate the intrafibrillar compartment of mineralized collagen and degrade the collagen fibrils without affecting the apatite minerals. Using ELISA, TGF-β1 was found to be extracted from dentin covered with Ca(OH)₂ for 3 months. Unlike acids that dissolve the mineral component of dentin to release bioactive molecules, alkaline materials such as Ca(OH)₂ or TSC released growth factors such as TGF-β1 via collagen degradation.

SIGNIFICANCE

The bioactive molecule extraction capacities of Ca(OH)₂ and TSC render these dental materials excellent for pulp capping and endodontic regeneration. These highly desirable properties, however, appear to be intertwined with the untoward effect of degradation of the collagen matrix within mineralized dentin, resulting in reduced flexural strength.

Profiling of Oral Microbiota in Early Childhood Caries Using Single-Molecule Real-Time Sequencing

Background: Alterations of oral microbiota are the main cause of the progression of caries. The goal of this study was to characterize the oral microbiota in childhood caries based on single-molecule real-time sequencing. Methods: A total of 21 preschoolers, aged 3-5 years old with severe early childhood caries, and 20 age-matched, caries-free children as controls were recruited. Saliva samples were collected, followed by DNA extraction, Pacbio sequencing, and phylogenetic analyses of the oral microbial communities. Results: Eight hundred and seventy six species derived from 13 known bacterial phyla and 110 genera were detected from 41 children using Pacbio sequencing. At the species level, 38 species, including Veillonella spp., Streptococcus spp., Prevotella spp., and Lactobacillus spp., showed higher abundance in the caries group compared to the caries-free group (p < 0.05). The core microbiota at the genus and species levels was more stable in the caries-free micro-ecological niche. At follow-up, oral examinations 6 months after sample collection, development of new dental caries was observed in 5 children (the transitional group) among the 21 caries free children. Compared with the caries-free children, in the transitional and caries groups, 6 species, which were more abundant in the caries-free group, exhibited a relatively low abundance in both the caries group and the transitional group (p < 0.05). We conclude that Abiotrophia spp., Neisseria spp., and Veillonella spp., might be associated with healthy oral microbial ecosystem. Prevotella spp., Lactobacillus spp., Dialister spp., and Filifactor spp. may be related to the pathogenesis and progression of dental caries.