Primary Root Canal Infections Research Articles

Comparison of antimicrobial efficacy of green tea extract and Triphala as root canal irrigants against Fusobacterium nucleatum using real-time polymerase chain reaction – An in vitro study

Aim: Fusobacterium nucleatum has gained attention in the endodontic literature as it is a predominant microorganism in primary, secondary, and persistent root canal infections. Current irrigants have lot of drawbacks and are unlikely to predictably achieve a bacteria-free root canal system, which can lead to these failures. Herbal alternatives are now gaining popularity in the field of endodontics, paving a new way in the disinfection of root canals. The aim of this study is to evaluate the antimicrobial efficacy of green tea extract and Triphala as root canal irrigants against F. nucleatum using real-time Polymerase chain reaction (PCR). Methods: Extracted teeth were taken and inoculated with F. nucleatum, which was grown in a Mueller–Hinton agar plate under anaerobic conditions. The samples were cleaned and shaped and irrigated with green tea extract, Triphala extract, and dimethyl sulfoxide, which were compared to the widely used irrigant, sodium hypochlorite. Cycle threshold value was used to calculate the efficacy of the irrigant against F. nucleatum after which the samples were subjected to reverse transcriptase PCR. The data were analyzed and the data between the group were compared using the one-way ANOVA followed by a post hoc Tukey’s test. Results: Triphala extract demonstrated high antimicrobial activity against F. nucleatum1. It revealed statistically significant differences between Triphala extract and sodium hypochlorite (NaOCL) (P = 0.001). Green tea extract also displayed antimicrobial activity. Both the Triphala and green tea extracts showed a significant difference (P < 0.001). Conclusion: Triphala extract showed better antibacterial efficacy when compared to 3% NaOCl and green tea extract against F. nucleatum.

The root canal microbiome diversity and function. A whole-metagenome shotgun analysis.

To evaluate the root canal microbiome composition and bacterial functional capability in cases of primary and secondary apical periodontitis utilizing whole-metagenome shotgun sequencing. Twenty-two samples from patients with primary root canal infections, and 18 samples obtained from previously treated teeth currently diagnosed with apical periodontitis were analysed with whole-metagenome shotgun sequencing at a depth of 20 M reads. Taxonomic and functional gene annotations were made using MetaPhlAn3 and HUMAnN3 software. The Shannon and Chao1 indices were utilized to measure alpha diversity. Differences in community composition were evaluated utilizing analysis of similarity (ANOSIM) using Bray-Curtis dissimilarities. The Wilcoxon rank sum test was used to compare differences in taxa and functional genes. Microbial community variations within a community were significantly lower in secondary relative to primary infections (alpha diversity p = .001). Community composition was significantly different in primary versus secondary infection (R = .11, p = .005). The predominant taxa observed among samples (>2.5%) were Pseudopropionibacterium propionicum, Prevotella oris, Eubacterium infirmum, Tannerella forsythia, Atopobium rimae, Peptostreptococcus stomatis, Bacteroidetes bacterium oral taxon 272, Parvimonas micra, Olsenella profusa, Streptococcus anginosus, Lactobacillus rhamnosus, Porphyromonas endodontalis, Pseudoramibacter alactolyticus, Fusobacterium nucleatum, Eubacterium brachy and Solobacterium moorei. The Wilcoxon rank test revealed no significant differences in relative abundances of functional genes in both groups. Genes with greater relative abundances (top 25) were associated with genetic, signalling and cellular processes including the iron and peptide/nickel transport system. Numerous genes encoding toxins were identified: exfoliative toxin, haemolysins, thiol-activated cytolysin, phospholipase C, cAMP factor, sialidase, and hyaluronic glucosaminidase. Despite taxonomic differences between primary and secondary apical periodontitis, the functional capability of the microbiomes was similar.

Ex vivo Detection of Amyloid-β in Naturally Formed Oral Biofilm.

Oral infection has been implicated in the possible etiology of Alzheimer's disease. To detect amyloid-β (Aβ) within microbial biofilms. Freshly extracted teeth (N = 87) with periodontal disease were separated into Group A (N = 11), with primary root canal infection and Group B (N = 21) with failed endodontic treatment identified by the presence of, gutta percha root filling. Biofilm characteristics were observed by scanning electron microscopy (SEM). Demineralized paraffin wax embedded tooth sections and mineralized calculus biofilm were immunostained with the anti-Aβ antibody. The gutta perchas were processed either for on-section acrylic resin tissue immunocolloidal gold silver staining (IGSS) using the anti-Aβ antibody or in Araldite resin for ultrastructure. SEM demonstrated calculus and gutta percha in situ harboring a polymicrobial biofilm featuring extracellular polymeric substance (EPS) and water channels. Immunohistochemistry on rehydrated paraffin wax tooth sections from Group A, demonstrated Aβ staining on external (calculus and plaque) and all intracanal infected regions. In Group B, the gutta percha biofilm IGSS gave an inconclusive result for Aβ. Transmission electron microscopy of selected teeth with infected intra-canals (Group A) and 20% of gutta percha biofilm (Group B) EPS contained electron dense fibrils of variable sizes, some of which were typical of human Aβ fibrils. This study detected both soluble and insoluble Aβ fibrils within the EPS of periodontal and endodontic natural biofilm, strongly suggesting its role as an antimicrobial peptide in combatting local infection, with potential risk for cross-seeding into the brain for AD development.

Taxonomic abundance in primary and secondary root canal infections.

To evaluate the root canal microbiome composition in cases of primary and secondary apical periodontitis. Thirty-nine samples from patients with primary root canal infections obtained before root canal treatment, and 40 samples obtained during root-end resection procedures from previously filled cases with apical periodontitis were evaluated using 16S rRNA next-generation sequencing analysis (NGS). Demographic and clinical factors included age, sex, infection type, percussion sensitivity, and presence of pain. Differences in abundances of genera were evaluated using Kruskal-Wallis test. Alpha and beta diversity indices were calculated using mothur. The Shannon and Chao1 indices were used to measure alpha diversity. The Bray-Curtis dissimilarity was used to measure beta diversity. Differences in community composition were evaluated using analysis of similarity (ANOSIM) with Bonferroni correction for multiple comparisons. Significantly fewer operational taxonomic units values were observed from samples from secondary infections (p < .0001). While no significant differences were observed in the Chao 1 index between primary and secondary infections, the Shannon alpha diversity was significantly lower in secondary relative to primary infections (p=.008). Among samples, sex, age (adult vs. older adult), percussion sensitivity, and presence of pain all showed no significant effects on community composition via an analysis of similarity (ANOSIM). However, community composition was significantly different depending on whether the sample was from a primary or secondary infection (R=.051, p=.03). Nine microbial genera comprised the predominant taxa observed among samples (>3.3%) and included Parvimonas, Fusobacterium, Campylobacter, Arachnia, Eubacterium, Prevotella, Peptostreptococcus, Fretibacterirum, and Pseudoramibacter. Significantly greater relative abundances of Prevotella, Peptostreptococcus, Veillonella, Lactucaseibacillus, and Dialister were observed in primary infections. Primary endodontic infections are more diverse than secondary infections. The microbial composition is not associated with the clinical manifestations of apical periodontitis.

Impact of N-acetylcysteine (NAC) and calcium hydroxide intracanal medications in primary endodontic infection: a randomized clinical trial.

This RCT investigated the impact of N-acetylcysteine (NAC) and calcium hydroxide [Ca(OH)2] intracanal medications (ICMs) in primary endodontic infection with apical periodontitis (PEIAP). Thirty-six teeth with PEIAP were randomly divided into groups according to the ICM: NAC, Ca(OH)2 + saline solution (SSL), and Ca(OH)2 + 2% chlorhexidine-gel (2% CHX-gel) (all, n = 12). Root canal samples (RCSs) were collected before (s1) and after instrumentation (s2) and after 14days of ICM (s3). Chemomechanical preparation (CMP) was performed with a Reciproc file and 2.5% NaOCl. Checkerboard DNA-DNA hybridization was used to assess 40 target bacteria species. At s1, bacterial DNA was detected in 100% of RCSs (36/36). All 40 bacterial species were found in PEIAP. The mean number of species per RCS was 17.92 ± 13.18. The most frequent bacteria were S. mitis (65%), E. nodatum (63%), E. faecalis (63%), F. nucl sp vicentii (58%), T. forsythia (58%), and F. periodonticum (56%). CMP reduced the mean number of species per RCS to 6.8 ± 2.36 (p < 0.05). At s3, the intragroup analysis revealed a broader antimicrobial activity for Ca (OH)2 + 2% CHX-gel and NAC than Ca(OH)2 + SSL (p < 0.05). NAC eliminated 8/12 bacteria species resistant to both Ca (OH)2 ICMs, including P. micra, P. nigrescens, T. denticola, A. israelii, P. endodontalis, P. acnes, C. ochracea, and E. corrodens. Ca (OH)2 + 2% chlorhexidine gel (2% CHX gel) showed a greater bacterial elimination over the number of bacterial species; however, NAC eliminated 8/12 bacteria species resistant to both Ca (OH)2 ICMs (RBR-3xbnnn). The use of intracanal medication with a broad antimicrobial activity can optimize root canal disinfection. Ca(OH)2 + 2% CHX gel and NAC showed a broader antimicrobial activity than Ca(OH)2 + SSL against endodontic pathogens in primary root canal infection. Brazilian Registry of Clinical Trials (REBEC), No. RBR-3xbnnn.

A comprehensive in vitro comparison of the biological and physicochemical properties of bioactive root canal sealers

ObjectivesTo evaluate the biological and physicochemical features of bioactive root canal sealers.Materials and methodsHuman periodontal ligament fibroblasts (hPDLF) and human osteoblasts (hOB) were exposed to eluates of three bioactive root canal sealers, GuttaFlow® bioseal (GF), BioRoot™ RCS (BR), and TotalFill® BC Sealer (TF), and the epoxy resin–based sealer AH plus® (AH). Cytotoxicity and cellular inflammatory response were evaluated. The osteogenic potential was examined using human mesenchymal stem cells (hMSC). Film thickness, flowability, and pH were assessed. Root canal treatment was performed on human extracted teeth to evaluate the sealers’ tightness towards bacterial penetration. The antibacterial activity against common pathogens in primary root canal infections was tested.ResultsAH was severely cytotoxic to hPDLF and hOB (p < 0.001). The bioactive sealers were generally less cytotoxic. IL-6 levels in hPDLF were elevated in the presence of AH (p < 0.05). AH and GF suppressed IL-6 production in hOB (p < 0.05). AH and BR stimulated the PGE2 production in hPDLF and hOB (p < 0.05). BR was the only sealer that led to calcium deposits in hMSC (p < 0.05). TF and AH showed the lowest film thickness and the highest flowability. Bacterial tightness was best in teeth filled with AH and BR. All sealers showed similar antimicrobial activity, but the overall antimicrobial efficacy was moderate as the bacteria were reduced by just one log scale (p < 0.05).ConclusionsThis study revealed favorable in vitro results regarding the biocompatibility of the bioactive root canal sealers.Clinical relevanceBioactive root canal sealers may be a useful alternative to epoxy resin–based sealers.

Residual Bacteriome after Chemomechanical Preparation of Root Canals in Primary and Secondary Infections

IntroductionSecondary infections may be linked to the presence of residual microorganisms within dental root canals. The purpose of this study was to investigate the bacterial composition of primary and secondary root canal infections before and after chemomechanical treatment. MethodsSamples were collected before chemomechanical preparation (S1) and before obturation (S2) from 19 subjects (10 primary and 9 secondary infections). DNA was extracted, and the V3/V4 region of the 16S ribosomal RNA gene was amplified using the 347 F/803R primers and paired-end sequenced using the MiSeq (Illumina, San Diego, CA) instrument. ResultsSequencing analysis yielded partial 16S ribosomal RNA gene sequences that were taxonomically classified into 10 phyla and 143 genera. The most prevalent phyla in the S1 and S2 samples were Firmicutes and Bacteroides; however, when comparing between sample groups, Proteobacteria seem to have been enriched in secondary infections. The dominant genera in the primary S1 samples were Bacillus, Streptococcus, and Prevotella, whereas Bacillus, Streptococcus, and Selenomonas dominated the secondary infection S1 samples. Bacillus and Marinilactibacillus were the most dominant genera in the primary and secondary S2 samples. The mean number of operational taxonomic units per sample was 32,656 (±12,124 SD) and 37,113 (±16,994 SD) in the S1 and S2 samples, respectively. Alpha and beta diversities presented the same pattern within samples from both groups. ConclusionsGreat interindividual variations in the bacterial composition of the root canal biofilms were observed. There was no difference in the bacterial composition before and after treatment, although some genera survived and seem to be part of a residual microbiome. Our findings revealed a high diversity of the bacterial communities present in root canal infections after chemomechanical treatment, although the majority of the taxa detected were in low abundance.

Efek Ekstrak Daun Pluchea indica terhadap Hambatan Pertumbuhan Porphyromonas gingivalis

Background: Porphyromonas gingivalis is one of the bacteria causes primary root canal infections. Bacterial elimination using root canal irrigation agents is important in successful root canal treatment. NaOCl as the gold standard is known to have disadvantages such as irritating periapical tissue. Active compounds in Pluchea indicaleaves such as flavonoids, tannins and terpenoids posses antibacterial effects. Objectives: To determine the effect of Pluchea indica leaves extract on P. gingivalis growth inhibition. Method: This study is an in vitro experimental laboratory of agar well difusion method used Pluchea indica leaves extract in several concentrations (6,25%, 12,5%, 25%, 50%, and 100%) and NaOCl 5,25% as a positive control. The sample in this study was P. gingivalis. Result: This study showed that the diameter of inhibitor zone against P. gingivalis was exists on concentration of 50% and 100%, their values are 10,216 mm and 13,023 mm. The positive control showed an average inhibition zone of 12.803mm. Conclusion: Pluchea indica leaves extract showed antibacterial effect against P.gingivalis at the concentration of 50% and 100%. The 100% concentration had the largest inhibition zone and was equivalent to positive control in inhibiting P.gingivalis.

Effect of passive ultrasonic activation on microorganisms in primary root canal infection: a randomized clinical trial.

Objective:This clinical study sought to evaluate the effectiveness of passive ultrasonic activation (PUA) in eliminating microorganisms in primary endodontic infection (PEI) after instrumentation of root canals using microbiological culture and checkerboard DNA-DNA hybridization.Methodology:Twenty root canals with PEI and apical periodontitis were selected. The root canals were instrumented and then randomly divided into 2 groups, according to the irrigation method: PUA and conventional needle irrigation (CNI). Microbiological samples were collected before instrumentation (S1), after instrumentation (S2) and after irrigation with 17% EDTA (S3). The samples were subjected to anaerobic culture technique and checkerboard DNA-DNA hybridization analysis.Results:A statistically significant difference was found between CNI (23.56%) and PUA (98.37%) regarding the median percentage values for culturable bacteria reduction (p<0.05). In the initial samples, the most frequently detected species was S. constellatus (50%), and after root canal treatment was E. faecalis (50%).Conclusion:Both treatments significantly decreased the number of bacterial species compared with the initial sample. However, no statistical difference in the total microbial load between PUA and CNI groups was detected. The number of cultivable anaerobic bacteria reduced significantly using PUA, and the bacterial composition and number of bacterial species after using either CNI or PUA was similar.

Multiplex polymerase chain reaction detection of selected bacterial species from symptomatic and asymptomatic non-vital teeth with primary endodontic infections.

The aim of the present study was to investigate the presence of selective anaerobic microorganisms in primary root canal infections of symptomatic and asymptomatic non-vital teeth with periapical pathosis using multiplex polymerase chain reaction. A total of 100 root canal samples (50 from symptomatic and 50 from asymptomatic teeth) were obtained from patients with primary endodontic infections. DNA extracted from the samples was amplified by using specific primers for the 16S rRNA gene of each bacterium, and semiquantification was done to analyze the prevalence of microorganisms and their correlation to clinical features. Treponema denticola (T.denticola) was present in 21 (42%) and 29 (58%) samples in the symptomatic and asymptomatic groups, respectively. Tannerella forsythia, Porphyromonas gingivalis (P.gingivalis), and Fusobacterium nucleatum (F.nucleatum) were significantly high (P<.05) in the symptomatic group, whereas Prevotella intermedia was significantly high (P<.05) in the asymptomatic group. The mean counts of T.denticola and F.nucleatum were significantly high (P<.05) in the symptomatic group. For symptoms, P.gingivalis, T.denticola, and F.nucleatum were significantly associated with clinical features. Significant differences exist in the bacterial composition between asymptomatic and symptomatic primary endodontic infections. As well as presence of pathogens, other factors, such as the phenotypic trait of bacteria and interactions among bacterial members, might play a determining role in the pathogenicity of primary endodontic infections.

Comparison of Antibacterial Effect of Four Irrigation Solutions in Primary Root Canal Infections: A Clinical Study.

Reducing the bacterial count from the root canal system is one of the main stages in root canal treatment. The aim of the present clinical study was to compare the antibacterial effect of four intracanal irrigants in primary endodontic infections using both microbiological culture and quantitative Real-time Polymerase Chain Reaction (qRT-PCR) technique. Forty patients with primarily infected single rooted premolars were selected and then randomly divided into 4 groups according to the intra canal irrigant used: 5.25% Sodium hypochlorite (NaOCl), Hypoclean (Ogna Laboratori Farmaceutici, Muggiò, Italy), 2% chlorhexidine glouconate (CHX) and CHX-Plus (Vista Dental Products, Racine, WI, USA). Samples were collected before and after chemomechanical preparation and were evaluated by bacterial culture and RT-PCR technique for Enterococcus faecalis and Fusobacterium nucleatum. Data analyzed by repeated measured ANOVA. The significance level was set at 0.05. Four irrigation solutions significantly reduced the total numbers of cultivable bacteria (P<0.05). No statistically differences were found among the antibacterial effects of 5.25% NaOCl (99.93%), Hypoclean (99.94%), 2% CHX (99.77%) and CHX-Plus (99.83%) in reducing cultivable bacteria. Enterococcus faecalis and Fusobacterium nucleatum were no longer detected after preparation using four irrigants (100% reduction). All tested irrigants including 5.25% NaOCl, Hypoclean, 2% CHX and CHX-Plus significantly reduced the number of bacterial colonies in primary endodontic infections.

Can the Enterococcus faecalis identified in the root canals of primary teeth be a cause of failure of endodontic treatment?

Objective: This study investigated the presence of Enterococcus faecalis in primary teeth with primary root canal infections and related to the possible failure of pulpectomy outcome after 36 months.Material and methods: Root canal samples were obtained from 25 out of 244 patients using the sterile paper cone method. The identification of E. faecalis was done with culture and molecular tests using species-specific 16S rRNA gene-based polymerase chain reaction (PCR). After 36 months, the pulpectomy outcome was evaluated.Results: Enterococcus faecalis was found in five (20%) samples, and dental caries were the cause of primary infection in all of them. Pulpectomy outcome was evaluated only in teeth that completed the entire clinical protocol and were followed up to 36 months (n = 8). From these, 75% (n = 6) were successful and 25% (n = 2) failed. E. faecalis was present in 50% of both successful and failed cases.Conclusions: Enterococcus faecalis was not related to the failure of endodontic treatment of primary teeth.

OMICs in Cariology and Endodontology – what have we learned so far?

ABSTRACTDuring the last decade, OMICs techniques have conquered the field of oral microbiology. This has resulted in an exponential growth of publications on microbiome related to different stages of caries process, as well as on primary and recurrent root canal infections. But have these technological advances brought us any groundbreaking insights that would help a clinician in choosing the right treatment or prevention strategies? In this presentation the current knowledge on microbiome related to Cariology and Endodontology fields will be critically assessed. Then the potential pitfalls and shortcomings of the studies using OMICs approaches will be discussed and future directions will be highlighted.

Fungi in endodontic infections.

Fungi are chemoorganotroph eukaryotic microorganisms that can take part in endodontic infections and thereby may participate in the etiology of periradicular diseases. They possess virulence attributes--including adaptability to a variety of environmental conditions, adhesion to a variety of surfaces, the production of hydrolytic enzymes, morphologic transition, biofilm formation, and evasion and immunomodulation of the host defense--that may play a role in the pathogenesis of periradicular diseases. Fungi have occasionally been found in primary root canal infections, but they seem to occur more often in the root canals of obturated teeth in which treatment has failed. Candida albicans is by far the fungal species most commonly isolated from infected root canals, and this species has been considered a dentinophilic microorganism because of its invasive affinity to dentin. C albicans has also been discovered to be resistant to some intracanal medicaments, such as calcium hydroxide. Its ability to invade dentinal tubules and resistance to commonly used intracanal medicaments may help to explain why C albicans has been associated with cases of persistent root canal infections. Some medicaments, such as chlorhexidine digluconate, calcium hydroxide combinations (with camphorated paramonochlorophenol or chlorhexidine), and EDTA, have the potential to be used as effective intracanal medications for patients in whom fungal infection is suspected.

Identification of presence of Candida albicans in primary root canal infections: An in vitro study

Introduction: Microorganisms are recognized as the etiological agents for the majority of pulpal and periradicular diseases. Although bacteria are most researched, the contribution of fungi in endodontic infections is neglected. However, Candida albicans is the most commonly isolated fungi from the endodontic infections. Their identification is crucial for effective diagnosis and treatment planning. Hence, this study aimed to evaluate the presence of C. albicans in primary root canal infections using culture technique. Materials and Methods: Fifty root canal samples from primary endodontic infections were collected using file and paper point following disinfection protocol. Samples were inoculated in Sabouraud dextrose agar and incubated for 2–3 days. Taxonomy was evaluated using Gram-staining and germ tube test by macroscopic examination and optical microscopy. Results: Four out of 50 samples showed positive for C. albicans. Conclusion: This study confirmed the prevalence of 8% of C. albicans in primary endodontic infection.

In mixed biofilms Enterococcus faecalis benefits from a calcium hydroxide challenge and culturing.

To evaluate the fate of Enterococcus faecalis in dual-species and multispecies biofilms after treatment with calcium hydroxide (Ca(OH)2 ). Biofilms were cultured from laboratory strains of E.faecalis and Pseudomonas aeruginosa, or from microbiota retrieved from primary root canal infections. The biofilms were then treated with Ca(OH)2 . The proportion of E.faecalis and P.aeruginosa and their susceptibility to disinfection were evaluated in a viability assay. In the mixed-species assay, the presence and proportions of E.faecalis before and after Ca(OH)2 treatment were evaluated with a quantitative polymerase chain reaction assay. Groups were compared using Mann-Whitney U-test and Student's t-tests. An α <0.05 was considered statistically significant. After Ca(OH)2 treatment in dual-species biofilms, the proportion of E.faecalis had increased (P<0.001), whereas the total number of CFUs per biofilm was equal. Enterococcus faecalis was equally susceptible to disinfection by sodium hypochlorite (NaOCl) or by chlorhexidine. Pseudomonas aeruginosa had become more susceptible to NaOCl disinfection. The root canal isolates contained no detectable amounts of E.faecalis. After biofilm culturing or Ca(OH)2 treatment, it appeared that E.faecalis must have been present in 5 of 6 (83%) root canal samples. Calcium hydroxide favours the population of E.faecalis in a dual-species biofilm. Culturing multispecies root canal isolates makes E.faecalis detectable.E.faecalis was often present in primary endodontic infections, albeit in low numbers.

Correlation between Volume of Apical Periodontitis Determined by Cone-beam Computed Tomography Analysis and Endotoxin Levels Found in Primary Root Canal Infection

IntroductionThis clinical study was conducted to correlate the levels of endotoxins and bacterial counts found in primary endodontic infection with the volume of periapical bone destruction determined by cone-beam computed tomography (CBCT) analysis. Moreover, the levels of bacteria and endotoxins were correlated with the development of clinical features. MethodsTwenty-four root canals with primary endodontic disease and apical periodontitis were selected. Clinical features such as pain on palpation, pain on percussion, and previous episode of pain were recorded. The volume (cubic millimeters) of periapical bone destruction was determined by CBCT analysis. Endotoxins and bacterial samplings were collected by using sterile/apyrogenic paper points. Endotoxins were quantified by using limulus amebocyte lysate assay (KQCL test), and bacterial count (colony-forming units [CFU]/mL) was determined by using anaerobic culture techniques. Data were analyzed by Pearson correlation and multiple logistic regression (P < .05). ResultsEndotoxins and bacteria were detected in 100% of the root canal samples (24 of 24), with median values of 10.92 endotoxin units (EU)/mL (1.75–128 EU/mL) and 7.5 × 105 CFU/mL (3.20 × 105–8.16 × 106 CFU/mL), respectively. The median volume of bone destruction determined by CBCT analysis was 100 mm3 (10–450 mm3). The multiple regression analysis revealed a positive correlation between higher levels of endotoxins present in root canal infection and larger volume of bone destruction (P < .05). Moreover, higher levels of endotoxins were also correlated with the presence of previous pain (P < .05). ConclusionsOur findings revealed that the levels of endotoxins found in root canal infection are related to the volume of periapical bone destruction determined by CBCT analysis. Moreover, the levels of endotoxin are related to the presence of previous pain.

Progression analysis of periapical periodontitis caused by repeated root canal infection with Enterococcus faecalis

Objective To develop a rat model of periapical periodontitis caused by repeated root canal infection with Enterococcusfaecalis (E.faecalis),and to evaluate the disease progression by observing the periapical lesion area, inflammation,and TNF-αexpression in the root apex.Methods Thirty Sprague Dawley rats were used in this study.The pulps of the bilateral first maxillary molar teeth of each rat were exposed,absorbent cotton with lipopolysaccharides(LPS)was implanted,and then the teeth were exposed in the oral environment for four weeks to induce periapical periodontitis of primary root canal infection with mixed bacteria.Then the root canal was subjected to disinfection treatment for two weeks,followed by inoculation with E.faecalis suspension for one week to produce repeated root canal infection model with E.faecalis for a 3- week observation.X-ray,H-E staining and immunohistochemical staining were used to observe the periapical lesion area, inflammation,and TNF-αexpression in the root apex at one week,two weeks,three weeks after establishment of repeated root canal infection model;the above parameters were also observed for periapical periodontitis caused by primary root canal infection with mixed bacteria(6weeks later)and for root canal disinfected by Ca(OH)2(for 6weeks).Results (1)Periapical periodontitis caused by repeated root canal infection with E.faecalis had gradually increased periapical lesion area,with unclear damage border;the infection reached a severe level during the 1-2weeks and became chronic inflammation at week three;and the expression of TNF-αbegan to decrease after two weeks.(2)The periapical periodontitis caused by primary root canal infection with mixed bacteria had a smaller periapical lesion area,with clear damage border,slighter infiltration of inflammatory cells,and less TNF-αexpression.(3)The periapical periodontitis with root canal disinfected by Ca(OH)2had the smallest periapical lesion area,with disappeared inflammation,slight TNF-αexpression,and hyperplasia of cementum and alveolar bone.Conclusion E.faecalis has a strong periapical damaging effect,with continuous bone absorption observed even under the chronic inflammatory status.

Antibiotic resistance genes in anaerobic bacteria isolated from primary dental root canal infections

Fourty-one bacterial strains isolated from infected dental root canals and identified by 16S rRNA gene sequence were screened for the presence of 14 genes encoding resistance to beta-lactams, tetracycline and macrolides. Thirteen isolates (32%) were positive for at least one of the target antibiotic resistance genes. These strains carrying at least one antibiotic resistance gene belonged to 11 of the 26 (42%) infected root canals sampled. Two of these positive cases had two strains carrying resistance genes. Six out of 7 Fusobacterium strains harbored at least one of the target resistance genes. One Dialister invisus strain was positive for 3 resistance genes, and 4 other strains carried two of the target genes. Of the 6 antibiotic resistance genes detected in root canal strains, the most prevalent were blaTEM (17% of the strains), tetW (10%), and ermC (10%). Some as-yet-uncharacterized Fusobacterium and Prevotella isolates were positive for blaTEM, cfxA and tetM. Findings demonstrated that an unexpectedly large proportion of dental root canal isolates, including as-yet-uncharacterized strains previously regarded as uncultivated phylotypes, can carry antibiotic resistance genes.

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.