{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,20]],"date-time":"2026-07-20T16:07:46Z","timestamp":1784563666934,"version":"3.55.0"},"reference-count":79,"publisher":"Public Library of Science (PLoS)","issue":"8","license":[{"start":{"date-parts":[[2021,8,5]],"date-time":"2021-08-05T00:00:00Z","timestamp":1628121600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:sec id=\"sec001\">\n<jats:title>Objective<\/jats:title>\n<jats:p>To assess the prevalence of unculturable bacteria in periapical abscess, radicular cyst, and periapical granuloma.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec002\">\n<jats:title>Methods<\/jats:title>\n<jats:p>PubMed, Scopus, Science Direct, and Ovid databases were systematically searched from January 1990 to May 2020. All the included studies were cross-sectional design. The risk of bias was assessed using Joanna Briggs Institute check-list. Heterogeneity was described using meta-regression and mixed-effects model for lesion, country, and sequence technique moderators. Funnel plot and unweighted Egger\u2019s regression test were used to estimate the publication bias. Microbiome data on diversity, abundance, and frequency of unculturable bacteria in the periapical lesions were reviewed, analysed, and the principal component analysis (PCA) was performed.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec003\">\n<jats:title>Results<\/jats:title>\n<jats:p>A total of 13 studies out of 14,780, were selected for the final analysis. These studies focused on the prevalence of unculturable bacteria in periapical abscesses and related lesions. Approximately 13% (95% CI: 7\u201323%) of the cumulative number of bacteria derived from periapical abscesses was unculturable. Country moderator significantly (P = 0.05) affects the diversity summary proportion. While the pooled frequency of unculturable bacteria was 8%; 95% CI: 5, 14%, the estimate of the pooled abundance of unculturable bacteria was 5%; 95% CI: 2, 12% with a significant (P = 0.05) country moderator that affects the abundance summary proportion. Of the 62 unculturable bacteria, 35 were subjected to PCA and <jats:italic>Peptostreptococcus<\/jats:italic> sp. oral clone CK035 was the most abundant species in periapical abscesses. Hybridization techniques were found to be the most reliable molecular methods in detecting the abundance and frequency of unculturable bacteria.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec004\">\n<jats:title>Conclusion<\/jats:title>\n<jats:p>The significant prevalence of unculturable bacteria in the periapical abscess, suggests that they are likely to play, a yet unknown, critical role in the pathogenesis and progression of the disease. Further research remains to be done to confirm their specific contributions in the virulence and disease progression.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pone.0255485","type":"journal-article","created":{"date-parts":[[2021,8,5]],"date-time":"2021-08-05T17:41:43Z","timestamp":1628185303000},"page":"e0255485","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":14,"title":["Prevalence of unculturable bacteria in the periapical abscess: A systematic review and meta-analysis"],"prefix":"10.1371","volume":"16","author":[{"given":"Alaa Muayad","family":"Altaie","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4682-5927","authenticated-orcid":true,"given":"Basema","family":"Saddik","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammed Amjed","family":"Alsaegh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sameh S. 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bone","volume":"7","author":"E Cotti","year":"2004","journal-title":"Endod Topics"},{"issue":"3","key":"pone.0255485.ref003","first-page":"2","article-title":"Histopathological insight into periapical lesions: An institutional study from Punjab","volume":"3","author":"B Ramanpreet","year":"2012","journal-title":"Int J Oral Maxillofac Pathol"},{"issue":"2","key":"pone.0255485.ref004","first-page":"63","article-title":"A twenty-year survey of pathologic reports of two common types of chronic periapical lesions in Shiraz Dental School","volume":"2","author":"L Safi","year":"2008","journal-title":"J Dent Res Dent Clin Dent Prospects"},{"issue":"5","key":"pone.0255485.ref005","doi-asserted-by":"crossref","first-page":"355","DOI":"10.1590\/S1678-77572006000500011","article-title":"Histomicrobiologic aspects of the root canal system and periapical lesions in dogs\u2019 teeth after rotary instrumentation and intracanal dressing with Ca(OH)2 pastes","volume":"14","author":"JA Soares","year":"2006","journal-title":"J Appl Oral Sci"},{"key":"pone.0255485.ref006","volume-title":"Application of the international classification of diseases to dentistry and stomatology: ICD-DA","author":"World Health Organization","year":"1995","edition":"3"},{"key":"pone.0255485.ref007","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1111\/j.1600-0757.1997.tb00098.x","article-title":"Apical periodontitis: A dynamic encounter between root canal infection and host response","volume":"13","author":"PN Nair","year":"2000","journal-title":"Periodontol"},{"key":"pone.0255485.ref008","volume-title":"Glossary of endodontic terms","author":"American Association of Endodontics","year":"2020","edition":"1"},{"issue":"12","key":"pone.0255485.ref009","doi-asserted-by":"crossref","first-page":"1658","DOI":"10.1016\/j.joen.2009.09.028","article-title":"Identify and define all diagnostic terms for periapical\/periradicular health and disease states","volume":"35","author":"JL Gutmann","year":"2009","journal-title":"J Endod."},{"issue":"1","key":"pone.0255485.ref010","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/S0003-9969(99)00111-9","article-title":"Development of multi-species consortia biofilms of oral bacteria as an enamel and root caries model system","volume":"45","author":"M Shu","year":"2000","journal-title":"Arch Oral Biol"},{"issue":"6","key":"pone.0255485.ref011","doi-asserted-by":"crossref","first-page":"348","DOI":"10.1177\/154411130401500604","article-title":"Pathogenesis of apical periodontitis and the causes of endodontic failures","volume":"15","author":"PN Nair","year":"2004","journal-title":"Crit Rev Oral Biol Med"},{"issue":"2","key":"pone.0255485.ref012","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1111\/j.1399-302X.1991.tb00464.x","article-title":"Aerobic and anaerobic microbiology of periapical abscess","volume":"6","author":"I Brook","year":"1991","journal-title":"Oral Microbiol Immunol"},{"issue":"2","key":"pone.0255485.ref013","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1111\/j.1399-302X.2006.00270.x","article-title":"Molecular analysis of bacteria in asymptomatic and symptomatic endodontic infections","volume":"21","author":"M Sakamoto","year":"2006","journal-title":"Oral Microbiol Immunol"},{"issue":"6","key":"pone.0255485.ref014","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1016\/0167-7799(96)10025-1","article-title":"Identifying microbial diversity in the natural environment: A molecular phylogenetic approach","volume":"14","author":"P Hugenholtz","year":"1996","journal-title":"Trends Biotechnol"},{"key":"pone.0255485.ref015","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1111\/j.1600-0757.2009.00316.x","article-title":"Molecular microbial diagnosis","volume":"51","author":"BJ Paster","year":"2000","journal-title":"Periodontol"},{"issue":"19","key":"pone.0255485.ref016","doi-asserted-by":"crossref","first-page":"5002","DOI":"10.1128\/JB.00542-10","article-title":"The human oral microbiome","volume":"192","author":"FE Dewhirst","year":"2010","journal-title":"J Bacteriol"},{"issue":"12","key":"pone.0255485.ref017","doi-asserted-by":"crossref","first-page":"3770","DOI":"10.1128\/JB.183.12.3770-3783.2001","article-title":"Bacterial diversity in human subgingival plaque","volume":"183","author":"BJ Paster","year":"2001","journal-title":"J Bacteriol"},{"issue":"11","key":"pone.0255485.ref018","doi-asserted-by":"crossref","first-page":"5721","DOI":"10.1128\/JCM.43.11.5721-5732.2005","article-title":"Defining the normal bacterial flora of the oral cavity","volume":"43","author":"JA Aas","year":"2005","journal-title":"J Clin Microbiol"},{"issue":"1","key":"pone.0255485.ref019","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1111\/prd.12010","article-title":"Lessons learned and unlearned in periodontal microbiology","volume":"62","author":"R Teles","year":"2000","journal-title":"Periodontol"},{"issue":"3\u20134","key":"pone.0255485.ref020","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/j.anaerobe.2007.05.004","article-title":"The division \"Synergistes\"","volume":"13","author":"SR Vartoukian","year":"2007","journal-title":"Anaerobe"},{"issue":"12","key":"pone.0255485.ref021","doi-asserted-by":"crossref","first-page":"2743","DOI":"10.1099\/ijs.0.65213-0","article-title":"Jonquetella anthropi gen. nov., sp. nov., the first member of the candidate phylum \u2019Synergistetes\u2019 isolated from man","volume":"57","author":"E Jumas-Bilak","year":"2007","journal-title":"Int J Syst Evol Microbiol"},{"issue":"2","key":"pone.0255485.ref022","doi-asserted-by":"crossref","first-page":"458","DOI":"10.1099\/ijs.0.041038-0","article-title":"Fretibacterium fastidiosum gen. nov., sp. nov., isolated from the human oral cavity","volume":"63","author":"SR Vartoukian","year":"2013","journal-title":"Int J Syst Evol Microbiol"},{"issue":"5","key":"pone.0255485.ref023","doi-asserted-by":"crossref","first-page":"972","DOI":"10.1099\/ijs.0.000364-0","article-title":"Pyramidobacter piscolens gen. nov., sp. nov., a member of the phylum \u2019Synergistetes\u2019 isolated from the human oral cavity","volume":"59","author":"J Downes","year":"2009","journal-title":"Int J Syst Evol Microbiol"},{"issue":"4","key":"pone.0255485.ref024","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1128\/am.17.4.568-576.1969","article-title":"Isolation of anaerobic bacteria from human gingiva and mouse cecum by means of a simplified glove box procedure","volume":"17","author":"A Arank","year":"1969","journal-title":"Appl Microbiol."},{"key":"pone.0255485.ref025","doi-asserted-by":"crossref","first-page":"275","DOI":"10.1016\/0003-9969(63)90019-0","article-title":"The microbiota of the gingival crevice area of man. I. Total microscopic and viable counts and counts of specific organisms","volume":"8","author":"SS Socransky","year":"1963","journal-title":"Arch Oral Biol"},{"issue":"3","key":"pone.0255485.ref026","doi-asserted-by":"crossref","first-page":"537","DOI":"10.1128\/jcm.34.3.537-542.1996","article-title":"Molecular analysis of microflora associated with dentoalveolar abscesses","volume":"34","author":"D Dymock","year":"1996","journal-title":"J Clin Microbiol"},{"issue":"8","key":"pone.0255485.ref027","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1038\/ja.2010.87","article-title":"Uncultured microorganisms as a source of secondary metabolites","volume":"63","author":"K Lewis","year":"2010","journal-title":"J Antibiot"},{"issue":"1","key":"pone.0255485.ref028","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1186\/s12874-017-0468-4","article-title":"What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences","volume":"18","author":"Z Munn","year":"2018","journal-title":"BMC Med Res Methodol"},{"issue":"2","key":"pone.0255485.ref029","doi-asserted-by":"crossref","first-page":"e59","DOI":"10.1016\/j.radi.2014.12.004","article-title":"Claustrophobia in magnetic resonance imaging: A systematic review and meta-analysis","volume":"21","author":"Z Munn","year":"2015","journal-title":"Radiography"},{"issue":"1","key":"pone.0255485.ref030","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/2046-4053-4-1","article-title":"Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement","volume":"4","author":"D Moher","year":"2015","journal-title":"Syst Rev"},{"key":"pone.0255485.ref031","volume-title":"Joanna Briggs Institute Reviewer\u2019s Manual","author":"S Moola","year":"2017"},{"key":"pone.0255485.ref032","unstructured":"Expanded Human Oral Microbiome Database. eHOMD. Available from: http:\/\/www.homd.org\/."},{"key":"pone.0255485.ref033","unstructured":"The NCBI Taxonomy Homepage. Available from: https:\/\/www.ncbi.nlm.nih.gov\/Taxonomy\/taxonomyhome.html\/."},{"key":"pone.0255485.ref034","unstructured":"Culture Collection University of Gothenburg. CCUG. Available from: https:\/\/ccug.se\/."},{"key":"pone.0255485.ref035","author":"N Wang","year":"2018","journal-title":"How to conduct a meta-analysis of proportions in R: A comprehensive tutorial: Preprint"},{"issue":"11","key":"pone.0255485.ref036","doi-asserted-by":"crossref","first-page":"974","DOI":"10.1136\/jech-2013-203104","article-title":"Meta-analysis of prevalence","volume":"67","author":"JJ Barendregt","year":"2013","journal-title":"J Epidemiol Community Health"},{"key":"pone.0255485.ref037","article-title":"Learning to draw samples: With application to amortized MLE for generative adversarial learning","author":"D Wang","year":"2016","journal-title":"A conference paper at ICLR"},{"key":"pone.0255485.ref038","volume-title":"Applied meta-analysis for social science research","author":"NA Card","year":"2012"},{"issue":"3","key":"pone.0255485.ref039","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/0197-2456(86)90046-2","article-title":"Meta-analysis in clinical trials","volume":"7","author":"R DerSimonian","year":"1986","journal-title":"Control Clin Trials"},{"key":"pone.0255485.ref040","volume-title":"Cochrane handbook for systematic reviews of interventions","author":"JPT Higgins","year":"2011"},{"key":"pone.0255485.ref041","article-title":"Chapter 9: Analysing data and undertaking meta-anlysis","author":"JJ Deeks","year":"2011","journal-title":"Cochrane handbook for systematic reviews of interventions"},{"issue":"2","key":"pone.0255485.ref042","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1037\/1082-989X.11.2.193","article-title":"Assessing heterogeneity in meta-analysis: Q statistic or I2 index?","volume":"11","author":"TB Huedo-Medina","year":"2006","journal-title":"Psychol Methods"},{"issue":"2","key":"pone.0255485.ref043","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1002\/jrsm.11","article-title":"Outlier and influence diagnostics for meta-analysis","volume":"1","author":"W Viechtbauer","year":"2010","journal-title":"Res Synth Methods"},{"issue":"5","key":"pone.0255485.ref044","doi-asserted-by":"crossref","first-page":"1352","DOI":"10.1128\/JCM.02016-08","article-title":"Diversity of spirochetes in endodontic infections","volume":"47","author":"M Sakamoto","year":"2009","journal-title":"J Clin Microbiol"},{"key":"pone.0255485.ref045","unstructured":"Statistical tools for high-throughput data analysis. (STHDA). Quick principal component analysis data visualization\u2014R software and data mining. Available from: http:\/\/www.sthda.com\/english\/."},{"issue":"8","key":"pone.0255485.ref046","doi-asserted-by":"crossref","first-page":"1854","DOI":"10.1016\/j.joms.2011.09.009","article-title":"Molecular methods for diagnosis of odontogenic infections","volume":"70","author":"TR Flynn","year":"2012","journal-title":"J Oral Maxillofac Surg"},{"key":"pone.0255485.ref047","doi-asserted-by":"crossref","first-page":"30989","DOI":"10.3402\/jom.v8.30989","article-title":"Oral microbiota species in acute apical endodontic abscesses","volume":"8","author":"N George","year":"2016","journal-title":"J Oral Microbiol."},{"issue":"5","key":"pone.0255485.ref048","doi-asserted-by":"crossref","first-page":"610","DOI":"10.1016\/j.tripleo.2006.08.009","article-title":"Identification of bacteria associated with spreading odontogenic infections by 16S rRNA gene sequencing","volume":"103","author":"MP Riggio","year":"2007","journal-title":"Oral Surg Oral Med Oral Pathol Oral Radiol Endod"},{"issue":"12","key":"pone.0255485.ref049","doi-asserted-by":"crossref","first-page":"1135","DOI":"10.1016\/j.joen.2006.05.001","article-title":"Prevalence of selected bacterial named species and uncultivated phylotypes in endodontic abscesses from two geographic locations","volume":"32","author":"IN R\u00f4\u00e7as","year":"2006","journal-title":"J Endod."},{"issue":"10","key":"pone.0255485.ref050","doi-asserted-by":"crossref","first-page":"1359","DOI":"10.1016\/j.joen.2009.05.033","article-title":"Prevalence of new candidate pathogens Prevotella baroniae, Prevotella multisaccharivorax and as-yet-uncultivated Bacteroidetes clone X083 in primary endodontic infections","volume":"35","author":"IN R\u00f4\u00e7as","year":"2009","journal-title":"J Endod."},{"issue":"1","key":"pone.0255485.ref051","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0190469","article-title":"Frequency and levels of candidate endodontic pathogens in acute apical abscesses as compared to asymptomatic apical periodontitis","volume":"13","author":"IN R\u00f4\u00e7as","year":"2018","journal-title":"PLoS One"},{"issue":"2","key":"pone.0255485.ref052","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1111\/j.1399-302X.2006.00270.x","article-title":"Molecular analysis of bacteria in asymptomatic and symptomatic endodontic infections","volume":"21","author":"M Sakamoto","year":"2006","journal-title":"Oral Microbiol Immunol"},{"issue":"4","key":"pone.0255485.ref053","doi-asserted-by":"crossref","first-page":"398","DOI":"10.1111\/j.1601-0825.2006.01301.x","article-title":"Molecular detection and identification of Synergistes phylotypes in primary endodontic infections","volume":"13","author":"JF Siqueira","year":"2007","journal-title":"Oral Dis"},{"issue":"1","key":"pone.0255485.ref054","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1177\/0022034508328124","article-title":"The microbiota of acute apical abscesses","volume":"88","author":"JF Siqueira","year":"2009","journal-title":"J Dent Res"},{"issue":"2","key":"pone.0255485.ref055","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1016\/j.joen.2009.11.001","article-title":"Polymerase chain reaction-denaturing gradient gel electrophoresis, cloning, and sequence analysis of bacteria associated with acute periapical abscesses in children","volume":"36","author":"Q-B Yang","year":"2010","journal-title":"J Endod."},{"key":"pone.0255485.ref056","doi-asserted-by":"crossref","first-page":"103954","DOI":"10.1016\/j.micpath.2019.103954","article-title":"Identification of bacteria associated with periapical abscesses of primary teeth by sequence analysis of 16S rDNA clone libraries","volume":"141","author":"W Zhang","year":"2020","journal-title":"Microb Pathog"},{"issue":"1","key":"pone.0255485.ref057","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1111\/ipd.12226","article-title":"Analysis of bacterial community profiles of endodontically infected primary teeth using pyrosequencing","volume":"27","author":"KH Yun","year":"2017","journal-title":"Int J Paediatr Dent"},{"issue":"9","key":"pone.0255485.ref058","doi-asserted-by":"crossref","first-page":"3282","DOI":"10.1128\/JCM.39.9.3282-3289.2001","article-title":"Molecular identification of microorganisms from endodontic infections","volume":"39","author":"HJ Rolph","year":"2001","journal-title":"J Clin Microbiol"},{"issue":"11","key":"pone.0255485.ref059","doi-asserted-by":"crossref","first-page":"1778","DOI":"10.1016\/j.joen.2014.06.017","article-title":"Highly diverse microbiota in dental root canals in cases of apical periodontitis (data of illumina sequencing)","volume":"40","author":"V Vengerfeldt","year":"2014","journal-title":"J Endod"},{"issue":"6","key":"pone.0255485.ref060","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1111\/j.1399-302X.2007.00378.x","article-title":"Bacterial examination of endodontic infections by clonal analysis in concert with denaturing high-performance liquid chromatography","volume":"22","author":"RC Jacinto","year":"2007","journal-title":"Oral Microbiol Immunol"},{"issue":"2","key":"pone.0255485.ref061","doi-asserted-by":"crossref","first-page":"366","DOI":"10.1128\/JB.180.2.366-376.1998","article-title":"Novel division level bacterial diversity in a Yellowstone hot spring","volume":"180","author":"P Hugenholtz","year":"1998","journal-title":"J Bacteriol"},{"key":"pone.0255485.ref062","first-page":"1","article-title":"Bacterial diversity in persistent periapical lesions on root-filled teeth","author":"T Handal","year":"2009","journal-title":"J Oral Microbiol."},{"key":"pone.0255485.ref063","first-page":"5","article-title":"As-yet-uncultivated oral bacteria: Breadth and association with oral and extra-oral diseases","author":"JF Siqueira","year":"2013","journal-title":"J Oral Microbiol."},{"key":"pone.0255485.ref064","volume-title":"Advances in microbial ecology","author":"N.R. SDA Pace","year":"1986"},{"issue":"2","key":"pone.0255485.ref065","doi-asserted-by":"crossref","first-page":"255","DOI":"10.1128\/CMR.00082-12","article-title":"Microbiology and treatment of acute apical abscesses","volume":"26","author":"JF Siqueira","year":"2013","journal-title":"Clin Microbiol Rev"},{"issue":"1162","key":"pone.0255485.ref066","article-title":"Geography, ethnicity or subsistence-specific variations in human microbiome composition and diversity","volume":"8","author":"VK Gupta","year":"2017","journal-title":"Front Microbiol"},{"issue":"1","key":"pone.0255485.ref067","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s11157-020-09522-4","article-title":"Challenges of unculturable bacteria: Environmental perspectives","volume":"19","author":"A Bodor","year":"2020","journal-title":"Rev Environ Sci Biotechnol"},{"issue":"7604","key":"pone.0255485.ref068","doi-asserted-by":"crossref","first-page":"543","DOI":"10.1038\/nature17645","article-title":"Culturing of \u2018unculturable\u2019 human microbiota reveals novel taxa and extensive sporulation","volume":"533","author":"HP Browne","year":"2016","journal-title":"Nature"},{"issue":"4","key":"pone.0255485.ref069","doi-asserted-by":"crossref","first-page":"356","DOI":"10.1264\/jsme2.ME12092","article-title":"Are uncultivated bacteria really uncultivable","volume":"27","author":"ID Puspita","year":"2012","journal-title":"Microbes Environ"},{"issue":"5","key":"pone.0255485.ref070","doi-asserted-by":"crossref","first-page":"1469","DOI":"10.1128\/JCM.37.5.1469-1473.1999","article-title":"Detection of unculturable bacteria in periodontal health and disease by PCR","volume":"37","author":"R Harper-Owen","year":"1999","journal-title":"J Clin Microbiol"},{"issue":"6","key":"pone.0255485.ref071","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1111\/j.1399-302x.2004.00170.x","article-title":"Investigation of bacterial communities associated with asymptomatic and symptomatic endodontic infections by denaturing gradient gel electrophoresis fingerprinting approach","volume":"19","author":"JF Siqueira","year":"2004","journal-title":"Oral Microbiol Immunol"},{"issue":"1","key":"pone.0255485.ref072","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1111\/j.1399-302X.2007.00311.x","article-title":"Bacterial community profiles of endodontic abscesses from Brazilian and USA subjects as compared by denaturing gradient gel electrophoresis analysis","volume":"22","author":"JC Machado de Oliveira","year":"2007","journal-title":"Oral Microbiol Immunol"},{"issue":"351","key":"pone.0255485.ref073","volume":"12","author":"S-D Bor\u015fan","year":"2021","journal-title":"Romania. 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