慢性牙周炎患者中间普氏菌临床分离株中溶血基因的分布

目的：研究溶血基因在慢性成人牙周炎患者中间普氏菌临床分离株中的分布状况，探讨溶血基因与中间普氏菌致病性的关系。方法：收集符合纳入标准的57例慢性成人牙周炎病人的牙周袋内的朗下菌斑，采用厌氧培养技术分纯产黑色素的革兰氏阴性厌氧杆菌，用16SrRNA聚合酶链反应(PCR)方法鉴定为中间普氏菌的菌株，保存并用溶血基因的相应引物检测该基因。结果：57例慢性成人牙周炎患者中，20例捡出中间普氏菌，检出率为35．1％。35株中间普氏菌的临床分离株中，5株能够检测到溶血基因，另外30株不能检测到溶血基因。结论：溶血基因在中间普氏菌临床分离株中呈多态分布。     

慢性牙周炎患者牙周袋内硫化物水平与厌氧细菌分布的相关性研究

目的:探讨慢性牙周炎患者牙周袋内硫化物水平(sulfide levels in periodontal pockets,SUL)与牙龈卟啉单胞菌、中间普氏菌、伴放线放线杆菌分布的相关性.方法:用perio2000 system金刚探针牙周诊断仪测定慢性牙周炎患者SUL,采用PCR方法检测龈下菌斑中牙龈卟啉单胞菌、中间普氏菌和伴放线放线杆菌.结果:慢性牙周炎患者随着牙周袋内SUL浓度的增加牙龈卟啉单胞菌、中间普氏菌的检出率逐渐增加,相关系数分别为0.812和0.651(P<0.05);SUL阳性位点与阴性位点中牙龈卟啉单胞菌的检出率分别是为85.6%、26.7%,中间普氏菌的检出率分别为95.2%、53.3%.SUL阳性位点中牙龈卟啉单胞菌和中间普氏菌的检出率明显高于SUL阴性位点;在80.9%的SUL阳性位点中牙龈卟啉单胞菌与中间普氏菌共存.SUL阳性位点与阴性位点均未检出伴放线放线杆菌.结论:慢性牙周炎患者SUL与牙龈卟啉单胞菌和中间普氏菌分布关系较为密切.     

中间普氏菌在家庭成员牙周菌斑中的分布调查

目的：调查了解中间普氏菌在牙周健康人群中的分布状况。方法：收集符合纳入标准的６０个家庭、１８１例受试者的牙周颈缘龈上菌斑和龈下菌班，采用厌氧菌培养获得２７９株产黑色素的Ｇ＾－厌氧杆菌，然后进行产黑色素的Ｇ＾－厌氧杆菌的纯化培养及微量生化鉴定。结果：中间普氏菌在牙周较健康的父母和儿童牙周菌班中均可检出，儿童群体中中间普氏菌阳性率达７０．４９％，而成人群体中中间普氏菌阳性率为４３．３３％，二者有显著性     

牙龈卟啉单胞菌在龈下菌斑中的分布

研究牙龈卟啉单胞菌在牙周炎患者病变部位和健康部位龈下菌班中的分布情况,方法：选择６４例成年牙周炎患者,取龈下菌斑,经厌氧培养,挑战产黑色素菌落,经多聚酶链反应鉴定牙龈卟啉单胞菌。结果：产黑色素Ｇ＾－厌氧杆菌和牙龈卟啉单胞菌的患者检出率分别是６７．２％和６０．９％。牙龈卟啉单胞菌在病变部位和健康部位的检出率分别是３５．９％和２８．１％,二者差异无统计学意义;牙龈卟啉单胞菌在病变部位和健康部位的检出株     

产黑色素G-厌氧杆菌在牙周炎病人龈下菌斑中的分布

目的：研究牙龈卟啉单胞菌（P.g)，中间型普氏菌（P.i)和变黑普氏菌(P.n)在牙周炎病人病变部位和正常部位龈下菌斑中的分布。方法：选择64例慢性牙周炎患者，取龈下菌斑，经厌氧培养，挑取产黑色素菌落，纯化增菌保种，经多聚酶链反应鉴定P.g,P.i和P.n。结果：共对614株产黑色素G^-厌氧杆菌进行多聚酶链反应鉴定，得到207，112和49株P.G,P.i和P.n。在病变部位和正常部位，P.g的检出率分别是35．9％和28．1％，两者无统计学差异，P.i的检出率分别是28．1％和12．5％，有统计学差异（P＜0．05），P.n的检出率分别是14．8％和9．4％，无统计学差异。结论：提示G^-厌氧杆菌是作为内源性致病菌在特定条件下过度生长导致牙周破坏。     

中间普里沃菌在成人牙周炎患者龈下菌斑中的分布

目的 研究中间普里沃菌在牙周炎病人病变部位和健康部位龈下菌斑中的分布地选择６４例成年人牙周炎患者，分别取病变部位和健康部位龈下菌斑，经厌氧培养，挑取产黑色素菌落，经多聚酶链反应鉴定中间普里沃菌。结果 共对６１４株产黑色素Ｇ厌氧杆菌进行多聚酶链反应鉴定，有１１２株被鉴定为中间普里沃菌；在病变部位和健康部位，中间普里沃菌的检出率分别是２８．１％和１２．５％，有统计学差异（Ｐ〈０．０５）；在病变部位和健     

冠心病人口腔龈下菌斑中血链球菌、中间普氏菌的比较研究

目的:探讨口腔龈下菌斑中血链球菌、中间普氏菌与冠心病的关系。方法:检查与记录60例研究对象(冠心病组与对照组各30例)的牙龈指数(GI)、菌斑指数(PLI)、牙周袋探诊深度(PD)。应用生化法检测两组研究对象龈下菌斑中的血链球菌数,并用定性随机引物酶链反应法对两组研究对象龈下菌斑中的中间普氏菌进行了鉴定。结果:冠心病组的PD、PLI和龈下菌斑中的血链球菌数及中间普氏菌检出率明显高于对照组(P(0.05)。结论:冠心病组的牙周健康状况相对更差,与冠心病有关的口腔细菌除血链球菌外,龈下菌斑中的中间普氏菌也与冠心病的发病关系密切。     

龈下菌斑中产黑色素类杆菌群与牙周病变的关系

本文应用酶联免疫吸附试验（ＥＬＩＳＡ）检测了２２例牙周健康者、３１例慢性成人牙周炎、３６例龈炎患者龈下菌斑中的产黑色素类杆菌群菌株的检出情况。发现随着牙周病损的加重龈下菌斑中的牙龈卟啉菌、中间型普氏菌检出率明显增加。推测这些细菌与牙周病变的发生、发展有重要关系。     

人工种植牙的龈下菌群分析

目的:了解种植牙龈下菌群的构成状况,探索早期诊断以及预防和治疗种植体周围炎的方法.方法:检查了30名患者的47颗种植体的菌斑指数、牙龈指数、探诊深度及骨质吸收情况.选用多种选择性和非选择性培养基,对探诊出血和无探诊出血的种植牙进行了龈下菌斑标本的分离培养和鉴定.结果:种植牙龈下的牙龈卟啉菌、中间普氏菌和具核梭杆菌与种植牙的临床和X线指标具有相关性.出血组种植牙龈下的产黑菌、牙龈卟啉菌和中间普氏菌的检出率明显高于无出血组.结论:与种植牙周围软组织炎症和骨组织吸收密切相关的菌种是革兰氏阴性菌,主要为牙龈卟啉菌、中间普氏菌和具核梭杆菌.应当在种植患者的定期复查中加入微生物学检查的内容.     

维吾尔族慢性牙周炎中牙龈卟啉单胞菌菌fimA毒力基因型的分布

目的：分析维吾尔族慢性牙周炎患者龈下菌斑中牙龈卟啉单胞菌菌毛fimA毒力基因型的分布情况。方法：收集52例维吾尔族慢性牙周炎患者的龈下菌斑，采用16SrRNA PCR法检测牙龈卟啉单胞菌，并根据菌毛fima毒力基因型的特异引物，用聚合酶链反应（PCR）检测Ⅱ型fimA和Ⅳ型fima菌株的分布。结果：16SrRNA PCR法检测牙龈卟啉单胞菌在龈下菌斑中阳性检出率是76．9％。牙周袋PPD〉6mm位点龈下菌斑标本的P．gingivalis检出率高于4〈PPD≤6mm采样的位点，2组差异有统计学意义（P〈0．05）。牙龈卟啉单胞菌菌毛．fimA毒力基因型在牙龈卟啉单胞菌感染者的检出率分别是：Ⅱ fimA型为37．5％，ⅣfimA型为22．5％。结论：维吾尔族慢性牙周炎患者龈下菌斑中牙龈卟啉单胞菌有较高的检出率。牙龈卟啉单胞菌存在fima毒力基因多态性。     

Comparison of subgingival bacterial sampling with oral lavage for detection and quantification of periodontal pathogens by real-time polymerase chain reaction

BACKGROUND: Saliva has been studied for the presence of subgingival pathogens in periodontitis patients. With the anaerobic culture technique, the discrepancy between salivary recovery and subgingival presence has been significant, which makes this approach not suitable for practical use in the microbial diagnosis of periodontitis patients. The real-time polymerase chain reaction (PCR) technique represents a very sensitive technique to detect and quantify bacterial pathogens. The aim of the study was to compare the presence and numbers of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia, and Micromonas micros in subgingival plaque and mouthwash samples by the anaerobic culture and real-time PCR techniques. METHODS: Pooled subgingival plaque samples and 10-ml mouthwash samples were collected from 21 adult patients with periodontitis and analyzed by quantitative anaerobic culture and real-time PCR for A. actinomycetemcomitans, P. gingivalis, T. forsythensis, P. intermedia, and M. micros. RESULTS: The detection frequency of A. actinomycetemcomitans, P. gingivalis, and T. forsythensis in subgingival plaque was identical by culture and real-time PCR and was higher for P. intermedia and M. micros by real-time PCR. The highest detection frequencies for the target bacteria were found in mouthwash samples by real-time PCR. The additional value of the real-time PCR to detect target bacteria was 38% for P. gingivalis, 73% for T. forsythensis, 77% for P. intermedia, and 71% for M. micros. The sensitivity to detect target species in mouthwash by real-time PCR was 100% for all test species except for P. intermedia (93.8%). CONCLUSIONS: Rapid detection and quantification of periodontal pathogens in mouthwash samples are possible by real-time PCR. The procedure is significantly less time-consuming than subgingival sampling with paper points. This approach to detect major periodontal pathogens in mouthwash samples may simplify microbial diagnosis in periodontitis patients and may be used to monitor periodontal treatment.     

Metronidazole susceptibility testing of anaerobic bacteria associated with periodontal disease

The aim of the present investigation was to determine the susceptibility of Prevotella intermedia, Porphyromonas gingivalis, Fusobacterium and Peptostreptococcus micros to metronidazole in vitro. Two methods were applied on each isolated strain: agar dilution and epsilometer Etest. A total of fifty three wild test strains (13 P.intermedia, 14 P. gingivalis, 14 F.spp and 12 P.micros) were isolated from patients with periodontitis. The Etest appears to be a simple, rapid and reliable method for the metronidazole susceptibility testing. The results show that all P.intermedia, P.gingivalis and F.spp strains were susceptible to metronidazole. The mean values of minimal inhibitory concentration obtained with the agar dilution method were, respectively, 0.98 microg/ml, 0.122 microg/ml and 0.242 microg/ml. For P.micros, the minimal inhibitory concentration was of 12.14 microg/ml. Comparatively to break points, only 60% of P.micros strains seem to be susceptible, in vitro, to metronidazole. This study demonstrated the excellent activity of metronidazole against P.intermedia, P.gingivalis, F.spp except perhaps for P.micros.     

The additional value of real-time PCR in the quantitative detection of periodontal pathogens

BACKGROUND AND AIM: For the analysis of subgingival plaque, anaerobic bacterial culture has been the gold standard for many years. Currently, molecular microbial techniques have become available to identify and quantify target organisms with high specificity and sensitivity. The technique of real-time polymerase chain reaction(RT-PCR) provides a new tool to detect oral pathogens both in oral and non-oral human infections. The aim of this study was to compare the RT-PCR and anaerobic culture for detection and quantification of six periodontal pathogens in periodontal health and disease. MATERIAL AND METHODS: Subgingival plaque samples from 259 adult patients with periodontitis and 111 healthy controls were analysed with quantitative anaerobic culture and quantitative RT-PCR for Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Micromonas micros and Fusobacterium spp. RESULTS: All species were more frequently isolated from patients than controls with both culture and RT-PCR. P. gingivalis, T. forsythia and M. micros appeared significant markers for disease with both techniques. P. intermedia was significantly associated with periodontitis by RT-PCR only (OR 9.7), whereas A. actinomycetemcomitans showed a significant relationship by culture only. The critical differences between culture and RT-PCR were culture-negative/PCR-positive samples which amounted to 7% for A. actinomycetemcomitans, 3% for P. gingivalis, 7% for T. forsythia, 20% for P. intermedia, 6% for M. micros, and 0.8% for Fusobacterium spp. in periodontitis patients and 12%, 3%, 2%, 35%, 14% and 0%, respectively, in the periodontally healthy group. Furthermore, periodontitis individuals had significantly higher amount of all of the test species in the subgingival plaque samples compared with healthy subjects. CONCLUSION: RT-PCR provides a new rapid diagnostic tool and opens the opportunity to detect small numbers of oral pathogens in clinical specimens, which are under the detection limit by culture technique.     

Comparison of culture and real-time PCR for detection and quantification of five putative periodontopathogenic bacteria in subgingival plaque samples

OBJECTIVES: Bacterial cultivation is a well-established method for analyzing plaque samples. Real-time polymerase chain reaction (PCR) is a novel rapid method for the identification and quantification of periodontopathogenic bacteria that has been recently introduced. In this study, we compared real-time PCR with conventional anaerobic cultivation. METHOD: A total of 78 subgingival plaque samples were harvested from pockets > or =5 mm in 22 patients with advanced chronic periodontitis and immediately transferred into transport medium. Aliquots were evaluated with species-specific probes by real-time PCR (meridol Perio Diagnostics, GABA) and anaerobic bacteria culture on selective media for the detection of Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Tannerella forsythensis. The analysis was performed by two separate, blinded examiners. RESULTS: When real-time PCR was compared with the culture method (golden standard) for the detection of putative periodontopathogenic bacteria, the sensitivity and specificity for A. actinomycetemcomitans were 67% and 100%, respectively (kappa: 0.79); for F. nucleatum 73% and 53%, respectively (kappa: 0.21); for P. gingivalis 94% and 84%, respectively (kappa: 0.77); for P. intermedia 33% and 94%, respectively (kappa: 0.26) and for T. forsythensis 92% and 56%, respectively (kappa: 0.51). Spearman's correlation coefficients for the quantitative results of both methods were 0.82 for A. actinomycetemcomitans, 0.33 for F. nucleatum, 0.83 for P. gingivalis, 0.38 for P. intermedia and 0.67 for T. forsythensis. CONCLUSION: Overall, the agreement between both test methods was excellent for A. actinomycetemcomitans and P. gingivalis, fair for T. forsythensis and poor for F. nucleatum and P. intermedia. The discrepancies in the results may be explained by the inability of cultivation methods to distinguish between close related taxa, and the problems of keeping periopathogenic bacteria viable, which is required for standard cultivation.     

Transmission of periodontal disease-associated bacteria from teeth to osseointegrated implant regions

PURPOSE: The presence of periodontopathic bacteria is a risk factor for peri-implantitis. The present study examined colonization by periodontopathic bacteria and their transmission from periodontal pockets to osseointegrated implant sulcus. MATERIALS AND METHODS: Plaque samples were collected from 105 sites in the 15 patients who participated in the study. Colonization by these bacteria was examined by polymerase chain reaction (PCR) and culture. The transmission of periodontopathic bacteria from periodontal sites of natural teeth to the implant sulcus was analyzed by pulsed field gel electrophoresis (PFGE). RESULTS: The PCR detection rates of Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Bacteroides forsythus, and Treponema denticola were 80.0%, 53.3%, 46.7%, 60.0% and 40.0%, respectively. Colonizations by P gingivalis and A actinomycetemcomitans were statistically correlated with periodontal pockets and implant sulcus regions (P < .01). The PFGE patterns of the P gingivalis strains isolated from each patient were identical, but differed from those from other patients. The PFGE patterns of P intermedia strains were identical in 2 out of 3 patients. DISCUSSION: These analyses indicated that there appeared to be transmission of P gingivalis and P intermedia from the periodontal pocket to the peri-implant region. CONCLUSION: Elimination of these periodontal pathogens from the patient's oral cavity before administering dental implant treatment may inhibit colonization by these pathogens and reduce the risk of peri-implantitis.     

Pathogenicity of Prevotella intermedia and Prevotella nigrescens isolates in a wound chamber model in rabbits

The pathogenicity of 14 isolates identified as Prevotella intermedia or Prevotella nigrescens by serogrouping using monoclonal antibodies was compared in a tissue cage model in rabbits. Seven strains from periodontal abscesses, 5 strains from deep periodontal pockets and 2 strains from gingivitis were tested in the animal model comprising 6 Teflon tissue cages implanted on the back each of 34 rabbits. A total of 105–108 cells of P. intermedia or P. nigrescens strains were inoculated alone or together with either Actinobacillus actinomycetemcomitans or Streptococcus mitis. Five strains of Porphyromonas gingivalis were used as a reference. The infectivity was recorded as pus formation and log viable count in aspirated material for 3, 7 and 14 days. None of the Prevotella strains inoculated in monoculture survived more than 3 days, and they had no capacity to produce abscess. P. intermedia or P. nigrescens strains in combination with A. actinomycetemcomitans produced abscesses in 33–100% and with S. mitis in 42–100%. No difference in abscess formation or log viable count in samples after 14 days was recorded between serogroup I ( P. intermedia ) and serogroup II and III ( P. nigrescens ). The infectivity of P. intermedia or P. nigrescens strains did not differ whether they were isolated from periodontal abscess, periodontal pocket or gingivitis. P. intermedia and P. nigrescens strains produced abscesses in combination with a facultative anaerobic strain and appears to have a similar pathogenicity in the wound chamber model in rabbits.     

Antimicrobial susceptibility variation of 50 anaerobic periopathogens in aggressive periodontitis: an interindividual variability study

BACKGROUND/AIMS: The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient). MATERIAL AND METHODS: A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test. RESULTS: Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros. CONCLUSIONS: The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.     

Antimicrobial profiles of periodontal pathogens isolated from periodontitis patients in The Netherlands and Spain

BACKGROUND AND AIM: Antimicrobial resistance of periodontal pathogens towards currently used antibiotics in periodontics has been investigated in a previous study. Microbial resistance in the periodontal microflora was more frequently observed in Spanish patients in comparison with Dutch patients. The aim of the present study was to compare antimicrobial susceptibility profiles of five periodontal bacteria isolated from periodontitis patients in Spain and in The Netherlands. MATERIAL AND METHODS: Subgingival plaque samples from adult patients with periodontitis were collected and cultured on selective and non-selective plates. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Micromonas micros were isolated and used for minimal inhibitory concentration tests using the Epsilometer (E-test) technique. Eight different antibiotics were tested on all bacterial isolates. MIC50 and MIC90 values for each antibiotic and each species were determined and the percentage of resistant strains was calculated. RESULTS: Significantly higher MIC values were noted in Spanish strains of F. nucleatum for penicillin, ciprofloxacin, of P. intermedia for penicillin, amoxicillin and tetracycline, of M. micros for tetracycline, amoxicillin and azithromycin, and of P. gingivalis for tetracycline and ciprofloxacin. Based on breakpoint concentrations, a higher number of resistant strains in Spain were found in F. nucleatum for penicillin, amoxicillin and metronidazole, in Prevotella intermedia for tetracycline and amoxicillin, and in A. actinomycetemcomitans for amoxicillin and azithromycin. Resistance of P. gingivalis strains was not observed for any of the antibiotics tested both in Spain and The Netherlands. CONCLUSIONS: Differences exist in the susceptibility profiles of periodontal pathogens isolated from periodontitis patients in Spain and in The Netherlands. This implicates that antibiotic susceptibility testing is necessary to determine efficacy of antimicrobial agents. Also, clinical studies with antibiotics should take these differences into account. The information from the present study indicates that it may not be possible to develop uniform protocols for usage of antibiotics in the treatment of severe periodontitis in the European Union.     

The effects of a new mouthrinse containing chlorhexidine,cetylpyridinium chloride and zinc lactate on the microflora of oral halitosis patients: a dual-centre,double-blind placebo-controlled study

AIM: This study evaluated the microbial effects of a newly formulated mouthwash (Halita) on oral halitosis patients. METHODS: Forty subjects were included in this dual-centre, double-blind, placebo-controlled parallel study. Inclusion and exclusion criteria were used to select patients. At baseline and at 2 weeks post-treatment, full-mouth organoleptic odor scores, level of volatile sulphur compounds (VSC) and the Winkel Tongue Coating Index were recorded. Standardized samples of tongue coating, saliva and subgingival plaque were microbiologically investigated. Participants were randomly assigned to the test or placebo groups. RESULTS: High prevalences were observed for Fusobacterium nucleatum, Prevotella intermedia and Porphyromonas gingivalis in tongue coating, saliva and subgingival plaque samples. A significant positive correlation between baseline total counts of P. gingivalis in saliva samples and organoleptic and VSC scores was found. Two weeks post-treatment there was a reduction in total anaerobic counts in all samples in the test group. A significant positive correlation was observed between the reduction in total counts in saliva samples and the reduction in organoleptic scores in the test group. Significant reductions in total counts and proportions of F. nucleatum and total counts of P. intermedia in tongue coating samples were observed in the test group. CONCLUSIONS: The test mouthwash demonstrated efficacy in reducing the microbiological parameters in three oral niches in moderate to severe halitosis patients without periodontitis, and this was correlated with the improvements in organoleptic and VSC scores but not with the tongue coating scores.     

Molecular detection of black-pigmented bacteria in infections of endodontic origin

A 16S rDNA-directed polymerase chain reaction method was used to assess the occurrence of four black-pigmented anaerobic rods in root canal infections. Samples were obtained from 54 infected teeth. Ten cases were diagnosed as acute periradicular abscesses. DNA was extracted from the samples and analyzed using a polymerase chain reaction-based identification assay. The method allowed detection of black-pigmented bacteria anaerobes in 59.3% of the examined teeth. Twelve cases yielded more than one black-pigmented species. In general Porphyromonas endodontalis was found in 42.6%, Porphyromonas gingivalis in 27.8%, Prevotella nigrescens in 7.4%, and Prevotella intermedia in 5.6% of the cases. P. endodontalis was found in 70% of the pus samples, P. gingivalis in 40%, and P. intermedia in 10%. P. gingivalis was always found associated with P. endodontalis in abscessed teeth. P. nigrescens was not found in any pus sample. The high prevalence of P. endodontalis and P. gingivalis suggests that they can play an important role in the pathogenesis of periradicular diseases.