Periodontal bacterial profiles in pregnant women: response to treatment and associations with birth outcomes in the obstetrics and periodontal therapy (OPT) study

BACKGROUND: A recent clinical trial (Obstetrics and Periodontal Therapy [OPT] Study) demonstrated that periodontal therapy during pregnancy improved periodontal outcomes but failed to impact preterm birth. The present study evaluated seven target bacteria, Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia (previously T. forsythensis), Prevotella intermedia, Campylobacter rectus, and Fusobacterium nucleatum, in subgingival dental plaque of pregnant women in the OPT Study and their association with birth outcomes. METHODS: Pregnant women were randomly assigned to receive periodontal treatment before 21 weeks' gestation or after delivery. Subgingival plaque was sampled at baseline (13 to 16 weeks; 6 days of gestation) and at 29 to 32 weeks. We analyzed subgingival plaque samples from women who experienced fetal loss, delivered a live preterm infant (preterm women), or delivered a full-term infant (full-term women). Samples were analyzed using quantitative polymerase chain reaction. Associations between preterm birth and bacterial counts and percentages were tested using multiple linear regression. RESULTS: No significant differences were observed at baseline between preterm and full-term women for any measured bacterial species or group of species, after accounting for multiple comparisons. Changes in bacterial counts and proportions during pregnancy also were not associated with birth outcomes. In full-term and preterm women, periodontal therapy significantly reduced (P <0.01) counts of all target species except for A. actinomycetemcomitans. CONCLUSIONS: In pregnant women with periodontitis, non-surgical periodontal therapy significantly reduced levels of periodontal pathogens. Baseline levels of selected periodontal pathogens or changes in these bacteria resulting from therapy were not associated with preterm birth.     

孕妇牙周病与胎膜早破的相关性研究

目的:本研究通过检查比较胎膜早破孕妇与正常孕妇牙周健康状况,分析牙周健康状况与胎膜早破的关系,为胎膜早破的病因提供一定的临床依据。方法:选择早产胎膜早破(PPROM)孕妇18例、足月胎膜早破(PROM)孕妇20例作为实验组,足月正常孕妇(Non-PROM)28例作为对照组。检查牙周状况记录菌斑指数(PLI)、探诊深度(PD)和龈沟出血指数(SBI)。结果:胎膜早破组牙龈炎症明显,牙周状况差,PLI、SBI均高于正常对照组,差异有统计学意义(P<0.05)。各组间探诊深度无明显差别,无统计学意义。结论:牙周病可能是导致胎膜早破的原因之一。孕期及孕前的口腔保健及口腔健康教育,是预防和减少不良妊娠结局发生的有效措施。     

Periodontitis, a marker of risk in pregnancy for preterm birth

BACKGROUND: Why chronic periodontitis may induce an inflammatory response with premature pregnancy termination is unclear. AIMS: (1) To assess if periodontitis predicts premature gestation; (2) to study amniotic fluid cytokines and periodontitis variables in early-stage pregnancy. MATERIAL AND METHODS: A periodontal examination and collection of amniotic fluid was performed (weeks 15-20) of pregnancy in 36 women at risk for pregnancy complications. Amniotic fluid (bacteria), vaginal smears and intra-oral plaque samples were studied. Cytokine levels in amniotic fluid were studied in relation to other study variables. RESULTS: Periodontitis was diagnosed in 20% of normal and in 83% of preterm birth cases (p<0.01). Bacteria were never found in the amniotic fluids studied. Sub-gingival plaque samples including bacteria in the orange and red complexes were found in 18% of full-term 100% of preterm cases (p<0.001) and total colony-forming units (CFUs) were higher in preterm birth (p<0.01). Amniotic levels of interleukin (IL)-6 and prostaglandin-E2 (PGE2) were higher in preterm cases (p<0.001). Amniotic IL-6 (r=0.56, p<0.01) and PGE2 (r=0.50, p<0.01) cytokine levels were correlated with CFU from sub-gingival plaque samples (r2=0.44).The odds ratio of preterm delivery and having periodontitis was 20.0 (95% confidence interval (CI): 2.0-201.7, p<0.01). The odds of >60 CFU in sub-gingival plaque and preterm birth was 32.5:1 (95% CI: 3.0-335.1, p<01). CONCLUSIONS: Pregnant women with findings of elevated amniotic fluid levels of PGE2, IL-6 and IL-8 in the 15-20 weeks of pregnancy and with periodontitis are at high risk for premature birth. The implication of this is that periodontitis can induce a primary host response in the chorioamnion leading to preterm birth.     

牙周状况、血清白细胞介素-1β水平与妊娠关系初探

目的探讨牙周状况、血清白细胞介素- 1β（IL- 1β）水平与妊娠间的关系。方法以40例先兆早产孕妇（TPL组）和40例正常孕妇（Non- TPL组）为研究对象，检查全口牙齿的牙周状况，记录菌斑指数（PLI）、探诊深度、临床附着丧失和出血指数（BI），并计算牙周炎位点率。酶联免疫吸附试验检测血清IL- 1β水平。对各项检查指标进行统计分析。结果①TPL组40例孕妇中26例足月产（TPL- TB小组），14例早产（TPL- PB小组）；Non- TPL组40例孕妇皆足月产。TPL组和Non- TPL组、TPL- TB小组和TPL- PB小组的分娩孕周、新生儿出生体重、PLI、牙周炎位点率和血清IL- 1β水平间的差异均有统计学意义（P<0.05）。②分娩孕周和牙周炎位点率、BI、IL- 1β水平呈负相关（P<0.05），IL- 1β水平与牙周炎位点率和BI呈正相关（P<0.05）。结论牙周感染可能是早产的原因之一。     

Porphyromonas gingivalis lipids and diseased dental tissues

BACKGROUND/AIM: Porphyromonas gingivalis synthesizes several classes of dihydroceramides and at least one of these lipid classes promotes proinflammatory secretory reactions in gingival fibroblasts as well as alters fibroblast morphology in culture. The purpose of this investigation was to determine whether the dihydroceramide lipids of P. gingivalis are recovered in lipid extracts of subgingival plaque, diseased teeth, and diseased gingival tissue samples. METHODS: Lipids were extracted from P. gingivalis, subgingival plaque, subgingival calculus, teeth laden with gross accumulations of subgingival calculus, and gingival tissue samples obtained from chronic severe periodontitis sites. Lipid samples were analyzed by gas chromatography-mass spectrometry as trimethylsilyl derivatives or by electrospray-mass spectrometry as underivatized products. High-performance liquid chromatography fractions of P. gingivalis lipids and gingival tissue lipids were also analyzed by electrospray-mass spectrometry analysis. RESULTS: P. gingivalis phosphorylated dihydroceramides were recovered in lipid extracts of subgingival plaque, subgingival calculus, calculus contaminated teeth, and diseased gingival tissue samples. However, the distribution of phosphorylated dihydroceramides varied between these samples. CONCLUSION: Subgingival plaque, subgingival calculus, diseased teeth, and gingival tissue are contaminated with phosphorylated dihydroceramides produced by P. gingivalis. The previously reported biological activity of these substances together with the recovery of these lipids at periodontal disease sites argues strongly for their classification as virulence factors in promoting chronic inflammatory periodontal disease.     

Associations between systemic status, periodontal status, serum cytokine levels, and delivery outcomes in pregnant women with a diagnosis of threatened premature labor

BACKGROUND: Threatened premature labor (TPL) often results in preterm birth (PB). The aim of the present study was to evaluate the associations of periodontal and general health conditions with TPL and PB in relation to serum cytokine levels and the composition of subgingival plaque. METHODS: Eighty-eight women were enrolled in the study. Systemic conditions were assessed, and subgingival plaque samples obtained for bacterial analysis. Periodontal examinations included assessments of plaque, gingivitis, clinical attachment level, probing depth, and bleeding on probing. Serum cytokine levels also were analyzed. Gestational age at delivery was recorded, and the mothers were divided into a TPL or non-TPL group, and into a non-TPL-TB (term birth), non-TPL-PB, TPL-TB, or TPL-PB group, accordingly. RESULTS: Forty subjects were classified as TPL and 18 as TPL-PB. There were significant differences between the TPL and non-TPL subjects in several of the systemic and periodontal parameters and serum cytokine levels. Significant differences were observed between the TPL-TB and TPL-PB groups in the percentage of Tannerella forsythensis (Tf, formerly Bacteroides forsythus), and the serum interleukin (IL)-8 and IL-1beta levels. Significant negative correlations between the gestational age at delivery and several periodontal parameters and serum IL-8 and IL-1beta levels, and significant positive correlations between periodontal status and serum IL-8 and IL-1beta levels, were observed. CONCLUSIONS: The TPL women revealed worsened periodontal conditions and elevated serum IL-8 and IL-1beta levels compared to the non-TPL women. The elevated levels of serum IL-8 and IL-1beta could have affected the maintenance of the proper uterine-fetus relationship, resulting in premature uterine contractions.     

Evaluation of periodontal pathogens in amniotic fluid and the role of periodontal disease in pre-term birth and low birth weight

Abstract

Background. Pre-term birth and/or low birth weight (PTLBW) is a serious problem in developing countries. The absence of known risk factors in ～ 50% of PTLBW cases has resulted in a continued search for other causes. The aim of this study was to examine the effect of periodontitis on pregnancy outcomes. Methods. Samples were taken from 50 pregnant women who underwent amniocentesis. Polymerase chain reaction was performed on amniotic fluid samples obtained during amniocentesis and on subgingival plaque samples to determine the presence of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Prevotella intermedia, Campylobacter rectus and Eikenella corrodens. Plaque index, gingival index, bleeding on probing, probing depth and clinical attachment level were evaluated. Medical records were obtained after birth. Results. Social and demographic variables were similar among the Gingivitis (G), Localized Periodontitis (LP) and Generalized Periodontitis (GP) groups. Four subjects gave birth to PTLBW neonates. Campylobacter rectus, T. forsythia, P. gingivalis and F. nucleatum were detected in the amniotic fluid and subgingival plaque samples of three patients who gave birth to PTLBW neonates. The amniotic fluid sample from the fourth patient was not positive for any of the tested pathogens. Conclusion. These findings suggest that the transmission of some periodontal pathogens from the oral cavity of the mother may cause adverse pregnancy outcomes. The results contribute to an understanding of the association between periodontal disease and PTLBW, but further studies are required to better clarify the possible relationship.     

Site-specific development of periodontal disease is associated with increased levels of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia in subgingival plaque

BACKGROUND: Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia (previously T. forsythensis), which are regarded as the principal periodontopathogenic bacteria, exist as a consortium in subgingival biofilms. We aimed to examine quantitative relationships between P. gingivalis, T. denticola, and T. forsythia in subgingival biofilms and the relationship between the quantity and prevalence of these three bacteria and site-specific periodontal health. METHODS: This study was cross-sectional. The study population consisted of 35 adult subjects who visited the Kyushu Dental College Hospital. Plaque samples were collected from 105 periodontal pocket sites. Quantitative analyses of each of the three periodontopathogenic bacteria were performed using real-time polymerase chain reaction with species-specific primers and hybridization probes. RESULTS: The plaque samples were divided into four groups based on the presence or absence of a periodontal pocket (probing depth [PD] > or =4 mm) and bleeding on probing (BOP), regardless of attachment loss. The proportions of all three target bacteria detected in samples from sites of periodontal disease (with PD and BOP) were markedly higher than those in the other sample groups. Cell numbers of P. gingivalis, T. denticola, and T. forsythia in the subgingival plaque of each sampling site were significantly mutually correlated and were increased in the plaque of sites of periodontal disease with PD > or =4 mm and BOP. CONCLUSION: The symbiotic effects of P. gingivalis, T. denticola, and T. forsythia, which coaggregate and exist concomitantly in subgingival biofilms, may be associated with the local development of periodontitis.     

Comparison of polymerase chain reaction and culture methods for detection of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in subgingival plaque samples

In this study, the major periodontal pathogens Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were detected in subgingival plaque samples from patients with periodontal disease by polymerase chain reaction (PCR) and conventional culture methods. 170 plaque samples from 43 patients were analysed; A. actinomycetemcomitans and P. gingivalis were each detected in 40 (24%) of samples by PCR. whereas conventional culture methods detected A. actinomycetemcomitans and P. gingivalis in 25 (15%) and 18 (11%) of samples, respectively. The proportion of patients carrying A. actinomycetemcomitans in at least 1 sampled periodontal site was 17/43 (40%) by PCR and 13/43 (30%) by culture; for P. gingivalis this was 2/43 (28%) by PCR and 9/43 (21%) by culture. Only 5 samples, from 3 patients, harboured both A. actinomycetemcomitans and P. gingivalis . It is concluded that PCR is more accurate than conventional culture methods for identification of these periodontal pathogens in subgingival plaque samples and has a higher frequency of detection.     

牙周病基础治疗前后龈下菌群的动态观察

目的：动态观察龈下细菌治疗前后在口腔内定植的变化，为牙周病病因学研究和治疗方案确定提供依据。方法：选取26例慢性牙周炎患者治疗前、治疗后1周、1个月和3个月时同一位点的龈下菌斑，测量牙周探诊深度，提DNA，洲浓度。扩增全细菌16SrRNA基因片段，变性梯度凝胶电泳分离，选择特异性的DNA条带，回收、测序。结果：测序结果表明治疗后消失的两个DNA条带与牙龈卟啉单胞菌有98％和99％的同源性；治疗后新出现的两个DNA条带与卟啉菌属的一种有99％的同源性。结论：牙龈卟啉单胞菌是慢性牙周炎的重要可疑致病菌。变性梯度凝胶电泳适用于分析大量微生物标本分布和类型。     

牙龈卟啉单胞菌PG1055基因在临床菌株中的表达

目的应用基因芯片技术检测PG1055基因在不同人群的牙龈卟啉单胞菌(P.gingivalis)中分布,探讨这些基因与牙周临床指数之间的关系。方法取龈下菌斑进行细菌分离培养,以临床采集样本提取的DNA为探针,以抑制消减杂交技术获得P.gingivalisW83的特异基因片段PG1055为目标序列,采用Cy5荧光标记目标序列。应用基因芯片技术检测PG1055基因在牙周病患者及健康人群的牙龈卟啉单胞菌中的分布。结果PG1055基因在牙周病患者及健康人群中的检出率有统计学差异,并且与牙周临床指数相关。结论PG1055基因与P.gingivalis的致病性有关。     

牙龈卟啉单胞菌PG0717基因与慢性牙周炎的相关性研究

目的检测慢性牙周炎患者和牙周健康者龈下菌斑中牙龈卟啉单胞菌（P.gingivalis）PG0717基因,探讨PG0717基因与牙周临床指数之间的关系。方法选取慢性牙周炎（CP）患者90例和牙周健康者90例,共采集龈下菌斑标本540个;记录临床牙周指数（牙周探诊深度、临床附着丧失和探诊出血）;设计特异性引物检测P.gingivalis阳性龈下菌斑标本的PG0717基因。结果在P.gingivalis阳性龈下菌斑中,CP组PG0717基因检出率显著高于对照组,分别为56.22%和41.27%（掊2=4.50,P＜0.05）;随着牙周探诊深度、临床附着丧失加重和探诊出血趋势的增加,CP组该基因检出率呈现增高趋势。结论PG0717基因与P.gingivalis的致病性有关。     

Microbiological and immunological studies of adult periodontitis in patients with noninsulin-dependent diabetes mellitus

The subgingival microflora and serum antibody response was examined in periodontitis patients with noninsulin-dependent diabetes mellitus (NIDDM), impaired glucose tolerance (IGT), and normal glucose tolerance (NGT). The predominant cultivable microflora was determined for subgingival plaque sampled from two deep periodontal pockets in each of eight adult periodontitis patients with NIDDM. Indirect immunofluorescence for Bacteroides intermedius, Bacteroides gingivalis, and Haemophilus actinomycetemcomitans was used to examine these same samples as well as 186 additional subgingival plaque samples from 47 patients with moderate to severe generalized periodontitis including 25 subjects with NIDDM, six subjects with IGT, and 16 subjects with NGT. Serum antibody levels to 13 microorganisms including seven oral bacterial species and one nonoral control species were measured by enzyme-linked immunosorbent assays (ELISA) in 377 subjects including 84 normal subjects without periodontal disease, 112 normal subjects with periodontitis, 19 periodontally normal subjects with IGT, 65 periodontitis patients with IGT, 15 periodontally normal subjects with NIDDM, and 82 periodontitis patients with NIDDM. Three hundred eighty-two bacterial isolates were recovered from the eight patients. B. intermedius was the most frequently isolated microorganism constituting 16% of the total isolates followed by Wolinella recta and B. gingivalis, which each accounted for 13% of the total. Streptococcus sanguis was the most prevalent microorganism, which was found in 75% of the sites. Subgingival plaque samples examined by immunofluorescence demonstrate a high prevalence of black-pigmented Bacteroides and suggest that the proportion of B. gingivalis but not B. intermedius is higher in NIDDM with periodontitis than in other groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of periodontal therapy on pregnancy outcome in women affected by periodontitis

BACKGROUND: There is convincing evidence to suggest that infections affecting the mother during pregnancy may produce alterations in the normal cytokine- and hormone-regulated gestation, which could result in preterm labor, premature rupture of membranes, and preterm birth (PTB). Studies in the late 1990s associated periodontitis with preterm low birth weight (PLBW) deliveries, and this may have similar pathogenic mechanisms as other maternal infections. This study determined the effect of non-surgical periodontal therapy on pregnancy outcome. METHODS: A total of 200 pregnant women with periodontitis were randomly assigned to treatment and control groups. Detailed data about previous and current pregnancies were obtained. All women received a full-mouth periodontal examination, including oral hygiene index-simplified, bleeding index, and clinical attachment level. The women in the treatment group received non-surgical periodontal therapy during the gestational period, and those in the control group received periodontal treatment after delivery. Periodontal therapy included plaque control instructions and scaling and root planing performed under local anesthesia. The outcome measures assessed were gestational age and birth weight of the infant. PTB was recorded when delivery occurred at <37 weeks of gestation, and low birth weight (LBW) was recorded when the infant weighed<2,500 g. RESULTS: There were 53 PTBs in the treatment group and 68 PTBs in the control group. Twenty-six LBW infants were recorded in the treatment group, and 48 LBW infants were noted in the control group. The mean gestational ages were 33.8+/-2.8 weeks and 32.7+/-2.8 weeks in the treatment and control groups, respectively. The difference was statistically significant at P<0.006. The mean birth weight was 2,565.3+/-331.2 g in the treatment group and 2,459.6+/-380.7 g in the control group, with the difference being statistically significant at P<0.044. A multiple regression model showed a significant effect of periodontal treatment on birth outcomes. CONCLUSIONS: Non-surgical periodontal therapy can reduce the risk for preterm births in mothers who are affected by periodontitis. Additional multicentered, randomized, controlled clinical trials are required to confirm this link between periodontitis and PLBW.     

Microbiologic analysis of periodontal pockets and carotid atheromatous plaques in advanced chronic periodontitis patients

BACKGROUND: In recent years, many researchers have focused their attention on the ability of periodontal pathogens to colonize atheromatous plaques. Nevertheless, a clear correlation between the detection rates of periodontopathic bacterial DNA in atheromas and in subgingival plaque samples has not been established. The aim of our study was to assess the presence of five periodontal pathogens (Actinobacillus actinomycetemcomitans, Prevotella intermedia, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia [formerly Tannerella forsythensis]) in periodontal pockets and in carotid atheromas recovered from the same patients. METHODS: Thirty-three patients with advanced chronic periodontitis scheduled for endarterectomy were enrolled in the study. DNA was extracted from subgingival plaque samples and carotid atheromas. Universal bacteria primers for general detection of bacteria and species-specific primers for detection of periodontal pathogens were used to amplify part of the 16S rRNA gene by polymerase chain reaction. RESULTS: All subgingival plaque samples were positive for at least one target microorganism. The prevalence of T. forsythia, P. gingivalis, T. denticola, P. intermedia, and A. actinomycetemcomitans were 69.7%, 63.6%, 54.5%, 45.4%, and 33.3%, respectively. Bacterial DNA was detected in 31 out of 33 endarterectomy specimens. However, none of the samples tested positive for DNA from periodontal pathogens. CONCLUSION: The presence of periodontal bacteria in atheromatous plaques was not confirmed by this investigation; thus, no correlation could be drawn between periodontitis bacteria and microorganisms involved in the atherosclerotic lesions.     

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.     

Real-time polymerase chain reaction for detection and quantification of bacteria in periodontal patients

BACKGROUND: Accurate laboratory tests for the detection and quantification of periodontopathogens in subgingival plaque samples of periodontal disease patients are becoming essential to study the pathogenesis of this polymicrobial condition. We used a real-time polymerase chain reaction (PCR) assay for the quantification of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Dialister pneumosintes, Campylobacter rectus, and Micromonas micros as well as total eubacteria in subgingival plaque samples from individuals with periodontitis. METHODS: Eighty-three subgingival samples from periodontally diseased patients and 43 samples from periodontally healthy subjects were tested and the results of bacterial quantification were correlated to clinical parameters. Quantification was performed with specific 16S rRNA target sequences with double fluorescence labeled probes and serial dilutions of plasmid standards by real-time PCR. RESULTS: Results showed that patients as well as healthy subjects were positive for the presence of target periodontopathogens; however, median values were higher in samples from periodontitis subjects. In addition, a positive association was observed between colonization at high levels by P. gingivalis and M. micros and the presence of deep periodontal pockets. CONCLUSION: Real-time PCR provides a reliable high-throughput method for quantification of periodontopathogens and may be useful for understanding the complex etiology observed in periodontal diseases.     

Genotypic characterization of Porphyromonas gingivalis isolated from subgingival plaque and blood sample in positive bacteremia subjects with periodontitis

Aim: The objective of this study was to investigate clonal relationship among Porphyromonas gingivalis isolated from subgingival plaque and blood samples in positive transient bacteremia subjects with periodontitis.
Material and Methods: Unrelated patients with general chronic periodontitis or general aggressive periodontitis requiring scaling and root planing (SRP) were included in the study. Genotyping of each isolate was performed using pulsed field gel electrophoresis technique. Genetic relatedness of strains isolated within an individual or between different patients was determined by dendogram analysis.
Results: Following SRP, from 16 patients, seven patients showed positive P. gingivalis bacteremia and nine were negative. Thirty-two strains were isolated from subgingival plaque and blood samples before and during induced transient bacteremia. The majority of the patients harboured one clonal type. Two patients showed different clones in plaque and blood samples suggesting that more than one clone can be found in subgingival plaque. P. gingivalis isolates from periodontitis patients after transient bacteremia following SRP, revealed a high heterogeneity among isolates.
Conclusion: In 6/16 subjects the same P. gingivalis isolate was found in the blood and in oral cavity. P. gingivalis heterogeneity suggests no association of a unique clonal type with transient bacteremia.     

龈下菌斑中牙龈卟啉单胞菌牙龈素基因片段的检测

目的：检测慢性牙周炎患者龈下菌斑中牙龈卟啉单胞菌（Porphyromonas gingivalis,P.gingivalis）的2个基因片段kgp-cd和rgpB-cd,探讨2个基因片段的存在和缺失与牙周临床指标之间的关系.方法：选择慢性牙周炎患者龈下菌斑84个,对P.gingivalis阳性的龈下菌斑样本进行kgp-cd和rgpB-cd基因片段检测;根据2个基因片段的有无,将P.gingivalis分为A型和B型,采用SPSS11.5统计软件包,用t检验和x2检验分析不同基因型P.gingivalis与牙周临床指标的关系.结果：A型P.gingivalis在慢性牙周炎中的检出率高于B型（P＜0.05）,分别为85.29%和14.71%.不同基因型P.gingivalis引起的牙周袋探诊深度和牙龈出血倾向存在显著性差异（PD：t=2.85,P＜0.05;BOP：P＜0.05）.结论：kgp-cd和rgpB-cd基因与P.gingivalis的致病性有关.     

牙周炎症时基质金属蛋白酶-9的表达与胎膜早破的关系

目的分析牙周状况与胎膜早破的关系,为孕前及孕期妇女口腔疾病防治提供依据。方法选择18例早产胎膜早破孕妇设为PPROM组,20例足月胎膜早破孕妇设为PROM组,28例足月正常孕妇作为对照组,检查并记录3组的菌斑指数（PLI）、探诊深度（PD）和龈沟出血指数（SBI）,并采用免疫组织化学法检测宫颈部胎膜基质金属蛋白酶-9（MMP-9）的分布与表达,分析MMP-9与牙周状况的关系。结果PPROM组和PROM组胎膜MMP-9的表达强度均高于对照组,且差异有统计学意义。绒毛膜中MMP-9表达与PD没有相关性（r=0.053,P=0.075）,与SBI呈正相关（r=0.433,P<0.05）,与PLI呈正相关（r=0.310,P<0.05）。羊膜中MMP-9表达与PD没有相关性（r=0.077,P=0.597）,与SBI呈正相关（r=0.430,P<0.05）,与PLI呈正相关（r=0.324,P<0.05）。结论MMP-9参与了胎膜早破及牙周炎症的病理过程。