The in vitro effects of chlorhexidine on subgingival plaque bacteria

The purpose of this study was to determine the susceptibility to chlorhexidine of a range of bacteria which may be isolated from subgingival plaque. In addition, the effect of chlorhexidine on the survival of bacteria in subgingival plaque samples from patients with chronic inflammatory periodontal disease was investigated. The minimum inhibitory concentration (MIC) of chlorhexidine for 52 strains of bacteria ranged from 8 to 500 micrograms/ml. The modal value of the MIC was found to be 62 micrograms/ml, 64% of the strains tested being inhibited at this concentration. A concentration of 250 micrograms/ml of chlorhexidine inhibited the growth of all bacteria in the 25 subgingival plaque samples investigated. The MIC of chlorhexidine for the samples ranged from 31 to 250 micrograms/ml, the modal value being 125 micrograms/ml.     

Characterization of hemolytic bacteria in subgingival plaque

Three-quarters of the patients with periodontal diseases surveyed in this study had one or more distinct types of hemolytic bacteria in their subgingival plaque. Twelve different species of bacteria were identified, belonging to five genera (Actinomyces, Streptococcus, Staphylococcus, Prevotella, and Actinobacillus). Nine hemolytic isolates, consisting of four Prevotella denticola strains, two Actinomyces naeslundii genospecies 2 strains, and one each of P. melaninogenica, Streptococcus constellatus, and A. naeslundii genospecies 1 strains were characterized. Incorporation of pronase into blood agar medium inhibited hemolysis by all of the isolates, suggesting a proteinaceous component for each of their hemolysins. With one exception, hemolysin production appeared to be regulated by the concentration of environmental iron: exogenous hemin was found to inhibit hemolysin production, and the iron scavenging compound, 2,2′-dipyridyl, was found to promote hemolysin production by all of the strains except for the S. constellatus isolate. Genomic libraries of each of the hemolytic plaque isolates were prepared in Escherichia coli using pBR322. Hemolytic clones were isolated on blood agar medium containing ampicillin at frequencies ranging from 1–6.7 × 10^?4. Extensive restriction mapping revealed regions of homology in the case of clones derived from three P. denticola strains isolated from the same subject. Two of the P. denticola-derived clones were virtually identical throughout the entirety of their > 5 Kb inserts. The clone derived from the third strain showed good homology to the other two within a 1.3 Kb region, but the flanking DNA showed no homology even though all three P. denticola isolates were shown to be clonally related by ribotyping. The results indicate that hemolytic bacteria are frequently recovered from active disease sites of subjects with periodontal diseases. The hemolytic phenotype appears to be restricted to a small proportion of the total number of species normally resident in subgingival plaque. Restriction mapping suggested that a variety of hemolysin genes may be involved and that, at least in certain cases, they may be on mobile genetic elements.     

生物活性玻璃对3种细菌和龈下早期混合菌斑抗菌效果的研究

目的研究不同浓度生物活性玻璃(bioactive glass,BG)对3种浮游细菌及其形成的单菌种菌斑、三菌种早期龈下混合菌斑的抗菌效果。方法测定血链球菌(Streptococcus sanguinis,Ss)、具核梭杆菌(Fusobacterium nucleatum,Fn)、伴放线放线杆菌(Actinobacillus actinomycetemcomitans,Aa)的最小抑菌浓度(minimal inhibitory concentration,MIC)、最小杀菌浓度(minimal bactericidal concentration,MBC)、最小菌斑清除浓度(minimal biofilm eradication concentration,MBEC)。20、40、80 mg/m L的生物活性玻璃和惰性玻璃二氧化硅(Si O2)处理24 h早期三菌混合菌斑,于激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)下摄片观察分析生物膜厚度和平均荧光强度。结果 BG对菌斑的MBEC明显大于对浮游菌的MIC和MBC,MBEC为MIC的2~16倍。随着生物玻璃浓度加大,混合菌斑生物膜厚度变薄,团块减小,菌斑活性比减低,与空白对照组和阳性对照Si O2组有显著统计学差异(P<0.05)。结论 BG可抑制和杀灭血链球菌、聚合梭杆菌、伴放线放线杆菌浮游菌及其单菌种菌斑生物膜,对浮游细菌效果优于菌斑生物膜。低浓度BG对龈下混合菌斑有一定抗菌效果。     

高压氧对人牙周炎袋底不同形态细菌的作用

目的 探讨高压氧（HBO）对人牙周炎患者牙周各临床指标和袋内不同形态细菌的作用。为HBO治疗牙周炎的机理研究及临床应用提供依据。方法 选20例牙周炎患者,用HBO治疗,常规方法测定患牙各临床指标的变化。用刚果红负性染色法观察袋底不同形态细菌的变化。结果 HBO治疗后牙龈指数（GI）、牙周袋深度（PD）、牙周附着丧失（AL）和龈沟液（GCF）量与治疗前比有非常显著性差异。菌斑指数（PLI）轻度降低;HBO可明显减少牙周袋底的直杆菌,弯杆菌,梭状菌和螺旋体的百分比,使袋底的致病菌明显减少,非致病性的球菌比例增加,且对螺旋体的比率改变程度最大,结论 HBO对人牙周炎有明显的治疗作用。其原因为HBO到达牙周袋袋底抑制了杆菌,梭状菌及螺旋体等的生长和繁殖,HBO可作为牙周炎基础治疗的重要辅助手段。     

Adherence to experimental pellicle of rough-type lipopolysaccharides from subgingival plaque bacteria

The adherence of lipopolysaccharides (LPSs) from periodontal disease-associated bacteria to saliva-coated hydroxyapatite (S-HA) and serum-coated HA beads was examined by chromogenic Limulus activity (toxicolor test). Phenol-water extracted LPS preparations from Bacteroides intermedius, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, Eikenella corrodens, and rough-type LPS from Escherichia coli adhered to S-HA and serum-coated beads and agglutinated human erythrocytes. The adhered LPSs to S-HA and serum-coated HA beads were not removed by vigorous washing with distilled water. LPSs from Bacteroides (Porphyromonas) gingivalis strains and wild-type E. coli did not adhere to S-HA, serum-coated HA beads or show hemagglutinating activity. SDS-PAGE patterns stained with silver stain showed that LPSs adhered to S-HA, and serum-coated HA beads and erythrocytes possessed a distinct fast-migrating band similar to rough-type LPS. B. gingivalis LPSs possessed slow-migrating and repeating ladder bands similar to wild-type LPS.     

The survival of subgingival plaque bacteria in an amine fluoride-containing gel

Abstract. Subgingival plaque samples from 20 patients with chronic inflammatory periodontal disease were exposed to a commercial gel formulation containing 2 amine fluorides. The MIC of the gel for these samples ranged from 33 to 260 μ/ml with a modal value of 260 μ/ml. In each sample, the most resistant organisms (i.e., those organisms surviving at one doubling dilution below the MIC) were identified. 33 such organisms were isolated, of which 22 (67%) were strict anaerobes, and 25 (75%) were Gram negative. The 2 most frequent isolates were Bacteroides ruminicola ss. brevis and a Selenomonas species, neither of which is a recognised periodontopathogen. The gel had a rapid effect on the viability of the bacteria in the plaque samples, the 90% kill time being 17 min or less for 90% of the samples (range <5 to 71 min).     

Lethal photosensitization of bacteria in subgingival plaque from patients with chronic periodontitis

Subgingival plaque samples from patients with chronic periodontitis were exposed to light from a 7.3 mW Helium/Neon laser for 30 s in the presence and absence of 50 μg /ml toluidine blue O as a photosensitizer. Viable counts of various groups and species of bacteria were carried out before and after irradiation. The median numbers of viable bacteria initially present in the 30-μl aliquots irradiated were 1.13 × 10⁵ cfu (aerobes), 4.08 × 10⁵ cfu (anaerobes), 4.92 × 10³ cfu (black-pigmented anaerobes), 4.75 × 10² cfu ( Porphyromonas gingivalis ), 6.15 × 10³ cfu ( Fusobacterium nucleatum ) and 1.7 × 10⁴ cfu (streptococci). The dye/laser combination achieved significant reductions in the viability of these organisms, the median reductions in the viable counts being 91.1% for aerobes, 96.6% for anaerobes, 100% for black-pigmented anaerobes, P. gingivalis and F. nucleatum and 94.2% for streptococci. Overall, the viability of bacteria in the 20 plaque samples was not significantly decreased by the dye alone. However, in a small minority of samples there were indications of light-independent, dye-induced toxicity. Low-power lasers, in conjunction with appropriate photosensitizers, may be a useful adjunct to mechanical debridement in the treatment of inflammatory periodontal diseases if a similar effectiveness against subgingival plaque bacteria can be achieved in vivo .     

Subjective criteria and probing attachment loss to evaluate the effects of plaque control and root debridement

11 adult patients with moderate to advanced periodontitis were treated with oral hygiene instruction and an initial, single episode of root debridement. Before therapy, 3 independent clinicians examined all patients and identified sites that in their opinion probably would not respond to the therapy and would continue to lose attachment. On 2 occasions, 3 and 12 months later, the clinicians re-examined and re-evaluated all patients and all sites. The results of therapy were also monitored by probing attachment level measurements performed every 3rd month. All 11 patients completed 24 months of follow-up, and 6 subjects were available until 36 months. Sites with probing attachment loss after 12, 24 and 36 months were identified using linear regression analysis and compared to the clinicians' prediction of probing attachment loss. The results demonstrated a limited agreement between probing attachment loss determined by linear regression and the clinicians' predictions of probing attachment loss. It appears that the traditional clinical signs and factors used to forecast and identify periodontal disease activity are only moderately associated with probing attachment loss. This suggests that attachment loss may be caused by several factors, at least following initial therapy. The progression of an inflammatory disease of microbial etiology may be only 1 of such causes. Further studies are needed to clarify the nature and cause of probing attachment loss.     

Applicability of monoclonal antibodies to quantitatively monitor subgingival plaque for specific bacteria

The aim of the present investigation was to assess the applicability of monoclonal antibodies For the quantitative determination of specific bacteria in subgingival plaque. Periodonlal pocket samples from sites with recurrent periodontal breakdown were investigated in parallel by culture analysis, by direct immunofluorescence with species-specific polyclonal antiscra to Bacteroides gingivalis and Bacteroides intermedius , and by indirect immunofluorescence with one monoclonal antibody specific for Bacteroides forsythus , 3 monoclonal antibodies directed against B. gingivalis and 3 monoclonal antibodies recognizing B. intermedius, B. forsythus was consistently detected in high numbers by immunofluorescence, but never by cultural analysis. For B. gingivalis and B. intermedius culture scores were similar or lower than those obtained with the serological technique. Monoclonal and polyclonal antibodies yielded quantitatively very similar results. Neither evidence for a significant interference of host antibodies with the labelling of target bacteria by single epitope-specific monoclonal reagents, nor for unspecific staining due to the labelling of crossreactive antigens was observed. The results demonstrate that, following careful selection and characterization, monoclonal antibodies can indeed by successfully applied for a rapid, quantitative and highly sensitive species - or serotype-specific screening of subgingival plaque.     

Bacterial species in subgingival plaque and oral bone loss in postmenopausal women

BACKGROUND: Oral bacteria are widely recognized in the etiology of periodontal disease. We investigated the prevalence of subgingival bacterial infection with eight species, tested associations between infection and oral bone loss, and assessed potential confounding factors and effect modifiers of those associations in a large community-based cohort of postmenopausal women. METHODS: A cross-sectional study of oral health and osteoporosis in 1,256 postmenopausal women recruited from the Buffalo, New York Women's Health Initiative Observational Study was conducted. Standardized dental radiographs were used to measure alveolar crestal height (ACH). Subgingival plaque samples were taken, and the presence of eight bacterial species was assessed by indirect immunofluorescent microscopy in each participant. RESULTS: The most prevalent infection was Streptococcus sanguis (59.5%), followed by Prevotella intermedia (43.4%), Tannerella forsythensis (37.9%), Capnocytophaga sp. (36.9%), Eubacterium saburreum (32.7%), Campylobacter rectus (17.4%), Porphyromonas gingivalis (15.1%), and Fusobacterium nucleatum (14.2%). Infections with P. gingivalis, T. forsythensis, P. intermedia, and C. rectus were associated with an increased likelihood of having oral bone loss as measured by ACH, even after adjustment for age, smoking, and income. The body mass index (BMI) was a modifier of this association. Overweight women with T. forsythensis infection were more likely to have oral bone loss (OR = 3.37; 95% confidence interval [CI]: 2.08 to 5.46) than normal weight (OR = 1.27; 95% CI: 0.82 to 1.98) or obese (OR = 1.26, 95% CI: 0.72 to 2.20) women with T. forsythensis infection. CONCLUSIONS: The prevalence of specific bacterial infections was determined for a large group of postmenopausal women. Those with infection were more likely to have oral bone loss. Further studies should investigate potential modifying effects of BMI and/or inflammatory factors.     

Relationship between some subgingival bacteria and periodontal pocket depth and gain or loss of periodontal attachment after treatment of adult periodontitis

We studied the association between post-treatment periodontal disease activity and subgingival Bacteroides gingivalis, Bacteroides intermedius, spirochetes and motile rods. 20 adults, 22-62 years, with moderate-to-severe periodontitis participated in a split-mouth treatment study. All individual quadrants received supragingival cleaning and in addition, subgingival scaling and a NaHCO3-NaCl-H2O2 slurry, subgingival scaling alone, slurry alone, or no subgingival treatment. Post-treatment periodontal disease status was determined over a period of 12 months by changes in probing periodontal pocket depth and probing periodontal attachment level. Subgingival specimens obtained by paper point-sampling were evaluated for B. gingivalis and B. intermedius using indirect immunofluorescence and for spirochetes and motile rods using bright light phase contrast microscopy. A total of 142 periodontitis lesions representing all 4 quadrants of the 20 subjects were studied. The relationship between clinical data and bacteria was analyzed using logistic regression. The probability of the study organisms being present in subgingival sites at 3 to 6 months after treatment increased with increased residual pocket depth. The presence of B. gingivalis showed a strong positive association (p less than 0.004) with loss of periodontal attachment. A significant association was also found for spirochetes (p less than 0.008) but not for motile rods (p greater than 0.35) or B. intermedius (p greater than 0.13). Similar results were obtained at 12 months after therapy, except that the presence of motile rods was significantly associated with loss of periodontal attachment (p less than 0.03). Caution must be exercised when using B. gingivalis or spirochetes to evaluate treatment efficacy. If the presence of these organisms was utilized to indicate progressing periodontitis, many active lesions could be identified, and only 1 to 17% and 13 to 43% of sites in remission at 3-6 months after therapy would be expected to harbor B. gingivalis and spirochetes, respectively. The consequences of treating periodontal sites in remission would mainly be limited to cost and inconvenience. However, since several active periodontitis lesions did not reveal the organisms, treatment decisions based solely on the absence of the organisms may result in the omission of needed therapy. As a practical consideration, periodontal treatment should be continued as long as B. gingivalis and maybe spirochetes are detectable in the subgingival microflora. In the absence of these organisms, and until additional periodontal pathogens have become known, the decision to continue or conclude periodontal therapy must b     

不同采样方法对龈下牙周致病菌检出的比较研究

目的:比较4-site法和full-mouth法对慢性牙周炎病人龈下菌斑中牙龈卟啉单胞菌、福赛斯坦纳菌、伴放线菌嗜血菌、具核梭杆菌检出的影响.方法:对30例慢性牙周炎病人用纸尖收集4个区牙周袋探诊最深位点龈下菌斑(4-site法)和收集全口龈下菌斑(full-mouth法),采用16S rRNA PCR方法检测两种方法收集到的龈下菌斑样本中的牙龈卟啉单胞菌、福赛斯坦纳菌、伴放线菌嗜血菌、具核梭杆菌.结果:两种方法一致性较好,4-site法与full-mouth法无显著差异(P>0.05).结论:4-site法采集到的龈下菌斑具有良好的代表性.     

纸尖法和刮匙法对龈下牙周致病菌检出比较研究

目的：比较纸尖法和刮匙法对慢性牙周炎患者龈下菌斑中牙龈卟啉单胞菌、福赛斯坦纳菌、伴放线菌嗜血菌、具核梭杆菌检出的影响。方法：对30例慢性牙周炎患者分别用纸尖和刮匙法收集4个区域牙周袋探诊最深位点龈下菌斑，采用16SrRNAPCR方法检测两种方法收集到的龈下菌斑样本中的牙龈卟啉单胞菌、福赛斯坦纳菌、伴放线菌嗜血菌、具核梭杆菌。结果：两种方法一致性较好，纸尖法与刮匙法无显著差异（P〉0．05）。结论：纸尖法与刮匙法均为比较准确的取样方法。     

The prevalence of beta-lactamase producing bacteria in subgingival plaque and their sensitivity to Augmentin

Subgingival plaque samples from 20 patients with chronic periodontitis who had received no antibiotics for at least 3 months were screened for the presence of beta-lactamase-producing bacteria. Thirteen of the patients harboured beta-lactamase producing bacteria, most of which were members of the genus Bacteroides. The most frequently isolated species were Bacteroides melaninogenicus and Bacteroides capillosus which are often implicated in acute oral infections. All of the beta-lactamase-producing bacteroides strains were sensitive to a combination of amoxycillin with clavulanic acid (Augmentin).     

Cigarette smoking may have a local effect on patterns of attachment loss

J Evid Base Dent Pract 2002;2:50-51     

Presence or absence of plaque on subgingival restorations

abstract — One hundred and eight extracted teeth with restorations placed below the gingival margin were stained and examined under the stereomicroscope with the aim of scoring presence or absence of subgingival plaque. Individual observations showed that a subgingival restoration can be completely covered with plaque in as short a time as 6 weeks and it can be free of plaque for as long as 2 years. In the material as a whole about 9 out of 10 of the restorations were covered with plaque subgingivally. Since the material is selected, these proportions cannot be claimed to be valid for the population as a whole, but the observations suggest that plaque sooner or later will accumulate on most if not all subgingival restorations. Rough surfaces and or inadequate marginal adaptation are likely to facilitate a more rapid adherence of bacteria to the restorations than to the smooth tooth surface. It is concluded that restorations placed below the gingival margin indirectly are strongly involved in the etiology of destructive periodontal disease and the cause of many extractions.