Subgingival microflora and periodontal disease

Bacterial adhesion to oral tissues: a model for infectious diseases

The majority of bacteria which colonize humans display sharp host and tissue tropisms; consequently, relatively little is known about how they initiate colonization on mucosal surfaces. The mouth has a variety of features which have enabled it to serve as a useful model for the discovery of basic principles of host-parasite interactions occurring in mucosal environments. Early studies demonstrated that indigenous bacteria attach to surfaces of the mouth in a highly selective manner; attachment was often observed to correlate with colonization. These studies led to the recognition that bacterial attachment is an essential step for colonization in environments which contain surfaces exposed to a fluid flow. Bacterial adhesion has subsequently grown into a major area of infectious disease research. Many bacteria have been found to possess proteinaceous components, called "adhesins", on their surfaces which bind in a stereochemically specific manner to complementary molecules, or "receptors", on the tissue surface. Adhesins are often lectins which bind to saccharide receptors, but some adhesins are thought to bind to proteinaceous receptors. Studies of components of human saliva, which adsorb to hydroxyapatite (HA) surfaces similar to those of teeth, and promote the attachment of prominent plaque bacteria, have revealed that the acidic proline-rich proteins (PRPs) promote the attachment of several important bacteria. These include strains of Actinomyces viscosus, Bacteroides gingivalis, some strains of Streptococcus mutans, and others. The salivary PRP's are a unique family of molecules. However, segments of PRPs are structurally related to collagen. This may be significant, since B. gingivalis and certain cariogenic streptococci bind to collagenous substrata, and such interactions may facilitate their invasion into gingival tissues, or into dentin or cementum, respectively. Another unexpected observation was that although A. viscosus and other bacteria bind avidly to PRPs adsorbed onto apatitic surfaces, they do not interact with PRPs in solution. PRP molecules evidently undergo a conformational change when they adsorb to HA, and adhesins of A. viscosus recognize cryptic segments which are only exposed in adsorbed molecules. This provides the bacteria with a mechanism for efficiently attaching to teeth while suspended in saliva. It also offers a molecular explanation for their sharp tropisms for human teeth. It has proven convenient to refer to such hidden receptors for bacterial adhesins as "cryptitopes" (from cryptic, meaning hidden, and topo, meaning place).(ABSTRACT TRUNCATED AT 400 WORDS)

Rapidly progressive periodontal disease associated with HIV infection: report of case

A case of rapidly progressive periodontal disease associated with human immunodeficiency virus (HIV) infection is presented. Rapid horizontal bone loss, with only moderate inflammation, occurred during a 13-month period. Pocket depth was significantly less than anticipated, given the degree of bone loss. The patient had no signs or symptoms of acquired immune deficiency syndrome (AIDS). The cause, features, diagnosis, and management are discussed.

Studies on the virulence properties and metabolism of pleiotropic mutants of Porphyromonas gingivalis (Bacteroides gingivalis) W50

Porphyromonas gingivalis (Bacteroides gingivalis) strain W50 and variants isolated from continuous culture designated W50/BP1 (black pigmented), W50/BR1 (brown pigmented) and W50/BE1 (beige or non-pigmented) were previously shown to lose virulence with the loss of pigmentation. Major properties which may affect the virulence and metabolism of P. gingivalis were compared amongst the 4 strains. The non-pigmented strain lost the ability to hemagglutinate sheep erythrocyte, had a reduced hydrophobicity and possessed lower levels of proteolytic activity. Defects in the electron transport system occurred at the level of cytochrome b but not menaquinone synthesis and resulted in an altered metabolic end product profile of the non-pigmented strain.

Antibodies to Bacteroides gingivalis in patients with treated and untreated periodontal disease

It is proposed that the development of periodontal disease is associated with rising levels of serum and gingival crevice fluid (GCF) IgG antibodies to specific organisms, while treatment of periodontal disease is associated with a decline in specific IgG antibodies. This study examined the immune response to Bacteroides gingivalis, a suspected periodontal pathogen, in serum and GCF of patients with adult periodontitis. Three groups of subjects were studied: (1) patients with untreated adult periodontitis, (2) patients with treated adult periodontitis, and (3) patients with gingivitis (controls). An enzyme-linked immunosorbent assay was employed using whole formalinized B. gingivalis (ATCC 33277) as antigen. Results showed that the untreated adult periodontitis patients had a humoral immune response to B. gingivalis, producing significantly higher serum levels of IgG antibody to that organism than did patients with treated adult periodontitis (p less than or equal to 0.01) or gingivitis (p less than or equal to 0.005). The untreated patients also demonstrated a local immune response to B. gingivalis in that their GCF levels of IgG antibody to that organism were also significantly higher than levels in treated adult periodontitis patients (p less than or equal to 0.005) and gingivitis patients (p less than or equal to 0.001). These results are consistent with reports by other investigators. However, ratios of GCF antibody to serum antibody in the untreated adult periodontitis group were not significantly higher than ratios in the other two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of granulation tissue, dental calculus and contaminated root cementum on periodontal wound healing. An experimental study in monkeys

The rôle of gingival granulation tissue, dental calculus and contaminated root cementum in marginal periodontal formation of new attachment was studied experimentally after chemical conditioning of the root surfaces of premolars and molars in 8 monkeys. Each treatment procedure was carried out in 4 monkeys. The other 4 monkeys served as controls. A morphometrical method was used to evaluate the results. It was concluded that a significant amount of new attachment including formation of new adhering cementum will result only on chemically-conditioned cementum surfaces. Small amounts of calculus or granulation tissue left in situ do not seem to influence healing, provided the cementum is left intact after chemical cleansing.

Treatment of recurrent periodontal disease by root planing and Ornidazole (Tiberal). Clinical and microbiological findings

The purpose of this study was to evaluate the use of Ornidazole as an adjunct to root planing in the therapy of patients suffering from recurrent periodontal disease. In 10 individuals who had previously been treated with scaling, root planing and periodontal surgery and who had followed a regular maintenance program including recall visits every 3-5 months for 1-7 years, 2 sites with recurrent periodontitis and 1 shallow site were selected. Reinfected sites had a record of losing clinical attachment of more than 3 mm since the completion of initial therapy, were bleeding upon probing and had a mean pocket probing depth of 7.85 +/- 1.31 mm. They had been reinstrumented several times by a registered dental hygienist, when clinical signs of recurrence of disease had appeared and the root surfaces were judged to be smooth and free of deposits. Clinical parameters were recorded and microbial samples were collected twice prior to retreatment. Then, 500 mg Ornidazole, to be taken twice a day for 10 days, was administered, and the whole dentition was thoroughly scaled and root planed. At day 10 as well as 2, 5, 8 and 11 months thereafter, samples were again obtained. At baseline, reinfected sites showed over 20% spirochetes, over 20% motile rods and over 9% fusiform organisms in darkfield preparations of subgingival plaque samples. Culturally, over 1/10 of organisms were identified as black pigmenting Bacteroides and in 18% of all baseline samples collected, B. gingivalis was found.(ABSTRACT TRUNCATED AT 250 WORDS)

The detection of platelet-activating factor in inflamed human gingival tissue

Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; PAF) is a biologically active lipid, like the prostaglandins, which mediates allergic and inflammatory reactions. Aggregation of washed rabbit platelets was induced by a lipid prepared from inflamed gingiva. The mobility of the active lipid was coincident with that of authentic PAF on thin-layer chromatography. The aggregation was dose-dependent and inhibited by pretreatment with a specific PAF antagonist, ONO 6240, but not by indomethacin or creatine phosphate/creatine phosphokinase, which inhibit the platelet aggregation due to arachidonic acid or ADP, respectively. Thus the active lipid was identified as PAF; the amount of PAF detected was 118.1 +/- 79.7 pg/50 mg tissue (n = 6, mean +/- SD), the amount in normal tissue being 13.0 +/- 11.3 pg/50 mg tissue (n = 6). There was therefore a significant difference between the tissues. Lyso PAF, the metabolite of PAF with acetylhydrolase, was not detectable in either gingival tissue. Thus PAF was produced more in inflamed gingival tissue than in normal tissue; PAF may be involved in the occurrence and maintenance of periodontal disease.

The role of Bacteroides gingivalis in periodontal disease

The microbial flora in adult advanced periodontitis lesions is comprised of Gram-negative rods, with Bacteroides gingivalis as one of the major representatives. This review deals with biological properties of surface antigens, hemagglutinin (attachment factor), and capsular structure of B. gingivalis. Sera containing high IgG antibody levels to B. gingivalis enhanced the complement-mediated bactericidal activity in vitro, although the susceptibility to complement-mediated lysis differed among B. gingivalis strains. The protective effect of immunization against B. gingival is infection was examined in hamsters in which cotton threads had been tied to the gingival margins of the mandibular first molar. Repeated oral topical application of hyper-immune sera against B. gingivalis resulted in effective elimination of the organisms from the periodontal lesions in the experimental animals.

Characterization and immunobiologic activities of lipopolysaccharides from periodontal bacteria

Bacterial surface structures play a critical role in the initiation of infectious diseases. Various surface components of pathogenic bacteria have been reported to be involved in host injury. There is a great deal of evidence incriminating certain Gram-negative, anaerobic bacteria present in the gingival crevice as etiologic agents of human periodontal diseases. We have isolated endotoxic cellular components from suspected periodontopathic bacteria and examined their immunobiological activities. Lipopolysaccharides (LPS) and lipid-associated proteoglycans (LPG) were prepared from whole cells by the phenol-water and butanol-water procedures, respectively. LPS from Bacteroides gingivalis, B. intermedius, B. oralis, and B. loescheii, Fusobacterium nucleatum and F. necrophorum, and Actinobacillus (Haemophilus) actinomycetemcomitans were found to possess biological activities comparable with those of LPS from E. coli K235 in terms of activation of Limulus lysate, B-cell mitogenicity, polyclonal B-cell activation, induction of bone resorption, and IL-1 production by macrophages. These LPS contained mainly sugars, amino sugars, and fatty acids. No heptose or 2-keto-3-deoxyoctonate (KDO) was detected in the Bacteroides LPS, while LPS from Actinobacillus and Fusobacterium species contained significant amounts of heptose as well as small quantities of KDO. Bacteroides LPS were clearly mitogenic for spleen cells of C3H/HeJ mice, which are non-responsive to LPS from E. coli, A. actinomycetemcomitans, and Fusobacterium species. Furthermore, polymyxin B was found to abrogate the mitogenic activity of LPS from E. coli, Actinobacillus, and Fusobacterium species, but not those from Bacteroides species. Spleen cells from both C3H/HeN and C3H/HeJ mice responded to all butanol-water-extracted LPG preparations, including those from E. coli, A. actinomycetemcomitans, and Fusobacterium species. It may be concluded that LPS and LPG isolated from suspected periodontopathic bacteria possess marked immunobiological potencies on lymphoreticular and bone cells.

Gene cloning and expression of a Bacteroides gingivalis-specific protein antigen in Escherichia coli

Gene banks of chromosomal DNA from Bacteroides gingival is 381 were constructed utilizing the bacteriophage replacement vector λCharon4A. A clone encoding a protein antigen from B. gingivalis was identified by Western-blot screening, with use of antiserum induced to extracts of B. gingivalis cells. DNA fragments from the phage clone were subcloned into the plasmid vector pACYC184 to yield an immunoreactive clone. Cell extracts from the subclone reacted with antiserum against B. gingivalis, but did not react with antisera to B. asaccharolyticus, B. intermedius, or B. melaninogenicus. The antiserum against the purified clone products reacted with N-lauryl sarcosine extracts from B. gingivalis cells, but did not react with those of other Bacteroides cells. In addition, human serum from periodontitis patients reacted with the clone product by Western electrophoretic transfer and immunoblotting analysis. These data suggest that the gene coding for a B. gingivalis-specific protein antigen was successfully cloned and functionally expressed in Escherichia coli. This clone product may prove useful for further studies of B. gingival is as a periodontal pathogen.

Monitoring of subgingival Bacteroides gingivalis and Actinobacillus actinomycetemcomitans in the management of advanced periodontitis

In a series of clinical trials involving 79 adult periodontitis patients, we evaluated the clinical and microbiological effects of H2O2, NaHCO3, and a commercially available povidine solution, as adjuncts to mechanical periodontal debridement. Each trial included a placebo as a control. The healing response was monitored clinically by measurement of changes in probing attachment levels after treatment. The current report includes data from single-rooted teeth only.

In general, healing in severely advanced periodontal lesions (initial pocket depth ≥ 7 mm) was enhanced by the use of the listed topical antimicrobial agents administered subgingivally during mechanical debridement.

Correlations were sought between changes in probing attachment levels 12 months after treatment, and the presence of subgingival B. gingivalis and A. actinomycetemcomitans in the periodontal lesions. For a total of 428 lesions included in this report, B. gingivalis was detected in 53.1% of lesions showing probing attachment loss (≥1.5 mm), but in only 4.7% of lesions showing gain (≥ 1.5 mm). Either B. gingivalis or A. actinomycetemcomitans was detected in 70.1% of the lesions showing loss and in only 4.8% of those showing gain. These studies indicate the benefits of the adjunctive antimicrobial therapy described, and the usefulness of specific microbiological monitoring as an aid to clinical measurements in the evaluation of success or failure of treatment of chronic adult periodontitis.

The origin of periodontal infections

Periodontal diseases are recognized as bacterial infections, and some forms are associated with specific organisms, such as Actinobacillus actinomycetemcomitans in juvenile periodontitis, and Bacteroides gingivalis and others in adult periodontitis. The source of the periodontal organisms, whether they are part of the indigenous or resident flora and overgrow to become opportunistic oral pathogens, or whether they are exogenous oral pathogens, is important to determine. The chain of periodontal infection, microbial agent(s) and their transmission, and host response are reviewed with respect to the role of A. actinomycetemcomitans in localized juvenile periodontitis and B. gingivalis in adult periodontitis. The present data lead us to hypothesize that some periodontal organisms may be exogenous pathogens.

Prevention of periodontal diseases may be influenced by the knowledge of whether various forms are caused by opportunistic organisms or exogenous pathogens. If exogenous pathogens are responsible, prevention can be directed to intercepting transmission, thereby preventing colonization. On the other hand, if the organisms are opportunistic pathogens, prevention might be directed at interfering with initial acquisition of the flora earlier in life, as well as suppressing them to low levels consistent with health. For those exogenous periodontal infections, attempts at eradication and prevention of re-infection are likely to be effective. If the organisms are part of the indigenous flora, there is little hope of complete elimination of the organism.

Criteria for distinguishing exogenous periodontal pathogens from opportunistic periodontal pathogens include the prediction that exogenous pathogens would be transient members of the oral flora associated with periodontal disease, likely to be comprised of one or a few clonal types, and intrinsically virulent. In contrast, opportunistic periodontal pathogens would likely be members of the indigenous flora and would overgrow. They would likely be comprised of many clonal types, and have an intrinsically low level of virulence.

Identification of periodontopathic bacteria based upon their peptidase activities

Black-pigmented Bacteroides (BPB) and spirochetes are associated with some forms of periodontal diseases. The enzymes produced by these bacteria may participate in the destruction of gingival and periodontal tissues. Certain proteases and peptidases are unique to Bacteroides gingivalis and Treponema denticola. Our purpose was to study the peptidases of periodontopathogens and to evaluate the use of unique peptidases for detection and identification of these bacteria.

Bacteria used were BPB, Treponema, Fusobacterium, Capnocytophaga, Actinobacillus (Haemophilus), and Eikenella species. Twenty-five substrates, including mono-, di-, and tri-peptides of β-naphthylamide (β-NA) were employed for examination of peptidase activity. Clinically isolated BPB were obtained from 16 adult periodontitis patients. One hundred and ninety-three BPB strains were identified by conventional identification methods, and the peptidase activity was determined with N-Carbobenzoxy-glycyl-glycyl-L-arginine-β-naphthylamide (N-CBz-Gly-Gly-Arg-β-NA) used as a substrate.

Among tested periodontopathic bacteria, only B. gingivalis and T. denticola could strongly hydrolyze some substrates such as N-CBz-Gly-Gly-Arg-β-NA and N-Benzoyl-L-valyl-glycyl-L-arginine-4-methoxy-(3-naphthylamide (Bz-Val-Gly-Arg-β-NA). In subgingival plaque samples, all patients showed BPB, and eight out of 16 patients possessed B. gingivalis by culture. One hundred and ten strains out of 193 BPB isolated were identified as B. gingivalis. Ninety-nine percent of these B. gingivalis strains identified showed N-CBz-Gly-Gly-Arg-β-NAhydrolyzing activity on a newly developed colorimetric plate assay. However, none of the other strains showed this activity in cultures of subgingival plaque which did not allow growth of spirochetes.

Enzymes, such as N-CBz-Gly-Gly-Arg-peptidase and Bz-Val-Gly-Arg-peptidase, specific for B. gingivalis and T. denticola seem to be useful for rapid detection and identification of these bacteria.

Effect of clindamycin on neutrophil killing of gram-negative periodontal bacteria

Periodontal diseases are infections of the tissues supporting the dentition. Recognition that relatively specific microfloras are associated with distinct clinical forms of periodontal disease has prompted the use of antimicrobial agents as adjuncts in periodontal therapy. Clindamycin is one of several antibiotics known to concentrate in bioactive form in neutrophils and to potentiate phagocyte bactericidal activity against certain bacteria. Neutrophils appear to play a key role in host defense against periodontopathic gram-negative bacteria. In the present study, we evaluated the effect of preincubation of neutrophils with therapeutically achievable concentrations of clindamycin upon subsequent in vitro bactericidal activity against three species of gram-negative periodontal bacteria, including Actinobacillus actinomycetemcomitans, Eikenella corrodens, and Capnocytophaga ochracea. In each instance, clindamycin neither enhanced nor inhibited the kinetics of bactericidal activity at low bacterium-neutrophil multiplicities. Further, this antibiotic had no demonstrable effect upon neutrophil bactericidal capacity, as assessed at bacterium-neutrophil ratios as high as 50:1. Our results indicate that clindamycin does not potentiate neutrophil bactericidal activity against the species of gram-negative periodontal organisms tested.

Use of antimicrobial containing acrylic strips in the treatment of chronic periodontal disease. A three month follow-up study

Local antimicrobial therapy has been considered for use in the treatment of chronic periodontal disease. This study evaluated chlorhexidine, metronidazole, and tetracycline delivered into periodontal pockets in an acrylic resin vehicle and compared the results with root planed and untreated sites over a three-month follow-up period. One site per patient where pocketing greater than or equal to 6 mm associated with a single rooted tooth was randomly allocated to one of the five possible regimens. Baseline and follow-up measurements included probing depth, loss of attachment, bleeding on probing, crevicular fluid flow, and dark-field microscopy of a subgingival plaque sample. Intratreatment evaluations revealed no significant changes in any parameter for untreated sites. Significant improvements in many parameters occurred with all four therapies although the magnitude and duration were greater in metronidazole and root planing groups. The more important intertreatment comparisons indicated that most treatments produced significant benefits compared with the control group; however, again these were greater with metronidazole and root planing. Furthermore, significantly greater effects were noted for metronidazole and root planing compared with tetracycline and more particularly chlorhexidine. It is concluded that some locally delivered antimicrobials alone may be useful in the treatment of chronic periodontal disease. However, at this time local antimicrobial therapy should be considered as adjunctive to conventional debridement techniques.

Natural occurrence of black-pigmented Bacteroides species in the gingival crevice of the squirrel monkey

The objective of this study was to determine whether the squirrel monkey (Saimiri scuireus) is indigenously colonized with black-pigmented bacteroides (BPB) resembling human Bacteroides gingivalis and Bacteroides intermedius (suspected periodontal pathogens) and to determine the usefulness of the squirrel monkey as an in vivo model for studying colonization by putative pathogens. We assayed the subgingival plaques of 138 monkeys of various ages and in four different colonies for the presence of anaerobic BPB microorganisms. We also tested half the animals for the presence of Actinobacillus actinomycetemcomitans. Clinical indices and levels of serum antibody to B. gingivalis were recorded. We detected BPB in 50% of the animals and A. actinomycetemcomitans in 69% of the animals. The presence of BPB was generally associated with increased age, increased gingival index, presence of calculus, and increased levels of serum antibody. These data indicate that the squirrel monkey may be a good model for studying the parameters of natural infection of the gingival crevice with suspected periodontopathogenic BPB microorganisms.

Facial radicular groove in a maxillary central incisor. A case report

A facial radicular groove may occur in central maxillary incisors and act as a funnel for accumulating plaque and calculus. Since it is inaccessible to routine oral hygiene efforts of the patient and to treatment manipulations of the dentist, this anomaly predisposes the tooth to localized periodontal disease. Conservative or surgical treatment of such teeth should restore periodontal health by creating an environment more favorable for plaque control.

Attachment of Bacteroides gingivalis to collagenous substrata

The ability of Bacteroides gingivalis 381 to attach to hydroxyapatite (HA) beads, treated with either human type I or type IV collagen, or to particles of bovine bone collagen was studied. All preparations were blocked with human albumin prior to being incubated with 3H-thymidine-labeled B. gingivalis 381 cells. The presence of collagen on HA surfaces (C-HA) significantly promoted attachment of the organism. HA treated with Type IV collagen bound B. gingivalis cells more effectively than did HA treated with type I collagen. Attachment of two additional strains of B. gingivalis to HA was also promoted by collagen. Binding to type I or type IV C-HA occurred rapidly, and equilibrium was attained within 45 min. B. gingivalis 381 cells also bound to particles of bovine bone collagen, and this appeared to be biphasic. Heating the bacteria abolished their ability to bind to C-HA. Attachment of B. gingivalis 381 cells to HA treated with type I collagen was strongly inhibited by the presence of soluble type I or type IV collagen, or gelatin, but not by the presence of human albumin, salivary proline-rich protein 1, or saliva. Human serum, fibronectin, fibrinogen, certain protease inhibitors, and some peptides were also inhibitory. 3H-fibronectin bound to bovine bone collagen particles and blocked the attachment of 14C-B. gingivalis cells. Mild trypsin treatment of the fibronectin-collagen complex restored its ability to promote 14C-B. gingivalis attachment concomitant with the loss of 3H-fibronectin. We suggest that elevated levels of proteases in the gingival sulcus, such as are associated with poor oral hygiene and gingivitis, might remove fibronectin and expose collagen molecules in the basement membrane, thereby promoting the attachment of B. gingivalis cells and facilitating their invasion into gingival tissues.

Impaired polymorphonuclear leukocyte 15-lipoxygenase activity in juvenile and rapidly progressive periodontitis

15-lipoxygenase activity was investigated in sonicated polymorphonuclear leukocytes (PMNLs) from patients with juvenile and rapidly progressive periodontitis and adult periodontitis. The group with juvenile and rapidly progressive periodontitis had 17 patients (6 male, 11 female, mean age 27.4 years), and the age matched control group had 18 normal individuals (11 male, 7 female, mean age 26.3 years). The group with adult periodontitis had 14 patients with 9 male, 5 female, mean age 45.2 years and the age-matched control group had 6 normal subjects with 5 male, 1 female, mean age 43.7 years. 15-hydroxyeicosa-tetraenoic acid (15-HETE) synthesized in the group with juvenile and rapidly progressive periodontitis was 0.219 +/- 0.102 ng/mg protein (mean +/- S.D.), while it was 0.410 +/- 0.138 ng/mg protein in the age-matched control group. There was a significant difference between the two groups. The group with adult periodontitis produced 0.358 +/- 0.124 ng/mg protein and the age matched control group produced 0.448 +/- 0.176 ng/mg protein (no significant difference). These results are relevant to reports that PMNLs of patients with juvenile and rapidly progressive periodontitis have abnormal functions, while those of patients with adult periodontitis are normal.

Clinical and microbiological effects of root debridement in periodontal furcation pockets

The aim of the present study was to investigate longitudinally over 52 weeks the clinical and microbiological effects of plaque control and root debridement at molar furcation sites. The results were compared with changes at non-molar sites. 24 non-molar sites and 31 grade II molar furcation sites with probing depth greater than or equal to 5.0 mm were monitored in 11 patients. Clinical measurements consisted of plaque scores, probing depths, and changes in probing attachment level. Microbiological monitoring was carried out with phase-contrast microscopy and anaerobic culturing. The debridement resulted in improvement in probing measurements and microbiological counts for both groups of sites. A slightly less favorable clinical response was noted for molar furcation sites. Higher post-operative microbiological counts were found throughout the 52-week observation period for molar furcation sites. Sites with probing attachment loss showed higher microbial counts and higher proportions of spirochetes, black pigmented colony forming units (CFU), and Bacteroides gingivalis CFU than sites with probing attachment gain. Individual site analysis, however, demonstrated marked variations of the microbiological counts at the different postoperative time points. In the few available sites undergoing probing attachment loss, no apparent association between target micro-organisms and periodontal deterioration was observed.

Combined antibiotic (metronidazole) and mechanical treatment effects on the subgingival bacterial flora of sites with recurrent periodontal disease

5 patients in maintenance, 1-3 years after periodontal therapy who showed sites with reinfected pockets and bleeding despite regular recall visits were selected. Darkfield microscopy from 3 sites in each patient showed an average of 41% spirochetes and 21% motile rods. Probing depths ranged from 7 to 9 mm and loss of clinical attachment from 6 to 13 mm in these sites. The patients were given 3 times 250 mg/day of metronidazole (Flagyl) for 10 days. Darkfield microscopy and microbiological cultures of the subgingival plaque were performed twice prior to the study, at the end of the medication and after 3 weeks, 3 and 6 months. The plaque and gingival indices, probing depth and loss of clinical attachment were recorded. During the medication and at 3 and 6 months, the teeth were scaled and root planed. The samples were obtained with 3 paper points and cultured anaerobically in the glove box on non-selective and selective media and representative bacterial colonies identified by aerobic growth, gram stain and rapid biochemical tests. Presumptive pathogenic micro-organisms including Bacteroides were identified. The % of spirochetes, motile rods and non-motile bacteria were enumerated by darkfield microscopy. The clinical results show that administration of metronidazole and repeated root planing significantly decreased gingival inflammation, probing depth and loss of clinical attachment in reinfected sites. After treatment, these sites harbored significantly less spirochetes and more non-motile bacteria, while motile rods tended to return to baseline levels with time. The combined antibiotic and mechanical therapy resulted in a statistically significant decrease of gram-negative rods, Fusobacteria and Bacteroides gingivalis over 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Serological studies of oral Bacteroides intermedius

Bacteroides intermedius is a gram negative, anaerobic microorganism associated with certain forms of human periodontal disease, including adult periodontitis and acute necrotizing ulcerative gingivitis. Previous studies have indicated the presence of two DNA homology groups which could be distinguished by analysis of protein patterns on polyacrylamide gel electrophoresis, as well as at least two serogroups within B. intermedius. The present study examined the serology of B. intermedius and determined the distribution of B. intermedius serogroups in clinical isolates and patient plaque samples. Serological reactions with unabsorbed rabbit antisera and antisera immunoabsorbed with B. intermedius strains demonstrated a previously unreported antigenic group within B. intermedius, serogroup C, in both immunodiffusion and immunofluorescence assays. Of 79 B. intermedius isolates from 68 subjects examined with specific antisera, 55% of the isolates and 52% of the subjects were categorized in serogroup C, 40% of the isolates and 46% of the subjects were in serogroup B, and 5% of the isolates and 6% of the subjects were in serogroup A. In 31 samples of subgingival dental plaque from adolescents known to harbor B. intermedius, 81% demonstrated serogroup B, 16% had serogroup A, and 3% had serogroup C.

The predominant cultivable microbiota of active and inactive lesions of destructive periodontal diseases

Subgingival plaque samples were taken from active and inactive lesions in 33 subjects exhibiting active destructive periodontal diseases. Active diseased sites were those which showed a significant loss of attachment within a 2-month interval as computed by the "tolerance method". The predominant cultivable species from 100 active sites were compared with those found in 150 inactive sites of comparable pocket depth and attachment level loss. Among the 33 subjects, W. recta, B. intermedius, F. nucleatum, B. gingivalis and B. forsythus were elevated more often in active sites; whereas, S. mitis, C. ochracea, S. sanguis II, V. parvula and an unnamed Actinomyces sp. were elevated in inactive sites. The likelihood of a site being active was increased if B. forsythus, B. gingivalis, P. micros, A. actinomycetemcomitans, W. recta, or B. intermedius were detected in that site, and decreased if S. sanguis II, the Actinomyces sp., or C. ochracea were detected.

Antimicrobial agents in the prevention and treatment of periodontal diseases

It has been estimated that there are more than 400 diseases affecting the oral cavity. In terms of prevalence, however, the major public health problems are caries and periodontal disease. Although these two destructive entities are completely different in many respects, they share a common denominator: the initial lesions are brought about by an aggregate of bacteria known as plaque. This article discusses chemical control of plaque in the treatment of gingivitis and antimicrobial control of subgingival plaque in the treatment of periodontitis. The authors address the use of antibiotics in the treatment of localized juvenile periodontitis, the ideal properties of antiplaque agents, and adjunctive subgingival application of antimicrobial agents.

Effects of oral hygiene measures on clinical and microbiological parameters of periodontal disease

The effects of a 12-week period of oral hygiene alone on gingival conditions and subgingival microflora in 15 patients with severe periodontitis were investigated. Clinical measurements and plaque samples from selected sites were taken at week 0 (baseline), week 6, and week 12. Plaque samples were also taken at week 13, that is, 1 week following debridement. At week 0, the patients were instructed in supragingival plaque control and at week 6, the hygiene regimen was supplemented with the subgingival use of a toothpick device. At week 12, the patients received a full mouth supra- and subgingival debridement under local anesthesia. In those patients who complied with oral hygiene instructions (subgroup A), the gingival condition improved moderately while no improvement was found in less compliant patients (subgroup B). No significant changes were noted in the subgingival microflora in either subgroups A or B throughout the 12-week period of oral hygiene alone. However, significant reductions for all microbial parameters were found 1 week after debridement. Therefore, while moderate clinical improvements followed oral hygiene alone, no measurable changes in the subgingival microflora were observed concomitantly.

Clinical, microbiological and immunological features of subjects with destructive periodontal diseases

76 subjects with prior evidence of destructive periodontal diseases were monitored clinically and immunologically every 2 months for up to 5 years. Clinical parameters measured included bleeding on probing, gingival redness, plaque accumulation, suppuration, pocket depth and attachment level. Blood samples were taken by venipuncture and serum antibody levels to a series of 18 subgingival species determined. 33 of these subjects showed evidence of active disease during the monitoring period, based on changes in attachment level measurements assessed using the tolerance method of analysis. Mean attachment loss in these 33 subjects varied from 1.4 mm to 9.0 (median value 3.4 mm) and subjects whose mean attachment level was above the median showed a higher % of pockets greater than 3 mm and more suppuration. Severity of gingival inflammation related poorly to mean attachment loss. Subgingival plaque samples were taken from the active site(s) and from control sites of equal pocket depth and attachment loss in the same active disease subjects, prior to therapy, for predominant cultivable microbiota studies. 50 randomly selected isolates were identified from each sample. Predominant cultivable species in 170 pretreatment active and inactive sites combined (8500 isolates) were enumerated. The most frequently detected species were F. nucleatum (112 sites) and S. intermedius (106 sites), although the predominant species in the samples from each subject differed. The distribution of putative pathogens differed among subjects. For example, A. actinomycetemcomitans was found in 21 samples in 11 subjects and B. forsythus was found in 18 samples from 10 individuals. Antibody response patterns to the 18 subgingival species also varied among subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Biology of asaccharolytic black-pigmented Bacteroides species

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The effect of retained subgingival calculus on healing after flap surgery

This study investigated the effects of retained subgingival calculus on healing of the periodontium at ten, 30 and 120 days. Eight beagle dogs between eight and ten years old with naturally occurring periodontal disease were used. One dog that died before any procedures were done provided information on the extent of gingival inflammation prior to surgery. Quadrants from seven dogs meeting the criteria for inclusion were selected, and each quadrant was randomly designated as either an instrumented or noninstrumented, surgical site. The gingival index for the selected sites was recorded along with clinical probing measurements. Instrumented sites were treated by reflection of a facial mucoperiosteal flap followed by thorough root planing. Non instrumented sites were treated by a facial mucoperiosteal flap alone. All flaps were returned to their preoperative position and secured with interrupted sutures. No antibiotics were given. Meticulous daily plaque control was begun the day after surgery and continued until sacrifice. There was a statistically significant reduction in gingival index scores for the 30- and 120-day instrumented sites and for the 120-day noninstrumented sites. Mean probing depths for the instrumented group showed a significant reduction at 30 and 120 days and for the noninstrumented group at 120 days after surgery. Forty percent of the noninstrumented roots and 10% of the instrumented roots displayed subgingival calculus. At all evaluation periods and in both instrumented and noninstrumented roots, inflammation was more intense when calculus was present; the difference was significant at ten days with the instrumented and at ten and 30 days with the noninstrumented specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors associated with occurrence and reversibility of connective tissue attachment loss

Marginal periodontitis appears to be site-specific, demonstrates rapid bursts of connective tissue attachment destruction, and may, at times, repair spontaneously. The present study was undertaken to investigate associations between bacterial populations and periodontal destruction parameters within the first 14 days after induction of experimental periodontitis in animals receiving metronidazole. Metronidazole was administered orally to four squirrel monkeys for 17 days at a daily dose of 100 mg/kg body weight. After three days (baseline), marginal periodontitis was induced by tying silk ligatures at the gingival margins of maxillary and mandibular bicuspids and molars. Subgingival bacterial samples were taken and periodontal destruction evaluated at baseline, and 3, 7 and 14 days after ligature placement. Dark-field microscopy was used to quantitate motile forms, spirochetes, straight and curved rods, filaments, cocci and fusiforms. Levels of connective tissue attachment, crestal alveolar bone and the volume of bone were assessed histometrically. Bacterial and histometric parameters were analyzed using analysis of variance. The results indicated that subgingival plaque, prior to induction of periodontitis, consisted primarily of cocci. At three days after ligature placement, cocci were significantly decreased, while straight rods became the predominant bacterial group for the remainder of the study. Spirochetes and motile forms were virtually absent at all time points. Histometric analyses showed significant loss of connective tissue attachment at three and seven days, which was reversed and repaired at 14 days. Factors relating to initiation, potentiation, and reversibility of connective tissue attachment loss are discussed.

Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans in human periodontal diseases

Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans seem to be major pathogens in advancing periodontitis in man. First, these organisms are recovered in higher prevalence and proportions from progressive periodontitis lesions than from quiescent periodontal sites. Second, antibody levels against B. gingivalis and A. actinomycetemcomitans are markedly elevated in serum and gingival crevice fluid of periodontitis patients compared to normal controls. Third, B. gingivalis and B. intermedius elaborate potent proteases and A. actinomycetemcomitans various noxious substances which have the potential to perturb important host defenses and to disintegrate key constituents of the periodontal tissues. Monitoring these bacteria in advanced periodontal lesions may greatly assist the assessment of treatment efficacy and risk of further periodontal breakdown.

A comparison of the reactivity of Eubacterium species with localized and serum immunoglobulins from rapidly progressive and adult periodontitis patients

Immunoglobulins in sera and in supernatant fluids of explant cultures of diseased gingival tissues from 20 rapidly progressive and 20 adult periodontitis sites were tested by an ELISA assay for reactivity with typed strains of Eubacterium alactolyticum, E. brachy, E. limosum and E. nodatum. Immunoglobulins present in tissue culture fluids from both rapidly progressive and adult periodontitis samples reactive with E. brachy and E. nodatum were significantly greater (P less than 0.05) than those reactive with E. alactolyticum or E. limosum. The titers to E. brachy in tissue culture fluids from adult periodontitis were significantly greater (P less than 0.05) than those from rapidly progressive periodontitis; there was no difference in titers to the other three species. The only significant difference in serum titers was that sera from patients with rapidly progressive periodontitis had significantly greater reactivity to E. alactolyticum than did sera from adult periodontitis patients. These data indicate that immunoglobulins in the sera of rapidly progressive and adult periodontitis patients do not necessarily reflect the reactivity of localized immunoglobulins present in the diseased gingival tissue explant culture fluids from these patients.

The degradation of type I collagen and human plasma fibronectin by the trypsin-like enzyme and extracellular membrane vesicles of Bacteroides gingivalis W50

A soluble trypsin-like enzyme (STE) was purified from a cell- and particle-free culture supernatant of this bacterium by a combination of ultra-centrifugation, ammonium-sulphate precipitation and gel-filtration chromatography on Sephacryl S-200. Trypsin-like activity in the culture supernatant was associated with a 58 kDa peptide and also with a higher molecular-weight complex. The STE and extracellular vesicle (ECV) fraction of B. gingivalis W50 rapidly degraded human plasma fibronectin in the presence and the absence of 10 mM dithiothreitol (DTT). The STE yielded a range of lower molecular-weight fibronectin digestion products. Under conditions where little activity was expressed by mammalian trypsin, both STE and ECV depolymerized a denatured and a native type I collagen substrate. Quantitative and qualitative differences were observed in the patterns of digestion products generated by both STE and ECV fraction following incubation with and without 10mM DTT. Inclusion of DTT appeared to reduce the degradative effect of both ECV and STE towards the type I collagen and plasma fibronectin substrates.

An in vitro model to study bacterial invasion of periodontal tissues

In periodontal disease, the abilities of bacteria to adhere to and degrade in vivo basement membranes should be considered as two of the rate-limiting steps for the potential active or passive invasion of gingival connective tissues. To study these mechanisms in greater detail, we used the PF HR-9 basement-membrane-like matrix to establish an in vitro model of bacterial invasion and degradation. Three gram-negative anaerobic periodontopathic organisms, Bacteroides gingivalis, Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans, bound in considerably higher numbers to the HR-9 matrix than did 6 strains of gram-positive facultative organisms typically associated with periodontal health. In a further experiment with B. gingivalis, the organism rapidly degraded Type IV collagen, the major macromolecular component constituting the HR-9 matrix. Streptococcus mitis, the nonperiodontopathic bacterium tested, did not degrade this model matrix. This study provides evidence that B. gingivalis, a periodontopathic bacterium, is able to adhere to and degrade basement membranes, whereas nonperiodontopathic organisms appear not to share in these abilities.

Attachment of oral bacteria to a basement-membrane-like matrix and to purified matrix proteins

The purpose of this study was to investigate the adherence of oral bacteria to an in vitro basement-membrane-like matrix and to selected individual macromolecular constituents of this matrix. Radiolabeled bacteria were incubated with basement-membrane-like matrices isolated from PF HR-9 cells. Bacteroides gingivalis 33277, Fusobacterium nucleatum FN-2, and Actinobacillus actinomycetemcomitans GA3(A) bound to the matrix in the range of 44 to 70%, considerably higher than the ranges of A. actinomycetemcomitans GA3(NA) and SUNY AB67 (range, 20 to 25%). The attachment of selected strains of gram-positive bacteria such as Streptococcus and Actinomyces spp. was much less frequent (range, 6 to 25%). Competitive inhibition studies demonstrated that preincubating the bacteria with fibronectin significantly decreased the binding of B. gingivalis by 51% but increased the binding of other gram-negative and gram-positive organisms tested. Similarly, preincubating the matrices with antifibronectin antibodies decreased the binding of B. gingivalis by 31%, whereas the other bacteria tested were either unaffected or binding was increased. The adherence of bacteria to purified basement membrane proteins was also investigated. Strain and species differences were seen in binding, but no clear relationship emerged between binding to an intact matrix and binding to isolated matrix proteins. The results of this study suggest that some gram-negative oral bacteria commonly associated with periodontal disease, such as B. gingivalis, A. actinomycetemcomitans, and F. nucleatum, bound in high numbers to basement-membrane-like matrices in vitro. On the other hand, the gram-positive strains tested bound in much fewer numbers. The results suggest that further studies with this in vitro model may aid in understanding the mechanisms by which oral bacteria adhere to basement membranes.

Periodic subgingival antimicrobial irrigation of periodontal pockets. II. Microbiological and radiographical observations

The purpose of this study was to evaluate the microbiological effects of repeated subgingival irrigation of deep periodontal pockets as a single measure of treatment as well as combined with mechanical debridement, and to study the concomitant radiographical changes of the alveolar bone. 2-3 interproximal sites per jaw quadrant in 10 patients showing a probing depth of greater than or equal to 6 mm and bleeding on pocket probing were selected for the study. The pockets in the various quadrants were randomly assigned to professionally performed subgingival irrigation with 0.2% chlorhexidine gluconate, 3% hydrogen peroxide or saline or to non-irrigation. During a first phase of treatment, the pockets were periodically irrigated (every 2nd-3rd day during weeks 1-2 and 5-6) and no subgingival mechanical debridement was performed. During a second phase, subgingival scaling and root planning were carried out with adjunctive subgingival irrigation of the pockets. During the entire trial, the patients' plaque control was carefully supervised. Sampling of the subgingival microflora was performed before and after the first and second treatment phases and 3 months after the termination of the active treatment. Dark-field assessment and cultivation of the bacterial samples were performed. The radiographical examination was carried out at the start of each treatment phase and 3 months after the termination of phase II and the radiographs were analysed by the use of a subtraction technique. The results demonstrated that periodic subgingival antimicrobial irrigation per se had only limited and transient effects on the subgingival microflora.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved selective culture media for Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus

By modifying the previously described media tryptic soy-serum-bacitracin-vancomycin (TSBV) agar and tryptic soy-serum-bacitracin-vancomycin-fluoride (TSBVF) agar, two improved selective culture media were developed for isolation and enumeration of Actinobacillus actinomycetemcomitans (A medium) and Haemophilus aphrophilus (H medium) in oral specimens. Both media were supplemented with fusidic acid and spiramycin, and carbenicillin was also added to A medium. The growth yields of pure cultures of A. actinomycetemcomitans on A medium and of H. aphrophilus on H medium were comparable with those on the reference media. Compared with blood agar, the selective media inhibited these species about 10-fold or less. In addition, A and H media suppressed the growth of pure cultures of Capnocytophaga spp. and Neisseria spp., commonly found as contaminants on TSBV and TSBVF, 10(5) times or more compared with that on blood agar. In samples from diseased periodontal pockets, the recoveries of A. actinomycetemcomitans on A medium and H. aphrophilus on H medium equaled those on TSBV and TSBVF, respectively. In about 50% of the cultures on the reference media, contaminating bacteria were detected at levels higher than 10(4) CFU/ml of sample. The corresponding value for both A and H media was about 2%.

Lipopolysaccharide (endotoxin) from individual periodontally involved teeth

The amount of lipopolysaccharide (LPS) in the root surface-associated material from individual periodontally-involved teeth has been determined. LPS was found in the surface material from all of the teeth and the amount present ranged from 19-394 ng/tooth. No significant correlation was found between the amount of LPS extracted from a particular tooth and the mean pocket depth associated with the tooth. However, a weak correlation (rs = +0.461, 0.05 greater than p greater than 0.01) was found between the amount of LPS and the % loss of attachment.