Subgingival microflora and periodontal disease

A clinical, demographic and microbiologic study of ANUG patients in an urban dental school

35 ANUG patients were examined and compared clinically and demographically. Plaque removed from ulcerated sites in 20 patients was cultured using quantitative anaerobic procedures and examined by electron and darkfield microscopy. Patients were classified as having ANUG when presenting with ulceration and necrosis of interproximal papillae, pain and bleeding. The clinical symptoms of fetid odor, pseudomembrane formation, lymphadenopathy and elevated body temperature were present in 97%, 85%, 61% and 39% of the ANUG patients, respectively. 83% of the patients were smokers. The ANUG patients demonstrated a lower average age (24 years) than the general clinic population (32 years). There was a slightly higher % of male (54%) than female (46%) and the % of Caucasian (51%) and black (49%) ANUG patients were almost equal. Cultural studies revealed that gram-negative rods were the predominant cultivable micro-organisms present in the plaque, representing 78.2% of the total recoverable count. Of these, nearly half were strict anaerobes with Bacteroides gingivalis and Fusobacterium nucleatum accounting for 7.8% and 3.4%, respectively. Anaerobic and facultative gram-positive cocci (15.5%), gram-negative cocci (3.5%) and gram-positive rods (2.8%) were also isolated. Microscopic analysis of the morphologic composition of plaque revealed that rods (43%) constituted the greatest % of the total microorganisms observed followed by spirochetes (30%) and cocci (27%). 8 distinct types of spirochetal periplasmic flagellar arrangement were observed by electron microscopy, the "2-4-2" periplasmic flagellar arrangement being most numerous.

Cell surface hydrophobicity of Actinobacillus actinomycetemcomitans Y4

Oral bacteria colonize the dento-gingival tissues in a selective manner. Hydrophobic reactions have been suggested as one of the major mechanisms of adhesion. Hydrophobicity of Actinobacillus actinomycetemcomitans Y4 (Aa) cells was studied in vitro using adherence to the liquid hydrocarbon, octane. Adherence of Aa cells to octane varied from 60-90%, depending on the medium in which they were grown, age of the culture and the buffer in which the assay was carried out. These data suggest that Aa is a hydrophobic bacterium, the hydrophobicity of which is expressed to a varying degree, and may have a rôle in its adherence to oral tissues.

Growth inhibitory effects of endotoxins from Bacteroides gingivalis and intermedius on human gingival fibroblasts in vitro

Purified endotoxin or lipopolysaccharide from Bacteroides gingivalis and Bacteroides intermedius caused a similar dose-dependent inhibition of growth of cultured human gingival fibroblasts as determined by 3H-thymidine incorporation and direct cell count. Approximately 200 micrograms/ml endotoxin caused a 50% reduction in 3H-thymidine uptake of logarithmically growing cells. Inhibition of growth was similar in cultures of fibroblasts derived from either healthy or diseased human gingiva. When examining the change in cell number with time of exposure in culture, the rate of proliferation was significantly suppressed during the logarithmic phase of growth. However, the cells recovered so that the rate of proliferation, although reduced, was sufficient to produce a cell density similar to the control cells with prolonged culture. The endotoxins were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The profiles of the Bacteroides endotoxins were different. B. gingivalis endotoxin showed a wide range of distinct bands indicating a heterogeneous distribution of molecular species. Endotoxin from B. intermedius exhibited a few discrete low molecular weight bands, but the majority of the lipopolysaccharides electrophoresed as a diffuse band of high molecular weight material. The apparent heterogeneity of the two Bacteroides endotoxins and the similarity in growth inhibitory capacity suggest that growth inhibitory effects of these substances cannot be attributed to any polysaccharide species of endotoxin.

Human serum antibody responses to oral microorganisms. IV. Correlation with homologous infection

Recent microbiological studies of periodontal disease in humans have supported the concept of a specific bacterial etiology. While individual agents have not been unequivocally identified, numerous Gram-negative members of the subgingival microflora have been implicated. In addition, elevations in systemic antibody responses have been consistent with certain oral microorganisms being involved in an infectious process associated with the disease. This report delineates the relationship between elevated systemic antibody levels and oral colonization with the homologous microorganism at active disease sites. Thirty-four patients with various types of periodontal disease were examined. Using ELISA, each patient was shown to have an elevated antibody response to at least one organism from a battery of 18 oral microorganisms that were tested. Subsequently, subgingival plaque was cultured from disease-active and -inactive sites of each subject. The results demonstrated that the same microorganism to which the individual exhibited elevated serum antibody responses was detected in nearly 55% of the disease-active sites, while only 18% of the inactive sites showed the microorganism. Certain microorganisms including Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Eikenella corrodens and Wolinella recta were primarily or exclusively correlated with active disease lesions. These findings support the hypothesis that elevated systemic antibodies to periodontopathic bacteria are reflective of subgingival colonization and exist as a response to a bacterial infection at disease-active sites.

Structural determinants of activity of chlorhexidine and alkyl bisbiguanides against the human oral flora

We assayed chlorhexidine and a series of its analogues, in which the chlorophenyl terminal substituents were replaced with alkyl chains, for their in vitro antimicrobial activity against the Gram-negative and Gram-positive oral bacteria. Changes in antimicrobial activity were correlated with changes in agent structure for identification of structural criteria which may be important in the optimization of agent activity. Chlorhexidine showed substantial antimicrobial activity against the Gram-negative as well as the Gram-positive oral bacteria. The alkyl agents were comparable with chlorhexidine in their activity against Bacteroides gingivalis and Bacteroides intermedius, black-pigmented Gram-negative obligate anaerobes associated with periodontal disease in adults. Alkyl agents alexidine, heptihexidine (1,6-bis-n-heptylbiguanidohexane), hexoctidine (1,8-bis-n-hexylbiguanidoctane), and hexhexidine (1,6-bis-n-hexylbiguanidohexane), as well as chlorhexidine, were active against Actinobacillus actinomycetemcomitans, a Gram-negative organism associated with localized juvenile periodontitis. Hexidecidine (1,10-bis-n-hexylbiguanidodecane) and heptoctidine (1,8-bis-n-heptylbiguanidooctane) were more active, and hexhexidine was as active as chlorhexidine against Fusobacterium nucleatum, also associated with periodontal disease. Seven of the agents were more active than chlorhexidine against Actinomyces species. All test agents were active against Streptococcus mutans, a Gram-positive coccus associated with dental caries. Hexidecidine had activity equal to that of chlorhexidine when evaluated against the entire battery of organisms. Analysis of structure-activity relationships revealed that alkyl chains could replace chlorophenyl groups with retention or improvement of antimicrobial activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Taxonomic study of spirochetes isolated from human periodontal lesions

Nineteen strains of spirochetes obtained from subgingival plaque of 19 patients with advanced periodontitis were studied morphologically, biochemically, and genetically and compared with type strains of Treponema denticola and Treponema socranskii. The results showed that 16 strains which biochemically resembled T. denticola could be divided into two groups based on G + C content and DNA homology. Two isolates appeared to belong to the T. socranskii species. One intermediate size isolate did not fit any known Treponema species.

Salt and peroxide compared with conventional oral hygiene. II. Microbial results

This study was designed to investigate the effect of conventional oral hygiene (n = 116 subjects) versus a salt and peroxide oral hygiene regimen (n = 115 subjects) on subgingival microorganisms. Subgingival plaque for microscopic evaluation was obtained from eight index tooth sites in each of 231 adult subjects. Microbial forms were microscopically identified at baseline, 8, 16, and 24 months. For both oral hygiene groups, cocci were increased (P less than 0.05) and motile rods were decreased (P less than 0.05) at 8 months and returned to baseline by 16 months. Spirochetes were decreased (P less than 0.05) and remained low through 24 months in both oral hygiene groups. The frequency of agreement between clinical (bleeding) and microbial (greater than or equal to 15% spirochetes or motile rods or greater than or equal to 20% spirochetes + motile rods) criteria for instrumentation was 59.8%. It was also found that fewer total instrumentations for test subjects were observed when microbiological criteria were used as compared with clinical criteria. The greater number of instrumentations based on clinical criteria was highly significant (P less than or equal to 0.001). A significant change in microbial signs associated with peridontal disease may be obtained with either a conventional oral hygiene or a salt and peroxide oral hygiene home care regimen.

Antigenic heterogeneity of non-pigmented Bacteroides species isolated from the human oral cavity

Serological studies on 27 strains of non-pigmented Bacteroides isolated from the human oral cavity revealed multiple serotypes within B. buccae. B. capillus (= B. buccae) and B. pentosaceus (= B. buccae) were found to be serogroups within B. buccae. B. denticola possessed cross-reactive antigens with B. buccae. Tested strains of B. oralis, B. veroralis, B. oris, and B. heparinolyticus were clearly differentiated from each other.

The effect of plaque control after scaling and root planing on the subgingival microflora in human periodontitis

The aim of the present study was to evaluate the effect of a strict supragingival plaque control regimen on bacterial repopulation following scaling and root planing. 7 patients with moderate to severe inflammatory periodontal disease received a full-mouth scaling and subgingival curettage. Using a split-mouth design, 2 sites of opposite quadrants were submitted to professional supragingival plaque control 3 X a week while the contralateral sites served as controls. Clinical and bacterial examination were performed on days 7, 14, 28, 49, 56, 63 and 70 following therapy. All clinical parameters (P1I, GI, probing depth, attachment levels) showed significant improvement after scaling and root planing. Shifts in the subgingival bacterial population observed by dark field were also noticed following curettage: there was a decrease in the proportions of spirochetes and motile rods and an increase in that of coccoid cells. However, bacterial distribution tended to return to base line values towards the end of the observation period. No difference in the pattern of bacterial recolonization of the subgingival area could be detected between the sites under strict supragingival plaque control and the control sites.

Microbial and clinical measurements of periodontal pockets during sequential periods of non-treatment, mechanical debridement and metronidazole therapy

Microbial and clinical parameters were studied in 11 subjects with chronic inflammatory periodontitis. 2 periodontal pockets per subject were studied longitudinally. The microbial parameters included counts of different subgingival micro-organisms by dark field microscopy, counts of the total colony forming units (c.f.u.) on anaerobic blood agar, the facultative anaerobic counts and counts of black-pigmented Bacteroides, Fusobacterium and E. corrodens. The clinical parameters were probing pocket depth, bleeding after probing and crevicular fluid production. Clinical and microbial observations were compared during 3 consecutive periods of non-treatment, debridement and metronidazole therapy. The experimental sites were debrided by deep scaling while no debridement was carried out at the control sites. The effect of this treatment was studied over a period of 3 months. Then, at the experimental sites, a 2nd session of debridement was followed by administration of metronidazole. The effect of metronidazole alone and combined with mechanical debridement was studied during a subsequent 3-month period. The disease activity did not correlate with the microbial parameters and was evident in the presence as well as in the absence of black-pigmented Bacteroides. A single session of subgingival debridement resulted in significant reductions in probing depth, spirochetes, motile organisms, black-pigmented Bacteroides and E. corrodens. Repopulation of the subgingival sites was observed. However, the composition of the subgingival microbiota remained significantly changed during the 3 months after debridement. The re-isolation of the same Bacteroides-species and the same B. gingivalis type after treatment indicated an outgrowth of micro-organisms remaining at these sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Certain bacterial species and morphotypes in localized juvenile periodontitis and in matched controls

Subgingival microflora in localized juvenile periodontitis (LJP) was examined by culture of certain bacterial species and by direct dark-field microscopy in affected and unaffected periodontal pockets of 11 patients and in their age- and sex-matched controls. Only Actinobacillus actinomycetemcomitans (A.a.) correlated to periodontal destruction and occurred most frequently at the affected LJP sites. A.a., Bacteroides intermedius and Fusobacterium nucleatum were isolated in proportions greater than 5% of the flora at the affected LJP sites, but various Actinomyces spp. at the unaffected and control sites. The proportions of straight rods, fusiforms and small spirochetes correlated to gingival bleeding tendency and were higher at the affected LJP sites than at the control sites. Certain nonpigmented Bacteroides spp. and Eikenella corrodens were never isolated when only cocci were seen at dark-field microscopy. The more complex the flora, the more frequently B. intermedius occurred. The results support a significant role for A.a. in LJP and indicate that certain bacterial species appear to prefer occurring in the complex composition of subgingival microflora.

Enzymatic and antigenic characterization of immunoglobulin A1 proteases from Bacteroides and Capnocytophaga spp

Bacteroides and Capnocytophaga species have been implicated as periodontal pathogens. Some of these species possess immunoglobulin A1 (IgA1) proteases that are capable of cleaving the human IgA1 molecule in the hinge region, leaving intact Fc alpha and Fab alpha fragments. The purpose of this study was to characterize this activity. In addition to IgA1 protease activity in already known species, IgA1 protease activity was a feature of Bacteroides buccalis, Bacteroides oralis, Bacteroides veroralis, Bacteroides capillus, and Bacteroides pentosaceus. Results of immunoelectrophoretic and sodium dodecyl sulfate-polyacrylamide gel electrophoretic analyses suggested that all species cleave the alpha-chain at the same peptide bond, i.e., the prolyl-seryl bond between residues 223 and 224 in the hinge region. The Bacteroides proteases could be classified as thiol proteases, which were at the same time dependent on metal ions, while the Capnocytophaga proteases were metallo enzymes. None of the proteases were inhibited by the physiologic proteases inhibitors alpha 2-macroglobulin and alpha 1-proteinase inhibitor. Investigations with enzyme-neutralizing antibodies raised in rabbits against protease preparations from the respective type strains revealed that, despite otherwise identical characteristics, the IgA1 protease of each Bacteroides species was antigenically distinct. Bacteroides buccae and the two later synonymous species B. capillus and B. pentosaceus produced identical proteases. In contrast, IgA1 proteases from Capnocytophaga ochracea and Capnocytophaga sputigena strains were apparently identical, while Capnocytophaga gingivalis had a protease that differed from those of the other Capnocytophaga species.

Purification and biochemical properties of a bacteriocin from Actinobacillus actinomycetemcomitans

Extracts of certain strains of Actinobacillus actinomycetemcomitans are inhibitory to strains of Streptococcus sanguis such as S. sanguis ATCC 10556. The isolation of a protein from an A. actinomycetemcomitans sonic extract which copurified with the inhibitory activity was accomplished by preparative isoelectric focusing, Sephadex G-100 gel filtration chromatography, and preparative polyacrylamide gel electrophoresis (PAGE). The resulting isolated protein, which focused at a pH of 6.1 to 6.3, appeared as a single band in anionic nondissociating PAGE analysis. This protein could be dissociated into two subunits with molecular weights of 50,000 and 70,000, which were resolvable by PAGE analysis. A 1,758-fold increase in specific activity was seen in the purified inhibitory protein compared with the crude sonic extract starting material. The properties of the inhibitory activity in the A. actinomycetemcomitans extract are characteristic of a bacteriocin. Accordingly, we propose the name actinobacillicin for the inhibitory protein.

Isolation and characterization of a protease from Bacteroides gingivalis

A protease was purified from Bacteroides gingivalis ATCC 33277 culture fluid by sequential procedures including ammonium sulfate precipitation, ion-exchange chromatography, and isoelectric focusing. The enzyme was active against benzoyl-L-arginine-p-nitroanilide, carbobenzoxy-L-phenylalanyl-L-valyl-L-arginine-p-nitroanilide azoalbumin, azocasein, azocoll, and p-tosyl-L-arginine methyl ester. The molecular weight of the enzyme was about 300,000 as determined by gel filtration. Its isoelectric point was 5.0. The maximum activity was found at pH 7.5, and the optimum temperature for activity was between 40 and 45 degrees C. The apparent Km value for benzoyl-L-arginine-p-nitroanilide was 2 mM. The enzyme was inhibited by sulfhydryl group-blocking reagents, tosyl-L-lysine chloromethyl ketone, and EDTA. Soybean trypsin inhibitor and diisopropylfluorophosphate were not inhibitory.

The effects of antiformin-citric acid chemical curettage on the microbial flora of the periodontal pocket

This study investigated the hypothesis that antiformin-citric acid chemical curettage combined with scaling and root planing (SRP/AF) would significantly reduce pathogenic bacteria of the periodontal pocket when compared to scaling and root planing alone (SRP). Ten patients with moderate periodontitis participated. Four pockets per patient, one in each posterior sextant, were chosen. Pocket depths, attachment levels, and gingival index (GI) were measured. Bacterial samples were examined under dark-field microscope for: (1) spirochetes, (2) motile rods, and (3) all others. A randomized four-sextant treatment design was used. One sextant received no treatment, a second received SRP, and the two remaining sextants received identical treatments of SRP/AF. Of these two sextants, one was sampled at baseline and 12 weeks only in order to serve as an additional control. The remaining sextants were sampled at 1, 4, 8, and 12 weeks. Both SRP and SRP/AF significantly reduced the percentage of spirochetes and motile rods. A significant reduction in GI and pocket depths was also noted. Attachment level showed no significant change. Results of both treatment groups showed no significant differences among any of the parameters. A comparison of the two SRP/AF groups indicated no significant difference among clinical or bacterial parameters due to sampling.

The effect of supragingival plaque control on the composition of the subgingival microflora in human periodontitis

The aim of this study was to evaluate the effect of supragingival plaque control on the composition of the subgingival microflora. 8 subjects with moderate to severe periodontitis were chosen for the study. Sites with periodontal destruction (GI greater than 2; probing depth greater than 6.5 mm; vertical alveolar bone loss on radiographs) were submitted to professional plaque control 3 X a week for 3 weeks. Contralateral sites received no prophylaxis and served as controls. Patients maintained usual oral hygiene during the observation period: it consisted exclusively of tooth brushing once or twice a day with no use of interdental cleaning aids. Clinical examination and bacterial sampling were performed every week. At the end of the study, PlI scores for the experimental sites showed a marked diminution compared with the control sites. No variations were observed in GI or probing depth in test or control sites during the study. The composition of subgingival plaque in both groups showed no significant variations during that period.

Extrachromosomal systems and gene transmission in anaerobic bacteria

Obligately anaerobic bacteria are important in terms of their role as medical pathogens as well as their degradative capacities in a variety of natural ecosystems. Two major anaerobic genera, Bacteroides and Clostridium, are examined in this review. Plasmid elements in both genera are reviewed within the context of conjugal transfer and drug resistance. Genetic systems that facilitate the study of these anaerobic bacteria have emerged during the past several years. In large part, these developments have been linked to work centered on extrachromosomal genetic systems in these organisms. Conjugal transfer of antibiotic resistance has been a central focus in this regard. Transposable genetic elements in the Bacteroides are discussed and the evolution and spread of resistance to lincosamide antibiotics are considered at the molecular level. Recombinant DNA systems that employ shuttle vectors which are mobilized by conjugative plasmids have been developed for use in Bacteroides and Clostridium. The application of transmission and recombinant DNA genetic systems to study these anaerobes is under way and is likely to lead to an increased understanding of this important group of procaryotes.

Purification and characterization of a protease from Bacteroides gingivalis 381

An intracellular membrane-free, trypsinlike protease was isolated from cells of Bacteroides gingivalis 381. The protease was extracted from the cells by ultrasonic treatment and was purified about 250-fold with a recovery of 2% by sequential procedures. The properties of the protease were as follows: its optimal pH was 8.5; its activity was almost completely lost on incubation at 50 degrees C for 15 min; its activity was inhibited by diisopropylfluorophosphate, p-toluenesulfonyl-L-lysine chloromethyl ketone hydrochloride, leupeptin, Mn2+, Cu2+, and Zn2+; it hydrolyzed casein, azocasein, N-alpha-benzoyl-DL-arginine-p-nitroanilide (BAPNA), bovine serum albumin, azocoll, and gelatin, but not N-alpha-benzoyl-DL-lysine-p-nitroanilide or human serum immunoglobulin A; its molecular weight was estimated as 45,000 by gel filtration and 50,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; and its Km values for azocasein and BAPNA were 1.11% and 0.19 mM, respectively.

A comparison of the effectiveness of hand scaling and ultrasonic debridement in furcations as evaluated by differential dark-field microscopy

There have been no previous reports in the literature comparing the effects of hand scaling with ultrasonic debridement in furcations, or which have used dark-field microscopy for this comparison. The purpose of this study was to compare the efficacy of these two modes of debridement in various classes of furcations, using gingival crevicular fluid flow and dark-field microscopy as parameters. A total of 33 furcated molars were evaluated. Results indicated that both hand scaling and ultrasonic debridement were equally effective in Class I furcations in changing the gingival fluid flow and bacterial proportions to those of a healthy state. In contrast, ultrasonic debridement was significantly more effective than hand scaling in Class II and Class III furcations in altering these parameters.

The use of monoclonal antibodies to detect Bacteroides gingivalis in biological samples

Hybridomas were established which produce monoclonal antibodies specific for Bacteroides gingivalis, a pathogen associated with human periodontal disease. Spleen cells from BALB/c mice immunized with formalinized B. gingivalis were fused with Sp2/0-Ag14 myeloma cells. Of 1,050 wells with positive growth, 60 contained antibody reactive with the immunizing strain of B. gingivalis by enzyme-linked immunosorbent assay. Expansion of these cultures and cloning by limited dilution resulted in 28 clones which reacted with B. gingivalis but not with other orals and nonoral black-pigmented Bacteroides species or any of 29 representative strains of other oral bacteria. Of these 28 clones, 14 were also specific for B. gingivalis by indirect immunofluorescence microscopy. One clone, BBG-12 producing immunoglobulin G2b(kappa), was chosen to identify B. gingivalis in subgingival plaque because of its high reactivity in indirect immunofluorescence assays. This antibody reacted strongly with all 17 representative B. gingivalis strains obtained from diverse sources. Furthermore, when this reagent was applied to subgingival plaque samples, B. gingivalis was stained with high specificity and low background fluorescence, indicating that it may be useful for clinical identification of this organism.

Tooth mortality in women in a 12-year follow-up of a population sample in Gothenburg, Sweden

Women of different age groups in Gothenburg, Sweden were examined in 1968-69 and in 1980-81 by means of orthopantomography. The frequencies of missing teeth and edentulousness were determined. The follow-up results among the same women showed only a small increase in edentulousness and in number of lost teeth during the period. A substantial decrease in edentulousness and frequency of missing teeth was observed between women of comparable age groups over the 12-yr interval, presumably as a result of preventive measures and increased availability of dental health care resources.

Is antibiotic therapy justified in the treatment of human chronic inflammatory periodontal disease?

New insight into the possible involvement of specific bacteria in the etiology of periodontal disease has stimulated interest in antibiotic therapy. However, current knowledge does not allow the designation of one or more pathogens in periodontal diseases. Some bacteria are considered suspected periodontal pathogens due to their predominance in the pocket and their potential pathogenicity, yet they all appear to be indigenous bacteria. For this reason, one can question the rationale for the use of antibiotics in the treatment of periodontal disease since the theoretical basis for their application seems small. Several reports of clinical trials in which antibiotics were administered as an adjunct to scaling and rootplaning in adult periodontitis conclude with encouraging statements concerning bacterial inhibition and the cure of inflammatory periodontal disease. However, the data are conflicting and mostly negative. Antibiotic treatment in combination with scaling and rootplaning in juvenile periodontitis and refractory adult periodontitis has shown some benefit, but the clinical trials were not sufficiently controlled to permit conclusions. So far, antibiotics have been applied as a last resort in order to supplement the non-specific approach of mechanical root debridement, but it can be doubted whether this approach offers any benefit in the long run.

Arylaminopeptidase activities of oral bacteria

Protease and peptidase enzymes are thought to play a role in the virulence of many oral organisms, especially those associated with periodontal diseases. In order to evaluate the peptidases of periodontopathogens, we compared the arylaminopeptidase activities of Bacteroides gingivalis with those of other oral and non-oral bacteria. Sixty-three bacterial strains representing the prominent cultivable organisms in human periodontal pockets were tested, including representatives of the black-pigmented Bacteroides, Actinobacillus, Actinomyces, Campylobacter, Capnocytophaga, Eikenella, Fusobacterium, Haemophilus, Lactobacillus, Streptococcus, and Veillonella species. Each micro-organism was examined for its ability to hydrolyze 18 synthetic substrates of beta-naphthylamide derivatives of amino acids, dipeptides, and tripeptides. Quantitation of the enzyme activity was accomplished by colorimetric measurement of the amounts of released beta-naphthylamines. N-CBz-glycyl-glycyl-L-arginine-beta-naphthylamide was readily cleaved by B. gingivalis, but slightly or not at all by the other oral strains tested. L-arginine-beta-naphthylamide was cleaved by B. gingivalis, Capnocytophaga species, and Streptococcus species, but not readily by the other Bacteroides strains. Some dipeptide substrates tested, such as glycyl-L-arginine- and glycyl-L-proline-beta-naphthylamide, were strongly cleaved by B. gingivalis and weakly cleaved by other Bacteroides strains. Since high levels of N-CBz-glycyl-glycyl-L-arginyl-aminopeptidase activity are characteristic of B. gingivalis, its measurement may be valuable in the identification of this organism in clinical samples as an aid in diagnosis and monitoring of periodontal infections. Furthermore, this and other aminopeptidases produced by B. gingivalis and other oral organisms may play a role in the tissue destruction seen in periodontal disease.

Chemotherapy in juvenile periodontitis

Juvenile periodontitis has been described as a separate entity among the human periodontal diseases. Several forms of the disease based on the number and types of involved teeth as well as the age of the patient have been reported. The present review deals with the "classical" localized juvenile periodontitis (LJP). The etiology of LJP has been explained according to 3 theories: (1) a genetic (hereditary) defect in the host defense mechanism; (2) a specific infection; (3) a combination of 1 and 2. In all 3 alternatives, bacterial infection is the direct cause of the breakdown of the tissues. This is supported by reports of success following therapy aimed at eliminating the microbial challenge. Arguments favoring the use of chemotherapeutic agents as an adjunct to mechanical debridement, or instead of it, as well as arguments against such use are discussed. The conclusion seems to be dependent on which of the 3 theories of etiology the arguments are related to. If antibiotics are to be used, the choice of drug would depend on the sensitivity of the suspected pathogen(s). At present tetracycline seems to be the one suggested by most authors, but routine use of antibiotics in the treatment of LJP does not seem necessary and is not recommended.

Topical antimicrobial therapy and diagnosis of subgingival bacteria in the management of inflammatory periodontal disease

Bacterial specificity in human periodontal diseases suggests the possibility of diagnosing and treating periodontitis as specific infections and using microbiological diagnostic means to evaluate the efficacy of periodontal therapy. In a series of clinical trials, the usefulness of topical antimicrobial agents in combination with surgical and non-surgical conventional periodontal therapy were tested. The healing result was estimated by monitoring probing attachment levels (PAL). The usefulness of clinical and microbiological parameters to evaluate post-treatment healing result was tested. 9 of the patients exhibiting sites with recurrent periodontal disease were then evaluated for clinical and microbiological parameters to define accurate means to differentiate between active and inactive periodontal disease. The results showed that the frequency of periodontal lesions with significant loss of PAL after treatment was less in patients treated with antimicrobial agent. Specific microbiological parameters showed stronger correlation than clinical parameters with gain and/or loss of PAL post-treatment. Thus Actinobacillus actinomycetemcomitans and Bacteroides gingivalis occurred in periodontal lesions with progressing disease after treatment, but were rarely detected in samples from pockets of the same depths which did not exhibit further loss of PAL over a study period of 1 year. This study points to the usefulness of topical antimicrobial agent as an adjunct to mechanical subgingival debridement in the treatment of periodontitis in adults. The results also indicate the utility of diagnostic microbiology in the assessment of periodontal disease activity post-treatment.

Chlorhexidine compared with other locally delivered antimicrobials. A short review

Based on the association of bacterial plaque with the initiation of chronic gingivitis and progression of chronic periodontitis, chemical antiplaque agents have been employed both in prevention of periodontal disease and its treatment. In supragingival plaque control regimens, chlorhexidine has not been superceded as a chemical anti-plaque agent, although other compounds have been shown to be useful. The local side-effects of chlorhexidine and other cationic antiseptics, however, limit their long-term use for prevention. Extrinsic tooth staining in particular remains the greatest problem. Short-term anti-plaque uses for chlorhexidine include as an adjunct to mechanical cleaning in the initial oral hygiene phase of treatment, in situations where mechanical oral hygiene is difficult, including postsurgery, intermaxillary fixation, fixed orthodontic therapy, physically and mentally handicapped individuals, systemic diseases with oral manifestations such as leukaemia. More recent interest in chlorhexidine has resulted from the delivery of compounds subgingivally in the treatment of chronic periodontitis. Such methods have extended the use of chlorhexidine into areas inaccessible to the action of antimicrobial drugs delivered locally by conventional means, such as tooth brushing or mouth rinsing. Available evidence suggests that chlorhexidine may not be as effective as some antimicrobial drugs whose activity is more specific for those organisms considered particularly pathogenic to the periodontal tissues.

The effect of amoxicillin on destructive periodontitis. A case report

In a 22-year-old female patient, advanced localized periodontal destruction was observed. The planned treatment consisted of oral hygiene instructions, professional plaque control, deep scaling and root planning and finally modified Widman flap surgery. One molar had to be extracted but was left untreated initially as a control. During the treatment period of 9 months and during 1 year thereafter, samples were taken of the subgingival plaque for dark-field microscopy. The unplanned use of amoxicillin by the patient for a middle ear infection resulted in a suppression below detection level of spirochetes at the investigated sites. At the nontreated control site, the absence of spirochetes was accompanied by a 3-mm reduction of pocket depth and a 2-mm gain in clinical probing attachment, while some formation of new alveolar bone was observed. At the treated sites, clinical improvement was observed. However, a distinction between the effect of the periodontal therapy and the nonscheduled use of amoxicillin could not be made at the treated sites. It is concluded that a single course of systematically administered amoxicillin changed the composition of the subgingival microflora over a long period of time (17 months) and had a beneficial effect upon the status of the periodontium.

Systemic antibody response of clinically characterized patients with antigens of Eubacterium brachy initially and following periodontal therapy

Eubacterium brachy, a gram-positive anaerobic rod, has been implicated by cultural studies to be associated with the microflora of periodontal diseases. Serum samples from 184 clinically characterized patients were evaluated in a standardized enzyme-linked immunosorbent assay (ELISA) for reactivity to E. brachy antigens. Sera from clinically healthy subjects (HS) served as controls. Sera from rapidly progressive periodontitis (RP) patients demonstrated significantly greater reactivity by ELISA than did HS when reactivity with E. brachy antigens was determined (P less than 0.05). Juvenile periodontitis (JP) and adult periodontitis (AP) patients did not differ in reactivity by ELISA from HS (P greater than 0.05). Three to 4 years following successful periodontal therapy, reactivity was not significantly altered in any patient group (P greater than 0.05). The possible significance of these findings and the importance of an extracellular antigen of E. brachy in the immunopathology of periodontal diseases are discussed.

Clinical and microbiological effects of sustained release chlorhexidine in periodontal pockets

Previous studies have shown that a 3-day exposure of the pocket flora to the sustained release of chlorhexidine significantly reduced the relative numbers of spirochetes and motile rods in periodontal pockets to negligible amounts. By 14 days post-treatment, their numbers had returned to pre-treatment levels. The present study extended the exposure time of the pocket flora to the sustained release of chlorhexidine in an attempt to prolong the suppression of the microbial flora for a clinically significant period of time. Clinical parameters were also studied. Sustained release devices (SRD) were inserted into 13 pockets from 8 patients. Pocket depth ranged between 5 and 8 mm. The SRD's were replaced every 3 days to give a total exposure of 9 days. Plaque index (PlI), bleeding on probing and pocket depth were measured, and bacterial samples taken for dark field microscopy and anaerobic culture. There was a marked decrease in the relative proportions of spirochetes and motile rods and the total anaerobic count post-treatment. Pocket depth was reduced in all 13 pockets. These results indicate that a prolonged exposure to chlorhexidine suppresses the pocket flora to negligible amounts and reduces pocket depth for up to 11 weeks post-treatment.

Fluorescent antibody and flagella stains for rapid detection of bacteria at periodontally healthy and diseased sites

Two rapid methods of identifying bacteria associated with periodontal disease were investigated to determine their diagnostic usefulness in longitudinal or epidemiologic studies. Three nonmotile organisms were identified by fluorescent antibody stains (FA) while percentages of motile bacteria were assessed by counting all spirochetes, flagellated and nonflagellated organisms stained with a simplified silver-plating stain for flagella. Relationships between disease activity and these bacteria from subgingival plaque samples taken at 18 individual sites (12 diseased, 6 healthy) were determined by correlating the quantity of detectable bacteria with the Gingival Index (GI), Plaque Index (PLI) and probing depth (PD). The highest correlations found with the FA stains were between Bacteroides gingivalis and probing depth (rs = 0.85), GI (rs = 0.80) and PLI (rs = 0.80). Bacteroides melaninogenicus and/or Bacteroides intermedius also correlated well with the GI (rs = 0.66), PLI (rs = 0.64), and PD (rs = 0.59), but to a lesser degree than B. gingivalis. Flagella stains showed that spirochetes correlated highly with PD (rs = 0.82), as did the total motile group with PLI (rs = 0.82). Motile bacteria alone were only moderately associated with the clinical parameters measured. The results of this investigation suggest that FA- and flagella-staining methods can be valuable screening tools for the detection of bacterial species and motile organisms in longitudinal or epidemiologic studies.

Failure of a microbial assay to reliably predict disease recurrence in a treated periodontitis population receiving regularly scheduled prophylaxes

The purpose of this study was to evaluate the reliability of differential dark-field microscopy (DDFM) of subgingival bacteria to correctly predict the recurrence of periodontitis in treated patients on 2 different recall schemes. The results are based on data from 51 patients on 3-month recalls (C group) and 39 patients (T group) who received periodontal prophylaxes according to a customized regimen based on DDFM of subgingival bacterial morphotypes. No significant differences were detected in the rate of recurrence of periodontitis between the 2 groups, although the incidence of disease recurrence tended to be greater in the C group. The proportions of spirochetes and motile rods observed at base line, or the average of the values observed at base line, 3 months and 6 months, were compared between subjects with and without disease recurrences. Significantly elevated proportions of these bacterial morphotypes were observed in patients of the T group who demonstrated evidence of disease recurrence during the first year as compared to subjects without disease recurrence. No significant differences could be detected in bacterial morphotypes between patients resistant to disease recurrence and those who developed recurrences at some time during the 3-year period covered by this report. The ability of DDFM of subgingival bacterial morphotypes to predict future disease occurrence was tested for 1- and 3-year periods, in both the C and T groups. The test appears to be reliable only for subjects on the experimental maintenance regimen (group T) and for prediction of disease recurrence for the initial 1-year period.(ABSTRACT TRUNCATED AT 250 WORDS)

Subgingival microflora and periodontal conditions in healthy teenagers

The composition of subgingival flora was correlated with clinical periodontal conditions in 100 teenagers aged 12 to 17 years. The Community Periodontal Index of Treatment Needs (CPITN) was used for the clinical examination. Subgingival bacterial samples were taken from the mesial surface of each first molar, two samples for dark-field microscopy and two samples for Actinobacillus actinomycetemcomitans (A.a.) cultivation. Fifty-nine subjects had at least three healthy sextants. Score 1 was the highest CPITN recording in 61 subjects and Score 2 in 30 subjects. None had scores 3 or 4. In dark-field microscopy, cocci predominated in most samples. Straight rods, fusiforms and motile rods correlated negatively to the number of healthy sextants per subject. Straight rods and fusiforms showed a positive correlation to gingival bleeding tendency at the sampled site. A.a. was isolated in four subjects. Motile microorganisms and A.a. were detected rarely in subjects with good periodontal conditions.

The autologous mixed lymphocyte reaction (AMLR) as a possible indicator of immunoregulation in chronic inflammatory periodontal disease

Immunoregulatory control at both a local and systemic level is likely to be an important factor in the control of chronic inflammatory periodontal disease, explaining, at least in part, the individual variations between patients as well as the cyclical nature of the disease process. The autologous mixed lymphocyte reaction (AMLR), which is due to the stimulation of T cells by autologous HLA-DR positive non-T cells in the absence of specific antigen, is thought to be an in vitro correlate of immunoregulation. It is possible therefore, that the AMLR may detect systemic immunoregulatory phenomena in chronic inflammatory periodontal disease and that aberrations in the AMLR may be a manifestation of the disease and in turn reflect disease activity. Recent evidence does in fact suggest that the peripheral blood AMLR may identify particular disease groups, provided age and time of peak responsiveness are taken into account and hence may have an epidemiological application. It remains to be determined, however, that when used in a longitudinal fashion, the AMLR does reflect individual disease activity. These results are reviewed and areas of future research discussed.

The occurrence of Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and Bacteroides intermedius in destructive periodontal disease in adults

A total of 235 subgingival sites, including 104 progressive deep lesions from 61 untreated patients, 26 progressive deep lesions from 10 treated patients, 33 nonprogressive deep sites from 20 untreated patients, and 72 nonprogressive sites from 55 treated patients were examined for Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and Bacteroides intermedius. The periodontal disease progression was mainly determined on the basis of radiographic changes in the crestal alveolar bone level. A. actinomycetemcomitans isolation was carried out using the selective TSBV medium and B. gingivalis and B. intermedius isolations were performed using a nonselective blood agar medium. 1 or more of the 3 bacteria studied appeared in 99.2% of progressive periodontal lesions but only in 40.0% of nonprogressive sites. Culture-positive progressive periodontal sites in comparison with culture-positive nonprogressive sites showed higher median recovery rates of A. actinomycetemcomitans (0.5% vs 0.3%), B. gingivalis (30.5% vs 0.3%) and B. intermedius (4.9% vs 0.5%). Of total progressive lesions, 12.3% yielded solely A. actinomycetemcomitans, 21.5% demonstrated solely B. gingivalis, and 20.8% revealed solely B. intermedius. The A. actinomycetemcomitans--B. intermedius combination was found in 24.6% of progressive lesions. A. actinomycetemcomitans appeared in significantly higher prevalence in treated-progressive lesions (80.8%) than in nontreated-progressive lesions (42.3%). 32 of the 42 culture-positive nonprogressive sites yielded B. intermedius as the sole test organism. The main conclusion is that A. actinomycetemcomitans, B. gingivalis and B. intermedius are closely related to disease-active periodontitis, and more closely than to periodontal pocket depth. This finding is important in understanding periodontal disease etiology and pathogenesis and may also aid in a clinical setting to differentiate progressing and nonprogressing periodontal sites.

Darkfield microscopy of subgingival plaque of an urban black population with poor oral hygiene

A low socio-economic community residing in Crossroads, Cape Town, consists of people who originated from the Eastern Cape areas of the Ciskei and Transkei. These individuals have had virtually no dental care, with the exception of emergency treatment for pain. A darkfield microscopic study of a random sample of 52 individuals was undertaken to determine the predominant morphological forms in the subgingival plaque of this population. Spirochetes were found to constitute 42.1% and motile rods, 7.7%, of the total darkfield microscopic count. Clinical assessment of the periodontal status of 100 individuals revealed the following mean values; plaque index (PI) = 1.44, gingival index (GI) = 1.31, probing depth (PD) = 2.35 mm and loss of attachment = 0.64 mm. Subgingival calculus deposits were present in 42% of the group and little or no mobility of the teeth was evident. Poor oral hygiene resulted in 90% of the tooth surfaces of the sampled population in Crossroads being covered with plaque, yet these individuals appear to be resistant to periodontitis. The high proportions of spirochetes and motile rods found in the subgingival plaque of this group were not indicative of periodontitis and therefore, fail to confirm the findings of other investigators.

Experimental gingivitis in relation to susceptibility to periodontal disease. II. Phase-contrast microbiological features and some host-response observations

In the present investigation, a number of histological and immunohistochemical characteristics of periodontal tissues as well as the phase-contrast microscopy of dental plaque were studied after experimentally-induced gingival inflammation in relation to susceptibility to periodontal disease. The study included a younger (mean age 34.1 years) and an older age group (mean age 48 years) with a reduced but healthy periodontium. Both age groups had the same amount of loss of attachment which may suggest that they had different degrees of susceptibility to periodontal disease. At the start of the experiment, each patient was instructed to abstain from oral hygiene in one quadrant of the mouth for a period of 18 days. At the end of the 18-day period, supra-gingival plaque and gingival tissue samples were taken. As determined by phase-contrast microscopy, the plaque samples of both age groups contained relatively high proportions of spirochetes. This may indicate that the patients are at risk for recurrence of periodontal breakdown. The general histopathologic picture of the gingival tissue samples of both age groups was similar to the so-called 'early lesion'. However, IgA-producing plasma cells were found in most tissue samples of both age groups. The first part of this study showed that the younger, in comparison to the older, patients developed inflammation in terms of bleeding on probing more rapidly. These clinical results cannot be explained by the host-parasite parameters investigated in the present study.

Desulfuration of cysteine and methionine by Fusobacterium nucleatum

Fusobacterium nucleatum is a Gram-negative anaerobic rod-shaped bacterium frequently isolated from human dental plaque. It is capable of the desulfuration of cysteine and methionine, resulting in the formation of sulfide and thiol volatiles, respectively. Intact cells, as well as cell-free extracts produced by French pressure cell lysis of F. nucleatum, hydrolyzed radiolabeled cysteine to produce sulfide, pyruvic acid, and ammonia. The hydrolysis products of radiolabeled methionine were a volatile thiol, ketobutyrate, and ammonia. Both activities were associated with the cytoplasmic component, not the membrane. The desulfuration mechanisms are heat-labile, inhibited by the presence of excess substrate, and rates are dependent upon substrate concentration. These dissimilar pathways by F. nucleatum can account in part for the presence of sulfur-containing volatile products that occur in the mouth.

Sensitization with Fusobacterium nucleatum targets antibody-dependent cellular cytotoxicity to mammalian cells

Incubation of mammalian tumor cells with either soluble of insoluble fractions (10 to 100 micrograms/ml) of Fusobacterium nucleatum sensitizes them to the destructive activity of antibody-dependent cellular cytotoxicity (ADCC) effector cells in the presence of anti-F. nucleatum antisera. All three types of ADCC effector cells are capable of destroying F. nucleatum-sensitized target cells with varying degrees of effectiveness (lymphocytes much greater than monocytes greater than neutrophils). Hyperimmune rabbit anti-F. nucleatum antisera were active at a dilution as high as 1/100,000. Our studies indicated that F. nucleatum must be bound to the target cells since if either the effector cells are treated with F. nucleatum or F. nucleatum is directly to an ADCC reaction, there is no significant effect on cytotoxicity. The kinetics of F. nucleatum-targeted ADCC are identical to those of classical ADCC, suggesting a similar mechanism. The specificity of F. nucleatum-targeted ADCC was demonstrated by cold target inhibition studies and by showing that other antibacterial antisera were incapable of mediating the activity.

Chemotactic response to formate by Campylobacter concisus and its potential role in gingival colonization

Cells of Campylobacter concisus 288 were chemotactic toward formate, but not to any other compound tested. Chemicals that were not chemoattractants included 20 sugars, inorganic salts, amino acids, and their derivatives, purines and pyrimidines, fatty acids, and natural mixtures such as saliva, serum, crevicular fluid, and mucin. Chemotaxis was measured quantitatively by a modification of the capillary method. Cells were suspended in 0.01 M Tris buffer, pH 7.5, supplemented with 5 mM KCl, 0.1% Na2S2O3, and 0.1 mM dithiothreitol. Whole, parotid, and submandibular salivas were also suitable as chemotaxis buffers. Optimum response (0.4 X 10(6) to 1.5 X 10(6) cells per capillary) for chemotaxis occurred with 5 X 10(-2) M formate at 30 degrees C for 60 min. At 5 to 15 degrees C, cells were motile, but chemotaxis was not detected. Glutamine, asparagine, homoserine, and methionine inhibited formate chemotaxis at threshold concentrations of 0.1 to 1.0 mM, whereas the threshold for all other amino acids tested was 50 mM. Sugars and fatty acids at concentrations up to 0.1 M did not inhibit formate chemotaxis. C. concisus 484, Wolinella recta 371, W. curva VPI 9584, and W. succinogenes 602 were also chemotactic to formate, but C. fetus subsp. jejuni VPI H641 and C. fetus subsp. intestinalis VPI 1176 were not. Motile bacteria harvested directly from subgingival plaque were also chemotactic to formate and, to a lesser extent, lactate. Selected sugars, other fatty acids, and amino acids did not serve as chemoattractants for these plaque bacteria.

Gingivitis

Gingivitis is caused by substances derived from microbial plaque accumulating at or near the gingival sulcus; all other suspected local and systemic etiologic factors either enhance plaque accumulation or retention, or enhance the susceptibility of the gingival tissue to microbial attack. Microbial species specifically associated with gingival health include Streptococcus sanguis 1, S. D-7, and Fusobacterium naviforme. Bacteria involved in the etiology of gingivitis include specific species of Streptococcus, Fusobacterium, Actinomyces, Veillonella, and Treponema and possibly Bacteroides, Capnocytophaga, and Eikenella. Microbial colonization and participation is sequential, with the complexity of the associated flora increasing with time. The pathogenesis has been separated into the initial, early, and established stages, each with characteristic features. The initial lesion is an acute inflammation which can be induced experimentally by application of extracts of plaque bacteria to normal gingiva. The early lesion is characterized by a lymphoid cell infiltrate predominated by T lymphocytes, characteristic of lesions seen at sites of cell-mediated hypersensitivity reactions. The early lesion can be induced by application of purified contact antigens to the gingival tissues of previously sensitized animals. As the clinical condition worsens, the established lesion appears, predominated by B lymphocytes and plasma cells. Established lesions may remain stable for indefinite periods of time, they may revert, or they may progress. Periodontal destruction does not result from the conversion of a predominantly T cell to a predominantly B cell lesion as has been suggested, but rather from episodes of acute inflammation. Clinical manifestations of gingivitis are episodic phenomena characterized by discontinuous bursts of acute inflammation. Most lesions are transient or persistent but not progressive. Attachment loss may precede alveolar bone loss and may occur without the manifestations of a concurrent or a precursor gingivitis. On the other hand, the evidence indicates that a portion of gingivitis lesions can and does progress to periodontitis. Gingivitis and the periodontal microflora differ in children and adults. Clinical signs of gingivitis either do not appear as plaque accumulates, or they are greatly delayed in children, and the inflammatory infiltrate consists mostly of T lymphocytes. The conversion to a B cell lesion does not appear to occur. The evidence supports the conclusion that gingivitis is a disease, and that control and prevention is a worthwhile goal and a health benefit.(ABSTRACT TRUNCATED AT 400 WORDS)