Microbial flora of periodontitis and monitoring of the effect of initial preparation by immunofluorescence microscopy

The effect of initial preparation in adult periodontitis was evaluated by changes in clinical parameters and immunofluorescence microscopic counts of periodontal disease associated bacteria. Subgingival plaque samples were taken with sterilized paper points from 10 sites of 5 periodontally healthy persons and 44 sites of 23 adult periodontitis patients. Twenty-one diseased sites were periodically examined after plaque control and scaling, root planing. The direct immunofluorescence technique was used to detect Bacteroides gingivalis, Eikenella corrodens, Fusobacterium nucleatum and Treponema denticola, Bacteroides intermedius, Actinobacillus actinomycetemcomitans, Bacteroides forsythus and Wolinella recta were counted by the indirect immunofluorescence technique. The proportions of B. gingivalis, B. forsythus, F. nucleatum, E. corrodens, T. denticola and W. recta in periodontitis lesions were significantly higher than those in healthy sites. The proportions of B. gingivalis and T. denticola were significantly related to GI, PlI, BI and PD, those of B. forsythus and W. recta to GI, PlI and BI, E. corrodens to GI and PlI, and F. nucleatum to BI. Reduced proportions of T. denticola were found in samples taken after establishment of proper plaque control. Subgingival scaling and root planing resulted in the reduction of proportions of B. gingivalis, E. corrodens, T. denticola and B. forsythus in the samples. The samples from positive bleeding sites contained higher proportions of B. gingivalis, T. denticola, B. forsythus and W. recta than did resolved sites. The present study shows that the immunofluorescence technique which detects B. gingivalis, T. denticola and B. forsythus is useful in monitoring the efficacy of initial preparation.     

DNA probe detection of periodontopathogens in advanced periodontitis

Species-specific DNA probes were used to determine the presence of Actinobacillus actinomycetemcomitans (A.a.), Porphyromonas (Bacteroides) gingivalis, Prevotella intermedia, Treponema denticola. Eikenella corrodens, Fusobacterium nucleatum , and Wolinella recta in subgingival plaque from deep pockets/sites of patients with advanced periodontitis. The subjects were 20 patients with severe adult periodontitis, 13 men and 7 women (mean age 45.6 ± 6.7 yr). For each subject, 9–10 subgingival sites with the deepest probing depths from each quadrant were sampled by the paper point method, a total of 198 sites, with mean probing depth 7.2 ± 1.6 mm and clinical attachment level 9.5 ± 2.7 mm. A.a . was present in at least one site in 75% of the subjects; P. gingivalis was found in 95%; P. intermedia and W. recta were found in 90%, respectively; and T. denticola, E. corrodens , and F. nucleatum were found in all subjects. In the 198 samples, A.a . was detected in 25.8%, P. gingivalis in 51.5%, P. intermedia in 64.1%, T. denticola in 60.6%, E. corrodens in 72.9%, F. nucleatum in 74.7%, and W. recta in 65.7%. The predominant combination was the simultaneous presence of P. intermedia, T. denticola, E. corrodens, F. nucleatum , and W. recta in 89.5% of the subjects and 46.8% of the sites. Of these sites, 51.1% showed the combined presence of P. gingivalis and 28.4% that of both A.a . and P. gingivalis . None of the seven bacteria could be detected in 14.4% of the total sites sampled. The present study indicates that severe destructive adult periodontitis is a multibacterial infection and that certain combinations of periodontopathogens seein to be important in the pathogenesis of the disease.     

Multicenter evaluation of tetracycline fiber therapy. III. Microbiological response

In a multicenter study of the effects of tetracycline (TC) fiber therapy, subgingival plaque samples were tested for 6 probable periodontal pathogens by DNA probe analysis. Levels of Actinobacillus actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas (Bacteroides) gingivalis, Prevotella intermedia (Bacteroides intermedius), and Wolinella recta were quantitatively determined in samples taken at baseline, and immediately after TC fiber removal, control fiber removal, and scaling and root planing. At untreated sites, samples were taken at baseline and 10 d later. Specificity of the DNA probe method was evaluated by testing the hybridization to 83 reference cultures. Interaction of the F. nucleatum probe with Fusobacterium periodonticum, and of the W. recta probe with Wolinella curva were the only cross-hybridizations noted. Species were detected at an average sensitivity of 2.9 x 10(4) organisms per sample. Approximately 70% of sites were initially infected with P. gingivalis and F. nucleatum; 50% with P. intermedia and E. corrodens; infections with W. recta and A. actinomycetemcomitans were less common (36% and 11% respectively). The average numbers of organisms found in the plaque samples were highest for F. nucleatum, P. gingivalis, and P. intermedia (ca. 10(6)). E. corrodens, W. recta, and A. actinomycetemcomitans occurred at 10-fold lower levels. Bacterial numbers and proportions of species in subgingival sites from the five centers did not differ appreciably. Both TC fiber therapy and scaling decreased the number of sites infected with all the monitored species. The bacterial composition at untreated sites and at sites where control fibers were placed was not significantly altered. The percentage reduction of the number of sites with detectable infection varied with each species: from 86% with W. recta to approximately 40% with P. gingivalis. Significant reduction of pocket depth and bleeding occurred at TC fiber-treated sites infected with each of the species. Significant attachment level gain occurred only at sites initially infected with P. gingivalis and treated with TC fibers.     

Associations between six DNA probe-detected periodontal bacteria and alveolar bone loss and other clinical signs of periodontitis

The purpose of the present study was to assess the associations between the presence and amounts of Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, B. intermedius, Eikenella corrodens, Wolinella recta, and Fusobacterium nucleatum in the periodontal pocket and the degree of alveolar bone loss and other clinical signs of periodonitis, such as probing pocket depth, attachment level, and presence of bleeding on probing at the same site. The study material comprised 16 subjects with or without approximal sites showing longitudinal alveolar bone loss who were selected from a group of 142 subjects monitored radiographically over the past 4 years. In this group 105 sites were examined, of which 58 showed recent alveolar bone loss greater than or equal to 1 mm. Subgingival plaque was collected with absorbent paper points and hybridized with 32P-labeled DNA probes specific for the above-mentioned bacteria. The amount of each bacterial species was correlated with the degree of bone loss over time and the three clinical measurements by means of Spearman rank correlation. A. actinomycetemcomitans showed poor correlations with all three clinical signs of periodontal inflammation, whereas B. gingivalis and W. recta demonstrated significant positive correlations with the three clinical measurements and with attachment level and pocket depth, respectively. In addition, the amount of A. actinomycetemcomitans, B. gingivalis and W. recta showed significant positive correlation with the extent of alveolar bone loss at the site. In contrast, the amounts of B. intermedius, E. corrodens, and F. nucleatum showed negative correlations with all four measurements.(ABSTRACT TRUNCATED AT 250 WORDS)     

DNA probe detection of periodontal pathogens in HIV-associated periodontal lesions

Recent studies have shown that an atypical gingivitis and a rapidly progressive periodontal disease may be early-occurring opportunistic infections associated with human immunodeficiency virus (HIV) infection. This study examined the prevalence of selected periodontal pathogens associated with these HIV-related periodontal lesions. Subgingival plaque samples were obtained from both HIV-seronegative and HIV-seropositive homosexual men and from presumably uninfected heterosexual men. DNA probes were used to detect Actinobacillus actinomycetemcomitans, Bacteroides intermedius, Bacteroides gingivalis, Eikenella corrodens and Wolinella recta in the plaque. The healthy sites in both the seronegative and seropositive homosexual groups showed a greater prevalence of all test bacteria, except for E. corrodens, than did the heterosexual group. HIV-associated periodontitis sites showed a microbial profile qualitatively similar to that of conventional periodontitis, except that B. gingivalis was more prevalent in conventional periodontitis. In contrast, HIV-associated gingivitis sites exhibited a greater prevalence of all bacteria tested than conventional gingivitis sites. In fact, HIV gingivitis generally showed a bacterial profile similar to that of the HIV periodontitis lesions, except that W. recta was significantly more prevalent in HIV periodontitis. These data suggest that the HIV gingivitis lesion is a precursor to HIV periodontitis. Thus, early identification and prophylactic treatment of high-risk individuals may prevent the destruction of periodontal tissues.     

Tetracycline fiber therapy monitored by DNA probe and cultural methods

Oligonucleotide DNA probe and selective cultural methods were compared in their ability to monitor 6 putative periodontal pathogens in a study evaluating local tetracycline fiber therapy. Subgingival plaque was sampled from 4 sites in each of 20 subjects. Samples were taken before and after therapy from sites assigned to the following test groups: tetracycline (TC) fiber, scaling and root planing, control fiber, and untreated. Each sample was analyzed by both DNA probe and cultural methods. Total anaerobic cultivable counts, Porphyromonas (Bacteroides) gingivalis and Prevotella intermedia (Bacteroides intermedius) were enumerated on nonselective blood agar. Actinobacillus actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum and Wolinella recta were isolated on selective media. TC fiber therapy and scaling reduced total cultivable counts from an initial value of 1 x 10(7) to approximately 2 x 10(5) following therapy. Total counts at untreated sites and at sites with control fibers did not change from baseline. A. actinomycetemcomitans and E. corrodens were detected more frequently by the cultural method; the other monitored species were detected more frequently by DNA probes than by the cultural methods. Agreements between methods were: 77.2% for A. actinomycetemcomitans; 72.2% for P. intermedia; 75.6% for E. corrodens; 39.4% for F. nucleatum; 35.6% for P. gingivalis; and 68.9% for W. recta. Limitations of the selective cultural methods used probably contributed to the discrepancies for P. gingivalis and F. nucleatum. DNA probe and cultural methods indicated comparable levels of suppression of the monitored species following TC fiber therapy and scaling. The microbiota of control fiber and untreated sites did not appear to be significantly altered by either method.     

Studies of the subgingival microflora in patients with acquired immunodeficiency syndrome

Two unique forms of periodontal disease, HIV-gingivitis and HIV-periodontitis, have been described in patients with Acquired Immunodeficiency Syndrome (AIDS). In order to determine the bacterial species associated with periodontitis in AIDS patients, the predominant cultivable microflora was examined in 21 subgingival plaque samples from 11 AIDS patients with periodontitis. The presence of putative periodontal pathogens including Actinobacillus actinomycetemcomitans, Bacteroides intermedius, Porphyromonas gingivalis (formerly B. gingivalis), and Wolinella recta was examined by immunofluorescence in 128 subgingival dental plaque samples from 50 AIDS patients including 32 patients with periodontitis. Of 666 bacterial strains isolated from the 21 subgingival plaque samples, Streptococcus sanguis II was the most frequently recovered species comprising 18.5% of the total number of isolates followed by Lactobacillus acidophilus (12.2%), Porphyromonas gingivalis (12%), Fusobacterium nucleatum (11.4%), Staphylococcus epidermidis (8.7%), Actinomyces naeslundii (7.5%), and Actinomyces viscosus (4.7%). Fusobacterium nucleatum was the most prevalent species and was found in 76% of the sites and 91% of the patients. Enteric species including Enterococcus avium and Enterococcus faecalis, Clostridium clostridiiforme and Clostridium difficle as well as Klebsiella pneumoniae also were recovered. Immunofluorescence assays detected similar carriage rates of A. actinomycetemcomitans, B. intermedius, and P. gingivalis in both gingivitis patients and periodontitis patients, while four times more periodontitis patients demonstrated W. recta. Subgingival yeast was a frequent finding in these AIDS patients, present in 62% of the subjects and 55% of the sites. This study indicates that subgingival plaque in AIDS patients with periodontitis can harbor high proportions of the same periodontal pathogens as are associated with periodontitis in non-HIV infected subjects as well as high proportions of opportunistic pathogens.     

Gram negative species associated with active destructive periodontal lesions

Apical subgingival plaque samples were taken from 19 subjects exhibiting active destructive periodontal disease. The predominant cultivable Gram negative species from 50 active sites were compared to 69 inactive sites of comparable pocket depth and attachment level loss. Active disease sites were chosen which showed a significant loss of attachment within a two-month interval. Proportions of Gram negative rods were higher in active periodontal disease sites than in inactive sites. Species which were found to be significantly elevated only in active sites were Bacteroides intermedius, "fusiform" Bacteroides, Actinobacillus actinomycetemcomitans and Wolinella recta. Fusobacterium nucleatum, Capnocytophaga gingivalis and Eikenella corrodens were found in significantly increased proportions in active sites of some subjects and inactive sites of others.     

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.     

The microbiology of HIV-associated periodontal lesions

2 intraoral lesions associated with human immunodeficiency virus (HIV) infection have recently been described: an atypical gingivitis and a rapidly progressive periodontitis. The microbiota associated with these gingival and periodontal lesions was investigated. Subgingival plaque samples were taken from 45 HIV-seropositive homosexual men and from 44 HIV-seronegative control subjects. Each sampled site was clinically and radiographically classified as HIV-associated gingivitis, HIV-associated periodontitis, healthy in an HIV-seropositive subject, or healthy, conventional gingivitis or classical periodontitis in a control subject. Plaque samples were examined by indirect immunofluorescence with polyclonal antisera to detect Bacteroides gingivalis, B. intermedius, Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans. Anaerobic culturing was used to detect black-pigmented Bacteroides species, Fusobacterium species, and A. actinomycetemcomitans to confirm the immunofluorescence findings. We detected B. gingivalis, B. intermedius, F. nucleatum, and A. actinomycetemcomitans in significantly more HIV-periodontitis sites (80, 65, 59 and 61% of sites, respectively) and HIV-gingivitis sites (61, 70, 52 and 52%, respectively) than in HIV-seropositive healthy and control sites (p less than 0.05). The results indicate that the microbiota found in HIV-periodontitis is similar to that of classical periodontitis. In contrast, however, the microbiota associated with HIV-gingivitis is strikingly different from that of conventional gingivitis. The similarity in the prevalence of periodontopathic organisms in both HIV-gingivitis and HIV-periodontitis suggests that the HIV-gingivitis lesion may be a precursor to the tissue destruction observed in HIV-periodontitis. Hence, early detection and treatment of the HIV-gingivitis lesion may prevent the rapid and extensive breakdown of periodontal tissues associated with HIV-periodontitis.     

Serological investigation of refractory human adult periodontitis

This study examined the difference between the serum antibody profiles in refractory adult periodontitis patients (group A), and compared to those (group B) who responded well to conventional periodontal treatment. The levels of specific IgG antibody to Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Fusibacteriumnucleatum, and Eikenella corrodens were assessed in a group of 19 patients (group A) and 11 patients (group B). Specific IgG serum antibody levels were estimated using biotin-avidin linked immunosorbent assay (BALISA). Results indicated that Actinobacillus actinomycetemcomitans, and Bacteroides gingivalis had very high levels of specific circulating antibody in the sera of both groups of patients; whereas, Fusobacterium nucleatum and Eikenella corrodens showed considerable lower levels of antibody than the other two antigens. However, the differences between the two groups with regard to the antibody levels against different bacterial antigens were not statistically significant.     

Prevalence of periodontopathic bacteria in aggressive periodontitis patients in a Chilean population

BACKGROUND: Actinobacillus actinomycetemcomitans is considered a major etiologic agent of aggressive periodontitis (AgP). Other periodontopathic bacteria such as Porphyromonas gingivalis are also suspected of participating in aggressive periodontitis although the evidence to support this is controversial. The aim of the present study was to determine the prevalence of eight periodontopathic bacteria in Chilean patients with AgP. METHODS: Subgingival plaque samples were collected from 36 aggressive, 30 localized, and six generalized periodontitis patients. Samples from 17 advanced chronic periodontitis (CP) patients were taken as controls. Samples collected from the four deepest periodontal pockets in each patient were pooled in prereduced transport fluid (RTF) and cultured. Periodontal bacteria were primarily identified by colony morphology under stereoscopic microscope and rapid biochemical tests. The identity of some bacterial isolates was confirmed by colony polymerase chain reaction (PCR). RESULTS: AgP showed a significatively higher prevalence of C. rectus than CP (P = 0.036). The only statistical difference found was for C. rectus. Patients with AgP showed a higher, but not statistically significant, prevalence of P. gingivalis, E. corrodens, P. micros, and Capnocytophaga sp. A similar prevalence in both groups of patients was observed for F. nucleatum and P. intermedia/nigrescens, and A. actinomycetemcomitans was less prevalent in AgP than CP patients. In localized AgP, P. intermedia/nigrescens, E. corrodens, F. nucleatum, and P. micros were the more prevalent pathogens in contrast to generalized AgP patients who harbored A. actinomycetemcomitans, P. gingivalis, and Capnocytophaga sp. as the most prevalent bacteria. CONCLUSIONS: C. rectus, P. gingivalis, E. corrodens, P. micros, and Capnocytophaga sp. were the most predominant periodontopathic bacteria of AgP in this Chilean population, but the only statistical difference found here between AgP and CP was for C. rectus, suggesting that the differences in clinical appearance may be caused by factors other than the microbiological composition of the subgingival plaque of these patients. In this study, the prevalence of A. actinomycetemcomitans was much lower than that of P. gingivalis.     

Clinical immunologic and microbiologic features of active disease sites in juvenile periodontitis

Eight juvenile periodontitis (JP) patients with progressing disease were evaluated for clinical, immunologic, and microbiologic features. Clinically, bleeding on probing, pocket depth, and attachment level were unrelated to progressing disease. Only Actinobacillus actinomycetemcomitans was related to a marked increase in attachment loss when examined on both a site and patient basis. Eikenella corrodens was significantly elevated in progressing sites with A. actinomycetemcomitans as opposed to non-progressing sites harboring A. actinomycetemcomitans. Eikenella corrodens may function synergistically with A. actinomycetemcomitans to enhance disease in JP patients. Darkfield microscopy was of no value in distinguishing disease activity. All patients screened had elevated serum IgG levels to the same serotype of A. actinomycetemcomitans as that isolated from the subgingival flora. Other elevated serum IgG responses were noted to various organisms including F. nucleatum. B. intermedius, B. gracilus, B. gingivalis and E. corrodens.     

Porphyromonas gingivalis,Bacteroides forsythus and other putative periodontal pathogens in subjects with and without periodontal destruction

BACKGROUND AND AIMS: Bacteria play an essential role in the pathogenesis of destructive periodontal disease. It has been suggested that not all bacteria associated with periodontitis may be normal inhabitants of a periodontally healthy dentition. In particular, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans have been isolated infrequently from subjects without periodontitis. The aim of the present study was to compare prevalence and proportions of a number of periodontal bacteria in periodontitis patients and control subjects. MATERIAL AND METHODS: In all, 116 consecutive subjects diagnosed with moderate to severe periodontitis (mean age 42.4) and 94 subjects without radiographic evidence of alveolar bone loss (mean age 40.4) were recruited for the study. The gingival condition in the control group varied between gingival health and various degrees of gingivitis. In patients, the deepest pocket in each quadrant was selected for microbiological sampling. In control subjects all mesial and distal sites of all first molars were selected for sampling. All paper points from a patient were pooled and processed for anaerobic cultivation within 6 h after sampling. Clinical variables of sampled sites included bleeding index, probing pocket depth and clinical attachment level. RESULTS: A. actinomycetemcomitans, P. gingivalis, Prevotella intermedia, Bacteroides forsythus, Fusobacterium nucleatum and Peptostreptococcus micros were significantly more often prevalent in patients than in controls. The highest odds ratios were found for P. gingivalis and B. forsythus (12.3 and 10.4 resp.). Other odds ratios varied from 3.1 to 7.7 for A. actinomycetemcomitans and P. micros, respectively. Absolute numbers of target bacteria were all higher in patients, but only the mean percentage of B. forsythus was significantly higher in patients in comparison to controls (P < 0.001). CONCLUSIONS:A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, F. nucleatum and P. micros are all significant markers for destructive periodontal disease in adult subjects. Based on calculated odds ratios, B. forsythus and P. gingivalis are the strongest bacterial markers for this disease and are infrequently cultured from subjects without periodontal bone loss.     

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.     

Reaction of human sera from juvenile periodontitis, rapidly progressive periodontitis, and adult periodontitis patients with selected periodontopathogens

The levels of serum antibody reactive to selected periodontopathogens were determined in 182 clinically characterized patients: 35 healthy control, 50 juvenile periodontitis, 42 adult periodontitis and 55 rapidly progressive periodontitis. Reactive antibody levels were determined using an enzyme-linked immunosorbent assay with whole cell preparations of Bacteroides gingivalis, Capnocytophaga (Bacteroides) ochraceus, Fusobacterium nucleatum and Actinobacillus actinomycetemcomitans (Y-4) serving as antigens. Increased reactivity to B. gingivalis and F. nucleatum was observed in all three disease groups studied while antibody reactive to A. actinomycetemcomitans was increased in juvenile and rapidly progressive periodontitis. Antibody levels reactive to C. ochraceus in healthy subjects did not differ from those observed in any disease patient groups. Possible implications in the etiology and progression of the diseases coupled with environmental changes which occur in the econiche of the periodontal pocket are described.     

The relationships between streptococcal species and periodontopathic bacteria in human dental plaque

The existence of antagonistic and commensal relationships between microorganisms was investigated. The predominant cultivable flora in 172 plaque samples from active and non-active sites in 32 human subjects with destructive periodontitis was determined. The presence of putative periodontopathic organisms (Bacteroides gingivalis, Bacteroides intermedius, Bacteroides forsythus, Wolinella recta, Actinobacillus actinomycetemcomitans, and Eikenella corrodens) in a site was correlated with the absence of certain viridans streptococci (Streptococcus sanguis, Streptococcus uberis and Streptococcus intermedius), and vice versa. A strong commensal relationship was found between B. gingivalis and Strep. intermedius. The second study involved 3 subjects with intractable periodontitis whose plaque harboured large numbers of one or more of these periodontopathic organisms. This plaque contained fewer organisms capable of inhibiting the growth of the periodontopathic strains in vitro when compared with a clinically-healthy control subject. Intermediate levels of inhibitors were found in plaque taken from non-active lesions. The majority of inhibitors in plaque from the healthy control were viridans streptococci. Hydrogen-peroxide production by these organisms appears to be the principal mechanism of growth inhibition for periodontopathic organisms. Bacterial interactions may thus be causally related to both periodontal health and disease.     

Microbial associations in periodontitis sites before and after treatment

Duplicate samples from 110 periodontal sites of 6 mm or more pocket depth in 16 patients were analyzed for the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Capnocytophaga spp., Campylobacter rectus, Eikenella corrodens and Fusobacterium nucleatum. The sites were sampled before and after nonsurgical periodontal treatment. No statistically significant associations were found before treatment between any of the analyzed species. After treatment, statistically significant associations were found between E. corrodens and all the other species, F. nucleatum and P. intermedia; Capnocytophaga spp. and C. rectus; P. intermedia vs Capnocytophaga spp. and P. gingivalis ; and C. rectus vs Capnocytophaga spp. and A. actinomycetemcomitans. Some of these associations could be explained either by patient-related factors or site-related characteristics such as the pocket depth. The proportion of P. gingivalis seemed to be unrelated to the proportion of P. intermedia in the samples. If one of the analyzed microbes was found in one of the sampled pockets in a patient, the probability of finding that microbe in all the sampled sites in the same patient before treatment was more than 50%. This probability was reduced after treatment for many species, especially P. gingivalis , which showed a probability of zero. The probability of detecting a bacterial species on at least one additional site if it was present on one in the same individual was nearly 100%, both before and after treatment, for all species studied. This study has shown several potential microbial associations in the subgingival plaque flora of deep periodontal pockets. Local factors of the periodontal pocket and factors related to the individual may mask the biological significance of these microbial interactions.     

Identification of bacteria using DNA probes

Since the microbial specificity of periodontal diseases is well established, having a valid microbial diagnostic test is essential for a correct and a coherent treatment planning. DNA probe will be used to identify and quantify the oral pathogens, most commonly associated with periodontitis. This test utilizes innovative DNA probe technology to identify unique segments of DNA in each of the following bacteria: Bacteroides gingivalis, Bacteroides intermedius, Actinobacillus actinomycetemcomitans, Wollinella recta, Fusobacterium nucleatum and the spirochete, Treponema denticola.