Longitudinal study of experimentally induced periodontal disease in Macaca arctoides: relationship between microflora and alveolar bone loss

Chlorine dioxide and chlorhexidine mouthrinses compared in a 3-day plaque accumulation model

BACKGROUND

The aim of this study was to investigate the inhibiting effect of a chlorine dioxide mouthrinse as opposed to a mouthrinse containing chlorhexidine (0.20%) during 3 days of plaque accumulation.

METHODS

At baseline, all participants (N=77) received a professional prophylaxis and were randomly assigned to the test (chlorine dioxide) or (positive) control (chlorhexidine) group. On the following 3 days, both groups rinsed twice daily for 1 minute with 10 ml test or control solution. At the end of the experimental period, plaque was assessed, and the panelists filled out a questionnaire.

RESULTS

Chlorhexidine inhibited plaque growth significantly more than the mouthrinse containing chlorine dioxide (plaque index=1.39 versus 1.96, respectively; P<0.001). The results of the questionnaire showed that the panelists found chlorhexidine easier to use and more effective. However, they preferred the taste of the chlorine dioxide mouthrinse and experienced less taste alterations.

CONCLUSION

Chlorine dioxide mouthrinse seems to be a less potent plaque inhibitor than chlorhexidine.

The effect of flavonoids on transduction mechanisms in lipopolysaccharide-treated human gingival fibroblasts

Periodontal disease comprises a group of infections that lead to inflammation of the gingival and destruction of periodontal tissues and is accompanied by the loss of the alveolar bone with eventual exfoliation of the teeth. Porphyromonas gingivalis is a Gram-negative bacteria obtained from the periodontal pocket of patients with aggressive and chronic periodontitis. This bacteria presents in the external membrane lipopolysaccharide (LPS). Flavonoids are molecules obtained from plants and possess anti-inflammatory properties. Herein we characterize the effect of the flavonoids quercetin, genistein, luteolin, and quercetagetin on LPS-activated transduction mechanism regulation in human gingival fibroblasts (HGF). In this study, we investigated the role of the previously mentioned flavonoids on mitogen-activated protein kinase (MAPK) activation induced by LPS obtained from P. gingivalis. Our results showed that LPS treatment induces activation of extracellular signal related kinase 1/2 (ERK1/2), p38, and c-jun-NH(2)-terminal kinase (JNK). All flavonoids demonstrated an inhibitory effect on MAPK activation, interleukin, 1beta, and cyclooxygenase-2 (COX-2) expression, IL-1beta and prostaglandin E2 (PGE2) synthesis. The most active flavonoid was quercetagetin. Finally we found that the treatment with quercetagetin had no effect on cellular viability or in genetic material integrity.

Luteolin inhibits lipopolysaccharide actions on human gingival fibroblasts

Periodontal disease comprises a group of infections that lead to inflammation of the gingiva, periodontal tissue destruction, and in severe cases is accompanied by alveolar bone loss with tooth exfoliation. Actinobacillus actinomycetemcomitans is a Gram-negative microorganism, which possesses and produces lipopolysaccharide (LPS) molecules that play a key role in disease development. Human gingival fibroblasts are the major constituents of gingival connective tissue and may interact directly with bacteria and bacterial products including LPS. Flavonoids possess antioxidant and anti-inflammatory properties that reduce inflammatory molecule expression in macrophages and monocytes. In this study, we evaluated the ability of diverse flavonoids to regulate nitric oxide production of LPS-stimulated human gingival fibroblasts, and studied the effect of luteolin on diminish phosphorylation in mitogen-activated protein kinase (MAPK) family members as well as in protein kinase B (Akt), nuclear factor kappa B (NF-kappaB) activation, inducible nitric oxide synthase (NOS) expression, and nitric oxide (NO) synthesis. We also found that pretreatment with three flavonoids, including quercetin, genistein, and luteolin, blocked nitric oxide synthesis in a dose-dependent fashion. Luteolin exerted the strongest blocking action on expression of this inflammatory mediator. Luteolin pretreatment attenuated LPS-induced extracellular signal-regulated kinase, p38, and Akt phosphorylation. LPS treatment of human gingival fibroblasts resulted in NF-kappaB translocation. Cell pretreatment with luteolin abolished LPS effects on NF-kappaB translocation. In addition, luteolin treatment blocked LPS-induced cellular proliferation inhibition without affecting genetic material integrity. We concluded that luteolin interferes with LPS signaling pathways, reducing activation of several mitogen-activated protein kinase family members, and inhibits inflammatory mediator expression.

Randomized controlled clinical trials on agents used for chemical plaque control

Taking into account the limitations of the daily self-performed oral hygiene the use of chemical agents that can be incorporated in dentifrice or mouth rinse formulations has been advocated. The present review deals with randomized controlled clinical trials of >or=6 months in duration, on the use of those agents and their effects on plaque and gingival inflammation.

Etiology and pathogenesis of periodontal diseases

The two most prevalent and most investigated periodontal diseases are dental plaque-induced gingivitis and chronic periodontitis. The last 10 to 15 years have seen the emergence of several important new findings and concepts regarding the etiopathogenesis of periodontal diseases. These findings include the recognition of dental bacterial plaque as a biofilm, identification and characterization of genetic defects that predispose individuals to periodontitis, host-defense mechanisms implicated in periodontal tissue destruction, and the interaction of risk factors with host defenses and bacterial plaque. This article reviews current aspects of the etiology and pathogenesis of periodontal diseases.

Modulation of clinical expression of plaque-induced gingivitis. I. Background review and rationale

OBJECTIVES

The purpose of this article is to provide the necessary background and rationale for the accompanying studies, which are ultimately aimed at identifying genetic and environmental factors determining gingivitis susceptibility.

MATERIALS AND METHODS

The literature on factors reported to modify the clinical expression of gingivitis, i.e., factors that determine individual variability in gingival inflammatory response to plaque, is presented.

RESULTS

Clinical evidence suggests that the gingival inflammatory response to plaque accumulation may differ substantially among individuals. However, most of the available studies are of small scale and not purposely designed to address the issue. Systemic factors implicated in modulation of the clinical expression of gingivitis include metabolic, genetic, environmental and other factors. The significance of such factors in designing and conducting a large-scale experimental gingivitis trial and means to account for them are discussed.

CONCLUSION

Although several factors have been implicated, genetic or environmental factors underlying differences in gingivitis expression are not fully elucidated. The accompanying studies aim to identify and characterize, among participants in a specifically designed large-scale experimental gingivitis trial, subjects that differ significantly in their gingival inflammatory response to plaque. This is the first step in an effort to determine genetic or environmental factors underlying such differences.

Periodontal diseases: current and future indications for local antimicrobial therapy

The microbial etiology of gingivitis and periodontitis provides the rationale for use of adjunctive antimicrobial agents in the prevention and treatment of periodontal diseases. Although mechanical removal of supra- and subgingival calcified and non-calcified plaque deposits has been proved effective to control the gingival inflammatory lesions as well as to halt the progression of periodontal attachment loss, some patients may experience additional benefits from the use of systemic or topical antimicrobial agents. Such agents are able to significantly affect supra- and subgingival plaque accumulation and/or suppress or eradicate periodontal pathogenic microflora. Currently, properly selected local antiseptic and systemic antibiotic therapies can provide periodontal treatment that is generally effective, low-risk and affordable. This paper will briefly review the host-related conditions in which the periodontal preventive and therapeutic approaches may be effectively assisted by a local antimicrobial regimen. Potential future indications for adjunctive local antimicrobial therapy will also be discussed.

Immunostimulating and protective effects of an oral polybacterial immunomodulator 'Dentavax' in a rabbit experimental model

The immunostimulating and protective effects of an oral polybacterial immunomodulator, Dentavax (D), composed of killed cells from Klebsiella pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Candida albicans and Lactobacillus acidophilus and their lysates, have been investigated on an experimental rabbit model. In this model, mixed suspensions of the above bacterial wild strains have been injected in six sides of oral mucosa. A long-lasting inflammation with the development of infiltrates and confluating abscesses has been observed. The influence of orally given Dentavax on the course of the model infection as well as on the dynamics of the immune response has been studied. A two-fold decrease in the duration and severity of inflammatory reaction, confirmed by the histological findings, has been registered. In immunised animals, an activation of polymorphonuclear phagocytosis, together with stimulation of humoral systemic and mucosal immunity with synthesis of specific serum (predominantly, IgG) and coproantibodies (predominantly, S-IgA) determined by ELISA, has been found. The results obtained proved the strong immunostimulating and protective effects of the preparation D, which is meant for the prophylaxis and treatment of inflammatory periodontal diseases.

Periodontal disease progression

BACKGROUND

The objective of this investigation is to use noninvasive, state-of-the-art, diagnostic techniques to measure periodontal disease progression and model periodontal disease activity over time. In this investigation, digital subtraction radiography and an electronic controlled force periodontal probe capable of attachment level measurement were used to measure bone loss and attachment loss, respectively. The use of these nearly continuous measures of attachment and bone loss allowed detection of small amounts of disease activity and provided data to be used in modeling of the disease process over time.

METHODS

Forty-four patients were studied for 18 months. Examinations used clinical attachment level measures at 1-month intervals and quantitative radiology at 6-month intervals. The sites were analyzed by regression for statistically significant changes. These data were used to determine sites of periodontal disease activity for testing various models of periodontal disease progression.

RESULTS

Overall 22.8% of sites lost attachment, 5.4% gained, and 71.7% demonstrated no statistically significant change. The mean time to lose 1 mm of attachment was 8.4 +/- 0.6 months. In the first model tested a step-wise discriminant analysis was used to determine whether or not baseline measurements of plaque (PI), gingival inflammation (GI), attachment loss, and probing depth (PD) could be used to derive a satisfactory model for disease progression. Although the overall model was statistically significant with PI, PD, and GI contributing to the model (Wilks' lambda = 0.859, F = 5.71, P <0.0012), its predictive power was relatively weak. A considerably stronger significant model resulted when the rate of attachment loss over the first 6 months, baseline PI, and baseline GI were included (Wilks' lambda = 0.712, F = 14.17, P<0.00001). A significant model also resulted when bone loss during the first 6 months and baseline probing depth were included (Wilks' lambda = 0.438, F = 61.48, P<0.00001). When the last model was applied to each site, the sensitivity in predicting disease progression was 80.0% and the specificity in ruling out progressive disease was 93.9%.

CONCLUSIONS

This study indicates that clinically significant progression of attachment loss in posterior tooth sites occurs as a frequent event in adult periodontitis. The modeling data also suggest that short-term (6 month) measures of periodontal disease progression greatly improve the ability to model attachment loss over a longer period in untreated periodontitis patients.

Oral microbial ecology and the role of salivary immunoglobulin A

In the oral cavity, indigenous bacteria are often associated with two major oral diseases, caries and periodontal diseases. These diseases seem to appear following an imbalance in the oral resident microbiota, leading to the emergence of potentially pathogenic bacteria. To define the process involved in caries and periodontal diseases, it is necessary to understand the ecology of the oral cavity and to identify the factors responsible for the transition of the oral microbiota from a commensal to a pathogenic relationship with the host. The regulatory forces influencing the oral ecosystem can be divided into three major categories: host related, microbe related, and external factors. Among host factors, secretory immunoglobulin A (SIgA) constitutes the main specific immune defense mechanism in saliva and may play an important role in the homeostasis of the oral microbiota. Naturally occurring SIgA antibodies that are reactive against a variety of indigenous bacteria are detectable in saliva. These antibodies may control the oral microbiota by reducing the adherence of bacteria to the oral mucosa and teeth. It is thought that protection against bacterial etiologic agents of caries and periodontal diseases could be conferred by the induction of SIgA antibodies via the stimulation of the mucosal immune system. However, elucidation of the role of the SIgA immune system in controlling the oral indigenous microbiota is a prerequisite for the development of effective vaccines against these diseases. The role of SIgA antibodies in the acquisition and the regulation of the indigenous microbiota is still controversial. Our review discusses the importance of SIgA among the multiple factors that control the oral microbiota. It describes the oral ecosystems, the principal factors that may control the oral microbiota, a basic knowledge of the secretory immune system, the biological functions of SIgA, and, finally, experiments related to the role of SIgA in oral microbial ecology.

Microbiota associated with experimental peri-implantitis and periodontitis in adult Macaca mulatta monkeys

This study examines the microbiota associated with the progression of experimental peri-implantitis and periodontitis induced concurrently in partially edentulous adult monkeys. Root-form and plate-form implants with fixed prosthesis in place for at least 12 months and their corresponding opposite molar teeth were ligated for 6 months. The microbiota in plaque around these ligated dental implants and molars were studied at 0, 1, 2, 3, and 6 months post-ligation. Plaque samples were analyzed by dark-field microscopy and selective and non-selective culture. Putative periodontal pathogens were detected as a major component of the microbiota cultured from plaque samples obtained from experimental peri-implantitis sites. Overall, the types and relative proportions of putative periodontal pathogens in plaque associated with ligature-induced peri-implantitis and ligature-induced periodontitis were similar. Only levels of anaerobic Actinomyces and spirochetes were significantly different between both sites. Spirochete levels were significantly higher at peri-implantitis sites when compared with levels at periodontitis sites after 6 months, and spirochete levels increased significantly between 0 and 6 months post-ligation at implant sites. Levels of spirochetes correlated significantly with probing depth and bone loss at peri-implantitis sites. Overall, Actinomyces levels were higher at periodontitis sites. Porphyromonas species were not detected continuously as part of the peri-implantitis microbiota. In conclusion, this study finds that the microbiota associated with the progression of experimental peri-implantitis and periodontitis occurring concurrently in partially edentulous mouths are similar.

Evidence for serum immunoglobulin G (IgG) antibody responses in Macaca fascicularis identified by monoclonal antibodies to human IgG subclasses

This investigation determined the capacity of murine monoclonal antibodies directed to human immunoglobulin G (IgG) subclasses to identify molecules with conserved epitopes in the serum of the nonhuman primate, Macaca fascicularis. We subsequently utilized this cross-reactivity to document the characteristics of IgG subclass antibody responses in M. fascicularis to parenteral immunization with intact oral microorganisms, antigens from oral microorganisms, and finally a defined protein toxin, tetanus toxoid. The IgG response in nonhuman primates immunized with tetanus toxoid showed a 40-fold and 110-fold increase after primary and secondary immunizations, respectively. The major IgG subclass responses were IgG1 and IgG3, with little, though significant, responses in the IgG4 and IgG2 subclasses. Seventy-five to 94% of the natural IgG antibody in nonhuman primate sera to Porphyromonas gingivalis, Prevotella intermedia and Campylobacter rectus was IgG1. IgG2 and IgG3 predominated to Bacteroides fragilis, IgG4 to Actinomyces viscosus and an equal distribution among the subclasses was noted in response to Fusobacterium nucleatum. Parenteral immunization of nonhuman primates with intact P. gingivalis elicited primarily IgG3 and IgG4, while the post-immunization IgG response to P. intermedia was largely IgG1. Nonhuman primates were also parenterally immunized with cell envelope antigens of P. gingivalis, P. intermedia, or a combination of cell envelope antigen from C. rectus and F. nucleatum and cell wall antigens of A. viscosus. The greatest IgG antibody response seen post-immunization was reactive with anti-human IgG1 for all of these antigens except to C. rectus which bound nonhuman primate antibody reactive with anti-human IgG2. It appears that the bacteria and their products exhibit unique differences in their induction of serum IgG subclass antibody responses. The characteristics of their immunogenicity as detected by the nonhuman primate may contribute to the ability of the immune responses to effectively interact with these pathogens.

Characteristics of systemic antibody responses of nonhuman primates to cell envelope and cell wall antigens from periodontal pathogens

The immune response of the primate, Macaca fascicularis, to cell envelope (CEA) or cell wall (CWA) antigens of several periodontal pathogens was examined to develop a strategy to interfere with ligature-induced periodontitis. Animals were parenterally immunized with CEA of either Porphyromonas gingivalis, Prevotella intermedia or a combination of CEA/CWA of Campylobacter rectus, Fusobacterium nucleatum and Actinomyces viscosus. Serum samples were taken every 2-4 weeks over a 4-month period, which included a 13-week interval with molar teeth ligated. All of the nonhuman primates in the study exhibited baseline levels of IgG, IgM and IgA antibody to formalinized whole cells of the bacteria. These levels increased significantly following immunization and were elevated above baseline throughout the remainder of the experiment. The largest change in antibody responses was seen in IgA antibody levels of P. gingivalis and C. rectus (42-fold above baseline), IgM antibody to P. intermedia, (41-fold increase) and IgG antibody to F. nucleatum and A. viscosus (32 and 63-fold increases). Moreover, the nonhuman primates exhibited differences in isotype response levels to whole microorganisms compared with the cell envelope antigens. These findings demonstrate the capacity of these nonhuman primates to produce an active immune response to microorganisms chronically colonizing the subgingival microbiota. Additionally, it appears that the bacteria may exhibit some unique differences in their immunogenicity as detected by the nonhuman primate and may contribute to the ability of the immune responses to effectively interact with these pathogens.

Experimental peri-implant tissue breakdown around hydroxyapatite-coated implants

This study monitored experimental peri-implant tissue breakdown around hydroxyapatite (HA)-coated titanium dental implants. Thirty-two HA-coated cylindrical implants, in groups of two, were bilaterally inserted in the posterior maxilla and mandible in 4 Macaca mulatta monkeys. Two months after healing-abutment connection, a 2-month plaque control program was initiated. Clinical and radiographic recordings and peri-implant submucosal microbial samples were then obtained (baseline). Cotton ligatures were next placed around the healing-abutments and plaque control measures were abandoned. Clinical and radiographic recordings were repeated at 5 and 10 months post-baseline. Microbial samples were repeated at 10 months post-baseline, and ligatures were removed. Clinical, radiographic, and microbial examinations were again repeated at 11 months post-baseline. Mean modified plaque index (mPI; P < 0.01), gingival index (G]; P < 0.01), and bleeding on probing (BOP; P < 0.05) scores increased over the plaque accumulation period. The mPI, and GI scores decreased after ligature removal (P < 0.001). Mean probing depth (PD) and clinical attachment level (AL) increased between baseline and the 5- and 10-month examinations (delta PD 3.0 mm; delta AL 2.7 mm; P < 0.05). PD values were reduced following ligature removal (P < 0.05). AL values and BP scores remained unchanged. A significant negative correlation was found between induced defect depth and width of keratinized mucosa at baseline (P = 0.03). At baseline, the submucosal microbiota was dominated by coccoid cells. Following ligature placement, the microbiota included a large proportion of Gram-negative anaerobic rods, predominantly Porphyromonas gingivalis, Bacteroides forsythus, and Fusobacterium species as well as beta-hemolytic streptococci. Ligature removal had a limited effect on the composition of the submucosal microbiota. This non-human primate study indicates that ligature-enhanced plaque accumulation is a precursor of progressive peri-implant tissue breakdown around HA-coated implants. The associated microbiota resembles that of peri-implantitis and destructive periodontal disease in humans. This preclinical model may be useful to study modalities aimed at arresting peri-implant tissue breakdown and at regeneration of bone in peri-implantitis defects.

Characteristics of systemic antibody responses of nonhuman primates following active immunization with Porphyromonas gingivalis, Prevotella intermedia and Bacteroides fragilis

Periodontal disease is an infectious disease manifested by the progressive change of a healthy resident commensal microbiota to a pathogenic one characterized by a specific microbiota. Thus, the prospect for the use of selected bacteria or their antigens as a vaccine to interfere with the microbial changes and resulting progression of periodontal tissue destruction has been proposed. As a first step in examining the use of bacterial antigens as immunogens in periodontitis, this study characterized the humoral immune response in Macaca fascicularis after systemic immunization with intact Porphyromonas gingivalis, Prevotella intermedia and Bacteroides fragilis. Parental immunization of the nonhuman primate with the intact bacteria resulted in the production of specific and significantly elevated levels of antibodies to P. gingivalis and P. intermedia, with the predominant isotype being immunoglobulin G (IgG). In contrast, the principal response to the nonoral, intestinal bacterium, B. fragilis, was of the IgM isotype. Immunization increased IgG, IgM, and IgA antibody by 14-227 fold to P. gingivalis and 8-108 fold to P. intermedia. The level of serum IgA antibody increased (77-227 fold). The kinetics of the antibody response post-immunization and post-ligation differed with respect to each of the bacteria tested. IgG antibody to P. gingivalis increased through week 16 of the experiment and remained elevated above baseline through week 32. The IgG antibody level to P. intermedia peaked at 4 weeks following the third immunization and decreased post-ligation to near baseline levels by week 16. Characterization of the immune response after active immunization in the nonhuman primate has demonstrated a substantial and specific increase in antibody response which was sustained for several weeks. The insights obtained from these studies should help optimize the potential for immunologic interference with progressing periodontitis.

Cell envelope and cell wall immunization of Macaca fascicularis: effect on the progression of ligature-induced periodontitis

The nonhuman primate, Macaca fascicularis, was used to study the role of immunization with selected members of the periodontopathic microbiota in the longitudinal progression of ligature-induced periodontitis. Animals were immunized with cell envelope antigens prepared from Porphyromonas gingivalis and Prevotella intermedia, and a mixture prepared from Fusobacterium nucleatum, Campylobacter rectus, and Actinomyces viscosus. Serum immunoglobulin G (IgG), IgM and IgA isotype antibodies increased significantly in all immunization groups and were specific for each of the immunogens. P. gingivalis and P. intermedia immunization resulted in a stabilization of the proportions of these species throughout most of the experiment. The high P. gingivalis antibody titer resulted in low P. gingivalis numbers being recovered. P. gingivalis immunization, while lowering recoverable viable P. gingivalis, resulted in significantly increased levels of Prevotella loescheii, Prevotella buccae, Bacteroides macacae and Prevotella melaninogenica compared with preligation and preimmunization levels. Actinobacillus actinomycetemcomitans, Capnocytophaga spp. and Eikenella spp. remained at preligation levels postimmunization. Campylobacter spp. increased significantly during the course of the experiment in all groups, whereas the levels of Fusobacterium spp. decreased. Plaque indices and bleeding on probing showed significant increases in all groups following ligation, with the placebo group showing the greatest increase. Pocket depth measurements revealed that , whereas the placebo animals showed an approximate 5% increase, the P. gingivalis- and P. intermedia-immunized groups showed nearly a 20% increase in pocket depth. Attachment level measurements showed significantly greater attachment loss in the P. gingivalis- and P. intermedia-immunized groups, and the F. nucleatum + C. rectus + A. viscosus immunization appeared to prevent significant changes in pocket depth/attachment level loss. Radiographic measurement of bone loss by computer-assisted densitometric image analysis revealed that the placebo group lost bone throughout the experiment. P. gingivalis- and P. intermedia-immunized groups showed an exacerbated loss of bone density and the group immunized with F. nucleatum + C. rectus + A. viscosus exhibited significantly lower amounts of bone loss when analyzed by computer-assisted densitometric image analysis, compared with the other immunized groups. Although immunization with P. gingivalis and P. intermedia cell envelope antigens had an effect on their emergence in the complex microbiota of the developing periodontal pocket, this immunization also resulted in greater bone loss than immunization with F. nucleatum + C. rectus + A. viscosus, suggesting that, whereas selective members of the putative periodontopathic microbiota may play a direct role in periodontal tissue destruction, the complexity of the subgingival microbiota dictates that considerable scrutiny is required to select useful immunogens that can elicit functional protection from periodontal tissue destruction induced by oral microorganisms that already colonize or infect the host.

Succession of putative peri-implant pathogens after root-form and plate-form implant placement in partially dentate adult monkeys

This report describes the succession of putative peri-implant pathogens in partially dentate monkeys after dental implantation and prosthetic reconstruction. Tooth and implant (6 root-end form, 4 blade-vent implants) sites in eight monkeys were monitored microbiologically and clinically during the pre-implant stage, abutment connection stage, bridge placement stage, and three and six months after the bridge placement stage. Tooth and implant sites were cleaned monthly post-extraction. Microbiological studies included dark field microscopy, selective and non-selective culture, and primary phenotypic characterization of culture isolates. After implant surgery, the median proportion of several putative peri-implant pathogens studied were significantly elevated. Following fixture placement, P. intermedia replaced P. melaninogenica as the predominant Black Pigmented Anaerobic Bacilli (BPAB) in the mouth. After abutment connection stage, levels of P. intermedia, A. actinomycetemcomitans, F. nucleatun, Haemophilus sp. and spirochetes were significantly elevated at implant and tooth sites. Three months after bridge installations, P. intermedia and A. actinomycetemcomitans remained significantly elevated at implant sites. At six months after bridge installation, levels of P. intermedia, F. nucleatum and A. actinomycetemcomitans declined significantly relative to levels at three months. Porphyromonas sp. and spirochetes were not significantly elevated although their levels correlated with gingival redness. P. intermedia, Porphyromonas sp. and spirochetes levels correlated significantly with probing depth. Correlation was detected between P. gingivalis and spirochetes; and between A. actinomycetemcomitans and F. nucleatum. Our studies show a transitional increase in levels of several organisms resembling putative pathogens of human peri-implant infection, associated with implant placements in partially edentulous mouths and supports early prophylactic interventions to control their levels.

Human antibody responses to outer envelope antigens of Porphyromonas gingivalis serotypes

Immunological studies examining the homogeneity of the major antigenic components of P. gingivalis have suggested 3 serotypes and have indicated a limited distribution of the serotypes in an individual patient. These studies prompted us to define the immunodominant antigens and distribution of immune responses to P. gingivalis serotypes. Serum IgG antibody levels in periodontitis patients in the present study were most frequently elevated above the normal subjects when tested against P. gingivalis serotype A (i.e., 33277). Nearly 1/3 of the patients showed significantly elevated antibody to multiple serotypes of the P. gingivalis apparently resulting from cross-reacting antigens. We determined distinctive differences among outer envelope protein and antigen patterns obtained from the three serotypes. Moreover, the results identified considerable similarities in the qualitative and quantitative antigen response patterns among patients to a particular serotype. There was a strong positive correlation between IgG antibody levels (ELISA) and the total level of reactivity determined in the immunoblots, as well as a positive correlation to the proportion of antibody to particular antigens. These findings suggest that responses to these antigens comprised a major portion of the response to the intact microorganism. Additionally, the detection of antibody to particular antigen bands was indicative of early responses to each of the P. gingivalis serotypes. The results of our study indicate that a subpopulation of periodontitis patients develop an extensive serum antibody response often to multiple serotypes of P. gingivalis and may define a patient population with a P. gingivalis disease. Finally, our results indicate a more consistent antigenic composition for P. gingivalis which may enhance the potential for strategies to immunologically interfere with disease caused by this microorganism.

Macaca fascicularis as a model in which to assess the safety and efficacy of a vaccine for periodontitis

We have assessed Macaca fascicularis as a potential model in which to test the efficacy and safety of a vaccine for periodontitis. Twenty-eight animals were surveyed and 20 studied in more detail. Clinical periodontal status was assessed, the subgingival microflora analyzed especially for the presence and proportions of Porphyromonas gingivalis and titers and avidities of serum antibodies reactive with P. gingivalis measured. Probing depths ranged from 0.90 mm to 3.80 mm, Gingival Index scores from 0.00 to 4.00 and Plaque Index scores from 0.00 to 3.00. About 40% of sites bled on probing. The animals manifested a subgingival flora characteristic of the anaerobic gram-negative bacteria found in human periodontal pockets, including Actinobacillus actinomycetemcomitans, P. gingivalis, Bacteroides forsythus, Campylobacter rectus, Prevotella intermedia and Fusobacterium nucleatum. P. gingivalis was detected in 70 of 80 samples studied, ranging from 0.01% to 20% of the total flora. Serum antibody reactive with antigens of P. gingivalis was observed in all animals, with titers ranging from 1.0 enzyme-linked immunosorbent assay (ELISA) unit to 25 ELISA units and avidities from 0.10 M to 2.20 M. Antibody titer and maximum percentage of P. gingivalis were inversely correlated, indicating that a humoral immune response may be effective in reducing P. gingivalis overgrowth. M. fascicularis appears to be an excellent model for use in vaccine development.

Microorganisms in polytetrafluoroethylene barrier membranes for guided tissue regeneration

This study examined the microflora in 11 barrier membranes around teeth with furcation involvement or 2 to 3 wall intrabony defects and in 16 membranes around implants with various types of bony defects. Total viable counts and the occurrence of selected microbial species were determined by non-selective and selective culture and by DNA probes. Study sites were examined for probing pocket depth and attachment level. All tooth-associated membranes yielded high levels of microorganisms. 4 of 5 teeth with membranes harboring less than 10(8) organisms gained 3 mm or more in probing attachment, whereas 6 teeth with membranes with more than 10(8) organisms exhibited loss or only small gains in attachment. 3 membranes with high levels of black-pigmented anaerobic rods lost 1 to 2 mm of attachment. Ten implant-associated membranes with no cultivable microorganisms demonstrated a mean probing gain of 4.9 mm. 6 implants with infected membranes only gained an average of 2.0 mm of supportive bone. The present findings underscore the importance of controlling or eliminating periodontal pathogens on barrier membranes in order to gain new attachment.

Oral microflora of the ferret at the gingival sulcus and mucosa membrane in relation to ligature-induced periodontitis

The aim of this study was to describe, in the domestic ferret, the composition of the normal gingival sulcus and the near related mucosa microflora and the shift in the composition during an acute periodontal breakdown induced by the placement of ligatures. Five animals were used. At the start of the experiment (day 0) and before the placement of the ligatures, 2 microbiological samples were obtained from the gingival sulcus and the related mucosa at the mid-buccal surface of the right upper P4. The same sites were sampled on the left side, serving as control sites. On day 28, new microbiological samples were taken from the same 4 sites. The samples were analyzed with darkfield microscopy and with viable counts. In the darkfield analysis, on day 0, the predominant bacterial morphotype was cocci, ranging from 88-92%. The viable counts showed that nearly 100% of the total cultivable flora was composed of facultative anaerobic gram-negative and gram-positive rods. Pasteurella spp., Corynebacterium spp. and Rothia spp. were the major components of these bacterial groups. No anaerobic bacteria were detected. On day 28, cocci decreased to approximately 75% in the experimental gingival sulcus sample, and filaments and rods increased significantly. Spirochetes remained largely unchanged during the experiment. The composition of the experimental site samples changed. There was a decrease in the mean numbers of facultative anaerobic gram-positive rods, and approximately one third of the microflora comprised anaerobic gram-negative rods, mainly Porphyromonas gingivalis and Fusobacterium spp. Although the composition of the microflora of the ferret presented few similarities to that described in dogs and monkeys, the anaerobic portion of the gingival sulcus and oral mucosa microflora related to ligature-induced periodontitis presented microorganisms observed in experimental periodontitis both in dogs and monkeys as well as in human periodontal diseases.

Macaca nemestrina: a non-human primate model for studies of periodontal disease

The non-human primate Macaca nemestrina was evaluated for use as a potential model in periodontal research by study of 16 animals. Using one incisor, premolar, and molar per quadrant, we measured supragingival plaque, severity of gingival inflammation, and pocket depth, and analyzed the subgingival flora. Serum IgG titers and avidities to antigens of Porphyromonas gingivalis (Pg) and Actinobacillus actinomycetemcomitans (Aa) were also assessed. Ten animals were between 13 and 24 years old, and six were between 4 and 5 years old. While mean gingival inflammation scores were significantly higher for older than for younger animals (2.2 vs 1.8, p < 0.05), mean plaque index scores and mean probing depths did not differ significantly. The animals harbored a subgingival microflora considered to be pathogenic for humans including Aa, Pg, Bacteroides forsythus, Prevotella intermedia I and II, Campylobacter recta and Fusobacterium nucleatum. Aa, however, was found only in the younger animals. All of the animals had serum IgG antibodies reactive with antigens of Pg and Aa, and titers for Pg but not for Aa were significantly higher in the older relative to the younger animals (t test p < 0.02). In contrast, antibody avidity did not significantly differ between the two groups. A combined clinical assessment index based on maximum probing depth, gingival index score, and tooth loss was used to assess the overall disease severity. Titers were positively associated with disease severity (Spearman's rank correlation 0.57, p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Non-human primates used in studies of periodontal disease pathogenesis: a review of the literature

The inability to examine initiation and progression of periodontal disease and to assess certain therapies in humans has led to a great interest in the use of animal models in periodontal research. Some of the most prominent animals used are non-human primates. This article reviews the characteristics of non-human primate models in periodontal health, in the transition from health to gingivitis to periodontitis, and in experimental gingivitis and periodontitis. Where possible, the results of these studies are compared with results from human studies. Only a few studies have compared in detail the anatomy, physiology, immunology, and tissue interactions in monkeys with those of humans. With the exceptions of differences and variations in size of the dentition, the number of each tooth type as well as larger canines, presence of diastemata between anterior teeth, and an edge-to-edge relationship of the incisors, the dental and periodontal anatomy of non-human primates seem quite similar to that of humans. Clinically healthy gingiva can be established and maintained in non-human primates, and gingivitis as well as periodontitis occur in these animals. It is possible to induce experimental periodontitis by placement of peri-dental silk ligatures or orthodontic elastics as well as by surgical removal of alveolar bone. Although the most appropriate model for studies of periodontal disease pathogenesis in non-human primates appears to involve the application of silk ligatures, some difficulties may occur in establishing periodontal break-down by using this model. Many clinical, histological, microbiological, and immunological characteristics of spontaneous and experimental marginal inflammation in most non-human primates are similar to those in humans. The most significant differences between small non-human primates and humans are the very limited number of lymphocytes and plasma cells in the inflammatory infiltrate of squirrel monkeys (Saimiri sciureus) and marmosets. Therefore, the use of squirrel monkeys and marmosets may not be appropriate in many studies of periodontal disease pathogenesis. The most significant microbial differences between macaque species and humans are a lower proportion of Actinomyces species, the presence of a catalase-producing Prevotella melaninogenica strain, and the high carrier rate for Actinobacillus actinomycetemcomitans in subgingival plaque of macaque species. The significance of these differences is presently unknown. It is concluded that the use of many non-human primate species due to the apparent close anatomic and biologic similarities to humans is appropriate in experimental studies of periodontal disease, provided the use of laboratory animals is requisite and lower species are not applicable.(ABSTRACT TRUNCATED AT 400 WORDS)

Sub-gingival microflora in Macaca mulatta species of rhesus monkey

The Macaca mulatta species of rhesus monkey is one of several non-human primate (nhp) models for periodontal disease. This report presents the bacteriology of the gingival sulci in M. mulatta monkeys. Three sub-gingival sites (maxillary right central incisor, the disto-buccal of the mandibular left second molar and mesio-buccal of the mandibular right second molar) of 9 monkeys were evaluated clinically before scaling and 7 days after scaling. Plaque samples were obtained from sub-gingival sites before clinical examination and studied bacteriologically by dark field microscopy, selective and non-selective culture, and by primary phenotypic characterizations of culture isolates. Several gingival sites presented with mild gingival inflammation. Anaerobic and facultatively anaerobic bacteria were the predominant flora colonizing the gingival sulci. The major microbial groups were Haemophilus species (100% of sites; percentage of total anaerobic count (TAC): 21-51), Peptostreptococcus micros (89%, 7.5-29.5), Actinomyces sp. (85%, 7-27), Fusobacterium nucleatum (90%, 5-8), Actinobacillus actinomycetemcomitans (73%, 1.3-12), black-pigmented anaerobic rods (BPAR) (80%, 0.6-6.5) and oral streptococci (80%, 0.2-1.0). Microbial groups detected less often were Wolinella sp. (66%, 0-2.6), Capnocytophaga sp. (30%), Eikenella corrodens (4.7%, 0), Campylobacter sp. (28%, 0-0.1) and spirochetes (4.7%, 0-0.07). Seven days after gingival sites were scaled, the plaque score and indices for gingival inflammation declined significantly. The gingival flora after scaling were characterized by lower proportions of the Actinomyces sp., P. micros and BPAR; and increased proportions of the oral streptococci, relative to pre-scaling levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunization with Porphyromonas (Bacteroides) gingivalis fimbriae protects against periodontal destruction

Adhesive fimbriae from Porphyromonas gingivalis are cell surface structures which may be important in the virulence of this oral pathogen and thus may serve as a critical or target antigen. Immunization with highly purified 43-kDa fimbrial protein protected against periodontal tissue destruction when tested in the P. gingivalis-infected gnotobiotic rat model. A similarly highly purified 75-kDa cell surface component did not provide protection. Heat-killed whole-cell and sonicated cell surface extracts which contain the 43-kDa protein as well as the 75-kDa component were protective also. This study indicates that the fimbrial protein may serve as a model for the development of effective vaccines against periodontitis, a major human oral disease.

Sequence analysis and characterization of the Porphyromonas gingivalis prtC gene, which expresses a novel collagenase activity

In order to examine the potential role of bacterial collagenases in periodontal tissue destruction, we recently isolated a gene, prtC, from Porphyromonas gingivalis ATCC 53977, which expressed collagenase activity (N. Takahashi, T. Kato, and H. K. Kuramitsu, FEMS Microbiol. Lett. 84:135-138, 1991). The nucleotide sequence of the gene has been determined, and the deduced amino acid sequence corresponds to a basic protein of 37.8 kDa. In addition, Southern blot analysis indicated that the prtC gene is conserved among the three major serotypes of P. gingivalis. The enzyme has been purified to near homogeneity from Escherichia coli clone NTS1 following Mono Q anion exchange and sequential gel filtration chromatography. The molecular mass of the purified enzyme was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be ca. 35 kDa, and the active enzyme behaved as a dimer following gel filtration chromatography. The collagenase degraded soluble and reconstituted fibrillar type I collagen, heat-denatured type I collagen, and azocoll but not gelatin or the synthetic collagenase substrate 4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-D-Arg. Enzyme activity was enhanced by Ca2+ and inhibited by EDTA, sulfhydryl-blocking agents, and the salivary peptide histatin. Preliminary evidence for the existence of a second collagenase expressed by strain 53977 was also obtained.

Salivary IgA responses to Porphyromonas gingivalis in the cynomolgus monkey. 1. Total IgA and IgA antibody levels to P. gingivalis

Porphyromonas gingivalis has been associated with the subgingival plaque of advancing disease lesions in various types of periodontitis. Additionally, this species of oral microorganism has been found to increase dramatically in ligature-induced periodontitis in nonhuman primates (Macaca fascicularis) and has recently been shown to induce progressing disease when implanted into the subgingival plaque in this animal model. Although systemic antibody responses have been demonstrated to P. gingivalis in both human and nonhuman primate with periodontitis, no information is available on the oral secretory IgA antibody response to this bacteria. This report describes the methods for reproducible collection of salivary secretions from cynomolgus monkeys and the development of methods for analyzing salivary IgA levels and specific IgA antibody in the saliva reactive with P. gingivalis. Purification of monkey salivary IgA allowed quantification of IgA using an enzyme-linked immunosorbent assay (ELISA). Estimation of total IgA levels in saliva showed approximately a 20% greater level of IgA in whole versus parotid saliva from a group of 13 monkeys, with a 2-3 fold variation in levels among this group of animals. Naturally occurring salivary IgA antibody to P. gingivalis, as measured by ELISA, were routinely detectable but low in whole saliva; however, many of the parotid saliva specimens collected exhibited negligible levels of antibody to this microorganism. The IgA antibody in whole saliva showed nearly an 18-fold variation among the samples from the monkeys. Correlational analyses indicated that, although there was a positive relationship between antibody levels in whole and parotid saliva, the majority of natural IgA antibody in whole saliva appears to be derived from other sources.(ABSTRACT TRUNCATED AT 250 WORDS)

Subgingival microbiota in squirrel monkeys with naturally occurring periodontal diseases

The squirrel monkey (Saimiri sciureus) has been proposed as an in vivo model for the study of subgingival colonization by suspected periodontopathogens, such as black-pigmented porphyromonads and prevotellas (BP/P). However, the indigenous microbiota of the squirrel monkey has not been well described. Therefore, in order to more fully characterize the oral microbiota of these animals, we studied two groups of squirrel monkeys from widely different sources. Group I consisted of 50 breeding colony monkeys ranging in age from 9 months to over 6 years which had been raised in captivity; group II consisted of 16 young sexually mature monkeys recently captured in the wild in Guyana. Group I animals in captivity had developed moderate to severe gingivitis, with a mean gingival index (GI) of 2.6; 52% of the sites bled, 26% had detectable calculus, and 83% had detectable BP/P. A group I subset (six animals), for which predominant cultivable microbiota was described, had a mean GI of 2.4. Colony morphology enumeration revealed that five of the six subset animals were detectably colonized with BP/P (range, 0 to 16.9%) and Actinobacillus actinomycetemcomitans (range, 0 to 3.9%); all subset animals were colonized with Fusobacterium species (range, 0.8 to 3.6%), Actinomyces species (range, 2.3 to 11%), and gram-positive cocci (range, 1.4 to 21.4%). Predominant cultivable microbiota results revealed the presence of many bacterial species commonly found in the human gingival sulcus. At baseline, group II animals were clinically healthy and had a mean GI of 1.4; 67% of the sites bled and 2.1% had calculus, and none of the animals had detectable BP/P. Neisseriae were very common in noninflamed sites. Subsequently, when inflamed sites were compared with noninflamed sites in group II animals after they had been maintained in captivity for 6 months, inflamed sites exhibited a more complex microbiota and increased proportions of gram-negative rods and asaccharolytic bacteria.

Systemic antibody responses to oral microorganisms in the cynomolgus monkey: development of methodology and longitudinal responses during ligature-induced disease

Systemic antibody responses to oral microorganisms were studied during ligature-induced periodontal disease in a non-human primate (Nhp) model. Methodology was developed using ELISA techniques to assess total IgG and IgM levels in the serum from the Nhp. In addition, an ELISA was developed utilizing affinity-purified anti-human isotype reagents to detect Nhp serum antibody responses to Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedia and Fusobacterium nucleatum. Results showed that the anti-human reagents detected IgG and IgM from Macaca fascicularis with an efficiency of 25-35% and 50-60%, respectively. Following ligation, groups of Nhp were treated with an immunomodulator ("Thymopentin", TP5) or placebo to examine the effect of the T-cell stimulating agent on periodontitis and host responses. No differences were noted in total serum IgG and IgM levels for individual Nhp or between groups when baseline, ligation and treatment intervals were compared. However, following ligation, 8/12 Nhp exhibited significant increases in IgG and/or IgM antibody to P. gingivalis that were coincident with increases in the percentage of this microorganism in the subgingival plaque from the ligated sites. During the treatment phase, the antibody levels in the placebo group continued to increase, while the levels in the TP5-treated group stabilized. The findings in this study indicate that the emergence of a microorganism in the subgingival plaque (P. gingivalis) during the conversion from gingivitis to progressing periodontitis in the Nhp, elicits a systemic antibody response that is specific for the microorganism.

Effects of immunization with Porphyromonas gingivalis and Prevotella intermedia on progression of ligature-induced periodontitis in the nonhuman primate Macaca fascicularis

The nonhuman primate (Nhp) has proven to be a useful model of human periodontitis. This study describes the immunological characteristics of this model and the ability of active immunization to interfere with ecological changes in the microbiota and its associated disease symptoms. Nhps were parenterally immunized with whole-cell antigens of Porphyromonas gingivalis and Prevotella intermedia. The immunization elicited an approximate 2-log increase in serum immunoglobulin G (IgG), IgM, and IgA isotype antibody that was highly specific for these immunogens. Postimmunization and postligation, there was minimal change in the levels of specific antibody. P. gingivalis immunization significantly inhibited the emergence of this species during disease progression. In contrast, induction of anti-P. intermedia antibody had a minimal effect on this species within the subgingival plaque. Plaque indices showed few changes that could be attributed to active immunization. Both bleeding on probing and loss of attachment were higher in ligated sites of immunized animals than in the placebo-treated group. A significant increase in bone density loss was observed in the ligated teeth from immunized versus control animals. These findings indicate that active immunization of Nhps can elicit a substantial systemic immune response; however, while this response may effect the emergence of an individual microorganism, it appears that other ecological considerations are critical in disease progression. It is also possible that the induction of a broad-based immune response to multiple bacterial antigens can result in increased disease, potentially associated with hypersensitivity reactions to the bacteria in the subgingival plaque.

Characterization and physical mapping of plasmids of black-pigmented Bacteroides

Eight species of black-pigmented Bacteroides (BPB) were examined for plasmid content. Three classes of plasmids with molecular sizes of 16.0 kilobase (kb), 5.4 kb and 5.0 kb were found in 7 of 125 Bacteroides intermedius strains. One strain each of Porphyromonas (former Bacteroides) asaccharolyticus and of Bacteroides levii were also shown to have plasmids. However, no plasmids were detected in 90 strains of Porphyromonas (Bacteroides) gingivalis. The plasmids were purified and digested with restriction endonucleases for restriction mapping. The maps obtained in this study have given us information on the scheme of constructing recombinants which may be usable as shuttle vectors, by the recombination of BPB and Escherichia coli plasmids.

Probe-specific DNA fingerprinting applied to the epidemiology of localized juvenile periodontitis

Although Actinobacillus actinomycetemcomitans has been recognized as a primary etiological agent in localized juvenile periodontitis, questions remain concerning the source of infection, mode of transmission, and relative virulence of strains. DNA fingerprinting analysis, using a randomly cloned chromosomal DNA fragment as a probe, revealed that previously characterized strains of A. actinomycetemcomitans displayed significant restriction site heterogeneity which could be applied to the typing of clinical isolates of this bacterium such that individual strains or variants could be traced within subjects from localized juvenile periodontitis families. Hybridization data derived from an analysis of bacterial isolates obtained from families participating in an ongoing longitudinal study of the disease showed that a single individual could be infected with more than one strain or variant of A. actinomycetemcomitans and that various members of the same family could harbor different strains or variants of the bacterium. In several cases the clinical isolates were matched to characterized laboratory strains by comparing hybridization patterns generated by digestion of the DNA with several restriction enzymes in independent reactions. Thus, probe-specific DNA fingerprinting of A. actinomycetemcomitans will permit us to determine if particular strains or variants are frequently associated with sites of periodontal destruction. Attention could then be focused on determining the virulence properties of those strains or variants that have in vivo significance.

Detection of high-risk groups and individuals for periodontal diseases: laboratory markers based on the microbiological analysis of subgingival plaque

Periodontal microbiology is reviewed with regard to the potential of certain characteristics to serve as markers of high risk groups or individuals for periodontal diseases. The generally accepted associations between particular organisms and the various periodontal diseases are discussed. The usefulness of various clinical study designs is reviewed. The ecology of the subgingival plaque microflora is discussed and a number of suggestions for future research are made. We have concluded that there is no monospecific aetiology to any of the various periodontal conditions. Nevertheless, we give particular attention to the role of the black-pigmented bacteroides based upon our belief that they, and Bacteroides gingivalis in particular, are fundamental to our understanding of the biology of periodontal diseases in humans and other animals. Consequently, the contribution of its various virulence factors and their potential as markers of disease susceptibility and activity is addressed.

Experimental infections by Bacteroides gingivalis in non-immunized and immunized rabbits

The interactions between Bacteroides gingivalis and systemic antibodies were studied in tissue cages implanted in the backs of New Zealand white rabbits. Infectivity was evaluated according to clinical signs and to leukocyte and bacterial counts in material aspirated from the tissue cages. Pre- and post-inoculation antibody levels to sonicated whole bacterial cells were determined by enzyme-linked immunosorbent and agar immunodiffusion assays. Rabbits immunized against B. gingivalis and then challenged with pure cultures of B. gingivalis revealed complete elimination or markedly lower postinoculation bacterial counts and considerably weaker tissue reactions than non-immunized animals. B. gingivalis co-inoculated with Actinobacillus actinomycetemcomitans caused significantly more severe infections than observed in monoinfected animals. The present results suggest that the immune system acting through systemic antibodies and/or cellular mechanisms may modulate the pathogenic potential of infecting periodontal pathogens.

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.

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.

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.

Protective efficacy of active and passive immunizations against experimental infection with Bacteroides gingivalis in ligated hamsters

The protective efficacy of immunization against Bacteroides gingivalis infection was examined in hamsters. Whole cells or extracted hemagglutinin of B. gingivalis 381 was injected with incomplete Freund adjuvant into the inguinal regions of hamsters. Two weeks after the rats received a booster injection, cotton threads were tied coronally to the gingival margins of the mandibular first molars, and then a streptomycin-resistant B. gingivalis 381R' strain was inoculated into the rats' oral cavities. The subcutaneous immunizations resulted in slight reductions in the numbers of B. gingivalis on the ligature threads compared with the sham-immunized group. Peroral administration of whole cells of B. gingivalis to hamsters elicited salivary immunoglobulin responses, but no reduction of B. gingivalis 381R' colonization was found in this group. Repeated passive immunizations with rabbit antiserum to B. gingivalis into the oral cavities of the hamsters resulted in a reduction in the number of organisms in the periodontal region.

Implantation of Bacteroides gingivalis in nonhuman primates initiates progression of periodontitis

Although periodontitis is a bacterial disease, its multidimensional nature and its bacterial complexity have made it difficult to definitively prove that specific microorganisms initiate the disease process. The successful implantation of a rifampin-resistant strain of the putative periodontal pathogen Bacteroides gingivalis into the periodontal microbiota of monkeys (Macaca fascicularis) resulted in an increase in the systemic levels of antibody to the microorganism and rapid and significant bone loss.

Bacteriology of periodontal disease in the cat

Subgingival plaque samples were obtained from 32 cats showing different stages of periodontal disease. Correlations were sought between gingival index scores and the prevalence of various microbial groups, and between microbial populations found in sites designated as most-affected and least-affected within individual cats. The tendency with higher gingival index scores, and with the most-affected sites, was toward a microbial population composed to a greater extent of anaerobic Gram-negative rods. The most common organism was an anaerobic Gram-negative rod in the black-pigmented Bacteroides group that was biochemically similar to B. gingivalis but had catalase activity. The black-pigmented Bacteroides group and Peptostreptococcus anaerobius were found in increasing numbers with increasingly severe periodontal disease. Pasteurella multocida was isolated from most samples and appeared to decrease in numbers with increasing periodontal disease.

Monoclonal antibody for identification of Bacteroides gingivalis lipopolysaccharide

A monoclonal antibody, BBG-25, raised in BALB/c mice demonstrated specificity for Bacteroides gingivalis lipopolysaccharide. Immunoblotting indicated that this monoclonal antibody does not cross-react with lipopolysaccharide prepared from enterobacterial organisms or from other Bacteroides species.