Host tissue response in chronic inflammatory periodontal disease IV. The periodontal and dental status of a group of aged great apes

Periodontal health, neutrophil activity and cardiovascular health in captive chimpanzees

OBJECTIVE

To investigate the association of dental and cardiac disease in a cohort of captive chimpanzees DESIGN: 12 captive chimpanzees underwent periodontal and cardiac examinations under anaesthesia during a relocation to a new enclosure. Blood samples were taken for analysis of circulating markers of cardiac health, nutritional status and isolation of neutrophils for functional assays. They were then observed for three years for signs of heart disease.

RESULTS

Although the chimpanzees displayed large quantities of supragingival plaque, they had low bleeding scores. Peripheral blood neutrophils responded to innate and adaptive immune stimuli. In the follow up period two animals died and post mortem confirmed heart disease. Levels of NT-proBNP were found to be high in chimpanzees that died from heart disease.

CONCLUSIONS

Whilst there appeared to be a correlation between probing depth and age, there appeared to be no correlation between dental data and heart data in this cohort.

Association between obesity and periodontitis in Australian adults: A single mediation analysis

BACKGROUND

Obesity and periodontitis are conditions with high burden and cost. This study aims to unfold the proposed pathways through which the effect of obesity in the presence of health behaviors (dental visiting behavior and diabetes) increases the risk of periodontitis?

METHODS

The effect decomposition analysis using potential outcome approach was used to determine obesity-related periodontitis risk using the Australian National Survey of Adult Oral Health 2004 to 2006. A single mediation analysis for exposure, "physical-inactivity induced obesity," mediator "dental visiting behavior (a de facto measure of healthy behaviors)," outcome "periodontitis," and confounders "age, sex, household income, level of education, self-reported diabetes, alcohol-intake and smoking," was constructed for subset of 3,715 participants, aged ≥30 years. Proposed pathways were set independently for each risk factor and in synergy. The STATA 15 Paramed library was used for analysis. Sensitivity analysis was conducted to detect unmeasured confounding using non-parametric approach.

RESULTS

The average treatment effect of physical inactivity induced obesity to periodontitis is 14%. Pathway effect analysis using potential outcomes illustrated that the effect of obesity on periodontitis that was not mediated through poor dental visiting behavior was 10%. Indirect effect of obesity-mediated through poor dental visiting behavior on periodontitis was 3%.

CONCLUSIONS

The direct effect of physical inactivity induced obesity on periodontitis was higher than the indirect effect of obesity on periodontitis through dental visiting behavior. Establishing a pathway of causal relationship for obesity and periodontitis could help in developing management strategies that focuses on mediators.

Caries and periodontitis associated bacteria are more abundant in human saliva compared to other great apes

OBJECTIVE

Caries and periodontitis are uncommon in free ranging great apes but a major oral disease in humans. The aim was to analyze abundance and diversity of oral bacteria of western humans and their closest relatives, to examine if zoo apes feeding on diet other than in their natural habitat show caries and periodontitis associated salivary bacteria and comparable susceptibility for oral civilization diseases as humans.

DESIGN

Bacterial composition of human and great ape saliva samples were compared by analyzing the V3 region of the bacteria 16S rRNA gene by Next Generation Sequencing with Ion Torrent.

RESULTS

Results show species-specific differences in the salivary bacteria phyla and genera composition among all apes. Moreover, salivary bacterial composition within non-human apes showed higher intra-individual differences than within humans. Human saliva exhibited lowest bacteria diversity. Different behavioral patterns including (oral) hygiene standards of humans and non-human apes might cause differences. All species differed in diversity and abundance of caries associated bacteria genera. Human saliva revealed higher abundance of caries and periodontitis relevant bacteria in contrast to other great apes, which might be supported by higher consume of refined cariogenic food items, possibly raising their risk for oral disease susceptibility.

CONCLUSIONS

The study offers first clues on caries and periodontitis relevant bacteria of captive great ape species in comparison to humans. Higher susceptibility to oral diseases for humans than for their closest relatives, leads to the question, if the oral microbiome changed during evolution and how it is influenced by the human life style.

Chronic periodontitis and smoking. Prevalence and dose-response relationship

OBJECTIVES

To determine the prevalence and dose-response relationship of chronic periodontitis among smokers in Pakistan.

METHODS

  This is a cross-sectional study among participants seeking dental care in Karachi Medical and Dental College, Karachi, Pakistan. A total of 443 participants with a mean age of 44.3 (±6.5) participated in the study from April 2011 to December 2011. Males comprised 64.7%, and females comprised 35.2%. Participants were interviewed on social demographics and oral habits. Participants with shallow pockets (3.5-5.5 mm) and deep pockets (greater than 5.5 mm) were considered suffering from chronic periodontitis. The characteristics of participants were assessed using frequency distribution for categorical variables and mean (standard deviation) for continuous variables. 

RESULTS

Among 443 participants, smokers were distributed as 55.1% and non-smokers as 44.9%. Smoking was found to be significantly related to young adults (p less than 0.007), male gender (p less than 0.001), and lower education level (p less than 0.01). Overall prevalence of chronic periodontitis among smokers was estimated at 81.6%. Heavy smoking was found to have significantly high prevalence (p less than 0.001) and severity (p less than 0.001) of periodontitis as compared with moderate and light smokers. The multivariate unadjusted model depicted 3.5 times higher risk of chronic periodontitis among smokers (p less than 0.001).

CONCLUSION

Chronic periodontitis had a high prevalence among smokers. Heavy smoking was found to have a higher risk for having periodontitis.

Role of high endothelial postcapillary venules and selected adhesion molecules in periodontal diseases: a review

Periodontitis is accompanied by the proliferation of small blood vessels in the gingival lamina propria. Specialized postcapillary venules, termed periodontal high endothelial-like venules, are also present, and demonstrate morphological and functional traits similar to those of high endothelial venules (HEVs) in lymphatic organs. The suggested role of HEVs in the pathogenesis of chronic periodontitis involves participation in leukocyte transendothelial migration and therefore proinflammatory effects appear. Recent observations suggest that chronic periodontitis is an independent risk factor for systemic vascular disease and may result in stimulation of the synthesis of acute phase protein by cytokines released by periodontal high endothelial cells (HECs). However, tissue expression of HEV-linked adhesion molecules has not been evaluated in the gingiva of patients with chronic periodontitis. This is significant in relation to potential therapy targeting expression of the adhesion molecules. In this review, current knowledge of HEV structure and the related expression of four surface adhesion molecules of HECs [CD34, platelet endothelial cell adhesion molecule 1, endoglin and intercellular adhesion molecule 1 (ICAM-1)], involved in the key steps of the adhesion cascade in periodontal diseases, are discussed. Most studies on the expression of adhesion molecules in the development and progression of periodontal diseases pertain to ICAM-1 (CD54). Studies by the authors demonstrated quantitatively similar expression of three of four selected surface markers in gingival HEVs of patients with chronic periodontitis and in HEVs of reactive lymph nodes, confirming morphological and functional similarity of HEVs in pathologically altered tissues with those in lymphoid tissues.

The effect of age on the gingival crevicular fluid composition during experimental gingivitis. A pilot study

Background:

Cytokines have been proposed as potentially useful diagnostic or prognostic markers of periodontal inflammation related alterations during the experimental gingivitis model. The role of ageing in periodontal disease needs further elucidation; therefore investigations of its influence on host response are needed.

Objective:

To study the effect of age on interleukins IL -6, IL-8 and TNF-a levels in gingival crevicular fluid (GCF) and their correlations to clinical parameters during experimental gingivitis.

Materials and Methods: Five young subjects (20-22 years old) and five old subjects (61-65 years old), all periodontal healthy, participated in this clinical trial. A professional plaque control programme was undertaken to establish healthy gingival conditions at baseline. Plaque index (PI), gingival index (GI) were recorded at 60 sites at baseline, after 21 days of no oral hygiene and one week later after professional cleaning and reestablishment of oral hygiene procedures. A total of 180 samples were analyzed with ELISA for levels of IL -6, IL-8 and TNF-a in gingival crevicular fluid. The examination included the mesiobuccal sites of the Ramfjord teeth. Comparisons between and within groups were performed by non-parametric tests (Mann- Withney) and correlations were sought for with Wilcoxon test. Significance was set at p=0.05.

Results:

Results showed significant diferences between the two groups with regard to the plaque and bleeding scores and GCF volume, all of which proved to be more pronounced in old group. With respect to laboratory data, mean cytokine concentrations were in general lower in young group. TNF-a had a steady increase for the adults, which was found to be statistically significant between Days 0 and 21, IL-8 showed a statistically significant decrease at Day 28 in the young group and finally IL-6 showed a fluctuation, which was totally adverse for the two groups at each time point.

Conclusion:

Within the limitations of the present study, age cannot be identified as a factor that strongly affects the cytokine expression and fluctuations even in a well-controlled environment of inflammation, such as experimental gingivitis.

Estrogen Suppression Induces Papillary Gingival Overgrowth in Pregnant Baboons

BACKGROUND

Alterations in sex steroids during pregnancy are associated with the development and exacerbation of reactive lesions involving the gingiva. Currently, few experimental animal models similar to humans are available to examine regulatory pathways involving sex steroids and the periodontium.

METHODS

In the present study, we used the baboon as a novel experimental model for the study of the regulatory actions of estrogen on the periodontium during pregnancy. Pregnant baboons (N = 5) were administered the potent, highly specific aromatase inhibitor CGS 20267 (2 mg/day subcutaneously) daily on days 60 through 165 of gestation (term = 184). Untreated females (N = 10) and females (5) concomitantly administered aromatase inhibitor and estradiol benzoate (2.0 mg/day each subcutaneously) served as controls. Gingival biopsies were taken between days 145 and 165 of gestation.

RESULTS

Administration of CGS 20267 in all females suppressed maternal serum concentrations of estradiol by 95% and induced the development of an exuberant papillomatous enlargement of the gingiva by gestational day 110, with the most prominent development involving the labial aspects of the anterior sextants. None of the untreated pregnant controls or females concomitantly administered aromatase inhibitor and estradiol benzoate developed gingival overgrowth. Thus, estradiol alone prevented the onset of gingival overgrowth induced by estrogen suppression. In all baboons, discontinuation of the aromatase inhibitor at time of cesarean section resulted in spontaneous regression and resolution of the papillomatous hyperplasia within 4 to 6 weeks. Clinically, the gingival papillary overgrowth was erythematous and edematous, with a propensity toward spontaneous subgingival hemorrhage. Histologically, the biopsy specimens demonstrated hyperplasia of the epithelium typified by mild hyperkeratosis, acanthosis, and elongation and isolated anastamoses of rete ridges. Subjacent to the intact epithelium was a loose connective tissue stroma with isolated areas of inflammatory cell infiltrate. Special stains verified the presence of isolated bacterial biofilms; however, no evidence of fungal filaments was present. Histological features suggestive of viral infection were notably absent in the epithelium. No evidence of viral particles or capsids was identified using transmission electron microscopy. Reverse transcription polymerase chain reaction analysis, using a panel of degenerate primers, was negative for papilloma family viruses.

CONCLUSIONS

These results are consistent with a significant role for estrogen during primate pregnancy in the regulation of cellular proliferation and differentiation within the gingiva. The baboon represents an important experimental model for studying the regulatory actions of estrogen on the periodontium during pregnancy.

Periodontal Regeneration with a Combination of Enamel Matrix Proteins and Autogenous Bone Grafting

BACKGROUND

Attempts to stimulate periodontal regeneration in the past have focused on either filling the defect with some type of material or providing a space for host cells to repopulate the site and elicit new tissue. In some cases, these approaches have been combined with the assumption that the filler material will help maintain the space necessary for the host cells to invade the area. Growth stimulating substances such as growth factors and other proteins have also been used to encourage periodontal tissue regeneration and histological evaluation supports the use of these substances. Thus, the role for and the necessity of a certain amount of space maintenance for periodontal regeneration is not exactly understood. In addition, it is not known if there is some critical size required for space maintenance or for exactly how long the space must be maintained in order for the host cells to stimulate new cementum, periodontal ligament, and bone. The goal of this study was to evaluate periodontal regeneration in intrabony defects of various sizes treated with a combination of enamel matrix proteins and autogenous bone graft.

METHODS

Periodontal defects ranging in size from 1 to 6 mm were randomized and created bilaterally beside three teeth in the mandibles of baboons. Plaque was allowed to accumulate around wire ligatures placed into the defects. After 2 months, the wire ligatures were removed, the teeth and roots scaled and root planed, and a notch was placed with a chisel at the base of the defect. On one side of the mandible, neutral ethylene diamine tetracetic acid and enamel matrix derivative (EMD) were first used to treat the defect. Autogenous bone taken from the same surgical site was treated with enamel matrix derivative in a dampen dish and then added to the EMD-treated defects. The other side of the mandible served as control with neutral ethylene diamine tetracetic acid and scaling and root planing. Flaps were sutured and the animals were allowed to heal without oral hygiene procedures. After 5 months, the animals were sacrificed and the teeth were processed for histological evaluation.

RESULTS

The results revealed new cementum, periodontal ligament with Sharpey's fibers, and new bone tissue similar to native periodontal tissues. Remnants of the autogenous bone chips were still present at this 5-month post-healing period. Thus periodontal regeneration occurred in all sizes of the periodontal defects. In general, EMD plus autogenous graft treatment resulted in greater tissue formation than controls. In fact, in many cases, very dramatic tissue formation occurred far coronal to the base of the defects in the EMD plus autogenous graft-treated lesions. In addition, horizontal bone fill occurred in the defects and was prominent in the 4 or 6 mm wide lesions. When evaluating the combined 1 and 2 mm defects, the height of new cementum with EMD plus graft was 3.88 mm versus 2.03 mm in the controls, a statistically significant (P < 0.005) difference. In the wider (4 and 6 mm) lesions, this difference was not significant and was much less between treated and control lesions with 2.78 and 2.57 mm of new cementum respectively. In the case of new bone height, in the smaller lesions EMD plus graft resulted in 4.00 mm new bone versus 2.22 mm in the controls, again a statistically significant (P < 0.005) difference. In the larger lesions, EMD plus autogenous bone graft had 3.24 mm new bone height compared to 2.71 mm in the controls, a difference that was not statistically significant. Additionally, in the smaller lesions, new cementum width at the level of the notch was twice as great (statistically significant, P < 0.015) in the EMD plus graft sites compared to control. The width of the periodontal ligament at the coronal aspect of the new bone tissue was similar in the smaller lesions between treated and control sites. The results from the wider defects must be interpreted cautiously as the interproximal bone heights were remodeled adjacent to the wider defects and likely limited the potential for regeneration.

CONCLUSIONS

The combination of enamel matrix derivative plus autogenous bone graft stimulated statistically significant periodontal regeneration in the more narrow 1 and 2 mm lesions. No statistically significant difference was observed in the wider 4 and 6 mm lesions. In many cases, dramatic amounts of new cementum, Sharpey's fibers, periodontal ligament, and bone tissue were formed far above the notch placed at the base of the contaminated defects. This was especially significant considering the width of some of the defects and the fact that no oral hygiene was performed over the 5-month healing period. This periodontal regeneration occurred in the absence of exogenous growth factors or barrier membranes. In summary, the combination of enamel matrix derivative and autogenous bone represents a therapeutic combination that can be highly effective in stimulating significant amounts of periodontal regeneration.

The effect of enamel matrix proteins on periodontal regeneration as determined by histological analyses

BACKGROUND

Therapeutic approaches to periodontal regeneration in the past have utilized bone replacement grafts, growth factors, barrier membranes, or combinations of these approaches. More recently, enamel extracellular matrix proteins have been introduced to stimulate periodontal regeneration. One factor thought to have an impact on the outcome of the regenerative process is the initial size of the periodontal defect. This is particularly the case when using proteins to stimulate regeneration, because the concepts of guided tissue regeneration emphasize the need for space maintenance to allow for selected cell repopulation. The goal of this study was to evaluate periodontal regeneration in intrabony defects of various sizes treated with enamel matrix proteins.

METHODS

Periodontal defects ranging in size from 1 to 6 mm were created bilaterally around 3 teeth in the mandibles of baboons. Plaque was allowed to accumulate around ligatures placed into the defects. After 2 months, the ligatures were removed, the teeth were scaled and root planed, and a notch was placed at the base of the defect. On one side of the mandible, neutral ethylene diamine tetracetic acid and enamel matrix proteins were used to treat the defects. The other side served as a control, with neutral ethylene diamine tetracetic acid treatment alone after scaling and root planing. Flaps were sutured and the animals were allowed to heal without oral hygiene procedures. After 5 months, the animals were sacrificed and the teeth were processed for histological evaluation.

RESULTS

Periodontal regeneration occurred in all sizes of the periodontal defects. Qualitatively, new cementum, periodontal ligament with Sharpey's fibers, and new bone tissue were observed. In general, enamel matrix protein treatment resulted in greater tissue formation than controls. In many instances, dramatic tissue formation occurred far coronal to the base of the defects. In addition, horizontal bone fill occurred in defects that were initially 4 or 6 mm wide. The resultant width of the periodontal ligament was similar in all defects regardless of the original defect width. The cementum width was slightly greater in the wider (4 and 6 mm) defects compared to the more narrow (1 and 2 mm) defects. When evaluating the combined 1 and 2 mm defects, the height of new cementum with enamel matrix protein treatment was 45% greater than the control, with 31% greater new bone height versus the control. In the combined wider defects (4 and 6 mm), new tissue height was more similar between enamel matrix protein-treated defects and control defects. The results from the wider defects must be interpreted cautiously, because the interproximal bone heights were resorbed more adjacent to the wider defects during the plaque accumulation period and likely limited the potential for regeneration.

CONCLUSIONS

The treatment of various sized periodontal defects with enamel matrix proteins stimulated substantial periodontal regeneration. In many cases, dramatic amounts of new cementum, Sharpey's fibers, periodontal ligament, and bone tissue were formed far coronal to the notch at the base of the defect, especially considering the width of the original defects. This periodontal regeneration occurred in the absence of exogenous growth factors, bone replacement grafts, barrier membranes, or their combination.

Quantitative assessment of apoptotic and proliferative gingival keratinocytes in oral and sulcular epithelium in patients with gingivitis and periodontitis

BACKGROUND

Periodontal disease is caused by a chronic infection inducing an inflammatory reaction that leads to a breakdown of tooth-supporting tissue. The maintenance of an equilibrium between the host defence and microorganisms in the sulcus is essential to preserve health. All multicellular organisms have mechanisms for killing their own cells, and use physiological cell death for defence, development, homeostasis and ageing. Apoptosis and proliferation are very important phenomena in regulating this and a disturbance is often associated with disease e.g. cancer, AIDS, Alzheimer's disease, rheumatoid arthritis.

OBJECTIVE

The aim of this study was to determine whether the number of apoptotic and proliferative gingival keratinocytes differed between patients with gingivitis and those with periodontitis.

MATERIAL AND METHODS

The distribution of neutrophil elastase, PCNA/cyclin, DNA fragmentation (apoptosis) and p53 was determined with immunocytochemical techniques. We used paraffin-embedded sections from gingival biopsies and did quantitative analyses.

RESULTS AND CONCLUSION

These showed that 5-12% of the keratinocytes in the basal layers of the epithelium proliferated in the two groups. Fewer apoptotic cells were seen in the oral epithelium than in the sulcus in all subjects in both groups. Only in the most apical part of the sulcus, close to the junctional epithelium, did the number of apoptotic keratinocytes exceed the proliferative ones in patients with periodontitis.

Periodontitis

The purpose of this review was to assess the scientific and clinical bases for the proposed classification of periodontitis. The clinical and histopathological signs and the etiology of periodontitis were described. Cross-sectional studies were analyzed to determine when onset of periodontitis most frequently occurs in adults. In addition, the progression rates of periodontitis have been assessed from longitudinal studies. No clinical, histopathological, or microbiological features could be identified that would characterize different disease entities of chronic periodontitis. The prevalence, extent, and severity of periodontitis were found to increase continually with higher age and there was no age when onset of disease would most likely occur. The rate of periodontitis progression varies largely between patients and there is no natural threshold for distinguishing various rates of disease progression. The incidence of periodontitis unresponsive to treatment depends on pretreatment progression rate, extent and severity of disease, tooth type, smoking, high levels of putative periodontal pathogens, a deficient immune response, and the type of therapy provided. There is no scientific basis for the classification "adult periodontitis" and "refractory adult periodontitis." Extensive clinical examinations are required for the diagnosis of "rapidly progressive adult periodontitis." It appears unrealistic that these examinations can be performed routinely in clinical practice. Therefore, the classification proposed by the Organizing Committee to define adult, rapidly progressive, and refractory periodontitis as specific disease entities was replaced with a simplified classification of periodontitis based on the scientific data available.

The effect of age on the development of gingivitis. Clinical, microbiological and histological findings

In the present "experimental gingivitis" study, the response of the marginal gingiva to plaque formation was studied in one group of young subjects, 20-25 years of age, and in one group of older subjects, aged 65-80 years. During a 4-week period, all subjects received a series of professional tooth cleaning to establish healthy gingival conditions. A baseline examination (Day 0) included assessments of plaque and gingivitis. Sites that were examined (the experimental sites) included the mesio-palatal, palatal, and disto-palatal surfaces of all teeth present in the 15 ... 25 tooth region. Among the experimental sites, microbial sampling and gingival fluid assessment were performed and one gingival biopsy harvested from each subject. Following the baseline examination, the participants abolished mechanical tooth cleaning measures in the palatal and approximal surfaces of 15 ... 25. The clinical examination and the gingival fluid measurement were repeated on days 7, 14 and 21 of no oral hygiene. The microbiological sampling and the biopsy procedure were repeated on days 7 and 21. The data collected demonstrated that old subjects, during a 3-week period of oral hygiene abstention, formed similar amounts of plaque as the young subjects, but developed more gingivitis than young subjects. Thus, the clinical gingivitis assessments, the gingival fluid measurements and morphometric determinations made in the biopsy samples documented that the gingival lesion which formed in the old individuals was more pronounced and contained more inflammatory cells than the corresponding lesion in the young subject sample.

Dental pathology in Pongo satyrus borneensis

The Selenka orangutan collection obtained from 1892 to 1896 from wild-shot specimens in West Borneo, provides an excellent opportunity to examine dental pathology in free-ranging primates. Two hundred and twenty-three skulls from this collection were analyzed for dental conditions, including carious lesions, local infections (infra-alveolar and periapical osseous defects), horizontal bone loss, and premortem tooth loss. Specimens were sexed, divided into three broad age groups, and compared to ascertain sex-related or age-related differences in occurrence of dental pathology. None of the subadults displays any evidence of dental disease. One individual (2%) in the young adult group has a periapical osseous defect and evidence of horizontal bone loss, and another (2%) has two adjacent interproximal carious lesions. The old adults have a much higher prevalence of individuals afflicted with dental pathologies, including 6% carious lesions, 26% local infections, 23% horizontal bone loss, and 3% premortem tooth loss. The differences between the young and old adults in number of individuals afflicted with dental pathologies is statistically significant for local infections and horizontal bone loss. When compared by sex, the old adult group reveals that females have a higher occurrence of dental pathologies than males in all types of lesions recorded and these differences are statistically significant for local infections and horizontal bone loss. Considering the importance diet plays in the development of dental disease, it is suggested that ecological separation of the sexes, with the subsequent dietary differences, could be an important factor determining the higher prevalence of dental lesions observed in female orangutans. Additionally, the importance of local ecological factors, which may affect dietary patterns, are recognized as a potential source of variation in dental pathologies among different samples of orangutans.

Comparison of canine and non-human primate animal models for periodontal regenerative therapy: results following a single administration of PDGF/IGF-I

Two commonly used animal models for evaluating putative periodontal regenerative therapies are the beagle dog model with natural periodontal disease and the non-human primate with ligature-induced attachment loss. The host response, microbiology, and skeletal rates of remodeling of these two models are summarized. In addition, the results of experiments comparing the healing response to periodontal surgery with and without concurrent use of the combination of platelet-derived growth factor (PDGF) and insulin-like growth factor-I (IGF-I) in these models are presented. At 1 month, PDGF/IGF-I administration resulted in a 64.1% and 51.4% increase in new attachment formation in the non-human primate and canine, respectively, while controls (surgery plus placebo) demonstrated 34.1% and 8.6% increases in new attachment formation in the non-human primate and canine models, respectively. Further, application of PDGF/IGF-I stimulated 21.6% and 65% osseous defect fill in the non-human primate and canine, respectively, while controls demonstrated 8.5% and 14.5% osseous defect fill in the non-human primate and canine, respectively. The osseous response in the canine appears greater than that of the non-human primate, and the new attachment formation was more substantial in the non-human primate than the canine. However, in general these data demonstrate a high degree of consistency in the effects of PDGF/IGF-I in promoting periodontal regeneration. Positive results in these two models--the dog with natural periodontal disease and the non-human primate with ligature-induced attachment loss--justify human clinical trial testing of a putative regenerative therapy.

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)

Gingivitis in young and old dogs

The aim of the investigation was to study the development of gingivitis in young and old dogs. 10 beagle dogs were used. 5 of the dogs were 1 year old and 5 dogs were between 8 and 9 years of age. On day 0, all the teeth of all 10 dogs were scaled and polished. A 6-week period of plaque control was initiated. On day 42, a clinical examination was performed, microbial samples from the gingival sulcus were harvested and biopsies obtained from tooth regions 3P and 4P. The tooth-cleaning measures were abandoned following biopsy and the animals were during the subsequent 3 weeks allowed to form plaque. On day 63, i.e., day 21 of plaque formation, the clinical examination, sampling of the subgingival plaque and harvesting of biopsies were repeated in the contralateral premolar regions (P3 and P4). The histological analysis revealed that the cellular infiltrate (the lesion) of inflamed gingiva was larger and extended more apically in the old than in the young dogs. The lesion in the old dogs contained significantly more plasma cells but less macrophages, lymphocytes and PMN cells than the infiltrate in the young dogs.

Biological and measurement issues critical to design of gingivitis trials

Chronic plaque-induced gingivitis is usually of little consequence, thus the concern about prevention and treatment must stem from the belief that preexisting gingivitis is necessary for periodontitis to develop. When clinical signs of gingivitis are present, an inflammatory infiltrate can be found upon histological evaluation. When clinical signs are absent, however, significant inflammation may still be present within the gingival tissues. Therefore, multiple clinical evaluations should be made, with special attention given to the visually inaccessible midinterdental area. The "gold standard" for evaluation of gingivitis is histological evaluation and other measurements should be evaluated against this standard. The significance of clinical severity measurements of gingivitis is not well-understood relative to onset of periodontitis; therefore, it is suggested that consideration be given to gingival evaluations based on the presence or absence of clinical signs of inflammation. Furthermore, equivalency and superiority of antigingivitis agents or devices should be predicated, at least in part, on their ability to prevent the onset of periodontitis.

The role of histopathology in the diagnosis and prognosis of periodontal diseases

The histological evaluation of surgical biopsies from affected tissues is a standard way of assessing pathological change and determining treatment in many diseases. In most forms of periodontal disease, however, this approach finds limited application. Here, we review what uses the histopathological approach has in the study and evaluation of the periodontal diseases. Current understanding of the changes in epithelial anatomy during pocket formation, the cellular composition and dynamics of the inflammatory infiltrate and the mechanisms of bone resorption and repair are reviewed from the perspective of the information available from microscopical investigation, including the uses and potential application of modern immunocytochemical methods to these questions. The usefulness of histological study of biopsy material is reassessed in the light of advances made in immunohistochemical techniques and their application to gingival inflammatory infiltrates and epithelia. Such techniques offer immediately valuable research opportunities with potential for diagnostic applications, noteably the recognition of phases of destructive activity and their differentiation from periods of effective host defence.

Comparative microbiological and immunological studies of subgingival dental plaque from man and baboons

Baboons may be useful as animal models for the study of human oral diseases and infections. They are closely related to man anatomically, physiologically, and phylogenetically. Plaque and gingival indices were relatively low in 18 baboons (Papio anubis). The mean scores ranged between 0.62 +/- 0.29 and 0.37 +/- 0.20, respectively. Gram-positive and Gram-negative cocci comprised 27.0 +/- 32.4 and 3.1 +/- 7.5% of the total viable counts in the dental plaque samples. Black-pigmented Bacteroides formed about 1.9 +/- 5.9% of the bacterial population in the samples. Anaerobic Gram-negative bacilli were found in 73.2% of the samples and averaged 19.2 +/- 26.3% of the total recovered flora. Species of the oral Actinomyces and other Gram-positive rods found in humans were not isolated. The composition of the oral flora in baboons appeared to be significantly different from that of man. Isolates of F. nucleatum, L. buccalis, and B. intermedius from the two mammals were biochemically similar, but were distinguishable by analysis with antibody, both by precipitin lines and/or differences between homologous and heterologous titers.

Effects of levamisole on experimental periodontitis

Although the chemotaxis and efflux of functionally normal polymorphonuclear leukocytes (PMN) into the periodontal sulcus may have a protective role in periodontitis, these cells are also associated with periodontal tissue destruction. The immunomodulating agent, levamisole hydrochloride, is known to enhance PMN chemotaxis. The present study was designed to evaluate the effects of enhanced PMN chemotaxis on the tissue destruction associated with an experimental periodontitis. Levamisole was administered by oro-gastric intubation to 4 squirrel monkeys (experimental) at 3 mg/kg/bw every 2 days for 18 days. After 2 doses of levamisole, marginal periodontitis was induced around maxillary and mandibular bicuspids and the maxillary first molars by tying plaque-retentive ligatures at the gingival margins. Periodontitis was induced around corresponding teeth in 4 animals (control) which had not received levamisole. All animals were killed 2 weeks after induction of periodontitis. Clinically, gingival inflammation was more pronounced in experimental animals at both 7 and 14 days after periodontitis induction. The progression of periodontitis was evaluated histometrically and alterations in the cell populations characterized using step serial sections. The results were analyzed statistically. No significant differences were observed between the groups with respect to areas of infiltrated supracrestal connective tissue and total numbers of cells present, loss of connective tissue attachment and loss of coronal alveolar bone. However, in experimental specimens, a much denser band of inflammatory cells was evident between the apical extent of the bacterial plaque and the gingival sulcular tissues the connective tissue of which contained significantly fewer inflammatory cells and demonstrated more pronounced fibrogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Gingivitis

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

Effects of gold salts on experimental periodontitis. II. Cell population characteristics

A previous study showed that the systemic administration of soluble gold salts (gold sodium thiomalate) resulted in significantly less periodontal destruction after 2 weeks of experimentally induced periodontitis. In order to provide information on the possible mechanisms of action of gold salts in the experimental periodontitis situation, the present study analyzed and compared the characteristics of the inflammatory cell populations in animals receiving gold salts with those present in animals which had not received gold salts. Maxillary gingival biopsy specimens were obtained from the buccal aspect of ligatured teeth after 2 weeks of experimental periodontitis. Cell populations were characterized and enumerated, on 1-micron sections, in an epithelial and superficial connective tissue zone, and a deep connective tissue zone. Significantly fewer inflammatory cells were present in experimental (gold receiving) specimens, and this reduction was due primarily to fewer polymorphonuclear leucocytes (PMNs). No significant reduction occurred in any other inflammatory cell-type. The reduction in number of PMNs in experimental specimens was associated with a decreased number of morphologically altered, degenerating fibroblasts in the connective tissue compared to the PMN-dominated lesion of control specimens. Mechanisms whereby gold salts can reduce chemotaxis and functional capabilities of inflammatory cells are discussed.

The pocket epithelium: a light- and electronmicroscopic study

The POCKET epithelium is important for the pathogenesis of gingivitis and periodontitis. However, this epithelial variant has never been adequately described. The bioptic material with supraalveolar pockets originated from previous studies in which cotton floss ligatures were placed around the crowns of premolars in eight dogs. After periods of 4 to 21 days or up to 5 months, block biopsies comprising dental and gingival tissues were taken on the buccal side. The tissues were processed for light- and electron microscopic examination. The observations revealed that the pocket epithelium (1) does not attach to the tooth, (2) forms irregular ridges and, over connective tissue papillae, thin coverings which occasionally ulcerate, (3) consists of cells only some of which show a tendency to differentiate, (4) presents a basal lamina complex with discontinuities and multiplications, and (5) is infiltrated mainly by lymphocytes, T- and B-blasts and plasma cells, and is transmigrated by neutrophilic granulocytes. It is concluded that the mosaic-like structure of the pocket epithelium reflects the heterogeneity of the adjacent plaque, that this structure together with the absence of membrane coating granules is the basis for an extremely high permeability, and that epithelial ridges may conduct and collect foreign substances which thereby become more easily recognizable for leukocytes.