Microbial populations and active tissue destruction in experimental periodontitis

Odontogenic abscesses in rhesus macaques (Macaca mulatta) of Cayo Santiago

OBJECTIVES

Odontogenic abscesses are one of the most common dental diseases causing maxillofacial skeletal lesions. They affect the individual's ability to maintain the dental structures necessary to obtain adequate nutrition for survival and reproduction. In this study, the prevalence and pattern of odontogenic abscesses in relation to age, sex, matriline, and living periods were investigated in adult rhesus macaque skeletons of the free-ranging colony on Cayo Santiago, Puerto Rico.

MATERIALS AND METHODS

The skulls used for this study were from the skeletons of 752 adult rhesus macaques, aged 8-31 years, and born between 1951 and 2000. They came from 66 matrilines ranging from 1 to 88 individuals. Fistulae or skeletal lesions caused by odontogenic abscesses drainage, carious lesions, tooth fractures, tooth loss, and alveolar resorption were evaluated visually.

RESULTS

Seventy-two specimens (9.57%) had odontogenic abscesses of varying severity. Males had a significantly higher prevalence than females. The prevalence of odontogenic abscesses in several matrilines was significantly higher than in the population as a whole. Animals born between 1950 and 1965 tended to have a higher prevalence of odontogenic abscesses than those born in later periods.

DISCUSSION

These results suggest that oral pathologies, such as dental and periodontal abscesses in rhesus macaques are fairly common, which may indicate familial effects interwoven with ecological and social factors. The closeness of the rhesus and human genomes allows insights to understand of the epidemiology of these diseases in the human population. Further assessment of the role played by environmental and familial factors on rhesus oral health and disease are warranted.

Subgingival microbiota from Cebus apella (capuchin monkey) with different periodontal conditions

This present study evaluated the subgingival microbiota of the Cebus apella with different periodontal conditions kept by the Tufted Capuchin Monkey Procreation Center (São Paulo State University - UNESP) or free-ranging monkeys. For this purpose, clinical specimens of subgingival biofilm were collected from 52 monkeys, of both genders, 40 kept in captivity and 12 free-ranging monkeys. The primates were submitted to periodontal evaluation and biofilm samples were transferred to VMGA III transport medium and ultrapure water. The microbiota was cultivated in selective and non-selective culture media and microbial DNA was extracted and the presence of periodontal pathogens was evaluated using PCR and real-time PCR. The actinomycetes, fusobacteria, Campylobacter rectus, Eikenella corrodens, black-pigmented Gram-negative anaerobic rods, Tannerella forsythia, staphylococci and streptococci represent the predominantly detected microorganisms. Aggregatibacter actinomycetemcomitans, Dialister pneumosintes and Prevotella nigrescens were rarely observed, whereas Treponema denticola was not found. Populations of C. rectus, E. corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, T. forsythia and the total microbial load were significantly higher in animals with bone loss and, in smaller extension, in animals with gingival bleeding.

Microbiological diagnostic testing in the treatment of periodontal diseases

A variety of microbiological diagnostic tests are available for clinicians to use for evaluation of patients with periodontal disease. Each one has its own unique set of advantages and disadvantages, and probably the most useful information for the clinician can be obtained using a combination of the various analytic methods. The tests appear to have their greatest utility when used on patients with chronic or aggressive periodontitis who do not respond favorable to conventional mechanical therapy. The major limitation of all microbiological tests is that the information obtained is relevant to the site sampled, and may not be representative of the microflora of the entire dentition. However, since it is often only specific sites that do not respond to initial therapy, knowing the constituents of the microflora that populate these sites is clinically relevant.

Necrotizing ulcerative gingivitis

Necrotizing periodontal diseases are unique in their clinical presentation and course. Data suggest that the etiology and pathogenesis of necrotizing periodontal diseases may also be distinctive from other periodontal diseases. Necrotizing ulcerative gingivitis (NUG) is a type of necrotizing periodontal disease in which the necrosis is limited to the gingival tissues. Three specific clinical characteristics must be present to diagnose NUG, pain (usually of rapid onset) interdental necrosis, and bleeding. Epidemiological and prospective clinical studies have found an altered ability to cope with psychological stress, immunosuppression, and tobacco use to be strongly associated with the onset of NUG.

Dark field microscopy of the subgingival microflora in insulin-dependent diabetics

The subgingival microflora was assessed by means of dark field microscopy in 106 pockets of 47 subjects with long-term insulin-dependent diabetes mellitus (IDD). The microbiota of 55 healthy sulci (probing depth < 4 mm) and 51 periodontally diseased (probing depth > or = 4 and 6 mm) pockets were analyzed. The mean duration of the IDD of the diabetic subjects was 23.7 years (range from 10 to 41 years). The diabetic patients, aged 30-65 years, were under medical treatment at the III Department of Medicine, University of Helsinki Central Hospital, and at 2 clinics of the Helsinki Health Centre. Based upon their long-term medical records, 26 subjects were assessed to have poorly controlled insulin-dependent diabetes mellitus (PIDD) and 21 had controlled insulin-dependent diabetes (CIDD). The PIDD subjects exhibited higher mean blood glucose levels (12.9 +/- 4.6 mmol/l, mean +/- S.D.) than the CIDD subjects (7.9 +/- 3.6 mmol/l) (p < 0.001, t-test). The mean glycosylated hemoglobin HBA1 (HBA1c) levels were 11.2 +/- 4.6% (10.3 +/- 1.2%) and 8.8 +/- 1.8% (7.7 +/- 1.4%) for PIDD and CIDD subjects, respectively. These differences were statistically significant (p < 0.01 and p < 0.001, t-test). For each individual, site-specific recordings were made for plaque index and bleeding index scores, probing depth, loss of attachment and radiographic loss of alveolar bone. Dark field microscopy analysis of the presence of spirochetes, motile rods, cocci, non-motile rods, filaments and fusiforms was performed in the total of 106 pockets. According to the results of the dark field microscopy, the % of spirochetes and motile rods in the periodontally diseased pockets was significantly higher in the PIDD than in the CIDD subjects (9.2 +/- 13.4% and 10.8 +/- 14.3% versus 4.0 +/- 5.2% and 3.1 +/- 3.2%, p < 0.01 and p < 0.001, chi 2-test, respectively). Moreover, the PIDD subjects had lower mean %s of coccoid cells in periodontally diseased sites than the CIDD subjects (52.1 +/- 20.8% versus 60.7 +/- 9.0%, p < 0.001, chi 2-test).

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)

Cell populations and episodic periodontal attachment loss in humans

The purpose of the present study was to assess possible associations between episodic probing attachment loss and cell populations in the supracrestal connective tissue in humans. 10 systemically healthy adult patients with untreated advanced periodontitis were monitored during a period of 10 months. At baseline and every month thereafter, probing attachment levels were measured at 6 sites of every tooth using an electronic pressure sensitive probe and flexible stents. Corresponding contralateral sites were identified where 1 site had lost 2 mm or more attachment within the previous month (P), and the other site had not (C). Supracrestal soft tissue biopsies were taken from these sites, processed and cut into 1 micron sections. Cell populations were identified in superficial and deep connective tissue areas by counting fibroblasts, macrophages, plasma cells, mast cells, granulocytes, lymphocytes, endothelial cells and the total number of inflammatory cells. Analysis of variance assessed differences in cell populations between P- and C-sites. There were statistically significantly higher numbers of fibroblasts in the standard areas of C-sites (p less than 0.0001). In P-sites, the numbers of macrophages, plasma cells, mast cells, lymphocytes and total inflammatory cells were significantly higher as compared to C-sites (p = 0.05-0.0001). There were no differences in cell populations between superficial and deep connective tissue areas within P- and C-sites (p greater than 0.2). Clinically assessed episodes of periodontal disease progression may be associated with site-specific shifts in inflammatory cell populations.

Antigens of Actinobacillus actinomycetemcomitans recognized by patients with juvenile periodontitis and periodontally normal subjects

Most juvenile periodontitis patients respond to infection by Actinobacillus actinomycetemcomitans by producing serum antibodies. Specific antigens inducing the humoral immune response have not been identified, nor has the role of the resulting antibodies in disease progression been determined. Adsorbed and unadsorbed sera from juvenile periodontitis patients and normal subjects were analyzed by enzyme-linked immunosorbent assay and Western blots (immunoblots), using digested and undigested bacterial sonicates and French pressure cell fractions to determine the biochemical class, cross-reactivity, and cellular location of the antigens in different A. actinomycetemcomitans serotypes. Antigens detected by using high-titer sera included the following: (i) serotype-specific nonprotein material located on the cell surface, (ii) soluble-fraction proteins showing highly variable antibody binding, (iii) cross-reactive proteins, and (iv) a protein present in soluble and cell wall fractions and immunopositive for all sera tested. In addition, one apparently nonprotein component that was enriched in the cell wall fraction was observed. Sera with high immunoglobulin G titers to one, two, three, or none of the three A. actinomycetemcomitans serotypes were observed. There was a high degree of variation from one patient to another in the humoral immune response to serotype-specific and cross-reactive antigens. As demonstrated by whole-cell adsorption experiments, the serotype-specific surface antigen accounted for approximately 72 to 90% of the total antibody-binding activity for sera with titers greater than 100-fold above background, while cross-reactive antigen accounted for less than 28%. Antibody binding the whole-cell sonicate for high-titer sera was inhibited 90% by lipopolysaccharide from the same serotype, strongly suggesting that lipopolysaccharide is the immunodominant antigen class.

Darkground microscopy of subgingival plaque from the top to the bottom of the periodontal pocket

Part of the results of a study of subgingival plaque by darkground microscopy was used to investigate morphotype distribution at different levels within the periodontal pocket. Subgingival plaque was sampled at coronal, middle and apical levels from each of 28 approximal surfaces on 28 teeth extracted from 28 adults with untreated moderate to advanced periodontitis. Sample preparation and darkground microscopy were as described previously. The data recorded only the subgingival level at which the maximum count occurred for a given morphotype and subject. It was found that the maximum count of spirochaetes occurred most frequently at the apical level (p less than 0.05) and the maximum count of 'others' at the coronal level (p less than 0.05). Also, coccal counts showed a trend to increase the more apical the sample. Standardised darkground microscopy was able to show that the sampled subgingival level had a significant influence on plaque bacterial morphotype distribution, indicating the importance of accurate sampling of subgingival plaque at the most apical level.

The effect of subminimal inhibitory concentrations of antimicrobial agents on three bacterial mixtures

A test tube technique was developed to screen bacterial mixtures to detect interbacterial interactions that play a role in determining sensitivity to antimicrobial agents. We found 3 mixtures where these bacterial interactions change the sensitivity to antimicrobials or change the proportions of each bacterial species in the mixture. The mixtures were: Fusobacterium nucleatum 102.3 and Bacteroides endodontalis ATCC 35406; F. nucleatum 102.3 and B. endodontalis BN11 a-f; and Capnocytophaga ochracea 1956c and Eubacterium saburreum 162.4. The antimicrobials used were metronidazole for the first 2 mixtures and tetracycline for the last. F. nucleatum seems to protect B. endodontalis from the action of metronidazole. Conversely, the growth inhibition of C. ochracea by E. saburreum was lifted when tetracycline was present. We also found that the growth of C. ochracea can then permit the subsequent growth of E. saburreum. The test tube method permits the evaluation both of interbacterial interactions and the detection of any protective mechanism against antimicrobial agents in a bacterial mixture. We found that F. nucleatum 102.3 can decrease the metronidazole level in the culture medium, and by the use of 14C-metronidazole we demonstrated that acetamide is produced from metronidazole.

Factors associated with occurrence and reversibility of connective tissue attachment loss

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