Ligature‐induced marginal inflammation around osseointegrated implants and ankylosed teeth. Clinical and radiographic observations in cynomolgus monkeys (Macaca fascicularis).

The purpose of the investigation was to gain more understanding of marginal inflammatory reactions around osseointegrated implants. The significance of the lacking periodontal ligament of implants was examined in the initial breakdown phase of supporting tissues by comparing clinical and radiographic manifestations of ligature‐induced marginal inflammation related to osseointegrated implants with those around ankylosed and normal control teeth in 8 cynomolgus monkeys ( Macaca fascicularis ). Bilateral extraction of the first and second mandibular molars was carried out initially, and 12 weeks later 2 implants were placed in each side. Ankylosis of the second maxillary molars was established by extracting and replanting the teeth after a drying period. When ankylosis and osseointegration were established, ligature‐induced marginal inflammation was induced in the right or left side at random around implants, ankylosed teeth and normal control teeth (second maxillary premolar) for 7 weeks. Although the clinical manifestations as expressed by plaque score, gingival score, probing depth and attachment loss were quite similar, the radiographic features differed. Significant loss of bone height was limited to implants and ankylosed teeth and did not occur in relation to normal control teeth. Furthermore, the bone loss around implants was significantly greater than the loss around ankylosed teeth. Bone loss was limited to implants and ankylosed teeth; the study therefore suggests that the presence of marginal inflammation around implants and ankylosed teeth may have more serious implications than does marginal inflammation around teeth with a periodontal ligament. However, variations in microbiota and susceptibility of different jaw positions to periodontal breakdown may influence the results of this study.     

Clinical and microbiological patterns of adults with periodontitis.

Although current data suggest that periodontitis may actually be multiple diseases each with varying responses to therapy, little evidence exists to support this theory in adult patients. This report describes the design and initial findings of a longitudinal field trial involving the diagnosis and treatment of adult and refractory periodontitis patients in private practice. Adult patients (N = 221) who met specific clinical criteria were selected from the private practices of 22 periodontists. Clinical characteristics were recorded and subgingival plaque samples were sent to microbiology laboratories at either UCLA or The University of Texas Health Science Center at San Antonio (UTHSCSA). Samples were processed according to protocols standardized between the 2 centers. Five different combinations of the initial clinical and microbial findings were evaluated for patterns in the data by means of cluster analysis. Plaque, bleeding on probing, bone loss scores, probing depth distributions, and microbial findings produced multiple cluster solutions. Solutions involving 6 clusters explained 39.4% to 76.4% of the variation between patients and produced ratios for variation between clusters to variation within clusters of 5.2 to 15.3. The optimal cluster solution incorporated both clinical and microbial findings, with some clusters characterized by high plaque and moderate bleeding on probing and bone loss, whereas others had low plaque but high bleeding on probing and bone loss. Microbial findings of each cluster exhibited distinct patterns with some clusters having a high prevalence (83% to 100%) of specific target bacterial species while other clusters had an absence of these species.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of an immunomodulating agent on peripheral blood lymphocytes and subgingival microflora in ligature-induced periodontitis

The peripheral blood lymphocyte populations and the subgingival levels of black-pigmented Bacteroides species were monitored during the conversion of chronic gingivitis to progressing periodontitis in cynomolgus monkeys. In addition, the effects of an immunomodulating agent, the pentapeptide of thymopoietin (TP5), were determined. After the induction of active periodontitis, proportions of helper T-cells (OKT-4 positive) decreased from 31.5 to 26.4%, and proportions of B-cells (surface immunoglobulin positive) increased from 44.5 to 51.8%. Proportions of suppressor T-cells (OKT-8 positive) remained unchanged, but the numbers of OKT-8-positive cells increased. During this same time period the total cultivable subgingival flora increased from 1.5 X 10(6) to 3.5 X 10(6) per sample, with Bacteroides gingivalis increasing from 5.3 to 16.6% of the total cultivable subgingival flora. After 10 weeks of active periodontitis, animals were treated with either TP5 or placebo. Treatment with TP5 produced an increase in helper T-cells but had no effect on B-cells. The OKT-4/OKT-8 cell ratio, which decreased from 1.3 to 0.8 with disease induction, was increased to 1.1 after TP5 treatment but remained at 0.9 in placebo-treated animals. TP5 had no effect on the total cultivable subgingival flora but significantly decreased the subgingival proportions of B. gingivalis and other black-pigmented Bacteroides species. In this model system, active periodontitis was associated with an increase in B. gingivalis, a decreased helper/suppressor T-cell ratio, and increased levels of B-cells. Treatment with TP5 increased the helper/suppressor T-cell ratio and decreased B. gingivalis levels, suggesting that lymphocyte subsets have the potential to influence subgingival levels of potential periodontal pathogens.     

Correction of density changes caused by methodological errors in CADIA

Quantitative evaluation of radiographic changes by computer-assisted densitometric image analysis (CADIA) requires exact knowledge about method errors. In the present study, density change errors were determined from pairs of films with "no change". From this distribution of error values, a series of threshold values for correction of changes due to method errors was selected. The threshold values were then applied to results from analysis of densitometric changes in sites with "known loss" or "no change" of the alveolar bone among films from cynomolgus monkeys. The density errors formed non-normal distributions with no difference in magnitudes between the absolute values expressing density decreases and density increases in the same areas. Calculation of sensitivity, specificity, type 1 and type 2 errors showed that these variables were clearly influenced by selection of different threshold values for correction of the density change errors. It is therefore recommended that threshold values be determined for each analytical system initially as well as following any equipment or computer program modification. Before selecting the threshold value for a specific radiographic analysis, the desired level of sensitivity and specificity should be evaluated.     

Clinical and microbiological evaluation of therapy for juvenile periodontitis

Eight patients (mean age 15.6 yrs) with severe molar-incisor bone loss and pocket formation characteristic of juvenile periodontitis were entered into a clinical protocol of three sequential stages: scaling and root planing (S/RP); S/RP concurrent with systemic tetracycline therapy (1 gm/day for 28 days); periodontal surgery concurrent with systemic tetracycline therapy. Clinical and microbiological examinations were scheduled at baseline, at 1 to 2 months after Stage I, at 1 to 2 months after completion of tetracycline therapy in Stages II and III, and during recall. A decision to progress to the next stage or to place the patient on a 3-month recall was based solely on clinical findings (suppuration, bleeding upon probing and pocket depth) at the deepest site in each patient. Paperpoint subgingival plaque samples from representative affected sites were analyzed for percentage of total cultivable microflora composed of black-pigmented Bacteroides species (BPB), surface translocating bacteria (STB) and Actinobacillus actinomycetemcomitans (Aa). At baseline, all sites bled to probing, seven of eight sites showed suppuration, and deepest pocket depths averaged 8.0 mm. STB were detected in one and BPB in four sites, respectively, and all sites demonstrated Aa, which constituted approximately 40% of the total cultivable flora. S/RP alone had essentially no effect on either clinical or microbiological findings, and all patients progressed to Stage II. Five went on to Stage III. S/RP with tetracycline was clinically and microbiologically more effective at sites in which Aa was predominant. Surgery was required in all sites containing high levels of both BPB and Aa. These results suggest that microbiological diagnosis may be useful in selecting and monitoring treatment for juvenile periodontitis.     

Caries control in the albino rat with chlorhexidine gluconate (Hibitane)

Varying concentrations of chlorhexidine gluconate (Hibitane) were added to the drinking water of albino rats maintained on caries promoting diet MIT No. 200. Animals receiving chlorhexidine showed reductions in buccal caries scores ranging from 31 to 75 per cent. Animals receiving 0.2 per cent chlorhexidine were found to consume less liquid and exhibited an impaired ability to gain weight. Although sulcal caries scores in animals receiving chlorhexidine were lower than scores of controls, the effectiveness of chlorhexidine on sulcal caries did not seem as great as on buccal surface caries.An attempt to increase the animals' acceptance of chlorhexidine by adding sucrose to the liquid produced apparent changes in liquid intake, which could not be replicated, however. By the termination of the experiment, the animals consuming chlorhexidine displayed varying degrees of hair loss. In microscopic studies, some animals exhibited an enhanced translucency of the enamel. It is concluded that chlorhexidine gluconate effectively reduces the incidence of caries in the albino rat, but body weight and tissue changes suggest the need for additional toxicity studies.     

Morphological studies on periodontal disease in the cynomolgus monkey

Histologic observations were made on the primate Macaca fascicularis in order to describe the features of both naturally-occurring gingivitis and gingivitis present at non-experimental sites when selected teeth were ligated to induce periodontitis. Semi-thin sections of glutaraldehyde-paraformaldehyde fixed, EDTA-decalcified, and epon-embedded specimens were used, supplemented by routine histologic methods.
The microscopic picture of the interdental areas was identical for the two types of gingivitis specimens and consisted of a chronic inflammatory reaction resembling the established lesion in humans. The highly infiltrated gingival tissue exhibited a predominance of plasma cells. Leukocytes were seen in pathways from the connective tissue, through the epithelium and to the surface of the plaque, and many neutrophils were interposed between the plaque and soft-tissue. The apical extent of the junctional epithelium was at or slightly below the cemento-enamel junction. Although perivascular inflammation was observed in the transseptal fiber region, the alveolar crest exhibited only evidence of normal bone remodelling.     

The predominant cultivable subgingival flora of beagle dogs following ligature placement and metronidazole therapy

Ligature-induced periodontitis was evaluated microbiologically in 8 beagle dogs. Gingival health was established by repeated cleaning. At day 0 subgingival plaque was sampled from individual sites in two quadrants. All teeth in one quadrant were then ligated at the CEJ, and the other quadrant served as a non-ligated control which was cleaned three times each week. At day 14, four dogs were given metronidazole for seven days. Plaque was cultured anaerobically on nonselcctive media, and the predominant cultivable flora was characterized. At day 0 Gram-negative facultative rods represented 56.8 % of the flora. with motile and surface translocating organisms predominating. At day 14 Bacteroides asaccharolyticus , including catalase positive B.asaccharolyticus-like organisms, increased at ligated sites to 34.7 % of the cultivable flora. After metronidazole therapy the total bacterial count decreased, and Gram-negative anaerobic rods became non-detectable. Gram negative facultative bacteria which were motile or surface translocating represented 52.7 % of the cultivable flora after metronidazole treatment.
In the beagle dog ligature placement was associated with a shift in the flora from Gram-negative facultative rods to Gram-negative anaerobic rods. Metronidazole treatment reduced the total cultivable flora and selectively reversed the microflora shifts which followed ligature placement.     

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.     

Effect of region-of-interest in computerized densitometric analysis of radiographs

The region-of-interest (ROI) in computer-assisted densitometric image analysis (CADIA) is defined by its size and location. This study evaluated the effects of these variables on two quantitative parameters, the change in density and the area with change in density. Pairs of radiographs for these analyses were obtained from sites with "no change" or "known loss" in Cynomolgus monkeys during a study of ligature-induced periodontitis. The size and location of the ROI had clear effects on the two CADIA parameters. To reduce these effects, a corrective procedure hypothesizing a linear relationship between the ROI size and the area with change in density was tested. While this procedure was sufficient to correct for ROI size-dependent differences among "no change" images, it was not effective in images with "known loss". In such images, additional adjustments by increasing threshold levels for the registered change in density were found to reduce but not to eliminate differences between ROIs of different size and location. When densitometric radiographic analysis is used for quantitative comparison of different sites, it is primarily recommended to select ROIs of similar size and location. Application of corrective procedures should follow only after careful evaluation of their effects on sensitivity and specificity.