Induction Of Periodontitis Research Articles

A new approach to treat tissue destruction in periodontitis with chemically modified dextran polymers.

Periodontitis are diseases of the supportive tissues of the teeth provoked by bacteria and characterized by gingival inflammation and bone destruction. We have developed a new strategy to repair tissues by administrating agents (RGTA) that mimic heparan sulfates by protecting selectively some of the growth factors naturally present within the injured tissue and interfering with inflammation. After periodontitis induction in hamsters, the animals were left untreated or received weekly i.m. injections of RGTA1507 at a dose of 100 microg/kg, 400 microg/kg, 1.5 mg/kg, or 15 mg/kg for 4 wk. RGTA treatment significantly reduced gingival tissue inflammation, thickened the pocket epithelium by increasing cell proliferation, and enhanced collagen accumulation in the gingiva. A marked reduction in bone loss was observed, resulting from depression of osteoclasia and robust stimulation of bone formation at the dose of 1.5 mg/kg. RGTA treatment for 8 wk at this dose reversed macroscopic bone loss, sharply contrasting with the extensive bone destruction in the untreated animals. RGTA treatment decreased gelatinase A (MMP-2) and B (MMP-9) pro-forms in gingival tissues. Our data indicate that a 4 wk treatment dose-dependently attenuated gingival and bone manifestations of the disease, whereas a longer treatment restored alveolar bone close to controls. By modulating and coordinating host responses, RGTA has unique therapeutic properties and is a promising candidate for the treatment of human periodontitis.

Disodium chlodronate prevents bone resorption in experimental periodontitis in rats.

Periodontitis is a chronic disease characterized by alveolar bone loss and inflammatory changes. We studied the effect of disodium chlodronate (CD), a bisphosphonate used in metastatic and metabolic bone disease as a bone resorbing drug, in an experimental periodontitis model (EPD) focusing on anti-resorptive and anti-inflammatory parameters. A nylon thread ligature was placed around the left maxillary molars of 72 male Wistar rats who were sacrificed after 7 or 11 days. Groups were treated daily with CD (1, 5, or 25 mg/kg/sc) starting at day 0 until day 7 (prophylactic CD) or from day 5 until day 11 (curative CD) after periodontitis induction. Non-treated group (NT) consisted of rats subjected to periodontitis that received no pharmacological treatment. Alveolar bone loss (ABL) was measured as the distance between the cuspid tips and the alveolar bone. The right jaw was used as control. The hemiarcades were processed for histopathologic analysis. In NT group there was significant ABL, severe mononuclear cells influx, and increase in osteoclast numbers. Prophylactic CD treatment decreased the ABL 25.8%, 61.6%, and 75.5% as compared to NT for the 1, 5, and 25 mg/kg CD doses, respectively. Curative CD treatment decreased the ABL 20%, 62%, and 69% as compared to NT for the 1, 5 and 25 mg/kg CD doses, respectively. Both prophylactic and curative CD decreased histological changes, as compared to NT rats (P <0.01). CD has both bone sparing and anti-inflammatory activity in EPD in rats when administered as a pretreatment or in an ongoing process. The possibility of using CD as an alternative treatment in human periodontitis should be considered.

Effects of chlorpromazine on alveolar bone loss in experimental periodontal disease in rats.

Chlorpromazine (CPZ), a phenothiazine derivative, possesses anti-inflammatory properties, inhibition of tumor neurosis factor-alpha (TNF-alpha) synthesis and bone resorption. TNF-alpha promotes inflammatory changes and bone resorption in periodontitis. We have studied the effect of CPZ in experimental periodontitis. Wistar rats were subjected to a ligature placement around the cervix of the right second upper molars. Alveolar bone loss was evaluated by the sum of the distances between the cusp tip and the alveolar bone along the axis of each molar root, which was subtracted from the contralateral side. Histopathological analysis of the periodontium was based on cell influx, osteoclast number, and alveolar bone and cementum integrity. Animals were weighed daily and total and differential peripheral white blood cell counts were performed 6 h and 1, 7 and 11 d after periodontitis induction. Groups were treated with CPZ 1 h before and daily up to the 11th d of periodontitis. Alveolar bone loss was inhibited 46%, 55.4%, and 76.5% by CPZ at 1, 3 and 9 mg/kg, respectively. Histological analysis showed a significant reduction of cell influx and osteoclast number, as well as preservation of the alveolar process and cementum. CPZ reversed leukocytosis but not weight loss. In conclusion, CPZ reduces bone loss in experimental periodontitis, probably via TNF-alpha blockade.

Interleukin-1 and tumor necrosis factor antagonists inhibit the progression of inflammatory cell infiltration toward alveolar bone in experimental periodontitis.

Periodontal disease is a significant cause of tooth loss in humans and is one of the most prevalent diseases associated with bone loss. Following bacterial colonization, the gingiva becomes inflamed and, in some cases, progresses to destruction of alveolar bone. To investigate the temporal movement of inflammatory cells toward alveolar bone and the role of interleukin-1 (IL-1) and tumor necrosis factor (TNF) in this process, studies were carried out in a Macaca fascicularis primate model of experimental periodontitis. IL-1 and TNF activity was inhibited by local application of soluble receptors to IL-1 and TNF by injection into interdental papillae. The results indicate that following induction of experimental periodontitis, the front of inflammatory cells progresses toward alveolar bone and is associated with osteoclast formation. These processes are inhibited by blockers to IL-1 and TNF. These studies suggest that the conversion from gingivitis to periodontitis is directly associated with the movement of an inflammatory infiltrate toward alveolar bone, and that this activity is at least partially dependent upon IL-1 and/ or TNF.

Changes in oxygen consumption in dog gingiva during induction of experimental periodontitis.

The purpose of this study was to examine changes in oxygen consumption in dog gingiva during induction of experimental periodontitis. The disease was induced in adult mongrel dogs during a 16-week period by placement of silk ligatures around selected teeth. The oxygen consumption rate of gingival tissue was determined in vivo by a non-invasive technique, tissue reflectance spectrophotometry. Changes in such clinical parameters as gingival index, plaque index, pocket depth, attachment level, and gingival crevicular fluid flow indicated acute inflammatory responses during the first three weeks after ligation, followed by the appearance of chronic inflammation during the remaining 13 weeks. The oxygen consumption rate increased during the first seven days after ligation and stayed near the maximum level for 2-7 weeks; this was followed by a gradual decrease during the final nine weeks. These results suggest that gingival oxygen consumption increases rapidly with the increase of acute inflammation responses and then decreases slightly with the gradual development of chronic inflammation. Positive correlations were observed between the oxygen consumption rate and other clinical indices. Thus, the tissue reflectance spectrophotometry is a new, useful method for objective, quantitative, and non-invasive assessment of gingival oxygen consumption.

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)

Haemoglobin concentration and oxygen saturation in dog gingiva with experimentally induced periodontitis

The index of haemoglobin concentration (Hb index) and apparent oxygen saturation (apparent SO 2) were determined by a new, non-invasive method, tissue reflectance spectrophotometry. The Hb index was positively correlated with the haemoglobin concentration. The relationship between the apparent SO 2 and oxygen partial pressure was a sigmoid curve resembling the haemoglobin oxygen dissociation curve. The Hb index and the apparent SO 2 were monitored continuously by tissue reflectance spectrophotometry during the induction of experimental periodontitis with silk ligatures. The Hb index increased rapidly during the first 7 days after ligation and then decreased gradually during the remaining period. The apparent SO 2 decreased during the first 7 days but gradually rose during the final 9 weeks. The maximum level of the deoxyhaemoglobin concentration after ligation was elevated about two times over that found before ligation, whereas the increase in oxyhaemoglobin concentration was relatively small. These results suggest that the oxygen supply to inflamed gingiva may increase to some extent, but not sufficiently to compensate for the increased oxygen consumption.

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.

Effect of metronidazole on development of subgingival plaque and experimental periodontitis.

Active tissue destruction in experimental periodontitis has been positively correlated with subgingival spirochetes and total number of organisms. The present study was designed to inhibit spirochete populations and evaluate the effect upon periodontal destruction. Metronidazole was administered orally to four squirrel monkeys (100 mg/kg/bwt) for 17 days. After 3 days, marginal periodontitis was induced around bicuspids and molars by tying silk ligatures at the gingival margins. Subgingival plaque samples were taken baseline and 14 days after ligature placement. Dark-field microscopy quantitated motile forms, spirochetes, straight and curved rods, filament, cocci and fusiforms. Periodontal destruction was evaluated at 2 weeks by histometric analysis of connective tissue attachment, crestal alveolar bone and infiltrated connective tissue. Bacterial and histometric comparisons were made with experimental periodontitis data from four animals (control) which had not received metronidazole. Subgingival plaque prior to periodontitis induction was dominated by cocci, but fusiforms and straight rods were also present. Straight rods formed a greater proportion of the plaque which developed in metronidazole-receiving animals. The absence of spirochetes and motile rods contrasted with the control group where spirochetes were the predominant type. The total number of bacteria was also larger in the control animals. Histometric analysis showed that areas of infiltrated supracrestal connective tissue were similar in both groups. Loss of connective tissue attachment and alveolar bone was significantly less in experimental animals, and the latter values did not differ significantly from baseline dimensions. The results indicated that the subgingival bacterial populations which developed during metronidazole administration did not result in an experimental periodontitis.

Microbial populations and active tissue destruction in experimental periodontitis.

Although specific subgingival microflora are being associated with active tissue destruction in periodontitis, little information exists on the relationship between subgingival flora and histological evidence of tissue destruction. The present study was undertaken to explore these relationships during experimental marginal periodontitis in squirrel monkeys. In 4 squirrel monkeys, experimental periodontitis was induced around bicuspids and molars using silk ligatures. The buccal part of the subgingival ligature was removed for bacterial sampling 3, 7, and 14 days after ligature placement. Dark-field microscopy was used to quantify motile forms, spirochetes, straight and curved rods, filaments, cocci and fusiforms. Subgingival plaque prior to periodontitis induction was dominated by cocci, but fusiforms and straight rods were also present. Spirochetes, filaments, curved rods and motile forms were absent. 3 days after induction of periodontitis, there were marked increases in spirochetes, motile forms, filaments, curved and straight rods. The proportions of coccoids and fusiforms decreased. The bacterial proportions stayed at approximately the same levels through 7 and 14 days. Histometric quantification of periodontal destruction showed loss of connective tissue attachment and crestal alveolar bone. A positive correlation was found between periodontal tissue destruction and both total number of subgingival bacteria and spirochetes.

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.

The effect of progressive and increasing tooth hypermobility on reduced but healthy periodontal supporting tissues.

The aim of the present investigation was to assess the effect of progressive and increasing tooth hypermobility on a periodontium reduced by marginal periodontitis, but in which the inflammatory lesion had been resolved. Periodontitis was induced by tying plaque‐retentive silk ligatures around the mandibular second and third bicuspids on one side of the jaw (experimental) in four squirrel monkeys. Ten weeks later the ligatures were removed and an oral hygiene regime of mechanical cleaning was started and continued 3 times a week for 20 weeks. Ten weeks after beginning oral hygiene, continual mesio‐distal jiggling trauma to the periodontium between these bicuspids was begun and continued for the remaining 10 weeks. Induction of periodontitis, removal of ligatures, and the oral hygiene regime were performed around the same teeth of the contralateral side (control) of the jaw so that the interproximal periodontium corresponded to the situation on the experimental side immediately before initiation of jiggling. The bicuspids had slight mobility prior to the initiation of jiggling; however, mobility increased progressively throughout the period of tooth displacement. Histologic examination showed that each periodontal ligament under compression had areas of acellularity, while those under tension were widened with dilated blood vessels. In contrast to the dense alveolar bone of control specimens, the alveolar bone of the experimental specimens was characterized by islands of osseous tissue surrounded by the connective tissue of the marrow spaces and periodontal ligaments. Histometric analysis showed that the progressively increasing tooth mobility on the reduced periodontium had significantly decreased the percentage of bone in the coronal interproximal periodontium, but it had not affected the level of crestal alveolar bone or the level of connective tissue attachment. It was concluded that teeth with markedly reduced but healthy periodontal tissues may continually accommodate to increasing and multidirectional forces by morphologic alterations in the periodontium which are independent of alterations in the level of connective tissue attachment.

Experimental induction of periodontal disease with arthus-type reactions

Arthus reactions were induced in the gingivae of monkeys sensitized to bovine serum albumin or ovalbumin. Challenge by placing antigen-soaked threads into the gingival sulcus or by gingival injection of the sensitizing antigen elicited inflammatory infiltrates composed largely of mononuclear cells. Increased deposits of IgG and C4 were also observed particularly in perivascular locations. Injections with 100 or 10 μg yielded not only increased inflammation which extended deeper into the bone of the alveolar crest, but also osteoclastic activity similar to that observed in human periodontitis. Injections of heterologous antigens and other control injections failed to induce such changes. Similar arthus reactions to oral bacterial antigens may contribute to the pathogenesis of human periodontal disease.

Chondroitin sulfatases in oral bacteria.

A possible function of bacteria in the etiology of periodontal disease may involve production of mucopolysaccharidases. The gel phase of ground substance of connective tissue contains acid mucopolysaccharides including chondroitin and chondroitin sulfates A, B, and C. These substrates, especially chondroitin sulfates, may be attacked by mucopolysaccharidases. By attacking the intercellular cementing substances of tissue, these enzymes could be a factor in the inflammation and destruction of the gingiva; they could increase tissue permeability to toxic substances in the oral cavity or destroy connective tissue. Several investigators have demonstrated the presence of such enzymes among a small number of poorly classified bacterial strains isolated from the oral cavity (PEPPER ET AL, J Dent Res 37:623, 1958; SCHULTZ-HAUDT ET AL, J Dent Res 33:624, 1954; SCHULTZ-HAUDT ET AL, J Dent Res 35:299, 1956.) The purpose of this study was to investigate more carefully the correlation between oral bacteria implicated in the production of periodontal disease and their ability to produce chondroitin sulfatase. Twenty bacterial strains were chosen. Eighteen were considered representative of the human oral microflora. Of these, 13 (Streptococcus mutans, strains BHT, 6715, 134, GS-5, FA-1, 20, HS-6; S faecalis, strains 547, 539; S sanguis, strain ATCC 10556, Actinomyces viscous, strain ATCC 74187, and Actinomyces spp strains I, J) have been implicated in formation of dental plaque, induction of periodontal disease, or etiology of dental caries. Three oral staphylococci were included (Staphylococcus aureus, strains HL-1, HL-2 and Staph epidermidis). Two strains of Proteus vulgaris, strain ATCC 6896 which produces chondroitin sulfatase and strain ATCC 13315 which does not produce the enzyme, were chosen to verify the methods of enzyme preparation and assay. The other oral strains were Actinomyces naeslundii, ATCC 12104 and Rothia dentocariosa, ATCC 14191. All strains were grown in appropriate media of minimal carbohydrate content with 0.1% chondroitin sulfate added as an enzyme inducer. Cells were separated by centrifugation at 37,000 X g and washed in 0.1 M phosphate buffer (pH 7.2), then resuspended in buffer and broken by homogenization with plastic beads. The broken cells were separated from the beads by passing

Changes in Vascular Resistance Following Induction of Chronic Unilateral Periodontitis in Dogs

Changes in Vascular Resistance Following Induction of Chronic Unilateral Periodontitis in Dogs