Ligature-induced Experimental Periodontitis Research Articles

Magnolol Ameliorates Ligature-Induced Periodontitis in Rats and Osteoclastogenesis:In VivoandIn VitroStudy

Periodontal disease characterized by alveolar bone resorption and bacterial pathogen-evoked inflammatory response has been believed to have an important impact on human oral health. The aim of this study was to evaluate whether magnolol, a main constituent of Magnolia officinalis, could inhibit the pathological features in ligature-induced periodontitis in rats and osteoclastogenesis. The sterile, 3–0 (diameter; 0.2 mm) black braided silk thread, was placed around the cervix of the upper second molars bilaterally and knotted medially to induce periodontitis. The morphological changes around the ligated molars and alveolar bone were examined by micro-CT. The distances between the amelocemental junction and the alveolar crest of the upper second molars bilaterally were measured to evaluate the alveolar bone loss. Administration of magnolol (100 mg/kg, p.o.) significantly inhibited alveolar bone resorption, the number of osteoclasts on bony surface, and protein expression of receptor activator of nuclear factor-κB ligand (RANKL), a key mediator promoting osteoclast differentiation, in ligated rats. Moreover, the ligature-induced neutrophil infiltration, expression of inducible nitric oxide synthase, cyclooxygenase-2, matrix metalloproteinase (MMP)-1 and MMP-9, superoxide formation, and nuclear factor-κB activation in inflamed gingival tissues were all attenuated by magnolol. In the in vitro study, magnolol also inhibited the growth of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans that are key pathogens initiating periodontal disease. Furthermore, magnolol dose dependently reduced RANKL-induced osteoclast differentiation from RAW264.7 macrophages, tartrate-resistant acid phosphatase (TRAP) activity of differentiated cells accompanied by a significant attenuation of resorption pit area caused by osteoclasts. Collectively, we demonstrated for the first time that magnolol significantly ameliorates the alveolar bone loss in ligature-induced experimental periodontitis by suppressing periodontopathic microorganism accumulation, NF-κB-mediated inflammatory mediator synthesis, RANKL formation, and osteoclastogenesis. These activities support that magnolol is a potential agent to treat periodontal disease.

Effects of Polycan, a β‐glucan, on experimental periodontitis and alveolar bone loss in Sprague‐Dawley rats

Polycan is a promising candidate for the treatment of periodontal disease. This study was undertaken to examine whether Polycan, a type of β-glucan, has a protective effect on ligature-induced experimental periodontitis and related alveolar bone loss in Sprague-Dawley rats. Polycan was orally administered, daily, for 10 d, at 21.25, 42.5 or 85 mg/kg, beginning 1 d after ligation. Changes in body weight and alveolar bone loss were monitored, and the anti-inflammatory effects of Polycan were determined by measuring the levels of myeloperoxidase (MPO), interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in gingival tissue. We also evaluated inducible nitric oxide synthase (iNOS) activity and malondialdehyde (MDA) concentrations as a measure of the antioxidant effect. Ligature placement led to a marked decrease in body weight, increased alveolar bone loss and increased concentrations of MPO, IL-1β, TNF-α and MDA, as well as increased iNOS activity and inflammatory cell infiltration and decreased collagen-fiber content. Histological examination revealed increases in the number and activity of osteoclast cells, decreases in alveolar bone volume and elevated percentages of osteclasts on the alveolar bone surface. Daily oral treatment with 42.5 or 85 mg/kg of Polycan for 10 d led to significant, dose-dependent inhibition of the effect of ligature placement. Taken together, these results suggest that 10 d of oral treatment with Polycan effectively inhibits ligature placement-induced periodontitis and related alveolar bone loss via an antioxidant effect.

Vitamin E does not prevent bone loss and induced anxiety in rats with ligature-induced periodontitis

ObjectiveThe purpose of this study was to investigate the effect of vitamin E on alveolar bone loss (ABL) and anxiety in rats with ligature-induced experimental periodontitis (EP). Material and methodsWistar rats were subjected to ligature-induced EP and treated with vitamin E (500mg/kg, orally) for 9 days. Then anxiety was tested using the elevated plus-maze (EPM) test. All of the animals were euthanised by cervical dislocation on day 11. ABL was analysed morphometrically and histopathologically. Lipid peroxidation quantification, activity of the enzyme superoxide dismutase and immunohistochemistry to tumour necrosis factor-alpha (TNF-α) and inducible isoform of nitric oxide synthases (iNOS) were also tested. ResultsEP induced a marked inflammatory process and intense ABL. Treatment with vitamin E decreased inflammatory reaction, prevented malondialdehyde formation and reduced the immunoreactivity to iNOS, but did not decrease ABL. Vitamin E had an anxiogenic effect on rats with or without EP. ConclusionsVitamin E may have potential to reduce oxidative damage and inflammatory response in EP but does not prevent ABL. Attention should be given to indiscriminate use of vitamin E due to the risk of causing anxiety in patients.

Curcumin inhibits inflammatory response and bone loss during experimental periodontitis in rats

Objective. Curcumin, an active ingredient of turmeric, is proved to be a potential candidate of controlling inflammation and bone resorption, but few reports are on the periodontitis. The purpose of this study was to evaluate whether the intra-gastric administration of curcumin could inhibit the inflammation and alveolar bone resorption in rats following ligature-induced experimental periodontitis. Materials and method.Male Wistar rats were randomly divided into three groups: no ligature placement and administration of vehicle, ligature placement and administration of vehicle, ligature placement and administration of curcumin. After the animals were sacrificed, their mandibles were collected for morphological, histological and immunohistochemical analysis; their gingival tissues were collected for cytokine measurements. Results. Bone resorption was significantly higher in the experimental periodontitis animals treated with vehicle compared with the curcumin-treated group or the control group. Furthermore, receptor activator of nuclear factor-κB ligand (RANKL), receptor activator of nuclear factor-κB (RANK), osteoprotegerin (OPG), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) expression levels were higher in the experimental periodontitis animals treated with vehicle compared with the curcumin treated group or the control group. Conclusions. Curcumin may decrease alveolar bone loss in the experimental periodontitis rats via suppressing the expression of RANKL/RANK/OPG and its anti-inflammatory properties.

Effect of obesity on alveolar bone loss in experimental periodontitis in Wistar rats

Obesity has been linked to higher inflammatory status and periodontal breakdown.Objective The purpose of this study was to investigate the effect of obesity on alveolar bone loss in experimental periodontitis in rats. Material and Methods Twenty-four female Wistar rats were randomly divided into two groups: obese (n=13), which were fed with "cafeteria diet" (CAF diet - high amounts of sucrose and fat) for 90 days in order to gain weight, and non-obese (n=11) regularly fed rats. Ligature-induced experimental periodontitis was created in all animals. Body weight differed statistically between obese and non-obese groups (277.59 and 223.35 g, respectively) at the moment of the ligature placement. Morphometric registration of alveolar bone loss was carried out after 30 days of ligature placement to determine the effect of obesity on the progression of experimental periodontitis. Results Intra-group comparisons showed significantly higher alveolar bone loss mean values in maxillary teeth with ligature (P<0.05). Alveolar bone loss [mean (SD), mm] was not statistically different between obese and non-obese groups [0.71 (0.09) and 0.65 (0.07) mm, respectively]. However, when palatal sides are analyzed separately, obese group presented significantly higher alveolar bone loss (P<0.05) as compared to non-obese [0.68 (0.12) and 0.53 (0.13) mm, respectively]. Conclusions In spite of the weak differences, it is possible to conclude that the progression of alveolar bone loss in ligature-induced periodontitis can be potentially influenced by body weight in rats.

Biochemical Analysis of Pentraxin 3 and Fibrinogen Levels in Experimental Periodontitis Model

Objective. Pentraxin 3 (PTX3), newly discovered inflammation marker, is a member of acute-phase proteins. The hypothesis, synthesis of gingival tissue and serum PTX-3 increases in the experimental periodontitis model (with 10-day and 40-day periods), was tested by detecting gingival tissue and serum PTX-3 levels in rats with experimental periodontitis. Methods. Thirty rats were randomly divided into three groups of ten animals each: ligature-induced experimental periodontitis groups (with 10-day (Group1) and 40-day periods (Group2)) and healthy group (Group3). At the end of experimental period, rats were sacrificed, and radiological and histomorphometric analyses were performed on the mandibles. PTX3 levels were measured in gingival tissue and serum samples using ELISA. Plasma fibrinogen levels were measured according to the nephelometric method. Results. Significant alveolar bone resorption and periodontal inflammation were evident in periodontitis groups. Levels of PTX3 in gingival tissue were statistically higher in Group 1 than those in groups 2 and 3 (P < 0.01). No significant difference was found in serum PTX3 levels between experimental periodontitis and control groups (P > 0.05). Plasma fibrinogen levels were significantly increased in the experimental periodontitis groups (P < 0.001). Conclusion. PTX3 seems to be associated with tissue destruction in earlier periods of inflammatory periodontal disease, contrary to the fibrinogen findings.

Effects of Calcium Gluconate on Experimental Periodontitis and Alveolar Bone Loss in Rats

We examined the effects of calcium gluconate, an anti-inflammatory calcium salt, on ligature-induced experimental periodontitis and related alveolar bone loss. Calcium gluconate was orally administered daily for 10 days at 250, 125 or 62.5 mg/kg, beginning 1 day after ligation. We recorded changes in body-weight and alveolar bone loss and quantified the anti-inflammatory effects of calcium gluconate by measuring levels of myeloperoxidase (MPO), IL-1β and TNF-α. We also evaluated inducible nitric oxide synthase (iNOS) activity and malondialdehyde (MDA) concentration as a measure of antioxidant effects. Ligature placement produced a marked decrease in body-weight, increased alveolar bone loss, and led to increased MPO, IL-1β, TNF-α and MDA concentrations, as well as elevated iNOS activity, increased inflammatory cell infiltration and decreased collagen fibre content in gingival tissue. Histopathology revealed decreased alveolar bone volume, increased osteoclast cell numbers and activity, and an elevated percentage of osteclasts on the alveolar bone surface. The effects of ligature placement were significantly and dose-dependently inhibited by 10 days of daily oral treatment with 250 and 125 mg/kg of calcium gluconate. The results suggest that 10 days daily oral treatment with calcium gluconate effectively inhibits ligature placement-induced periodontitis and related alveolar bone loss via antioxidant effects.

Reduction of orthodontic tooth movement by experimentally induced periodontal inflammation in mice

Orthodontic therapy is known to have an aggravating effect on the progression of destructive periodontitis if oral hygiene is not maintained. However, it is largely unknown how active periodontitis affects the velocity of orthodontic tooth movement. In this study, we examined the effect of periodontal inflammation on orthodontic tooth movement using a mouse model. Orthodontic force was applied on the maxillary first molar of mice, with or without ligature wire to induce experimental periodontitis. The distance moved by the first molar was significantly reduced by the ligature-induced experimental periodontitis. Tartrate-resistant acid phosphatase staining revealed that the number of osteoclasts present during orthodontic treatment was lower in the pressure zone of alveolar bone in the presence of periodontal inflammation. Consistently, the expression level of receptor activator of nuclear factor-kappaB ligand (RANKL) in the pressure zone was decreased in the ligature group. By contrast, experimental periodontitis increased the expression of cyclooxygenase-2 mRNA in the periodontal tissues, while in vitro treatment with prostaglandin E(2) decreased extracellular signal-regulated kinase phosphorylation and RANKL expression induced by mechanical stress in osteoblasts. Taken together, these results suggest that the orthodontic force-induced osteoclastogenesis in alveolar bone was inhibited by the accompanying periodontal inflammation, at least partly through prostaglandin E(2), resulting in reduced orthodontic tooth movement.

Effect of methotrexate on alveolar bone loss in experimental periodontitis in Wistar rats

Objective. Interleukin-1 (IL-1) and tumor necrosis factor (TNF) are pro-inflammatory cytokines directly related with tissue destruction in the pathogenesis of periodontitis. Inhibitory effects on IL-1 and TNF production have been attributed to the folate analog methotrexate. The purpose of this study was to evaluate the effect of methotrexate on the pathogenesis of alveolar bone loss in experimental periodontitis in rats. Methods. Ligature-induced experimental periodontitis was created in 44 Wistar rats. The animals were randomly divided into four groups and treated with methotrexate (0.1, 0.5, and 1.0 mg·kg−1) or saline. Morphometrical registration of alveolar bone loss was carried out after 28 days of ligature placement to determine the effect of methotrexate on the progression of experimental periodontitis. Results. Intra-group comparisons showed significantly higher alveolar bone loss mean values in maxillary sides with ligature (paired sample t-test; p<0.05). Mean alveolar bone loss was not different between groups and was independent of the dosage (range 0.63–0.67 mm, one-way ANOVA; p>0.05). Conclusion. Although methotrexate has important cytokine-inhibitory properties, its possible use in modulating the host immune-inflammatory response in periodontal disease was not confirmed.

Immune responses and vaccination against periodontal infections

The infectious aetiology of periodontitis is complex and no curative treatment modality exists. Palliative therapy is available. To review the evidence that active or passive immunization against periodontitis provides immune protection. PubMed (Medline), the National Institutes of Health, the Food and Drug Administration, and the Center for Disease Control electronic databases were searched to extrapolate information on immune responses to immunization against periodontitis. Studies in non-human primate models using ligature-induced experimental periodontitis suggest that antibody responses by active immunization against Porphyromonas gingivalis can safely be induced, enhanced, and obtained over time. Immune responses to whole bacterial cell and purified protein preparations considered as vaccine candidates have been evaluated in different animal models demonstrating that there are several valid vaccine candidates. Data suggest that immunization reduces the rate and severity of bone loss. It is also, temporarily, possible to alter the composition of the subgingival microflora. Natural active immunization by therapeutic interventions results in antibody titre enhancement and potentially improves treatment outcomes. Passive immunization of humans using P. gingivalis monoclonal antibodies temporarily prevents colonization of P. gingivalis. Probiotic therapy may be an alternative approach. Regulatory and safety issues for human periodontal vaccine trials must be considered. Shared infectious aetiology between periodontitis and systemic diseases may enhance vaccine effort developments. Proof of principle that active and passive immunization can induce protective antibody responses is given. The impact of natural immunization and passive immunization in humans should be explored and may, presently, be more feasible than active immunization studies.

Effects of Magnoliae Cortex and Zizyphi Fructus Extract Mixtures on the Progression of Experimental Periodontitis in Beagle Dogs

Periodontal disease is an inflammatory process caused by periodontopathic microorganisms in dental plaque. Numerous studies have interested in the use of antimicrobial agents to eradicate or decrease number of putative periodontal pathogenic microorganisms. Another approach has focused on the use of chemotherapeutic agents to modulate the host response. In the view of general reluctance to use antibiotics for the treatment of chronic infections with such a wide prevalence, interest has been directed largely towards the antiseptics. Most commonly used antiseptics in clinical periodontics are bisbiguanides, phenolic compounds, quaternary ammonium compounds, and etc. While these agents have been used for many years, they have exhibited many drawbacks such as tooth staining, development of resistant strains and desquamation of oral epithelium1-3). Systemic non-steroidal anti-inflammatory drugs (NSAIDs) therapy have been shown to arrest periodontal disease progression in animal models4-7) and clinical trials8-11). Although relative low dose systemic NSAIDs therapy has been successfully used to slow the rate of periodontal disease progression, its use also involves side effects such as gastrointestinal trouble12). In a previous study, it was suggested that magnolia and honokiol isolated from the stem bark of Magnolia obovate Thunb. have a significant antimicrobial activity against periodontopathic bacteria13). It was reported that Zizyphi fructus extract may prevent glucan production by cariogenic bacteria14) and prevent production of IL-1 βand PGE215, 16). This study focuses on the effect of oral administration of Magnoliae cortex and Zizyphi fructus extract mixtures on the disease progression in beagle dogs with ligature-induced experimental periodontitis.

Clinical and histological findings in ligature-induced experimental periodontitis in dogs.

Clinical and histological findings in ligature-induced experimental periodontitis in dogs.