Ligature-induced Periodontitis In Rats Research Articles

Effect of telmisartan on levels of IL‐1, TNF‐α, down‐regulated COX‐2, MMP‐2, MMP‐9 and RANKL/RANK in an experimental periodontitis model

AimThe aim of this study was to evaluate the effect of telmisartan (TELM) on inflammation, oxidation and the expression of matrix metalloproteinases (MMPs) and the expression RANKL/RANK/OPG in the periodontal tissue of a rat model for ligature-induced periodontitis.Materials and methodsMale Wistar albino rats were randomly divided into five groups of 10 rats each: (i) non-ligated, given water; (ii) ligated, given water; (iii) ligated, given 1 mg/kg TELM; (iv) ligated, given 5 mg/kg TELM; and (v) ligated, given 10 mg/kg TELM. All groups were treated with saline or TELM for 10 days. Periodontal tissue was analysed by histopathology; by the immunohistochemical examination of COX-2, MMP-2, MMP-9 and the RANKL/RANK/OPG pathway; and by ELISA analysis of the levels of IL-1β, IL-10, TNF-α, myeloperoxidase (MPO), malonaldehyde (MDA) and glutathione (GSH).ResultsTreatment with 10 mg/kg TELM resulted in reduced concentrations of MPO, MDA (p < 0.05) and the pro-inflammatory cytokine IL-1β (p < 0.05); reduced expression of MMP-2, MMP-9, RANK, RANKL and COX-2; and an increase in OPG. The levels of TNF-α were significantly reduced in all TELM-treated groups.ConclusionsThese findings confirm the involvement of TELM in reducing the inflammatory response, oxidative stress and bone loss in ligature-induced periodontitis in rats.

P17 The H2S-releasing naproxen-derivative ATB-346 inhibits alveolar bone loss and inflammation in rats with ligature-induced periodontitis

Periodontitis is the result of the extension of gingival inflammation far down the periodontium, thus damaging the structures responsible for tooth-bone insertion, which may subsequently cause tooth loss. Non-steroidal antiinflammatory drugs (NSAIDs) are widely prescribed for control of a variety of inflammatory conditions, although gastric effects limit their use. In experimental periodontitis, NSAIDs also decrease the associated alveolar bone loss. Since the addition of an H2S-releasing moiety to classical NSAIDs result in antiinflammatory compounds with improved gastric safeness [1] , we decided to compare the effects of naproxen with its H2S-releasing derivative ATB-346 (Antibe Therapeutics Inc., Canada) on ligature-induced periodontitis in rats. All animal procedures were approved by the local ICB-USP Ethics Committee. A 3–0 cotton ligature was subgingivally placed around the lower right first molar of male Wistar rats (220–250 g), previously anesthetized with ketamine and xylazine (80 mg/kg and 16 mg/kg, i.p., respectively); sham animals had the ligature removed immediately after the procedure. After ligature placement, groups of animals (n = 8) started to receive daily equimolar oral bolus doses of naproxen (10 mg/kg), ATB-346 (16 mg/kg) or vehicle (1 ml/kg of 0.5% CMC) during the following 7 days; a non-treated group was also included. After this period, the anesthetized animals were euthanized (exsanguination) and the mandibles were collected, X-rayed for alveolar bone loss measurement (distance between the cemento-enamel junction and the alveolar bone crest at the mesial face of the ligatured tooth), and prepared for histological analysis. Samples of stomach and gingiva were also collected for measurement of myeloperoxidase (MPO) activity (a marker of granulocyte infiltration) and interleukin (IL)-1β contents. Data were analyzed by one-way ANOVA followed by the Student-Neuman-Keuls test. Seven days after ligature placement, both untreated or vehicle-treated animals showed similar bone loss (0.94 ± 0.06 and 0.96 ± 0.08 mm, respectively), which was significantly inhibited by either naproxen (0.74 ± 0.06 mm, P These results show that the presence of the H2S-releasing moiety in the ATB-346 compound does not impair the effects of the parent naproxen on periodontitis, but rather prevents the occurrence of deleterious effects on the gastric mucosa due to long-term prostaglandin inhibition. Financial support: CAPES, CNPq, FAPESP.

Berberine's effect on periodontal tissue degradation by matrix metalloproteinases: an in vitro and in vivo experiment

Periodontal disease involves tissue destruction caused by interactions among bacterial antigens and inflammatory mediators including matrix metalloproteinases (MMPs). Berberine, an isoquinoline alkaloid isolated from medicinal herbs, can inhibit the degradative action of extracellular MMPs. The effect of berberine on the periodontal expression of MMPs was examined in vitro and in vivo. Gelatinolytic activity of pro-MMP-2, MMP-2, and MMP-9 in the human gingival fibroblast and/or U-937 was compared after treatment with Porphyromonas gingivalis lipopolysaccharide (P.g. LPS) in four medias containing 0, 1, 10 and 100μM of berberine each. Twelve animals were divided into three groups for the study: (A) non-ligation, (B) ligation, and (C) ligation-plus-berberine (75mg/kg berberine by gastric lavage daily); and the effect of berberine on periodontal destruction was evaluated in the ligature-induced periodontitis in rats for 8 days by micro computerized tomography (micro-CT), histology and immunohistochemistry (IHC). An enhancing effect of P.g. LPS on MMP activities was identified, with a greater effect on fibroblasts/U937 co-culture than on either culture alone. When berberine was added to the LPS-treated cultures, the activities of MMPs were significantly reduced in dose-dependent manner. In the animals, the trends of the following parameters were compared. 1. Micro-CT distances between cemento-enamel junction (CEJ) and dental alveolar bone crest: B>C>A. 2. Histometrically measured crest bone levels: B>C>A. 3. Amount of collagen deposited in tissue areas: A>C>B. 4. Attachment loss: B>C≈A. 5. Connective tissue (CT) attachment: B>either A or C. 6. Expression of cells stained positive for MMP-2 and -9 by IHC: B>C>A. In conclusion, berberine demonstrated in vitro an inhibitory effect on P.g. LPS-enhanced MMP activities of HGF and U937 macrophages, reducing in vivo gingival tissue degradation in periodontitic rats. We thus propose that berberine may slow periodontal degradation through the regulation of MMPs in periodontitis induced by bacterial plaque.

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.

Temporal expression of metalloproteinase‐8 and ‐13 and their relationships with extracellular matrix metalloproteinase inducer in the development of ligature‐induced periodontitis in rats

Matrix metalloproteinases (MMPs) play important roles in extracellular matrix degradation and may be regulated by extracellular matrix metalloproteinase inducer (EMMPRIN). The aim of this study was to investigate the temporal expression and localization of MMP-8 and MMP-13 during the development of ligature-induced periodontitis in rats, and to analyze the correlations of EMMPRIN with MMP-8 and MMP-13 in periodontitis. Periodontitis was simulated in rats by ligaturing the cervix of the lower first molars, as described in our previous method. The rats were killed 0, 3, 5, 7, 11, 15 and 21 d after ligation. Micro-computed tomography examinations were performed to detect alveolar bone loss. Semiquantitative western blotting was used to assess the temporal changes in the levels of MMP-8, MMP-13 and EMMPRIN proteins in gingival tissue. Immunohistochemistry was applied to detect the expression and locations of MMP-8 and MMP-13 in gingival tissue and alveolar bone. Alveolar bone loss showed an exponential increase from days 3 to 11, followed by a slower rate of loss at subsequent study time points. MMP-8 showed a rapid increase of expression from baseline to a peak on day 3, a gradual decrease from days 5 to 7 and then stabilized thereafter. MMP-8 was predominantly located in neutrophil-like cells. Statistically, the expression of MMP-8 was not correlated with the expression of EMMPRIN. The expression of MMP-13 and of EMMRPIN increased from days 3 to 7, and showed a moderate decrease thereafter. The immunoreactivity of MMP-13 was mainly detected in monocytes/macrophages, on the alveolar bone surface, in osteoclasts and in gingival epithelial cells. Statistically, MMP-13 had a strong, positive correlation with EMMPRIN (r = 0.855, p < 0.01). The levels of expression of MMP-8 and MMP-13 are temporally varied at different periods during the development of experimental periodontitis. The level of expression of EMMPRIN is closely associated with the expression of MMP-13, but not with the expression of MMP-8. In addition, MMP-13 might be involved in alveolar bone destruction, as well as in physiological bone remodeling.

Effect of crude extract and essential oil of Cordia verbenacea in experimental periodontitis in rats

Aim: To evaluate the effect of crude extract and essential oil of Cordia verbenacea (C.V.), systemically administered, on ligature-induced periodontitis in rats. Methods: Periodontitis was induced in 54 Wistar rats: one of the first mandibular molars was randomly assigned to receive a ligature, whereas the contralateral molar was left unligated. Then, animals were randomly assigned to one of the following groups: non-treatment group (n=18): animals that received 10 mL/day of vehicle; C.V. extract group (n=18): animals that received 100 mg/kg/day of crude extract of C. verbenacea; and C.V. essential oil group (n=18): animals that received 100 mg/kg/day of essential oils free of C. verbenacea. All therapies were administered orally 3 times daily, for 11 days. Next, the animals were sacrificed, and the specimens were processed for morphometric analysis. Bone loss was determined on the buccal surface of the lower first molars by the distance of the cementoenamel junction from the alveolar bone. Results: Both extract and essential oil of C. verbenacea orally administered decreased alveolar bone loss in the ligated teeth when compared with the non-treated group (p<0.05). Conclusions: The present study demonstrated that systemic administration of both formulations of Cordia verbenacea may attenuate the progression of ligatureinduced periodontitis.

Evaluation of the effect of an organic extract obtained from Ipomoea alba L. on experimental periodontitis in rats

The aim of this study was to evaluate the effect of an organic extract obtained from Ipomoea alba L. (Convolvulaceae or OE 1493), on experimental periodontal disease in rats. Periodontitis was induced in thirty six Wistar rats: a first mandibular molar was randomly assigned to receive a ligature, whereas the contralateral molar was left unligated. Animals were randomly assigned to two groups and treated topically, three times a day, for 11 days, as follows: Control Group - vehicle-treated (n = 18), and Test Group - OE 1493-treated (n = 18). The rats were sacrificed on the 12th day. Morphometrical measurements from the cementoenamel junction to the bone crest were performed to determine alveolar bone loss, using standardized photographs. Single- and multi-dose acute toxicity assays were carried out after OE 1493 treatment. Morphometrical analysis demonstrated that topically-administered OE 1493 showed no effect on reducing bone loss when compared with the control group (p > 0.05). In addition, OE 1493 did not present toxicity. Within the limits of this investigation, it may be concluded that OE 1493 did not show any positive influence on the progression of ligature-induced periodontitis in rats, when administered according to the regimen used in the present study.

Protective effects of ginkgo biloba extract on ligature-induced periodontitis in rats

Objective. The aim of this study was to test the hypothesis that the systemic administration of extract of Ginkgo biloba (EGb) would prevent excessive tissue destruction in ligature-induced periodontitis in a rat model. Materials and methods. Thirty-two male Wistar albino rats were used in the current study. The rats were randomly divided into four groups of eight rats each: (1) non-ligated treatment (NL) group, (2) ligature-only (LO) group, (3) ligature plus GB28 (28 mg/kg, daily for 11 days) group and (4) ligature plus GB56 (56 mg/kg, daily for 11 days) group. Results. Measurement of alveolar bone loss in the mandibular molar tooth revealed significantly lower bone loss values in the LO group compared to groups NL, GB28 and GB56 (p < 0.05). Conclusion. The present results are the first data which suggests that host response in periodontitis can be modified by EGb administration. EGb minimized progression of periodontal disease.

Effects of Forced Alcohol Intake Associated with Chronic Stress on the Severity of Periodontitis: An Animal Model Study

This study histometrically evaluated the effect of forced alcohol intake by stressed animals on the severity of ligature-induced periodontitis in rats. Thirty-two rats were randomly divided in four groups: group GAL—alcohol and ligature; group GASL—alcohol, chronic physical stress, and ligature; GNC—negative control; GPC—positive control. GAL and GASL received 20% ethanol ad libitum, and GNC received water ad libitum for 60 days. After 24 hours of exposition to alcohol intake—by GAL and GASL—immobilization was applied as a chronic stressor in the GASL group for a two-month period, six times a week, in random hours. The means of the respective groups were statistically compared (Analysis of Variance and Tukey tests, P < 0.05). The most severe periodontal breakdown was observed in nonstressed animals which drank alcohol (GAL), followed by stressed animals exposed to alcohol (GASL). GASL did not differ from the positive control group (GPC). The negative control group showed the lowest values of periodontal breakdown (P < 0.05). Conclusions. Non-stressed alcohol consumer animals showed the most severe pattern of periodontal breakdown. Although stressed animals which were forced to drink alcohol showed poorer periodontal status than the negative controls, their results were similar to those of positive controls.

Effects of two chronic stress models on ligature-induced periodontitis in Wistar rats

ObjectivesThe present study aims at comparing the effects of physical and variable chronic stress on ligature-induced periodontitis in rats. DesignForty-eight adult Wistar rats were randomly assigned to four groups (n=12): physical stress, variable stress, positive control and negative control. The models of physical stress were immobilization and immobilization associated with exposure to cold. The models of variable stress were exposure to intermittent light, 24h isolation, oral cavity examination, crowded environment, smell of blood and noise. After 10 days of physical or variable stress animals underwent experimental induction of periodontal disease in one oral side. Positive control also underwent experimental induction of periodontal disease on the 10th day. Negative control did not receive any type of intervention. At the end of the experimental period (60 days), all animals were euthanized. After routine laboratory processing, images of the histological sections were digitised and submitted to histometric measurement using two parameters: histologic attachment loss and bone loss. ResultsHistological attachment loss and bone loss were greater (p<0.05) in the physical stress group than in the other groups (variable stress, positive and negative control groups). On the non-periodontitis side, these same histological parameters did not significantly differ amongst groups. ConclusionsPhysical stress negatively modulated the response pattern to experimentally induced periodontitis in rats.

Impact of Cannabis Sativa (Marijuana) Smoke on Alveolar Bone Loss: A Histometric Study in Rats

Cannabis sativa (marijuana) can interfere with bone physiopathology because of its effect on osteoblast and osteoclast activity. However, its impact on periodontal tissues is still controversial. The present study evaluates whether marijuana smoke affects bone loss (BL) on ligature-induced periodontitis in rats. Thirty male Wistar rats were used in the study. A ligature was placed around one of the mandible first molars (ligated teeth) of each animal, and they were then randomly assigned to one of two groups: control (n = 15) or marijuana smoke inhalation ([MSI] for 8 minutes per day; n = 15). Urine samples were obtained to detect the presence of tetrahydrocannabinol. After 30 days, the animals were sacrificed and decalcified sections of the furcation area were obtained and evaluated according to the following histometric parameters: bone area (BA), bone density (BD), and BL. Tetrahydrocannabinol was positive in urine samples only for the rats of the MSI group. Non-significant differences were observed for unligated teeth from both groups regarding BL, BA, and BD (P >0.05). However, intragroup analysis showed that all ligated teeth presented BL and a lower BA and BD compared to unligated teeth (P <0.05). The intergroup evaluation of the ligated teeth showed that the MSI group presented higher BL and lower BD (P <0.05) compared to ligated teeth from the control group. Considering the limitations of this animal study, cannabis smoke may impact alveolar bone by increasing BL resulting from ligature-induced periodontitis.

Expression of suppressor of cytokine signaling 1 and 3 in ligature-induced periodontitis in rats

Objective: Evaluate expression of inducible negative regulators of JAK/STAT pathway and their target proteins during the course of ligature-induced experimental periodontal disease in rats. Design: Rats were sacrificed 07, 15 and 30days after disease induction for histological evaluation of periodontal inflammation and macroscopic analysis of alveolar bone loss. SOCS expression and the activation status of STAT1 and STAT3 were evaluated in gingival biopsies by real time PCR and Western blot. Results: Ligature-induced model presented significant progressive bone loss from 7 to 30days. Inflammation was evident and similar for 07 and 15days; however, a decrease on severity at the end of the experimental period was observed. There was a significant (p<0.05) increase on SOCS1 and SOCS3 gene expression in PD compared to control group at 15 and 30days. The SOCS1 and SOCS3 protein expression and activation of STAT1 and STAT3 were increased in earlier periods in the ligature model. Conclusion: This study suggests that SOCS1 and SOCS3 were directly correlated with regulatory mechanism of the inflammatory process responsible for the periodontal disease destruction.

Methodological model of chronic stress associated with ligature-induced periodontitis in rats: a radiographic study

This study evaluated the time efficiency of stress associated with ligature-induced periodontitis in rats. Sixty adult Wistar rats, housed in temperature-controlled rooms and receiving water and food ad libitum, were randomly separated into stress (n = 30) or control groups (n = 30). All animals were anesthetized, and nylon ligatures were placed at the gingival margin level of the maxillary right second molars. After the induction of periodontitis, rats in the stress group were subjected to physical restraint for 12 hours daily. The animals were euthanized after 7, 15 and 30 days by anesthetic overdose (10 animals per group per period). The right hemimaxillae were stored in formalin solution for 48 hours. Parallel radiographic images of the hemimaxillae were taken and processed following standard procedures. Radiographic examination was performed by a blinded and previously calibrated investigator. Bone height level was measured, and data were submitted to analysis of variance and post hoc Bonferroni tests (p < 0.05). Rats in the stress group had greater bone loss than those in the control group at 7 and 15 days post-induction (p < 0.05). After 30 days, there was no statistically significant difference between the groups (p > 0.05). Restraint stress modulates the short-term progression of periodontal disease in rats. Therefore, the 12-hour daily physical restraint stress model in rats applied for up to 15 days is suitable for the investigation of the combined effect of ligation and restraint stress on periodontal degradation.

Evidence that metyrapone in the presence of inflammation modulates cytokine mRNA expression

Objective Metyrapone (MT) has been used clinically to decrease glucocorticoid levels in human and animal studies. However, the potential effects of MT in the presence of inflammation are poorly understood. Thus, the aim of this study was to evaluate the effects of the administration of MT on the mRNA levels of pro-inflammatory cytokines in the presence of inflammation induced by the well-established model of ligature-induced periodontitis in rats. Material and methods Sixty animals were randomly assigned into three experimental groups of 20 rats each: G1-control; G2-periodontal disease (PD) induced by cotton ligature; G3-PD associated with 3 daily doses of MT (50 mg/kg/3 × 3 h). After 30 days, all animals were killed by decapitation. Blood samples were taken and the concentrations of corticosterone and catecholamines measured. Marginal tissues around ligated and non-ligated teeth were harvested and gene expression was assessed by quantitative polymerase chain reaction technique (qPCR). Moreover, the area of interradicular bone loss (ABL) was histometrically determined. Results Data analysis showed that: (i) ligature placement resulted in a significant ABL, as compared to non-ligated sites of G1 group; (ii) mRNA levels of all the pro-inflammatory factors assessed (INF-γ, TNF-α, IL-1β and IL-6) were increased in the PD group (G2) ( p < 0.05) when compared to G1; (iii) there were no significant differences in corticosterone and catecholamine plasmatic levels between the three groups; (iv) MT administration, in the presence of inflammation, induces an increased ABL and significantly increased mRNA levels of all pro-inflammatory cytokines analyzed ( p < 0.05). Conclusion Within the limits of this study, it can be concluded that MT in the presence of inflammation may modulate expression of pro-inflammatory cytokines, regardless of its effect on plasma corticosterone levels.

Effect of nifedipine on gingival enlargement and periodontal breakdown in ligature-induced periodontitis in rats

Objective A recent consensus report could not find specific reports of the effect of nifedipine on the destruction of the periodontal tissues. The aim of the present study was to evaluate the effect of nifedipine on gingival enlargement and periodontal breakdown using a ligature-induced periodontitis in rats. Materials and methods Fifty, male, 60 days old, Wistar rats, were divided into six groups. Cotton sutures were placed around the upper second molars. Two groups of 10 rats each did not receive ligatures and were treated daily with either saline solution or nifedipine 50 mg/kg/day. Two groups of 10 rats received ligatures and were also treated daily with saline solution or nifedipine 50 mg/kg/day. Two additional groups (nifedipine 10 and 100 mg/kg/day) were included to explore a possible dose–response relationship. Animals were euthanatised at 30 days. Internal and oral epithelium, total and inflamed connective tissue, gingival thickness and height, and bone loss were assessed histologically. Results Nifedipine alone was not sufficient to promote gingival enlargement or periodontal destruction in the absence of the ligature. Compared to animals with ligatures only, the group that received ligatures and nifedipine 50 mg/kg/day showed significant higher estimates for total and inflamed connective tissue, gingival thickness and height. No significant differences were observed for bone loss between these experimental groups. The other dosages of nifedipine did not provide additional information. Conclusion Nifedipine itself did not lead to gingival enlargement in rats. In the presence of biofilm accumulation, nifedipine yielded greater gingival enlargement and periodontal inflammation, but it did not increase periodontal destruction.

Anti-NGF Treatment Reduces Bone Resorption in Periodontitis

Periodontitis is characterized by periodontal tissue destruction, including the alveolar bone. One of its critical components is the release of pro-inflammatory neuropeptides from sensory nerve endings innervating the periodontium. Since nerve growth factor (NGF) has been reported to up-regulate neuropeptides in sensory neurons, we hypothesized that it would be increased in ligature-induced periodontitis in rats, and that systemic NGF neutralization would reduce the periodontitis-associated alveolar bone resorption. Real-time PCR analysis disclosed a statistically significant time-dependent up-regulation of NGF mRNA in gingiva during 2 weeks of periodontitis. Interestingly, NGF up-regulation was also detected in the contralateral gingiva. In addition, immunohistochemistry of trigeminal ganglion neurons innervating the gingivomucosa demonstrated increased expression of TrkA receptor for NGF. Systemic anti-NGF treatment during periodontitis significantly reduced interleukin-1β expression in gingiva and bilateral alveolar bone resorption. This suggests that NGF promotes periodontal inflammation and implicates a possible use of anti-NGF treatment in periodontitis.

Microbial profile of ligature-induced periodontitis in rats

Objective The aim of this study was to evaluate the composition of the biofilm accumulated around ligatures in rats by checkerboard DNA–DNA hybridization using probes made from human oral bacterial species. Methods 12 Wistar rats were selected for this study. One of the mandibular first molars of each animal received a ligature, while the contralateral tooth was left unligated to be used as a control. Forty-two days later, the ligatures and one sample of biofilm from each unligated teeth were analyzed by checkerboard DNA–DNA hybridization for 40 human periodontal species. The area of bone loss in the furcation area was determined histometrically. Results The unligated teeth did not present any of the bacterial species tested. Twenty five species were detected in the ligatures. Streptococcus- and Actinomyces-like species were found in high mean counts, followed by Fusobacterium-, Prevotella nigrescens- and Parvimonas micra-like species and Porphyromonas gingivalis- and Aggregatibacter actinomycetemcomitans-like species. Greater bone loss was observed in the furcation area of the ligated than of the unligated group ( p < 0.0001). Conclusion At 42 days, the ligature biofilm in rats presents various bacterial species that hybridize to probes of periodontal bacterial species commonly observed in human.

Influence of alcohol consumption on alveolar bone level associated with ligature-induced periodontitis in rats

Alcohol consumption is a risk indicator for periodontal disease. The purpose of this study was to morphometrically evaluate the influence of alcohol consumption on alveolar bone level associated with ligature-induced periodontitis in rats. Thirty-six female rats (Wistar, 120 days-old) were randomly divided into three groups that received a daily administration of a water diet (control, n = 12), a 10% alcohol diet (10% ethanol, n = 12) or a 20% alcohol diet (20% ethanol, n = 12). Four weeks after the onset of the experiment, cotton ligatures were placed around the cervix of the upper right second molar in six rats. The other 6 rats in each group remained unligated. The rats were sacrificed four weeks after ligature placement. The maxillary bones were removed and alveolar bone loss was analyzed by measuring the distance between the cementoenamel junction and the alveolar bone crest at 2 buccal and 2 palatal sites on the upper right second molar. Analyses between the ligated and unligated groups showed that the presence of ligature induced alveolar bone loss (p < 0.05). Unligated groups showed no significant differences between each other (p > 0.05). In the ligated groups, rats receiving 20% ethanol showed significantly greater bone loss compared to control rats or rats receiving 10% ethanol. These results demonstrate that alcohol consumption may increase alveolar bone loss in female rats in a dose-dependent manner.

Effect of neonatal clomipramine in the pathogenesis of ligature-induced periodontitis in Lewis rats

Objective. The aim of this study was to verify the association between an endogenous depression model and the development of ligature-induced periodontitis in rats. Material and methods. Nine male Lewis rats received 30 mg/kg clomipramine from neonatal day 8 to day 21 (depressed group), while 13 control Lewis rats were left untouched (control group). On day 150, ligatures were placed around the 2nd upper molars in both groups, i.e. the contralateral molar of the intra-group control. On day 190, the rats were killed and the maxillae were defleshed. The distance between the cemento-enamel junction and the alveolar bone crest was measured by a blinded examiner using standardized digital photographs. Results. The depressed rats showed hyperactivity in open field on day 142 and greater attempts to escape on day 143 compared to controls. The other behavioral data did not show statistically significant differences between the groups (Mann-Whitney, p>0.05). In teeth with ligature, mean alveolar bone loss varied from 0.51 to 0.60 and from 0.63 to 0.64 mm for tests and controls, respectively (t-test, p>0.05). In teeth without ligature, these values varied from 0.38 to 0.43 and 0.42 to 0.45 mm in the test and control groups, respectively (t-test, p>0.05). Conclusion. Induced depression did not alter ligature-induced bone loss in Lewis rats.

Administration of High Doses of Caffeine Increases Alveolar Bone Loss in Ligature‐Induced Periodontitis in Rats

Although some studies have reported a negative influence of caffeine on bone metabolism, there is no information about its effect on the progression of periodontitis. The aim of this study was to evaluate the effect of high doses of caffeine on ligature-induced periodontitis in rats. Twenty-two Wistar rats were assigned to one of the following groups: non-caffeine group (n = 12) = animals without caffeine ingestion; caffeine group (n = 10) = animals ingesting 10 mg/100 g body weight/day of caffeine via drinking water for 56 days. Two weeks after the beginning of caffeine intake, one of the mandibular molar was randomly assigned to receive a ligature, whereas the contralateral molar was left unligated. Forty-two days later, the animals were sacrificed, and the specimens were processed to obtain decalcified sections. The area of periodontal ligament and/or bone loss in the furcation region of the first molars was histometrically determined. Caffeine intake did not have a direct effect on the alveolar bone loss in unligated teeth. But on the ligated tooth, a greater area of bone loss was observed in the animals that ingested caffeine compared to those that did not (P <0.05). The present study demonstrated that daily intake of high doses of caffeine may enhance ligature-induced periodontitis progression.