Induction Of Experimental Periodontitis Research Articles

Effects of Coriander on the Repair Process of Experimentally-induced Periodontitis in Rats.

The aim of this study was to evaluate the effects of Coriandrum sativum L. (CSL) seed extract on gingival levels of antioxidant enzymes, pro-inflammatory cytokines and on alveolar bone and attachment levels after experimental periodontitis induction in rats and compare it with low-dose doxycycline (LDD). Forty adult male Wistar Albino rats were divided randomly into 5 groups as follows: 1 = periodontally healthy (control); 2 = periodontitis; 3 = periodontitis + CSL (32 mg/kg); 4 = periodontitis + CSL (200 mg/kg); and 5 = periodontitis + LDD (6 mg/kg). Gingival superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) levels were evaluated by enzyme-linked immunosorbent assay. The presence of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1βeta (IL-1β) immunoreactivity was detected immunohistochemically. Alveolar bone area in the furcation space (ABA), alveolar bone loss (ABL), and attachment loss (AL) were evaluated histomorphometrically. The SOD level was lower in group 5 than in groups 2, 3, and 4. The IL-1β level was highest in group 4. The TNF-α level was statistically higher in groups 2 and 4 than in groups 1, 3, and 5. The IL-6 level was highest in group 4. Its level was higher in groups 2 and 3 than in group 5. ABA was less in groups 2, 3, and 4 compared to groups 1 and 5. ABL was less in group 5 than in groups 2, 3, and 4. AL was greater in group 4 than in group 5. The use of 200 mg/kg CSL showed a pro-inflammatory effect and IL-1β and TNF-α levels decreased after 32 mg/kg CSL application in the treatment of periodontitis.

Sodium alendronate is an effective adjunctive therapy for treating periodontitis in male rats treated with anticancer chemotherapy

ObjectivesTo assess sodium alendronate as a local adjunctive therapy for treating experimental periodontitis in male rats treated with chemotherapy. DesignOne-hundred-eighty male rats were randomly divided into two groups (n = 90) based on the systemic treatments: PSS, physiological saline solution; and 5-Fluorouracil, and then, subdivided into three subgroups (n = 30): NT, no treatment; scaling and root planing; and sodium alendronate. Treatments were performed 7 days after induction of experimental periodontitis. Specimens were collected at 14, 22, and 37 days after induction. Alveolar bone level, percentage of bone in the furcation, percentage of non-vital bone in the furcation, histopathologic features, and immunolabeling pattern for tartrate-resistant acid phosphatase (TRAP) and osteocalcin (OCN) were evaluated. ResultsThe lowest amount of alveolar bone and highest amount of non-vital bone was found in group 5-Fluorouracil when no treatment was performed. In animals receiving 5-Flurouracil and subjected to periodontal treatment, adjunctive sodium alendronate resulted in higher percentage of bone in the furcation and higher alveolar bone loss, when compared with scaling and root planing alone. Better structural and cellularity patterns were found in the periodontal tissues when sodium alendronate was used, regardless of systemic treatment. Higher TRAP-expression was found when no treatment was performed. Sodium alendronate didn’t affect the immunolabeling pattern of osteocalcin in the presence of 5-Fluorouracil. ConclusionAdjunctive therapy with local sodium alendronate prevented alveolar bone loss and improved the histopathological features of the periodontal tissues following scaling and root planing in male rats with experimental periodontitis receiving anticancer chemotherapy with 5-Fluorouracil.

Initial Development of an Immediate Implantation Model in Rats and Assessing the Prognostic Impact of Periodontitis on Immediate Implantation.

To establish an immediate implantation rat model and to evaluate the effects of pre-existing periodontitis and two different socket rinse solutions on immediate implantation prognosis. Sprague-Dawley (SD) rats were randomly divided into three groups before immediate implantation, including the control group, the group with experimentally induced periodontitis (EP), in which rats have been experimentally induced periodontitis before implantation, and the group with induced periodontitis and with extraction sockets rinsed with three percent H2O2 (EP-H2O2), in which rats have been induced periodontitis before implantation, and extraction sockets were rinsed with three percent H2O2. Periodontitis was induced by ligating the thread around the molars for four weeks. Six weeks after titanium alloy implants were self-tapped and left to heal transmucosally, maxillae were dissected after the clinical examination to perform micro-CT and histological analysis. An immediate implantation model was successfully built in rats. There was no significant difference in implant survival rates between the EP and control groups. However, the clinical examination results, micro-CT analysis, and histological analysis in EP and EP-H2O2 groups showed a significantly worse prognosis than in the control group. Three percent H2O2 showed a similar effect with saline. This study presented a protocol for establishing a rat immediate implantation model and showed that periodontitis history might negatively affect the prognosis of immediate implantation. These findings urge caution and alternative strategies for patients with periodontal disease history, enhancing the long-term success of immediate implantation in dental practice. Additionally, the comparable outcomes between 3% H2O2 and saline suggest the use of saline as a cost-effective and safer alternative for implant site preparation in dental practice.

The ameliorating role of epithelial cell rests of Malassez in the alleviation of experimentally-induced periodontitis in rats

ObjectiveThe present study aimed to investigate the effect of experimentally-induced periodontitis on epithelial cell rests of Malassez (ERM) distribution and its subsequent role in regenerating periodontal ligament (PDL). Design: The study included 60 rats, aged seven months, randomly and equally divided into two groups: Group I, the control group, and Group II, the experimental group, in which ligature-periodontitis was induced. Ten rats from each group were euthanized at 1, 2, and 4 weeks. For ERM detection, specimens were processed for histological and immunohistochemical examination of cytokeratin-14. Additionally, specimens were prepared for the transmission electron microscope. Results: Group I demonstrated well-organized PDL fibers with few ERM clumps close to the cervical root portion. In contrast, one week after periodontitis induction, Group II showed marked degeneration, a damaged cluster of ERM cells, narrowing of the PDL space, and early signs of PDL hyalinization. After two weeks, a disorganized PDL was observed with the detection of small ERM clumps enclosing very few cells. After four weeks, PDL fibers were reorganized, and ERM clusters increased significantly. Notably, ERM cells were positive for CK14 in all groups. Conclusion: Early-stage ERM may be affected by periodontitis. However, ERM is capable of recovering its putative role in PDL maintenance.

In Vitro and In Vivo Characterisation of a Mucoadhesive Buccal Film Loaded with Doxycycline Hyclate for Topical Application in Periodontitis

Mucoadhesive films loaded with doxycycline hyclate (Doxy Hyc), consisting of mixtures of hydroxypropylmethyl cellulose (HPMC) E3, K4 and polyacrylic acid (Carbopol 940), were prepared by casting method, aiming to design a formulation intended for application in the oral cavity. The obtained film formulations exhibited a Doxy Hyc content between 7.52 ± 0.42 and 7.83 ± 0.41%, which had adequate mechanical properties for application in the oral cavity and pH values in the tolerance range. The x-ray diffraction studies highlighted the amorphisation of Doxy Hyc in the preparation process and the antibiotic particles present on the surface of the films, identified in the TEM images, which ensured a burst release effect in the first 15 min of the in vitro dissolution studies, after which Doxy Hyc was released by diffusion, the data presenting a good correlation with the Peppas model, n < 0.5. The formulation F1, consisting of HPMC K4 combined with C940 in a ratio of 5:3, the most performing in vitro, was tested in vivo in experimentally-induced periodontitis and demonstrated its effectiveness in improving the clinical parameters and reducing the salivary levels of matrix metalloproteinase-8 (MMP-8). The prepared Doxy Hyc loaded mucoadhesive buccal film could be used as an adjuvant for the local treatment of periodontitis, ensuring prolonged release of the antibiotic after topical application.

Effects of adjacent periodontitis on osseointegrated dental implants.

This study aimed to investigate whether new-onset periodontitis or apical periodontitis in the adjacent teeth affects osseointegrated dental implants in a beagle dog model. One control group and 2 experimental groups (periodontitis and apical periodontitis groups) were defined based on the presence of experimental periodontitis or apical periodontitis, with 1 beagle dog randomly assigned to each group. The mandibular second and fourth premolars on both sides of the 3 beagles were extracted. Eight weeks after extraction, 4 bone-level implant fixtures, 2 on both sides of each mandible, were placed in each beagle. Six weeks after implant surgery, healing abutments were connected. After sufficient osseointegration, plaque control was performed in the control group, while periodontitis and apical periodontitis were induced in the experimental groups. The beagles were euthanized for histological analyses 20 weeks after induction of experimental periodontitis. Statistical analyses were performed using the Kruskal-Wallis test with the Bonferroni correction to compare the 3 groups. The implants in the control and apical periodontitis groups were well-maintained, while those in the periodontitis group showed clinical signs of inflammation with bone resorption. The bone-to-implant contact (BIC) and bone area values in the periodontitis group were lower than those in the other groups. The distance between the implant shoulder and the first BIC was significantly greater in the periodontitis group than in the control group (P<0.05). The presence of periodontitis in adjacent teeth can pose a risk to dental implants, potentially resulting in peri-implantitis. However, this was not observed for apical periodontitis. Within the limitations of this study, periodontal care is necessary to reduce the impact of periodontitis in adjacent teeth on osseointegrated implants.

Probiotic Lactobacillus rhamnosus EM1107 prevents hyperglycemia, alveolar bone loss, and inflammation in a rat model of diabetes and periodontitis.

This study evaluated the antihyperglycemic, anti-bone-resorptive, and anti-inflammatory efficacy of the probiotic Lactobacillus rhamnosus EM1107 in an experimental model of ligature-induced periodontitis in diabetic rats treated with metformin (Met). A total of 114 male Wistar rats was randomly divided into six groups: (1) control, (2) experimental periodontitis (EP), (3) EP + diabetes mellitus (DM), (4) EP + probiotic (Prob), (5) EP + DM + Prob, and (6) EP + DM + Prob + Met. The animals received probiotic gavage during the 30 days of the experiment. DM was induced on the 14th day of the experiment with a single injection of streptozotocin into the penile vein, followed by ligature for EP induction and Met gavage on the 19th day and euthanasia on the 30th day. Heart blood, gingival and periodontal tissue, and hemimaxillae were collected. Biomolecular analysis, immunoenzymatic assays, histomorphology, and microtomographic analysis were performed. Data were statistically analyzed (p<0.05). There was a significant reduction in interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in the Prob groups (p<0.05) as well as in blood glucose levels in the Prob and Met groups (p<0.001). In addition, histomorphological analysis revealed that the Prob groups had a reduction in inflammatory infiltrate. Tartrate-resistant acid phosphatase (TRAP) and microtomographic analyses showed that the EP/DM/Prob/Met group had significantly lower linear and volumetric bone loss than those who had no treatment (p<0.01). SOD and GPx immunostaining decreased in all groups receiving probiotics. The findings suggest the immunoinflammatory efficacy of the probiotic L. rhamnosus EM1107 administered either alone or in association with Met in type 1 DM associated with periodontitis.

Healing effects of monomer and dimer resveratrol in a mouse periodontitis model

BackgroundThe antioxidant and anti-inflammatory effects of resveratrol have been reported previously. Particularly, monomeric trans-resveratrol has been demonstrated to produce positive effects in various pathological processes. We reported previously that resveratrol dimer-rich melinjo extract, among others, caused bone healing, decreased local oxidative damage, and activated antioxidants nuclear factor erythroid 2-related factor 2 (Nrf2) pathways in a mouse model of experimentally induced periodontitis (EP). This study aimed to compare the bone-healing effects of the resveratrol monomer to the resveratrol dimer (gnetin C found in melinjo seed extract) in a model of EP and investigate the involvement of Nrf2 for effects of either form of resveratrol.MethodsEP was induced experimentally in mice by placement of a 9 − 0 silk ligature around the left second molar. Mice received 10 mg/kg of either resveratrol monomer or dimer intraperitoneally on day 15 after induction of EP. The bone level around the ligated teeth was measured over time, and levels of proinflammatory cytokines and oxidative stress were measured in the periodontal tissues around the ligated teeth.ResultsResveratrol dimer induced greater periodontal bone healing as compared to that related to use of the resveratrol monomer. It appears that healing of periodontal bone in either group was likely related to master regulation of antioxidant nuclear factor erythroid 2-related factor 2 (Nrf2) significantly. Downregulation of IL-1β, a proinflammatory cytokine was also demonstrated in the resveratrol dimer group.ConclusionOur results showed that administration of resveratrol in either dimer form or the monomeric form reduced periodontal bone loss with greater inhibition of bone loss being demonstrated in the dimer group as compared to the monomer group and that these effects were related in all likelihood to decreased oxidative stress and hence reduction in local inflammation.

Experimental Periodontitis Deteriorates Cognitive Function and Impairs Insulin Signaling in a Streptozotocin-Induced Alzheimer's Disease Rat Model.

With advancements in periodontal medicine, the relationship between periodontitis and systemic diseases has garnered increasing attention. Recently, emerging evidence has indicated that periodontitis may be involved in the pathogenesis of Alzheimer's disease (AD). To assess the impact of experimental periodontitis on cognitive function deficits in a rat model of streptozotocin-induced AD and determine the mechanisms underlying these effects. Rats were randomly assigned to the control (C), experimental periodontitis (P), Alzheimer's disease (AD), and experimental periodontitis with streptozotocin-induced AD (AD-P) groups. Experimental periodontitis was induced using ligation and coating with Porphyromonas gingivalis. In the AD-P group, AD was induced by intracerebroventricular injection of streptozotocin after 6 weeks of experimental periodontitis induction. Compared with the group C rats, those in group P exhibited alveolar bone resorption, learning and memory function impairment, and decreased insulin sensitivity and insulin signaling-related protein expression. Glial cell activation and cognitive impairment in streptozotocin-induced groups with significantly increased phosphorylated tau levels were more pronounced relative to the C group. The number of neurons and insulin sensitivity and insulin signaling-related protein expression in group AD-P rats were lower than those in the AD alone group, while the expressions of glial fibrillary acidic protein, tau phosphorylation, interleukin-6, and cyclooxygenase-2 were significantly increased. Periodontitis may be a risk factor exacerbating cognitive deficits in an AD-like neurodegenerative context, possibly by impairing the insulin signaling pathway and stimulating gliosis and neuroinflammation.

Periodontitis promotes the expression of gingival transmembrane serine protease 2 (TMPRSS2), a priming protease for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

ObjectivesThe oral cavity is one of the main entry sites for SARS-CoV-2. Gingival keratinocytes express transmembrane serine protease 2 (TMPRSS2), responsible for priming the SARS-CoV-2 spike protein. We investigated whether periodontitis increased the expression of TMPRSS2. MethodsTo investigate gene expression in periodontitis, we analyzed the expression of specific genes from (1) the Gene Expression Omnibus (GEO) dataset of 247 human gingival tissues and (2) an experimentally-induced periodontitis mouse model. Human gingival tissues with or without periodontitis were immunohistochemically stained using an anti-TMPRSS2 antibody. Analysis of the TMPRSS2 promoter was performed using a ChIP-Atlas dataset. TMPRSS2 expression was detected in cultured human keratinocytes using quantitative reverse transcription (qRT)-PCR and Western blot analysis. ResultsGEO dataset analysis and an experimentally-induced periodontitis model revealed increased expression of TMPRSS2 in periodontitis gingiva. The keratinocyte cell membrane in periodontitis gingiva was strongly immunohistochemically stained for TMPRSS2. Using ChIP-Atlas and GEO datasets, we screened for transcription factors that bind to the TMPRSS2 promoter region. We found one candidate, estrogen receptor 1 (ESR1), highly expressed in periodontitis gingiva. Analysis of the GEO dataset revealed a correlation between ESR1 and TMPRSS2 expression in gingival tissues. An ESR1 ligand induced TMPRSS2 expression in cultured keratinocytes. ConclusionsPeriodontitis increases TMPRSS2 expression in the cell membrane of gingival keratinocytes.

Effect of systemic administration of silver nanoparticles in treatment of experimental periodontitis in albino rats

ABSTRACTIntroduction: Periodontal disease is one of the main dental diseases that affectmillions of people around the world. Modern nanotechnology progression andrenovations through nanodentistry providing a suitable solution for the treatment of manydental illnesses including periodontal disease. Aim: Histological and ultrastructuralevaluation of the effect of silver nanoparticles in treatment of periodontitis in albinorats. Materials and methods: A total of 18 adults male albino rats with body weightranging from 150 to 180 gm were used and divided into three groups group 1: served ascontrol, group 2: used for induction of experimental periodontitis using wiring aroundthe cervix of mandibular central incisors for two weeks, and group 3: after induction ofexperimental periodontitis as in group 2 they were subjected to intraperitoneal injectionwith silver nanoparticles for the treatment of periodontitis three times per week for fourweeks. Results: Histological and ultrastructural investigation revealed that periodontalligament around ligated mandibular incisors showed marked improvement in thedegenerated fibers after injection with silver nanoparticles in group 3 compared togroup 2 as the fibers regained their association in strong bundles and they regained theirattachment to regenerated bone and tooth surface. Conclusions: Marked regenerationof the periodontium of periodontally affected ligated mandibular incisors reflected thatsilver nanoparticles have a great anti-inflammatory effect

Development of experimentally-induced periodontitis in a Sprague Dawley rat model

Periodontitis is a common inflammatory disease that leads to the degradation of periodontium and results in alveolar bone loss. The development of a suitable animal model of periodontitis is a prerequisite to understanding better the mechanisms that underly this disease. This study evaluated periodontal disease induction via retentive ligature, intragingival injection of lipopolysaccharide (LPS), and their combination in a rat model.Seventy-two Sprague Dawley rats were divided into four groups. The first group (control) did not receive any treatment. The second group underwent the application of 4/0 nylon ligature around the second maxillary molars. The third group was treated with an intragingival injection of Porphyromonas gingivalis LPS into the palatal mucosa of the second maxilla molars, and the fourth group was treated with a combination of ligature and LPS injection (ligature-LPS). Morphological changes in the gingival tissues were evaluated after 7, 14, and 30 days of treatment.Significant degenerative changes were observed in the periodontal tissues and alveolar bone in the third and fourth groups, which were evident as early as seven days. The lesions remained until 14 days and declined with time in the third and fourth groups. The changes induced by ligature and ligature-LPS were not different. Injection with LPS alone resulted in minimal increases in the Gingival and Plaque Indices.The ligature technique induced periodontal disease successfully, more effective than the injection of LPS. The combination of ligature with LPS injection added no significant effect compared to ligature alone.

Milk Kefir therapy reduces inflammation and alveolar bone loss on periodontitis in rats

Periodontitis is a chronic inflammatory disease that affects the tooth-supporting tissues. This study evaluated the anti-inflammatory and antiresorptive effects of milk kefir (MK) on periodontitis in rats. Micro-Raman spectroscopy was performed on MK at different fermentation times to verify the presence of Lactobacillus kefiri. From these results, Wistar rats were divided into the following groups: C (Control); EP (experimental periodontitis); K1 (animals that received MK with one day of fermentation); K1+EP; K4 (animals without EP using MK with four days of fermentation) and K4+EP. MK was administered 28 days before EP induction and during the disease development period (11 days). On day 28, in the EP groups, periodontitis was induced. The animals were euthanized on day 39. The hemimaxillae were removed and the following parameters were evaluated: micro-Raman analysis of the presence of inflammation; histomorphometric analysis to quantify alveolar bone loss and immunohistochemistry for IL-6, TNF-α, IL-Iβ and IL-10 in the periodontal ligament. Micro-Raman analysis showed that four days fermentation MK has a higher intensity spectrum of L. kefiri. Furthermore, the administration of this probiotic reduced the intensity of the inflammation spectrum when compared to one day fermentation MK. It was observed that the animals from the K4+EP group showed significant reduction of alveolar bone loss, as well as a lower IL-6, TNF-α and IL-Iβ immunoexpression and a higher IL-10 immunoexpression, when compared to EP groups. We conclude that MK has anti-inflammatory and antiresorptive effects on periodontitis in rats and that these effects are fermentation time dependent.

Inhibition of experimental periodontitis by a monoclonal antibody against Porphyromonas gingivalis HA2

It is known that complexes of the multi-protein, gingipain, possess heme binding domains (hemagglutinin 2, HA2) that bind hemoglobin to provide heme and iron to the bacterium, Porphyromonas gingivalis. The DHYAVMISK peptide sequence was proposed to act as an inhibitor of hemin binding, and thus, it might be used to control or prevent periodontal disease. In this study, we created a monoclonal antibody (mAb) that targeted the DHYAVMISK peptide, aimed to determine whether it could inhibit the growth of P. gingivalis in vitro, and block its induction of experimental periodontitis and subsequent bone loss. Peptide DGFPG-DHYAVMISK conjugated to KLH (DK-KLH) was synthetic, and injected subcutaneously into BALB/c mice to generate specific mAbs with the hybridoma technique. We isolated mAb 1H11, which showed specific binding to DK. When we incubated these mAbs with P. gingivalis in vitro for 18 h, bacterial growth was significantly lower in cultures treated with mAb 1H11 compared to those treated with control (PBS; P < 0.05). Next, we induced experimental periodontitis in mouse models with a silk ligature and a P. gingivalis infection. When we injected the mAbs into the gingival sulcus, the group treated with mAb 1H11 displayed a reduction in bone loss compared to the other treatment groups. Thus, mAb 1H11 might provide protection against a P. gingivalis infection. Accordingly, this antibody could serve as a candidate therapy for periodontitis or other infections caused by P. gingivalis.

Effect of caloric restriction on alveolar bone loss in rats

AimsRecent research suggests an association between longevity, caloric restriction (CR) and reduction of chronic inflammatory diseases, such as periodontitis. Currently, the mechanisms related to the effects of CR are not yet fully understood. In the present study, we aimed to evaluate the effects of caloric restriction on alveolar bone loss (ABL) in Wistar rats with experimental periodontitis. Main methodsThe impact of CR on biometric data, clinical periodontal parameters, serum biomarkers and biochemical parameters were also investigated. The experimental protocol lasted 24 weeks. The CR rats were fed for 12 weeks with 70% of the standard food compared to the animals with ad libitum diet. Experimental periodontitis was induced in Wistar rats during 15 days before the end of the experiment. The animals were divided into four experimental groups (n = 12 animals/group), according to the presence or absence of caloric restriction and ligature-induced periodontitis. Hemimandibles were used to assess ABL. Key findingsThe groups with experimental periodontitis induction showed a significant decrease on alveolar bone loss in animals submitted to caloric restriction, in addition to attenuating gingival inflammation, demonstrated by the significant difference in gingival index. Biochemical and biometric data showed a significant reduction in the glycemic profile, body weight, adiposity index and abdominal circumference after caloric restriction. Caloric restriction did not significantly alter bone tissue biomarkers. SignificanceAccording to the findings, caloric restriction reduced alveolar bone loss, glycemic profile and biometric parameters in rats with experimental periodontitis.

Influence of systemic strontium ranelate on the progression and as adjunctive therapy for the nonsurgical treatment of experimental periodontitis.

BackgroundStrontium Ranelate (SR) presents overlapping osteoanabolic and anti-resorptive activity. However, the effects of SR on the progression of periodontitis through the alveolar bone and its potential applicability as adjunctive therapy to scaling and root planning remain poorly accessed. The aim of this study was to evaluate the effects of systemic (SR) both on the progression of experimental periodontitis (EP) and as adjunctive therapy to SRP. Material and MethodsEighty male rats were divided into four groups (n=20): EP-PSS: EP induction and systemic administration of physiological saline solution (PSS); EP-SR: EP induction and systemic administration of SR; EP-SRP/PSS: EP induction, SRP and systemic administration of PSS; EP-SRP/SR: EP induction, SRP and systemic administration of SR. Seven days after ligature placement, SRP was performed in EP-SRP/PSS and EP-SRP/SR, as well as the systemic administration of either PSS or SR were initiated and continued until euthanasia in all groups. Animals were euthanized at 7 and 30 days after the beginning of the systemic treatments. Histological, histometric (percentage of bone in the furcation [PBF]) and immunohistochemical (tartrate-resistant acid phosphatase [TRAP], Osteocalcin [OCN] and leukocyte common antigen [CD 45]) analyses were performed. Data were statistically analyzed. ResultsEP-SRP/PSS showed a significantly more organized pattern of the connective tissue and alveolar bone structure than EP-SRP/SR. EP-SR showed significantly higher PBF than EP-PSS, however, EP-SRP/PSS showed no difference with EP-SRP/SR at 30 days. ConclusionsSR reduced the alveolar bone loss in non-treated animals and presented no standout benefits over the conventional forms of treating EP. Key words:Strontium Ranelate, periodontal disease, root planing, alveolar bone loss.

The effects of zoledronic acid on the progression of experimental periodontitis in rats: histological and microtomographic analyses

PurposePeriodontitis is considered a local risk factor for medication-related osteonecrosis of the jaws (MRONJ). However, little is known about the progression of periodontitis in the presence of zoledronic acid (ZOL). The aim of this study was to evaluate the effects of the systemic use of ZOL on the progression of experimental periodontitis (EP) in rats, as ZOL could modulate the progression of periodontitis and concomitantly cause MRONJ in individuals with periodontitis.MethodsForty-eight male Wistar rats were randomly distributed in 6 groups (n=8 each). To induce EP, ligatures were placed around the right first mandibular molars. Three groups were treated with ZOL (0.15 mg/kg/week, intraperitoneal), and 3 with 0.9% saline solution (controls). In the ZOL/Lig30 and ZOL/Lig 15 groups, after 4 weeks of treatment with ZOL, EP was induced and euthanasia was performed after 30 and 15 days of EP induction, respectively. In both groups, the animals continued to receive ZOL after EP until the end of the experiment. In the Lig/ZOL group, EP was induced first, and 15 days later, ZOL was administered for 8 weeks, with euthanasia 1 week after the last dose. After euthanasia, the mandibles were evaluated using micro-computed microtomography (micro-CT) and histomorphometry. Bone loss was measured, and the presence of osteonecrosis was evaluated histologically. The data were evaluated using the Student t-test and the Mann-Whitney test, with a significance level of 5%.ResultsIn the Lig/ZOL group, micro-CT revealed less alveolar bone resorption in the distal root (P<0.01) than in the control group (Lig/Con). Histomorphometric analysis confirmed less alveolar bone resorption in the Lig/ZOL group (P=0.001). Histologically, osteonecrosis was more common in the ZOL groups.ConclusionZOL decreased alveolar bone resorption in rats with EP. However, it presented a higher risk for MRONJ.

O-Polysaccharide Plays a Major Role on the Virulence and Immunostimulatory Potential of Aggregatibacter actinomycetemcomitans During Periodontal Infection.

Aggregatibacter actinomycetemcomitans is a Gram-negative oral bacterium with high immunostimulatory and pathogenic potential involved in the onset and progression of periodontitis, a chronic disease characterized by aberrant immune responses followed by tooth-supporting bone resorption, which eventually leads to tooth loss. While several studies have provided evidence related to the virulence factors of A. actinomycetemcomitans involved in the host cell death and immune evasion, such as its most studied primate-specific virulence factor, leukotoxin, the role of specific lipopolysaccharide (LPS) domains remain poorly understood. Here, we analyzed the role of the immunodominant domain of the LPS of A. actinomycetemcomitans termed O-polysaccharide (O-PS), which differentiates the distinct bacterial serotypes based on its antigenicity. To determine the role of the O-PS in the immunogenicity and virulence of A. actinomycetemcomitans during periodontitis, we analyzed the in vivo and in vitro effect of an O-PS-defective transposon mutant serotype b strain, characterized by the deletion of the rmlC gene encoding the α-L-rhamnose sugar biosynthetic enzyme. Induction of experimental periodontitis using the O-PS-defective rmlC mutant strain resulted in lower tooth-supporting bone resorption, infiltration of Th1, Th17, and Th22 lymphocytes, and expression of Ahr, Il1b, Il17, Il23, Tlr4, and RANKL (Tnfsf11) in the periodontal lesions as compared with the wild-type A. actinomycetemcomitans strain. In addition, the O-PS-defective rmlC mutant strain led to impaired activation of antigen-presenting cells, with less expression of the co-stimulatory molecules CD40 and CD80 in B lymphocytes and dendritic cells, and downregulated expression of Tnfa and Il1b in splenocytes. In conclusion, these data demonstrate that the O-PS from the serotype b of A. actinomycetemcomitans plays a key role in the capacity of the bacterium to prime oral innate and adaptive immune responses, by triggering the Th1 and Th17-driven tooth-supporting bone resorption during periodontitis.

Chronic consumption of alcohol increases alveolar bone loss.

This study evaluated the effects of the chronic consumption of different concentrations of alcohol on the experimental periodontitis (EP). 160 rats were divided into 4 groups: (EP-NT) rats with EP and no alcohol exposure; (EP-A14) rats with EP exposed to 14% alcohol; (EP-A25) rats with EP exposed to 25% alcohol; (EP-A36) rats with EP exposed to 36% alcohol. The animals from the EP-A14, EP-A25 and EP-A36 groups were subjected to different concentrations of alcohol 30 days before EP induction. The histological characteristics, percentage of bone in the furcation (PBF) and bone metabolism in the furcation region were evaluated. The PBF and tartrate-resistant acid phosphatase (TRAP) data were subjected to statistical analysis. The EP-A14, EP-A25 and EP-A36 groups had lower PBFs compared with the EP-NT group. A more severe inflammatory process and a greater number of TRAP+ cells were also observed. In the EP-A14, EP-A25 and EP-A36 groups, the inflammatory process became more severe as the ingested alcoholic concentration increased. An increase in RANKL immunolabeling and a significantly higher number of TRAP+ cells were also observed. We conclude that chronic alcohol consumption increases the severity of experimental periodontitis in a dose-dependent manner by increasing the magnitude of local inflammatory responses and stimulating alveolar bone resorption.

Electroacupuncture Reduces Inflammation but Not Bone Loss on Periodontitis in Arthritic Rats.

Periodontitis and rheumatoid arthritis (RA) are inflammatory diseases characterized by chronic inflammation and bone erosion. Electroacupuncture (EA) shows anti-inflammatory and anti-resorptive effects in experimental periodontitis (EP) and in RA. It is important to investigate whether EA shows these effects in periodontal tissues in the presence of these two inflammatory diseases or not. For this, Wistar rats were divided into six groups: control (C); experimental rheumatoid arthritis (RA; bovine type II collagen-induced (CII)); experimental periodontitis (EP); RA/EP (RA + EP); EP/EA (EP treated with EA); RA/EP/EA (RA + EP treated with EA). EP was induced 21days after RA induction and EA was performed previously and during the EP induction period, every 3days until the 36th experimental day. The rats were euthanized on day 39. RA was evaluated by edema and the withdrawal threshold of hind paws. The maxillae were removed, and alveolar bone loss (ABL) and bone radiographic density (BRD) were evaluated. Immunohistochemical analyses for interleukins (IL)-6 and -17 and nuclear factor (NF)-κB were performed. Our results showed that EA reduced only the pain intensity in arthritic rats. Histomorphometric, macroscopic, and radiographic analyses did not show differences between the control and EP/EA groups. EA caused a reduction in ABL and BRD only in the presence of EP. EA caused a reduction in IL-6 and -17 in all groups, but NF-κB was only reduced in the arthritic rats with EP. In conclusion, EA reduced the inflammation related to periodontitis in arthritic rats but did not prevent ABL.