The Incidence and Severity of Medication Related Osteonecrosis of the Jaws is Similar in Male and Female Mice.

BACKGROUND: Medication related osteonecrosis of the jaws (MRONJ), a rare side-effect of antiresorptive medications, is described as exposed bone in the oral cavity that lasts for at least 8 weeks. Most studies report a female predilection for MRONJ; these findings could be due to the increased use of antiresorptives in females, or due to inherent differences between male versus female patients. PURPOSE: The purpose of this study was to measure and compare the incidence and severity of osteonecrosis of the jaws (ONJ) between male and female mice. STUDY DESIGN, SETTING, SAMPLE: We designed a randomized in-vivo animal study utilizing male and female mice treated with zoledronic acid (ZA). Experimental periodontitis was induced in 24 male and 24 female mice using a silk ligature following administration of saline or a potent bisphosphonate. After 8 weeks, animals were evaluated radiographically and histologically. INDEPENDENT VARIABLE: The independent variables were sex (male vs female) and treatment group (ZA vs saline control). Treatment was randomly assigned with balanced distribution between male and female animals. MAIN OUTCOME VARIABLE: The main outcome variable was ONJ status coded as present or absent. ONJ was defined as present if there was histologic contact between the ligature and the alveolar bone. Secondary outcomes of interest were radiographic and histologic parameters. ANALYSIS: Statistical differences were analyzed using a two-way analysis of variance with Tukey's post hoc test using a P value of 0.05 for significance. RESULTS: The final sample was composed of 24 vehicle treated and 24 ZA treated animals. In vehicle treated animals, 8% of female and 8% of male animals developed ONJ. In ZA treated animals, 83% of female and 92% of male animals developed ONJ. Sex was not associated with the risk (measured as incidence of disease) for developing ONJ or in the radiographic or histologic parameters that were assessed (P values >.1). CONCLUSIONS: Sex does not appear to affect the incidence of MRONJ or the severity of the disease as assessed by the radiographic and histologic parameters.

Caffeine induces alveolar bone loss in rats submitted to orthodontic movement via activation of receptor activator of nuclear factor Ò¡B, receptor activator of nuclear factor Ò¡B ligand, and osteoprotegerin pathway.

INTRODUCTION: Caffeine is a widely consumed substance with several effects on bone metabolism. This study aimed to investigate the effect of caffeine on the bone tissue of rats submitted to orthodontic movement. METHODS: Twenty-five male Wistar rats underwent orthodontic movement (21 days) of the first permanent maxillary molars on the left side. The experimental group (caffeine; n = 13) and control group (n = 12) received caffeine and water, respectively, by gavage. Microcomputed tomography was performed to analyze orthodontic movement. Histologic analysis of the inflammatory infiltrate and osteoclast count by tartrate-resistant acid phosphatase were conducted. Maxilla tissue was evaluated for receptor activator of nuclear factor Ò¡B (RANK), RANK ligand (RANKL), and osteoprotegerin by immunohistochemistry. RESULTS: Caffeine exhibited a lower bone volume/tissue volume ratio (78.09% ± 5.83%) than the control (86.84% ± 4.89%; P <0.05). Inflammatory infiltrate was increased in the caffeine group compared with the control group (P <0.05). A higher number of tartrate-resistant acid phosphatase-positive cells was observed in the caffeine (9.67 ± 1.73) than in the control group (2.66 ± 0.76; P <0.01). Immunoexpression of RANK and RANKL in the caffeine group was greater than the control (P <0.05). CONCLUSIONS: The use of caffeine thermogenic induces alveolar bone loss in rats submitted to orthodontic movement via activation of RANK, RANKL, and osteoprotegerin signaling pathways.

Effect of mouthwashes on gingival healing after surgical procedures: A systematic review.

The aim of the present study was to perform a systematic review of the literature regarding the effect of different mouthwashes on gingival healing after oral surgery in adults. Searches were conducted in seven databases (PubMed/MEDLINE, Cochrane Library, Clinical Trials Registry, Embase, LILACS, Web of Science, and Google Scholar) for relevant randomized controlled trials (RCTs) published up to April 2022. The selection of studies, data extraction, and risk of bias appraisal were performed independently by two reviewers, and a third researcher was consulted to resolve disagreements. Data syntheses were presented narratively for the different criteria of gingival wound healing. Among 4502 articles retrieved from the databases, 13 studies met the eligibility criteria and were included in the present review. Chlorhexidine was the most frequent mouthwash studied (eight studies) and was used in different concentrations and combinations. Cetylpyridinium chloride, H2 Ocean Sea Salt, Commiphora molmol 0.5%, chlorhexidine 0.12%, and essential oils reported better healing than a negative control. However, the uncertain risk of bias in most RCTs included in this review precludes definitive conclusions. Well-designed RCTs are therefore still needed in this area.

Local delivery of a CXCR3 antagonist decreases the progression of bone resorption induced by LPS injection in a murine model.

OBJECTIVES: This experimental study was carried out to investigate the effects of locally delivered nanoparticles (AMG-487 NP) containing a CXCR3 antagonist in inhibiting the progression of LPS-induced inflammation, osteoclastic activity, and bone resorption on a murine model. MATERIALS AND METHODS: Thirty, 7-week-old C57BL/6 J male mice were used. Inflammatory bone loss was induced by Porphyromonas gingivalis-lipopolysaccharide (P.g.-LPS) injections between the first and second maxillary molars, bilaterally, twice a week for 6 weeks (n = 20). AMG-487 NP were incorporated into a liposome carrier and locally delivered on sites where P.g.-LPS was injected. Control mice (n = 10) were injected with vehicle only. Experimental groups included (1) control, (2) LPS, and (3) LPS + NP. At the end of 1 and 6 weeks, mice were euthanized, maxillae harvested, fixed, and stored for further analysis. RESULTS: Volumetric bone loss analysis revealed, at 1 week, an increase in bone loss in the LPS group (47.9%) compared to control (27.4%) and LPS + NP (27.8%) groups. H&E staining demonstrated reduced inflammatory infiltrate in the LPS + NP group compared to LPS group. At 6 weeks, volumetric bone loss increased in all groups; however, treatment with the CXCR3 antagonist (LPS + NP) significantly reduced bone loss compared to the LPS group. CXCR3 antagonist treatment significantly reduced osteoclast numbers when compared to LPS group at 1 and 6 weeks. CONCLUSIONS: This study showed that local delivery of a CXCR antagonist, via nanoparticles, in a bone resorption model, induced by LPS injection, was effective in reducing inflammation, osteoclast numbers, and bone loss. CLINICAL RELEVANCE: CXCR3 blockade can be regarded as a novel target for therapeutic intervention of bone loss. It can be a safe and convenient method for periodontitis treatment or prevention applicable in clinical practice.

Association between metabolic syndrome and periodontitis: The role of lipids, inflammatory cytokines, altered host response, and the microbiome.

Periodontitis has been associated with many systemic diseases and conditions, including metabolic syndrome. Metabolic syndrome is a cluster of conditions that occur concomitantly and together they increase the risk of cardiovascular disease and double the risk of type 2 diabetes. In this review, we focus on the association between metabolic syndrome and periodontitis; however, we also include information on diabetes mellitus and cardiovascular disease, since these two conditions are significantly intertwined with metabolic syndrome. With regard to periodontitis and metabolic syndrome, to date, the vast majority of studies point to an association between these two conditions and also demonstrate that periodontitis can contribute to the development of, or can worsen, metabolic syndrome. Evaluating the effect of metabolic syndrome on the salivary microbiome, data presented herein support the hypothesis that the salivary bacterial profile is altered in metabolic syndrome patients compared with healthy patients. Considering periodontitis and these three conditions, the vast majority of human and animal studies point to an association between periodontitis and metabolic syndrome, diabetes, and cardiovascular disease. Moreover, there is evidence to suggest that metabolic syndrome and diabetes can alter the oral microbiome. However, more studies are needed to fully understand the influence these conditions have on each other.

AT1 and AT2 Receptor Knockout Changed Osteonectin and Bone Density in Mice in Periodontal Inflammation Experimental Model.

BACKGROUND: The aim of this study was to evaluate the role of AT1 and AT2 receptors in a periodontal inflammation experimental model. METHODS: Periodontal inflammation was induced by LPS/Porphyromonas gingivalis. Maxillae, femur, and vertebra were scanned using Micro-CT. Maxillae were analyzed histopathologically, immunohistochemically, and by RT-PCR. RESULTS: The vertebra showed decreased BMD in AT1 H compared with WT H (p < 0.05). The femur showed increased Tb.Sp for AT1 H and AT2 H, p < 0.01 and p < 0.05, respectively. The Tb.N was decreased in the vertebra (WT H-AT1 H: p < 0.05; WT H-AT2 H: p < 0.05) and in the femur (WT H-AT1 H: p < 0.01; WT H-AT2 H: p < 0.05). AT1 PD increased linear bone loss (p < 0.05) and decreased osteoblast cells (p < 0.05). RANKL immunostaining was intense for AT1 PD and WT PD (p < 0.001). OPG was intense in the WT H, WT PD, and AT2 PD when compared to AT1 PD (p < 0.001). AT1 PD showed weak immunostaining for osteocalcin compared with WT H, WT PD, and AT2 PD (p < 0.001). AT1 H showed significantly stronger immunostaining for osteonectin in fibroblasts compared to AT2 H (p < 0.01). CONCLUSION: AT1 receptor knockout changed bone density, the quality and number of bone trabeculae, decreased the number of osteoblast cells, and increased osteonectin in fibroblasts.

The Receptor AT1 Appears to Be Important for the Maintenance of Bone Mass and AT2 Receptor Function in Periodontal Bone Loss Appears to Be Regulated by AT1 Receptor.

A large number of experimental studies has demonstrated that angiotensin II (Ang II) is involved in key events of the inflammatory process. This study aimed to evaluate the role of Ang II type 1 (AT1) and Ang II type 2 (AT2) receptors on periodontitis. Methods: Experimental periodontitis was induced by placing a 5.0 nylon thread ligature around the second upper left molar of AT1 mice, no-ligature or ligature (AT1-NL and AT1-L), AT2 (AT2-NL or AT2-L) and wild type (WT-NL or L). Alveolar bone loss was scanned using Micro-CT. Cytokines, peptides and enzymes were analyzed from gingival tissues by Elisa and RT-PCR. Results: The blockade of AT1 receptor resulted in bone loss, even in healthy animals. Ang II receptor blockades did not prevent linear bone loss. Ang II and Ang 1-7 levels were significantly increased in the AT2-L (p < 0.01) group compared to AT2-NL and AT1-L. The genic expression of the Mas receptor was significantly increased in WT-L and AT2-L compared to (WT-NL and AT2-NL, respectively) and in AT1-L. Conclusions: Our data suggest that the receptor AT1 appears to be important for the maintenance of bone mass. AT2 receptor molecular function in periodontitis appears to be regulated by AT1.

Peri-implant health, peri-implant mucositis, and peri-implantitis: Case definitions and diagnostic considerations.

The objective of this review is to identify case definitions and clinical criteria of peri-implant healthy tissues, peri-implant mucositis, and peri-implantitis. The case definitions were constructed based on a review of the evidence applicable for diagnostic considerations. In summary, the diagnostic definition of peri-implant health is based on the following criteria: 1) absence of peri-implant signs of soft tissue inflammation (redness, swelling, profuse bleeding on probing), and 2) the absence of further additional bone loss following initial healing. The diagnostic definition of peri-implant mucositis is based on following criteria: 1) presence of peri-implant signs of inflammation (redness, swelling, line or drop of bleeding within 30 seconds following probing), combined with 2) no additional bone loss following initial healing. The clinical definition of peri-implantitis is based on following criteria: 1) presence of peri-implant signs of inflammation, 2) radiographic evidence of bone loss following initial healing, and 3) increasing probing depth as compared to probing depth values collected after placement of the prosthetic reconstruction. In the absence of previous radiographs, radiographic bone level ≥3 mm in combination with BOP and probing depths ≥6 mm is indicative of peri-implantitis.

Ligature-induced peri-implantitis and periodontitis in mice.

AIM: Peri-implantitis (PI), inflammation around dental implants, shares characteristics with periodontitis (PD). However, PI is more difficult to control and treat, and detailed pathophysiology is unclear. We aimed to compare PI and PD progression utilizing a murine model. MATERIALS AND METHODS: Four-week-old male C57BL/6J mice had their left maxillary molars extracted. Implants were placed in healed extraction sockets and osseointegrated. Ligatures were tied around the implants and second molars. Controls did not receive ligatures. Mice were sacrificed 1 week, 1 and 3 months (n ≥ 5/group/time point) post-ligature placement. Bone loss analysis was performed. Histology was performed for: haematoxylin and eosin (H&E), tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-8 (MMP-8), nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), toluidine blue and calcein. RESULTS: PI showed statistically greater bone loss compared to PD at 1 and 3 months. At 3 months, 20% of implants in PI exfoliated; no natural teeth exfoliated in PD. H&E revealed that alveolar bone surrounding implants in PI appeared less dense compared to PD. PI presented with increased osteoclasts, MMP-8 and NF-κB, compared to PD. CONCLUSION: PI exhibited greater tissue and bone destruction compared to PD. Future studies will characterize the pathophysiological differences between the two conditions.

Metformin Hydrochloride-Loaded PLGA Nanoparticle in Periodontal Disease Experimental Model Using Diabetic Rats.

Evidence shows that metformin is an antidiabetic drug, which can exert favorable anti-inflammatory effects and decreased bone loss. The development of nanoparticles for metformin might be useful for increased therapeutic efficacy. The aim of this study was to evaluate the effect of metformin hydrochloride-loaded Poly (d,l-Lactide-co-glycolide) (PLGA)/(MET-loaded PLGA) on a ligature-induced periodontitis model in diabetic rats. MET-loaded PLGA were characterized by mean diameter, particle size, polydispensity index, and entrapment efficiency. Maxillae were scanned using Microcomputed Tomography (µCT) and histopathological and immunohistochemical analysis. IL-1ß and TNF-α levels were analyzed by ELISA immunoassay. Quantitative RT-PCR was used (AMPK, NF-κB p65, HMGB1, and TAK-1). The mean diameter of MET-loaded PLGA nanoparticles was in a range of 457.1 ± 48.9 nm (p < 0.05) with a polydispersity index of 0.285 (p < 0.05), Z potential of 8.16 ± 1.1 mV (p < 0.01), and entrapment efficiency (EE) of 66.7 ± 3.73. Treatment with MET-loaded PLGA 10 mg/kg showed low inflammatory cells, weak staining by RANKL, cathepsin K, OPG, and osteocalcin, and levels of IL-1ß and TNF-α (p < 0.05), increased AMPK expression gene (p < 0.05) and decreased NF-κB p65, HMGB1, and TAK-1 (p < 0.05). It is concluded that MET-loaded PLGA decreased inflammation and bone loss in periodontitis in diabetic rats.

The soluble interleukin-6 receptor is a mediator of hematopoietic and skeletal actions of parathyroid hormone.

Both PTH and IL-6 signaling play pivotal roles in hematopoiesis and skeletal biology, but their interdependence is unclear. The purpose of this study was to evaluate the effect of IL-6 and soluble IL-6 receptor (sIL-6R) on hematopoietic and skeletal actions of PTH. In the bone microenvironment, PTH stimulated sIL-6R protein levels in primary osteoblast cultures in vitro and bone marrow in vivo in both IL-6(+/+) and IL-6(-/-) mice. PTH-mediated hematopoietic cell expansion was attenuated in IL-6(-/-) compared with IL-6(+/+) bone marrow, whereas sIL-6R treatment amplified PTH actions in IL-6(-/-) earlier than IL-6(+/+) marrow cultures. Blocking sIL-6R signaling with sgp130 (soluble glycoprotein 130 receptor) inhibited PTH-dependent hematopoietic cell expansion in IL-6(-/-) marrow. In the skeletal system, although intermittent PTH administration to IL-6(+/+) and IL-6(-/-) mice resulted in similar anabolic actions, blocking sIL-6R significantly attenuated PTH anabolic actions. sIL-6R showed no direct effects on osteoblast proliferation or differentiation in vitro; however, it up-regulated myeloid cell expansion and production of the mesenchymal stem cell recruiting agent, TGF-ß1 in the bone marrow microenvironment. Collectively, sIL-6R demonstrated orphan function and mediated PTH anabolic actions in bone in association with support of myeloid lineage cells in the hematopoietic system.

"Evaluation of 4 and 8 weeks of healing in a murine implant model".

Dental implants are increasing in prevalence as desirable options for replacing missing teeth. Unfortunately, implants come with complications, and animal models are crucial to studying the pathophysiology of complications. Current murine model experiments can be lengthy, with eight weeks of extraction socket healing before implant placement. Therefore, we aimed to investigate the efficacy of decreasing extraction healing time from eight to four weeks in a dental implant mouse model. Thirty-one three-week-old C57BL/6J male mice underwent maxillary first and second molar extractions followed by eight (control) or four (test) weeks of extraction socket healing before implant placement. Mice were euthanized after four weeks of implant osseointegration. Samples were analyzed via microcomputed tomography and histology. When mice received implants four weeks following extractions, there was no statistical difference in initial bone crest remodeling or surrounding bone volume compared to those after eight weeks of healing. Histologically, the hard and soft tissues surrounding both groups of implants displayed similar alveolar bone levels, inflammatory infiltrate, osteoclast count, and collagen organization. A four-week extraction healing period can be utilized without concern for osseointegration in a murine implant model and is a viable experimental alternative to the previous eight weeks of healing. While small animal implant models are less directly applicable to humans, advancements in experimental methods will ultimately benefit patients receiving dental implants through improved prevention and treatment of complications. Subsequent research could investigate occlusal effects or whether healing time affects prognosis following induction of peri-implantitis.

Experimental Model of Ligature-Induced Peri-Implantitis in Mice.

Dental implants have a high success and survival rate. However, complications such as peri-implantitis (PI) are highly challenging to treat. PI is characterized by inflammation in the tissues around dental implants with progressive loss of supporting bone. To optimize dental implants' longevity in terms of health and functionality, it is crucial to understand the peri-implantitis pathophysiology. In this regard, using mouse models in research has proven clear benefits in recreating clinical circumstances. This study aimed to describe an experimental model of ligature-induced peri-implantitis in mice and determine whether there is effectiveness in inducing this disease, given the observed bone and tissue changes. The experimental peri-implantitis induction comprehends the following steps: teeth extraction, implant placement, and ligature-inducted PI. A sample of eighteen 3-week-old C57BL/6J male mice was divided into two groups, ligature (N=9) and control non-ligature (N=9). The evaluation of clinical, radiographical, and histological factors was performed. The ligature group showed significantly higher bone loss, increased soft tissue edema, and apical epithelial migration than the non-ligature group. It was concluded that this pre-clinical model can successfully induce peri-implantitis in mice.

The potential impact of periodontitis on cerebral small vessel disease.

Cerebral small vessel disease (CSVD) is a term used to describe abnormalities in the intracranial microvasculature affecting small arteries, arterioles, capillaries, and venules. The etiology of these conditions is not fully understood but inflammation appears to play a significant role. Periodontal diseases have been associated with conditions such as stroke and dementia, which are clinical consequences of CSVD. Periodontitis is a highly prevalent chronic multifactorial inflammatory disease regulated by the host immune response against pathogenic bacterial colonization around the teeth. The inflammatory response and the microbial dysbiosis produce pro-inflammatory cytokines that can reach the brain and promote local changes. This review will explore the potential association between periodontitis and CSVD by assessing the impact of periodontitis-induced inflammation and periodontopathogenic bacteria on the underlying mechanisms leading to CSVD. Given the association of periodontitis with stroke and dementia, which are clinical features of CSVD, it may be possible to suggest a link with CSVD. Current evidence linking periodontitis with neuroimaging findings of CSVD enforces the possible link between these conditions.

Association between different dietary patterns and eating disorders and periodontal diseases.

Periodontal diseases is a highly prevalent chronic condition regulated by the host immune response to pathogenic bacterial colonization on the teeth surfaces. Nutrition is a critical component in the modulation of the immune system, hence the importance of a balanced diet. With the understanding of how dietary intake composition affects various health outcomes, nutrient diversity has been reported as a modifiable risk factor for periodontal disease. Eating disorders and different dietary patterns can be associated with periodontal diseases. In this sense, balanced and healthy nutrition plays a major role in maintaining the symbiosis between oral microbiota and periodontal health. Therefore, this review seeks to report the associations found in the literature between high- or low-fat/sodium/sugar, eating disorders and periodontal diseases. It was found that some dietary patterns such as high carbohydrate/sugar, high fat, and low fiber intake may be associated with periodontal disease. In addition, the presence of eating disorders can negatively impact patients' oral health and it is related to the development of several complications, including periodontal diseases. In both situations, nutritional and vitamin deficiencies can aggravate the periodontal condition. However, the relationship between periodontal disease, dietary patterns, and eating disorders still needs more scientific support to be well established, mainly in the sense of pointing out a protective relationship between both.

FBXO11 regulates bone development.

FBXO11 is the substrate-recognition component of a ubiquitin ligase complex called SKP1-cullin-F-boxes. The role of FBXO11 in bone development is unexplored. In this study, we reported a novel mechanism of how bone development is regulated by FBXO11. FBXO11 gene knockdown by lentiviral transduction in mouse pre-osteoblast MC3T3-E1 cells leads to reduced osteogenic differentiation, while overexpressing FBXO11 accelerates their osteogenic differentiation in vitro. Furthermore, we generated two osteoblastic-specific FBXO11 conditional knockout mouse models, Col1a1-ERT2-FBXO11KO and Bglap2-FBXO11KO mice. In both conditional FBXO11KO mouse models, we found FBXO11 deficiency inhibits normal bone growth, in which the osteogenic activity in FBXO11cKO mice is reduced, while osteoclastic activity is not significantly changed. Mechanistically, we found FBXO11 deficiency leads to Snail1 protein accumulation in osteoblasts, leading to suppression of osteogenic activity and inhibition of bone matrix mineralization. FBXO11 knockdown in MC3T3-E1 cells reduced Snail1 protein ubiquitination and increased Snail1 protein accumulation in the cells, which eventually inhibited osteogenic differentiation. In conclusion, FBXO11 deficiency in osteoblasts inhibits bone formation through Snail1 accumulation, inhibiting osteogenic activity and bone mineralization.

Association between sequelae of COVID-19 with periodontal disease and obesity: A cross-sectional study.

BACKGROUND: To assess the sequelae of coronavirus disease 2019 (COVID-19) and associated factors, such as obesity and periodontitis in adults. METHODS: The study included 128 individuals aged ≥35 years with a history of a diagnosis of COVID-19 through real-time polymerase chain reaction (RT-PCR), from Pelotas, Brazil. Self-report sequelae from COVID-19 were defined as the primary outcome. A questionnaire containing sociodemographic, medical, behavioral and self-report of sequelae of COVID-19 was applied. A complete periodontal clinical examination was performed. Weight and height were assessed. Uni-, bi- and multivariate analyses were performed using Poisson regression with robust variance. Additional analyses were performed considering obesity as a subgroup. RESULTS: When considering the whole sample, no statistically significant associations between sequelae of COVID-19 with periodontitis (prevalence ratio [PR]:1.14;95% confidence interval [95%CI]: 0.80-1.61) and obesity (0.93 [0.68-1.26]) were identified. In the subgroup analysis, considering only individuals with obesity, those diagnosed with generalized periodontitis had 86% higher probability to have sequelae of COVID-19 when compared to individuals with periodontal health or localized periodontitis. However, when only those without obesity were considered, no significant association with periodontal status was detected (0.82 [0.55-1.23). No significant association with periodontal status were observed when the severity of sequelae (no sequelae, 1 sequela, and >1 sequela) were considered (p > 0.05). CONCLUSIONS: Individuals diagnosed with obesity and periodontitis have a higher PR of reporting sequelae from COVID-19 compared to individuals with only obesity.

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

BACKGROUND: 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). METHODS: 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). RESULTS: There was a significant reduction in interleukin-1ß (IL-1ß) 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. CONCLUSION: 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.

The Microbiome in Periodontitis and Diabetes.

Objectives: To perform a comprehensive and integrative review of the available literature on the potential changes in the microbiome of healthy and individuals with diabetes under periodontal health and disease. Materials and Methods: The review was conducted by two independent reviewers. Indexed electronic databases (PubMed/Medline, Cochrane Library, Web of Science and Scopus) were searched, including articles published in English and dated from 5 years ago until December 2021. A manual search also was performed to identify co-related articles. Following the removal of duplicates and eligibility criteria, the articles were included in tables for analysis and described in the manuscript. Results: According to this review, diabetes mellitus was associated with significant changes in the subgingival and salivary microbiome, either in its association with periodontitis or in cases of periodontal health. In addition to affecting microbial diversity in terms of taxonomy, metagenomic studies have shown that this endocrine disorder may also be directly related to increased pathogenicity in the oral microbiome. Conclusion: Although the reviewed studies demonstrate important differences in the subgingival and salivary microbiome composition because of diabetes mellitus, further studies are needed to clarify the real effects of hyperglycemia on oral microbial profiles and support new diagnostic approaches and innovative treatments.

Inhibition of HMGB1/RAGE Signaling Reduces the Incidence of Medication-Related Osteonecrosis of the Jaw (MRONJ) in Mice.

Medication-related osteonecrosis of the jaw (MRONJ) is a severe complication of antiresorptive or antiangiogenic medications, used in the treatment of bone malignancy or osteoporosis. Bone necrosis, mainly represented by osteocytic death, is always present in MRONJ sites; however, the role of osteocyte death in MRONJ pathogenesis is unknown. High mobility group box 1 (HMGB1) is a non-histone nucleoprotein that in its acetylated form accumulates in the cytoplasm, whereas non-acetylated HMGB1 localizes in the nucleus. SIRT1 deacetylase regulates cellular localization of HMGB1. Interestingly, HMGB1 is released during cell necrosis and promotes inflammation through signaling cascades, including activation of the RAGE receptor. Here, we utilized a well-established mouse MRONJ model that utilizes ligature-induced experimental periodontitis (EP) and treatment with either vehicle or zolendronic acid (ZA). Initially, we evaluated HMGB1-SIRT1 expression in osteocytes at 1, 2, and 4 weeks of treatment. Significantly increased cytoplasmic and perilacunar HMGB1 expression was observed at EP sites of ZA versus vehicle (Veh) animals at all time points. SIRT1 colocalized with cytoplasmic HMGB1 and presented a statistically significant increased expression at the EP sites of ZA animals for all time points. RAGE expression was significantly higher in the submucosal tissues EP sites of ZA animals compared with those in vehicle group. To explore the significance of increased cytoplasmic and extracellular HMGB1 and increased RAGE expression in MRONJ pathogenesis, we used pharmacologic inhibitors of these molecules. Combined HMGB1/RAGE inhibition resulted in lower MRONJ incidence with statistically significant decrease in osteonecrotic areas and bone exposure versus non-inhibitor treated ZA animals. Together, our data point to the role of HMGB1 as a central alarmin, overexpressed at early phase of MRONJ pathogenesis during osteocytic death. Moreover, HMGB1-RAGE pathway may represent a new promising therapeutic target in patients at high risk of MRONJ. © 2022 American Society for Bone and Mineral Research (ASBMR).