Oral infection with periodontal pathogens induced chronic obstructive pulmonary disease-like lung changes in mice.

BACKGROUND: Epidemiological studies have demonstrated that periodontitis is an independent risk factor for chronic obstructive pulmonary disease (COPD). However, the mechanism underlying the association between these two diseases remains unclear. The lung microbiota shares similarities with the oral microbiota, and there is growing evidence to suggest that the lung microbiome could play a role in the pathogenesis of COPD. This study aimed to investigate whether periodontal pathogens could contribute to the pathogenesis of COPD in a mouse model. METHODS: We established mouse models with oral infection by typical periodontal pathogens, porphyromonas gingivalis (Pg group) or fusobacterium nucleatum (Fn group), over a three-month period. Mice that did not receive oral infection were set as the control group (C group). We assessed the level of alveolar bone resorption, lung function, and histological changes in the lungs of the mice. Additionally, we measured the levels of inflammatory factors and tissue damage associated factors in the lung tissues. RESULTS: Lung function indices, including airway resistance, peak inspiratory/expiratory flow and expiratory flow-50%, were significantly reduced in the Fn group compared to the C group. Additionally, histological examination revealed an increased number of inflammatory cells and bullae formation in the lung tissue sections of the Fn group. Meanwhile, levels of inflammatory factors such as IL-1ß, IL-6, IFN-γ, and TNF-α, as well as tissue damage associated factors like matrix metalloproteinase-8 and neutrophil elastase, were significantly elevated in the lung tissue of the Fn group in comparison to the C group. The Pg group also showed similar but milder lung changes compared to the Fn group. Pg or Fn could be detected in the lungs of both oral infected groups. CONCLUSION: The results indicated that oral periodontal pathogens infection could induce COPD-like lung changes in mice, and they may play a biological role in the association between periodontitis and COPD.

Effects of novel lactoferrin peptides on LPS-induced alveolar bone destruction in a rat model.

To develop novel bovine lactoferrin (bLF) peptides targeting bLF-tumour necrosis factor (TNF) receptor-associated factor 6 (TRAF6) binding sites, we identified two peptides that could target bLF-TRAF6 binding sites using structural analysis. Moreover, another peptide that could bind to the TRAF6 dimerization area was selected from the bLF sequence. The effects of each peptide on cytokine expression in lipopolysaccharide (LPS)-stimulated osteoblasts (ST2) and on osteoclastogenesis were examined using an LPS-treated co-culture of primary bone marrow cells (BMCs) with ST2 cells and a single culture of osteoclast precursor cells (RAW-D) treated with soluble receptor activator of NF-κB ligand. Finally, the effectiveness of these peptides against LPS-induced alveolar bone destruction was assessed. Two of the three peptides significantly suppressed LPS-induced TNF-α and interleukin-1ß expression in ST2 cells. Additionally, these peptides inhibited and reversed LPS-induced receptor activator of NF-κB ligand (RANKL) upregulation and osteoprotegerin (OPG) downregulation, respectively. Furthermore, both peptides significantly reduced LPS-induced osteoclastogenesis in the BMC-ST2 co-culture and RANKL-induced osteoclastogenesis in RAW-D cells. In vivo, topical application of these peptides significantly reduced the osteoclast number by downregulating RANKL and upregulating OPG in the periodontal ligament. It is indicated that the novel bLF peptides can be used to treat periodontitis-associated bone destruction.

Assessment and comparative study of diosgenin doses in alleviating experimental periodontitis.

BACKGROUND: This study was performed to determine the therapeutic effects of diosgenin (DG) which is a steroidal saponin, administered at different doses on alveolar bone loss (ABL) in rats with experimental periodontitis using immunohistochemical and cone-beam computed tomography (CBCT). METHODS: Thirty-two male Wistar rats divided into four equal groups: control (non-ligated), periodontitis (P), DG-48, and DG-96. Sutures were placed at the gingival margin of the lower first molars to induce experimental periodontitis. Then, 48 and 96 mg/kg of DG was administered to the study groups by oral gavage for 29 days. At day 30, the animals were sacrificed and ABL was determined via CBCT. The expression patterns of osteocalcin (OCN), alkaline phosphatase (ALP), type I collagen (Col-1), B cell lymphoma 2 (Bcl 2), Bcl 2-associated X protein (Bax), bone morphogenetic protein 2 (BMP-2), and receptor activator of NF κB ligand (RANKL) were examined immunohistochemically. RESULTS: Histopathologic examination showed all features of the advanced lesion in the P group. DG use decreased all these pathologic changes. It was observed that periodontitis pathology decreased as the dose increased. DG treatment increased the ALP, OCN, Bcl 2, Col-1, and BMP-2 levels in a dose-dependent manner, compared with the P group (p < 0.05). DG decreased the expression of RANKL and Bax in a dose-dependent manner (p < 0.05). ABL was significantly lower in the DG-48 and DG-96 groups than in the P group (p < 0.05). CONCLUSION: Collectively, our findings suggest that DG administration protects rats from periodontal tissue damage with a dose-dependent manner, provides an increase in markers of bone formation, decreases in Bax/Bcl-2 ratio and osteoclast activation.

Physical training minimizes immunological dysfunction, oxidative stress and tissue destruction on experimental periodontitis in rats.

The objective of this study is to investigate the effects of a moderate intensity physical training protocol, on alveolar bone morphology of rats submitted to ligature-induced periodontitis. Twenty-eight male Wistar rats were divided into four groups, considering the presence/absence of periodontitis and presence/absence of training. The training protocol was performed on a treadmill, 30 min/day, 5 days a week, for 4 weeks. In the experimental periodontal breakdown, with/without training, ligatures were placed on the lower first molars on the 14th day of the experiment, and were followed until the end of the protocol. At the end of the experiment, animals were euthanized and samples of plasma and mandibles were collected for immunoenzymatic evaluation of interleukins (IL)-1ß, IL-6, TNF-α and IL-10, evaluation of serum concentrations of C-reactive protein, analysis of lipid peroxidation (LPO) and reduced glutathione, histological and microtomographic analyses were performed. Physical training resulted in a reduced levels of IL-1ß, IL-6, TNF-α C-reactive protein and LPO and an increase in the levels of IL-10 in rats with periodontitis (p<0.05); a reduction in the inflammatory infiltrate and decreased fiber degradation was identified in histological analysis. Additionally, it was shown a decrease in vertical bone loss and an increase in the bone volume/trabecular volume ratio was identified in periodontitis+physical training group (p<0.05). Based on the results, the practice of frequent physical exercise, at moderate intensity, can contribute to the reduction of damage related to the disproportionate inflammatory response in periodontitis.

Evaluation of the relationship between periodontal bone destruction and mesial root concavity of the maxillary first premolar.

BACKGROUND: The purpose of this study was to investigate the morphology of maxillary first premolar mesial root concavity and to analyse its relation to periodontal bone loss (BL) using cone beam computed tomography (CBCT) and panoramic radiographs. METHODS: The mesial root concavity of maxillary premolar teeth was analysed via CBCT. The sex and age of the patients, starting position and depth of the root concavity, apicocoronal length of the concavity on the crown or root starting from the cementoenamel junction (CEJ), total apicocoronal length of the concavity, amount of bone loss both in CBCT images and panoramic radiographs, location of the furcation, length of the buccal and palatinal roots, and buccopalatinal cervical root width were measured. RESULTS: A total of 610 patients' CBCT images were examined, and 100 were included in the study. The total number of upper premolar teeth was 200. The patients were aged between 18 and 65 years, with a mean age of 45.21 ± 13.13 years. All the teeth in the study presented mesial root concavity (100%, n = 200). The starting point of concavity was mostly on the cervical third of the root (58.5%). The mean depth and buccolingual length measurements were 0.96 mm and 4.32 mm, respectively. Depth was significantly related to the amount of alveolar bone loss (F = 5.834, p = 0.001). The highest average concavity depth was 1.29 mm in the group with 50% bone loss. The data indicated a significant relationship between the location of the furcation and bone loss (X2 = 25.215, p = 0.003). Bone loss exceeded 50% in 100% of patients in whom the furcation was in the cervical third and in only 9.5% of patients in whom the furcation was in the apical third (p = 0.003). CONCLUSIONS: According to the results of this study, the depth of the mesial root concavity and the coronal position of the furcation may increase the amount of alveolar bone loss. Clinicians should be aware of these anatomical factors to ensure accurate treatment planning and successful patient management.

Toll-like receptor 4 deficiency affects the balance of osteoclastogenesis and osteoblastogenesis in periodontitis.

Toll-like receptor 4 (TLR4) acts as a double-edged sword in the occurrence and development of periodontitis. While the activation of TLR4 in macrophages aids in clearing local pathogens, it can also disrupt innate immune responses, upsetting microecological balance and accelerating the destruction of periodontal bone tissues. To date, the effects of TLR4 on osteogenesis and osteoclastogenesis in periodontitis have not been comprehensively studied. In this study, we investigated the development of periodontitis in the Tlr4-/- mice by ligating their second molars with silk threads. Compared to wild-type (WT) mice, Tlr4-/- mice demonstrated increased resistance to periodontitis-associated bone destruction, as evidenced by decreased bone resorption and enhanced bone regeneration. Mechanistically, the deletion of Tlr4 not only inhibited osteoclast formation by reducing the expression of NFATc1, CTSK and TRAP, but also enhanced osteogenic abilities through increased expression of OCN, OPN and RUNX2. In conclusion, TLR4 tips the balance of osteoclastogenesis and osteogenesis, thereby promoting periodontal bone destruction in periodontitis.

Th17-to-Tfh plasticity during periodontitis limits disease pathology.

Th17 cell plasticity is crucial for development of autoinflammatory disease pathology. Periodontitis is a prevalent inflammatory disease where Th17 cells mediate key pathological roles, yet whether they exhibit any functional plasticity remains unexplored. We found that during periodontitis, gingival IL-17 fate-mapped T cells still predominantly produce IL-17A, with little diversification of cytokine production. However, plasticity of IL-17 fate-mapped cells did occur during periodontitis, but in the gingiva draining lymph node. Here, some Th17 cells acquired features of Tfh cells, a functional plasticity that was dependent on IL-6. Notably, Th17-to-Tfh diversification was important to limit periodontitis pathology. Preventing Th17-to-Tfh plasticity resulted in elevated periodontal bone loss that was not simply due to increased proportions of conventional Th17 cells. Instead, loss of Th17-to-Tfh cells resulted in reduced IgG levels within the oral cavity and a failure to restrict the biomass of the oral commensal community. Thus, our data identify a novel protective function for a subset of otherwise pathogenic Th17 cells during periodontitis.

Are periodontitis and psoriasis associated? A pre-clinical murine model.

AIM: To investigate the bidirectional influence between periodontitis and psoriasis, using the respective experimental models of ligature- and imiquimod-induced diseases on murine models. MATERIALS AND METHODS: Thirty-two C57/BL6J mice were randomly allocated to four experimental groups: control (P- Pso-), ligature-induced periodontitis (P+ Pso-), imiquimod-induced psoriasis (P- Pso+) and periodontitis and psoriasis (P+ Pso+). Samples (maxilla, dorsal skin and blood) were harvested immediately after death. Measures of periodontitis (distance between the cemento-enamel junction and alveolar bone crest [CEJ-ABC] and the number of osteoclasts) and psoriasis (epidermal thickness and infiltrate cell [/0.03mm2]) severity as well as systemic inflammation (IL-6, IL-17A, TNF-α) were collected. RESULTS: The P+ Pso+ group exhibited the most severe experimental periodontitis and psoriasis, with the highest values of CEJ-ABC, number of osteoclasts, epidermal thickness and infiltrate cells in the dorsal skin, as well as the highest blood cytokine concentration. The P+ Pso- group presented with higher cell infiltrate (/0.03mm2) compared to the control group (p <.05), while the P- Pso+ group showed substantially higher alveolar bone loss (CEJ-ABC) than the control group (p <.05). CONCLUSIONS: Experimental periodontitis may initiate and maintain psoriasiform skin inflammation and, vice versa, experimental psoriasis may contribute to the onset of periodontitis. In a combined model of the diseases, we propose a bidirectional association between periodontitis and psoriasis via systemic inflammation.

Probiotics enhance alveolar bone microarchitecture, intestinal morphology and estradiol levels in osteoporotic animals.

BACKGROUND AND OBJECTIVE: Osteoporosis is associated with bone microarchitecture alterations, and the depletion of estrogen during menopause is a major contributing factor to its development. The literature highlights the noteworthy role of gut microbiota in bone metabolism, particularly in the progression of osteoporosis. Periodontal disease leads to alveolar bone loss, which may be influenced by estrogen deficiency, and this mechanism is intricately associated with an imbalance in systemic microbiota. The aim of this study was to evaluate the effects of Bifidobacterium animalis subsp. lactis HN019 (B. lactis HN019) and Lacticaseibacillus casei 01 (L. casei 01) administrations on an osteoporosis animal model. MATERIALS AND METHODS: Thirty-three female rats were randomly divided into three groups: control (C-OVX), C-OVX-HN019 and C-OVX-LC01. All animals were ovariectomized. In groups C-OVX-HN019 and C-OVX-LC01, the probiotics were administered for 4 months. All animals were euthanized after 16 weeks from ovariectomy. Microtomographic, histopathological and immunohistochemical examinations were conducted on periodontal tissues, whereas histomorphometry, histopathological and immunohistochemical analyses were carried out on the intestine. The levels of estradiol were assessed in blood using an immunoenzymatic assay. The data were subjected to statistical analyses (p < .05). RESULTS: The C-OVX-LC01 group exhibited a significant reduction in alveolar bone porosity and an increase in connective tissue density compared to C-OVX (p < .05). The C-OVX-HN019 and C-OVX-LC01 groups presented reduced expression of TRAP and RANKL compared to the C-OVX (p < .05). The C-OVX group presented villi defects, mild neutrophil infiltration, decrease in both villous height and intestinal crypts and reduced expression of intestinal junctional epithelium markers e-cadherin and claudin 01 compared to C-OVX-HN019 and C-OVX-LC01 (p < .05). The C-OVX group had lower estradiol levels than C-OVX-HN019 and C-OVX-LC01 (p < .05). CONCLUSION: The probiotic therapy promoted a reduction in alveolar bone destruction and intestinal permeability as well as an increase in estradiol levels in ovariectomized rats. Specifically, the probiotic strain Lacticaseibacillus casei 01 exhibited greater effectiveness compared to Bifidobacterium animalis subsp. lactis HN019, indicating strain-dependent outcomes.

NF-κB Decoy Oligodeoxynucleotide-Loaded Poly Lactic-co-glycolic Acid Nanospheres Facilitate Socket Healing in Orthodontic Tooth Movement.

Orthodontic space closure following tooth extraction is often hindered by alveolar bone deficiency. This study investigates the therapeutic use of nuclear factor-kappa B (NF-κB) decoy oligodeoxynucleotides loaded with polylactic-co-glycolic acid nanospheres (PLGA-NfDs) to mitigate alveolar bone loss during orthodontic tooth movement (OTM) following the bilateral extraction of maxillary first molars in a controlled experiment involving forty rats of OTM model with ethics approved. The decreased tendency of the OTM distance and inclination angle with increased bone volume and improved trabecular bone structure indicated minimized alveolar bone destruction. Reverse transcription-quantitative polymerase chain reaction and histomorphometric analysis demonstrated the suppression of inflammation and bone resorption by downregulating the expression of tartrate-resistant acid phosphatase, tumor necrosis factor-α, interleukin-1ß, cathepsin K, NF-κB p65, and receptor activator of NF-κB ligand while provoking periodontal regeneration by upregulating the expression of alkaline phosphatase, transforming growth factor-ß1, osteopontin, and fibroblast growth factor-2. Importantly, relative gene expression over the maxillary second molar compression side in proximity to the alveolus highlighted the pharmacological effect of intra-socket PLGA-NfD administration, as evidenced by elevated osteocalcin expression, indicative of enhanced osteocytogenesis. These findings emphasize that locally administered PLGA-NfD serves as an effective inflammatory suppressor and yields periodontal regenerative responses following tooth extraction.

Optimizing esthetic zone periodontal regeneration in a 1-2-wall infrabony defect using recombinant human platelet-derived growth factor BB and ß-tricalcium phosphate: A case report.

OBJECTIVE: Periodontitis is an inflammatory condition induced by subgingival bacterial dysbiosis, resulting in inflammatory-mediated destruction of tooth-supporting structures, potentially leading to the formation of infrabony defects. This case report describes the treatment of a patient who presented with a combination 1-2-wall defect on tooth 21. To maintain the residual periodontal attachment and minimize esthetic consequences, a regenerative approach was performed using recombinant human platelet-derived growth factor-BB (rh-PDGF-BB) and ß-tricalcium phosphate (ß-TCP). MATERIALS AND METHODS: At the time of postscaling/root planing reevaluation, a 34-year-old Asian male initially diagnosed with molar/incisor pattern stage III grade C periodontitis exhibited a 6-mm residual probing depth on the mesiopalatal aspect of tooth 21. Periodontal regenerative surgery was performed using rh-PDGF-BB with ß-TCP, without the use of a membrane. RESULTS: At the 1-year follow-up, a significant reduction in probing depth and radiographic evidence of bone fill were observed. Additionally, re-entry surgery for implant placement at site tooth 23 confirmed bone fill in the defect on tooth 21. CONCLUSION: These results demonstrate the efficacy of rh-PDGF-BB with ß-TCP in enhancing periodontal regeneration and support its use as a treatment option when treating poorly contained infrabony defects in the esthetic zone.

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.

Isobavachin attenuates osteoclastogenesis and periodontitis-induced bone loss by inhibiting cellular iron accumulation and mitochondrial biogenesis.

As bone-resorbing cells rich in mitochondria, osteoclasts require high iron uptake to promote mitochondrial biogenesis and maintain a high-energy metabolic state for active bone resorption. Given that abnormal osteoclast formation and activation leads to imbalanced bone remodeling and osteolytic bone loss, osteoclasts may be crucial targets for treating osteolytic diseases such as periodontitis. Isobavachin (IBA), a natural flavonoid compound, has been confirmed to be an inhibitor of receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation from bone marrow-derived macrophages (BMMs). However, its effects on periodontitis-induced bone loss and the potential mechanism of its anti-osteoclastogenesis effect remain unclear. Our study demonstrated that IBA suppressed RANKL-induced osteoclastogenesis in BMMs and RAW264.7 cells and inhibited osteoclast-mediated bone resorption in vitro. Transcriptomic analysis indicated that iron homeostasis and reactive oxygen species (ROS) metabolic process were enriched among the differentially expressed genes following IBA treatment. IBA exerted its anti-osteoclastogenesis effect by inhibiting iron accumulation in osteoclasts. Mechanistically, IBA attenuated iron accumulation in RANKL-induced osteoclasts by inhibiting the mitogen-activated protein kinase (MAPK) pathway to upregulate ferroportin1 (Fpn1) expression and promote Fpn1-mediated intracellular iron efflux. We also found that IBA inhibited mitochondrial biogenesis and function, and reduced RANKL-induced ROS generation in osteoclasts. Furthermore, IBA attenuated periodontitis-induced bone loss by reducing osteoclastogenesis in vivo. Overall, these results suggest that IBA may serve as a promising therapeutic strategy for bone diseases characterized by osteoclastic bone resorption.

[A preliminary in vivo and in vitro study of endothelial cell pyroptosis in the periodontal inflammatory environment].

Objective: To observe whether endothelial cells undergo pyroptosis in the inflammatory periodontal environment by using a model in vivo and in vitro, providing an experimental basis for indepth understanding of the underlying pathogenesis of periodontitis. Methods: According to the classification of periodontal diseases of 2018, gingival tissues were collected from periodontally healthy subjects and patients with stage Ⅲ-Ⅳ, grade C periodontitis, who presented Department of Oral and Maxillofacial Surgery and Department of Periodontology, School of Stomatology, The Fourth Military Medical University from April to May 2022. Immunohistochemical staining was performed to detect the expression level and distribution of gasdermin D (GSDMD), a hallmark protein of cell pyroptosis, in gingival tissues. Periodontitis models were established in each group by ligating the maxillary second molar teeth of three mice for 2 weeks (ligation group). The alveolar bone resorption was determined by micro-CT (mice without ligation treatment were used as the control group), and the colocalization of GSDMD and CD31 were quantitatively analyzed by immunofluorescence staining in gingival tissues of healthy and inflammatory mice. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro and treated with lipopolysaccharide (LPS) of Porphyromonas gingivalis (Pg) combined with adenosine triphosphate (ATP) at various concentrations of 0.5, 1.0, 2.5, 5.0, and 10.0 mg/L, respectively, and the 0 mg/L group was set as the control group at the same time. Scanning electron microscopy was used to observe the morphology of HUVECs. Western blotting was used to detect the expression of gasdermin D-N terminal domains (GSDMD-N) protein and immunofluorescence cell staining was used to detect the expression and distribution of GSDMD. Cell counting kit-8 (CCK-8) was used to detect the proliferative ability of HUVECs, and propidium iodide (PI) staining was used to detect the integrity of cell membrane of HUVECs. Results: Immunohistochemistry showed that GSDMD in gingival tissues of periodontitis was mainly distributed around blood vessels and its expression level was higher than that in healthy tissues. Micro-CT showed that alveolar bone resorption around the maxillary second molar significantly increased in ligation group mice compared with control subjects (t=8.88, P<0.001). Immunofluorescence staining showed significant colocalization of GSDMD with CD31 in the gingival vascular endothelial cells in mice of ligation group. The results of scanning electron microscopy showed that there were pores of different sizes, the typical morphology of pyroptosis, on HUVECs cell membranes in the inflammatory environment simulated by ATP combined with different concentrations of LPS, and 2.5 mg/L group showed the most dilated and fused pores on cell membranes, with the cells tended to lyse and die. Western blotting showed that the expression of GSDMD-N, the hallmark protein of cell pyroptosis, was significantly higher in 2.5 and 5.0 mg/L groups than that in the control group (F=3.86, P<0.01). Immunofluorescence cell staining showed that the average fluorescence intensity of GSDMD in 2.5 mg/L group elevated the most significantly in comparison with that in the control group (F=35.25, P<0.001). The CCK-8 proliferation assay showed that compared to the control group (1.00±0.02), 0.5 mg/L (0.52±0.07), 1.0 mg/L (0.57±0.10), 2.5 mg/L (0.58±0.04), 5.0 mg/L (0.55±0.04), 10.0 mg/L (0.61±0.03) groups inhibited cell proliferation (F=39.95, P<0.001). PI staining showed that the proportion of positive stained cells was highest [(56.07±3.22)%] in 2.5 mg/L group (F=88.24, P<0.001). Conclusions: Endothelial cells undergo significant pyroptosis in both in vivo and in vitro periodontal inflammatory environments, suggesting that endothelial cell pyroptosis may be an important pathogenic factor contributing to the pathogenesis of periodontitis.

Small extracellular vesicles derived from lipopolysaccharide-preconditioned dental follicle cells inhibit cell apoptosis and alveolar bone loss in periodontitis.

OBJECTIVE: This study aimed to explore the effects of small extracellular vesicles derived from lipopolysaccharide-preconditioned dental follicle cells (L-D-sEV) on periodontal ligament cells from periodontitis affected teeth (p-PDLCs) in vitro and experimental periodontitis in mice. DESIGN: In vitro, the biological function of p-PDLCs and the underlying molecular mechanism were investigated by flow cytometry, Western blot, and quantitative real-time PCR (qRT-PCR) analysis. Eighteen-eight-week-old male C57BL/6 mice were randomly divided into three groups: control (Con), periodontitis (Peri), and L-D-sEV groups. Mice periodontitis model was induced by placing the 5-0 silk thread (around the maxillary second molar) and P.gingivalis (1 ×107 CFUs per mouse). In vivo, the alveolar bone loss, osteoclast activity, and macrophage polarization were measured by micro-computed tomography and histological analysis. RESULTS: In vitro, the RANKL/OPG ratio and phosphorylation of JNK and P38 protein levels of p-PDLCs were significantly decreased after L-D-sEV administration. Besides, flow cytometry and qRT-PCR analysis showed that L-D-sEV reduced apoptosis of p-PDLCs, down-regulated apoptosis-related genes Caspase-3 and BCL-2-Associated X expression, and up-regulated B-cell lymphoma-2 gene levels. In vivo, L-D-sEV administration significantly reduced alveolar bone loss, inhibited osteoclast activity, and induced M2 polarization. The histological analysis showed that iNOS/CD206, RANKL/OPG, p-JNK/JNK, and p-P38/P38 ratios were significantly lower in the L-D-sEV group than in the Peri group. CONCLUSIONS: L-D-sEV administration alleviated alveolar bone loss by mediating RANKL/OPG-related osteoclast activity and M2 macrophage polarization, alleviating p-PDLCs apoptosis and proliferation via the JNK and P38 pathways.

Periodontitis and alveolar resorption in human skeletal remains: The relationship between quantitative alveolar bone loss, occlusal wear, antemortem tooth loss, dental calculus and age at death in a low socioeconomic status, modern forensic human collection from Yucatan.

OBJECTIVE: This paper assesses the relationship between the distance between the cemento-enamel junction and alveolar crest and risk factors commonly associated with periodontitis. MATERIALS: Eighty individuals between 28 and 92 years old with known biological sex and age were analyzed from a 20th century forensic human collection from Merida, Yucatan (Mexico). METHODS: Macroscopic assessment, along with metric analysis, was employed using a probe. RESULTS: Ante-mortem tooth loss was positively correlated with the distance between the cemento-enamel junction and alveolar crest, as was the presence of root calculus in females. CONCLUSIONS: Cemento-enamel junction to alveolar crest distance is not a reliable indicator of periodontitis since it is not directly related to periodontitis-causing infectious pathogens, and since ante-mortem tooth loss can affect root exposure. SIGNIFICANCE: This study demonstrates that a purely quantitative approach to diagnosing periodontitis in archaeological and forensic human remains can be misleading. LIMITATIONS: The skeletal collection is only representative of the low socioeconomic class of Merida, and its female cohort is underrepresented. In addition, because the Xoclan collection is modern, limitations (particularly with respect to tooth wear) of the applicability of these interpretations to older archaeological remains exist. SUGGESTION FOR FURTHER RESEARCH: A combination of quantitative and qualitative characteristics of alveolar bone is needed to reliably diagnose periodontitis in skeletal populations.

Regeneration of alveolar bone defects in the experimental pig model: A systematic review and meta-analysis.

OBJECTIVE: Pigs are emerging as a preferred experimental in vivo model for bone regeneration. The study objective was to answer the focused PEO question: in the pig model (P), what is the capacity of experimental alveolar bone defects (E) for spontaneous regeneration in terms of new bone formation (O)? METHODS: Following PRISMA guidelines, electronic databases were searched for studies reporting experimental bone defects or extraction socket healing in the maxillae or mandibles of pigs. The main inclusion criteria were the presence of a control group of untreated defects/sockets and the assessment of regeneration via 3D tomography [radiographic defect fill (RDF)] or 2D histomorphometry [new bone formation (NBF)]. Random effects meta-analyses were performed for the outcomes RDF and NBF. RESULTS: Overall, 45 studies were included reporting on alveolar bone defects or extraction sockets, most frequently in the mandibles of minipigs. Based on morphology, defects were broadly classified as 'box-defects' (BD) or 'cylinder-defects' (CD) with a wide range of healing times (10 days to 52 weeks). Meta-analyses revealed pooled estimates (with 95% confidence intervals) of 50% RDF (36.87%-63.15%) and 43.74% NBF (30.47%-57%) in BD, and 44% RDF (16.48%-71.61%) and 39.67% NBF (31.53%-47.81%) in CD, which were similar to estimates of socket-healing [48.74% RDF (40.35%-57.13%) and 38.73% NBF (28.57%-48.89%)]. Heterogeneity in the meta-analysis was high (I2 > 90%). CONCLUSION: A substantial body of literature revealed a high capacity for spontaneous regeneration in experimental alveolar bone defects of (mini)pigs, which should be considered in future studies of bone regeneration in this animal model.

Occlusal force orchestrates alveolar bone homeostasis via Piezo1 in female mice.

Healthy alveolar bone is the cornerstone of oral function and oral treatment. Alveolar bone is highly dynamic during the entire lifespan and is affected by both systemic and local factors. Importantly, alveolar bone is subjected to unique occlusal force in daily life, and mechanical force is a powerful trigger of bone remodeling, but the effect of occlusal force in maintaining alveolar bone mass remains ambiguous. In this study, the Piezo1 channel is identified as an occlusal force sensor. Activation of Piezo1 rescues alveolar bone loss caused by a loss of occlusal force. Moreover, we identify Piezo1 as the mediator of occlusal force in osteoblasts, maintaining alveolar bone homeostasis by directly promoting osteogenesis and by sequentially regulating catabolic metabolism through Fas ligand (FasL)-induced osteoclastic apoptosis. Interestingly, Piezo1 activation also exhibits remarkable efficacy in the treatment of alveolar bone osteoporosis caused by estrogen deficiency, which is highly prevalent among middle-aged and elderly women. Promisingly, Piezo1 may serve not only as a treatment target for occlusal force loss-induced alveolar bone loss but also as a potential target for metabolic bone loss, especially in older patients.

Daily occlusal force and estrogen synergistically maintain alveolar bone homeostasis. PIEZO1 in osteoblasts plays a critical role in sensing occlusal force and maintaining bone mass. PIEZO1 may promote osteoclastic apoptosis through osteoblast-secreted FasL through a PIEZO1-STAT3/ESR1-FasL pathway. Restoration of occlusal force with dental therapies as early as possible to prevent alveolar bone loss is the major priority in oral health care. PIEZO1 may serve as a potential target for bone metabolism disorders.

A radiographic and histological study to compare red (650 nm) versus near infrared (810 nm) diode lasers photobiomodulation for alveolar socket preservation.

Previous findings indicated that the laser photobiomodulation is more effective than the control or placebo in preserving the alveolar socket. This study aimed to compare two different lasers regarding their effectiveness in aiding alveolar socket preservation. Twenty extraction sockets were selected then divided into two equal groups. Group A was exposed to 650 nm Diode laser, and Group B to 810 nm Diode laser following the same protocol and parameters after a standard alveolar socket preservation procedure with collagen plug. Radiographic analysis with cone beam computed tomography was done to compare the alveolar bone surface area immediately after extraction and three months post-operatively, while bone samples collected before implant drilling were histologically examined for newly formed bone evaluation and histomorphometric analysis in terms of percentage of new bone surface area, percentage of unmineralized bone and finally, immunohistochemical analysis of Osteocalcin reaction surface area as well as optical density. Radiographically, infrared (810 nm) Diode effect on alveolar bone surface area has significantly exceeded the red laser, while histologically, red (650 nm) Diode has demonstrated statistical significance regarding all parameters; newly formed bone surface area percentage, unmineralized bone area percentage and finally Osteocalcin bone marker reaction surface area percentage and optical density. Under the specified conditions and laser parameters, photobiomodulation using the 810 nm Diode got the upper hand radiographically, yet histologically, the red 650 nm Diode managed to dominate all histological parameters when both employed as an adjunct to alveolar socket preservation procedures.

Hepatocyte growth factor is protective in early stage but bone-destructive in late stage of experimental periodontitis.

BACKGROUND AND OBJECTIVE: Clinical studies found high levels of hepatocyte growth factor (HGF) expression in patients with periodontitis. Studies suggest that HGF plays an important role in periodontitis, is involved in inflammation, and modulates alveolar bone integrity in periodontitis. This study aims to investigate the effects and mechanisms of HGF in the progression of experimental periodontitis. METHODS: We used silk thread ligation to induce periodontitis in HGF-overexpressing transgenic (HGF-Tg) and wild-type C57BL/6J mice. The effects of HGF overexpression on alveolar bone destruction were assessed by microcomputed tomography imaging at baseline and on days 7, 14, 21, and 28. We analyzed the cytokines (IL-6 and TNF-α) and lymphocytes in periodontitis tissues by enzyme-linked immunosorbent assay and flow cytometry. The effects of HGF on alveolar bone destruction were further tested by quantifying the systemic bone metabolism markers CTXI and PINP and by RNA sequencing for the signaling pathways involved in bone destruction. Western blotting and immunohistochemistry were performed to further elucidate the involved signaling pathways. RESULTS: We found that experimental periodontitis increased HGF production in periodontitis tissues; however, the effects of HGF overexpression were inconsistent with disease progression. In the early stage of periodontitis, periodontal inflammation and alveolar bone destruction were significantly lower in HGF-Tg mice than in wild-type mice. In the late stage, HGF-Tg mice showed higher inflammatory responses and progressively aggravated bone destruction with continued stimulation of inflammation. We identified the IL-17/RANKL/TRAF6 pathway as a signaling pathway involved in the HGF effects on the progression of periodontitis. CONCLUSION: HGF plays divergent effects in the progression of experimental periodontitis and accelerates osteoclastic activity and bone destruction in the late stage of inflammation.