Resorbable bilayer membrane made of L-lactide-ε-caprolactone in guided bone regeneration: an in vivo experimental study.

PURPOSE: Guided bone regeneration (GBR) is an accepted method in dental practice that can successfully increase the bone volume of the host at sites chosen for implant placement; however, existing GBR membranes exhibit rapid absorption and lack of adequate space maintenance capabilities. We aimed to compare the effectiveness of a newly developed resorbable bilayer membrane composed of poly (L-lactic acid) and poly (-caprolactone) (PLACL) with that of a collagen membrane in a rat GBR model. METHODS: The rat calvaria was used as an experimental model, in which a plastic cylinder was placed. We operated on 40 male Fisher rats and subsequently performed micro-computed tomography and histomorphometric analyses to assess bone regeneration. RESULTS: Significant bone regeneration was observed, which was and similar across all the experimental groups. However, after 24 weeks, the PLACL membrane demonstrated significant resilience, and sporadic partial degradation. This extended preservation of the barrier effect has great potential to facilitate optimal bone regeneration. CONCLUSIONS: The PLACL membrane is a promising alternative to GBR. By providing a durable barrier and supporting bone regeneration over an extended period, this resorbable bilayer membrane could address the limitations of the current membranes. Nevertheless, further studies and clinical trials are warranted to validate the efficacy and safety of The PLACL membrane in humans.

Comparison of Macro-and Micro-porosity of a Titanium Mesh for Guided Bone Regeneration: An In Vivo Experimental Study.

BACKGROUND/AIM: Guided bone regeneration (GBR) is one of the surgical methods used for vertical ridge augmentation prior to dental implant placements. Titanium meshes have been used for osteogenic space maintenance in GBR sites by clinicians. We aimed to compare the influence of micropores and macropores in a titanium mesh on bone regeneration in a rat calvarial vertical GBR model. MATERIALS AND METHODS: The calvaria of nine rats were exposed, and plastic cylinders were set bilaterally. Eighteen surgical sites were randomly allocated into three groups according to the materials of titanium lid and bone substitutes: microporous titanium lid+deproteinized bovine bone mineral (DBBM), macroporous titanium lid +DBBM, microporous titanium lid+carbonate apatite. Newly generated bone inside the cylinders was evaluated using micro-computed tomography (micro-CT). Furthermore, bone regeneration and angiogenesis were evaluated histologically at 12 weeks. RESULTS: Quantitative volumetric analyses using micro-CT showed a gradual increase in bone volume inside the cylinders in all three groups. Histological observation confirmed vigorous bone regeneration in the microporous groups compared to that in the macroporous group. In the upper part of the cylinders, soft tissue invaded the GBR site by passing through the pores of the macroporous mesh. The blood vessels in the upper part of the cylinders were smaller in the microporous groups than in the macroporous group. There was no difference in bone formation between cylinders filled with DBBM or carbonate apatite. CONCLUSION: Microvasculature penetrates 50-µm diameter micropores and accelerates bone formation inside the cylinder, which was set on rat calvaria. The microporous titanium mesh can facilitate angiogenesis from both the dura mater and periosteal in vertical ridge augmentation. Our data showed superiority of microporous titanium vascular permeability and osteoconductivity, supporting bone growth.

Epstein-Barr Virus Promotes the Production of Inflammatory Cytokines in Gingival Fibroblasts and RANKL-Induced Osteoclast Differentiation in RAW264.7 Cells.

Periodontitis is an inflammatory condition that causes the destruction of the supporting tissues of teeth and is a major public health problem affecting more than half of the adult population worldwide. Recently, members of the herpes virus family, such as the Epstein-Barr virus (EBV), have been suggested to be involved in the etiology of periodontitis because bacterial activity alone does not adequately explain the clinical characteristics of periodontitis. However, the role of EBV in the etiology of periodontitis is unknown. This study aimed to examine the effect of inactivated EBV on the expression of inflammatory cytokines in human gingival fibroblasts (HGFs) and the induction of osteoclast differentiation. We found that extremely high levels of interleukin (IL)-6 and IL-8 were induced by inactivated EBV in a copy-dependent manner in HGFs. The levels of IL-6 and IL-8 in HGFs were higher when the cells were treated with EBV than when treated with lipopolysaccharide and lipoteichoic acid. EBV induced IκBα degradation, NF-κB transcription, and RAW264.7 cell differentiation into osteoclast-like cells. These findings suggest that even without infecting the cells, EBV contributes to inflammatory cytokine production and osteoclast differentiation by contact with oral cells or macrophage lineage, resulting in periodontitis onset and progression.

Expression of the SARS-CoV-2 Receptor ACE2 and Proinflammatory Cytokines Induced by the Periodontopathic Bacterium Fusobacterium nucleatum in Human Respiratory Epithelial Cells.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is currently a global public health emergency. Periodontitis, the most prevalent disease that leads to tooth loss, is caused by infection by periodontopathic bacteria. Periodontitis is also a risk factor for pneumonia and the exacerbation of chronic obstructive pulmonary disease, presumably because of the aspiration of saliva contaminated with periodontopathic bacteria into the lower respiratory tract. Patients with these diseases have increased rates of COVID-19 aggravation and mortality. Because periodontopathic bacteria have been isolated from the bronchoalveolar lavage fluid of patients with COVID-19, periodontitis may be a risk factor for COVID-19 aggravation. However, the molecular links between periodontitis and COVID-19 have not been clarified. In this study, we found that the culture supernatant of the periodontopathic bacterium Fusobacterium nucleatum (CSF) upregulated the SARS-CoV-2 receptor angiotensin-converting enzyme 2 in A549 alveolar epithelial cells. In addition, CSF induced interleukin (IL)-6 and IL-8 production by both A549 and primary alveolar epithelial cells. CSF also strongly induced IL-6 and IL-8 expression by BEAS-2B bronchial epithelial cells and Detroit 562 pharyngeal epithelial cells. These results suggest that when patients with mild COVID-19 frequently aspirate periodontopathic bacteria, SARS-CoV-2 infection is promoted, and inflammation in the lower respiratory tract may become severe in the presence of viral pneumonia.

Aspiration of periodontopathic bacteria due to poor oral hygiene potentially contributes to the aggravation of COVID-19.

Coronavirus infectious disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was declared a pandemic in March 2020 by the World Health Organization. Periodontitis, one of the most prevalent diseases worldwide, leads to alveolar bone destruction and subsequent tooth loss, and develops due to pro-inflammatory cytokine production induced by periodontopathic bacteria. Periodontopathic bacteria are involved in respiratory diseases, including aspiration pneumonia and chronic obstructive pulmonary disease (COPD), and other systemic diseases, such as diabetes and cardiovascular disease. Patients with these diseases have an increased COVID-19 aggravation rate and mortality. Because aspiration of periodontopathic bacteria induces the expression of angiotensin-converting enzyme 2, a receptor for SARS-CoV-2, and production of inflammatory cytokines in the lower respiratory tract, poor oral hygiene can lead to COVID-19 aggravation. Conversely, oral care, including periodontal treatment, prevents the onset of pneumonia and influenza and the exacerbation of COPD. The reduced chance of receiving professional oral care owing to long-term hospitalization of patients with COVID-19 may increase the aggravation risk of infection in the lower respiratory tract. It can be hypothesized that periodontopathic bacteria are involved in the COVID-19 aggravation and therefore, the management of good oral hygiene potentially contributes to its prevention.

Exposure to Porphyromonas gingivalis Induces Production of Proinflammatory Cytokine via TLR2 from Human Respiratory Epithelial Cells.

Aspiration pneumonia is a major health problem owing to its high mortality rate in elderly people. The secretion of proinflammatory cytokines such as interleukin (IL)-8 and IL-6 by respiratory epithelial cells, which is induced by infection of respiratory bacteria such as Streptococcus pneumoniae, contributes to the onset of pneumonia. These cytokines thus play a key role in orchestrating inflammatory responses in the lower respiratory tract. In contrast, chronic periodontitis, a chronic inflammatory disease caused by the infection of periodontopathic bacteria, typically Porphyromonas gingivalis, is one of the most prevalent microbial diseases affecting humans globally. Although emerging evidence has revealed an association between aspiration pneumonia and chronic periodontitis, a causal relationship between periodontopathic bacteria and the onset of aspiration pneumonia has not been established. Most periodontopathic bacteria are anaerobic and are therefore unlikely to survive in the lower respiratory organs of humans. Therefore, in this study, we examined whether simple contact by heat-inactivated P. gingivalis induced proinflammatory cytokine production by several human respiratory epithelial cell lines. We found that P. gingivalis induced strong IL-8 and IL-6 secretion by BEAS-2B bronchial epithelial cells. P. gingivalis also induced strong IL-8 secretion by Detroit 562 pharyngeal epithelial cells but not by A549 alveolar epithelial cells. Additionally, Toll-like receptor (TLR) 2 but not TLR4 was involved in the P. gingivalis-induced proinflammatory cytokine production. Furthermore, P. gingivalis induced considerably higher IL-8 and IL-6 production than heat-inactivated S. pneumoniae. Our results suggest that P. gingivalis is a powerful inflammatory stimulant for human bronchial and pharyngeal epithelial cells and can stimulate TLR2-mediated cytokine production, thereby potentially contributing to the onset of aspiration pneumonia.

Butyric Acid in Saliva of Chronic Periodontitis Patients Induces Transcription of the EBV Lytic Switch Activator BZLF1: A Pilot Study.

BACKGROUND/AIM: Epstein-Barr virus (EBV) associates with human chronic periodontitis (CP) progression. We previously demonstrated that butyric acid (BA), produced by periodontopathic bacteria, induced EBV lytic switch activator BZLF1 expression. We investigated whether short chain fatty acids (SCFAs) in CP patients' saliva enabled EBV reactivation. MATERIALS AND METHODS: Saliva was collected from seven CP patients and five periodontally healthy individuals. SCFAs were quantified using HPLC. BZLF1 mRNA and its pertinent protein ZEBRA were determined with Real-time PCR and western blotting. Histone H3 acetylation (AcH3) was further examined. RESULTS: BZLF1 mRNA expression and transcriptional activity in EBV-infected Daudi cells were induced only when treated with the CP saliva. Among SCFAs, BA alone correlated significantly with the BZLF1 transcription (r=0.88; p<0.02). As expected, CP patients' saliva induced AcH3. CONCLUSION: BA in saliva may play a role in EBV reactivation and hence contribute to EBV-related disease progression in CP patients.

EBV LMP1 in Gingival Epithelium Potentially Contributes to Human Chronic Periodontitis via Inducible IL8 Production.

BACKGROUND/AIM: Human chronic periodontitis is a major health problem. Although some oral bacteria have been reported to be putative pathogens, Epstein-Barr virus (EBV) is reported to be associated with the progression of periodontitis. However, the role of EBV in the aetiology of periodontitis is unknown. Therefore, we investigated periodontal pathogenesis of EBV to confirm whether EBV-encoded latent membrane protein 1 (LMP1) induces Interleukin-8 (IL8) production in human gingival cells. MATERIALS AND METHODS: Real-time polymerase chain reaction, luciferase assay, enzyme-linked immunosorbent assay (ELISA), and western blotting were performed for determining IL8 mRNA expression, nuclear factor kappa B (NF-ĸB) transcription, IL8 production, and the phosphorylation of NF-ĸB p65 and Inhibitor of kappa B alpha (IĸBα), respectively, in Ca9-22 human gingival epithelial cells. Two LMP1 mutants lacking C-terminal activating region (CATR) domains responsible for activating NF-ĸB were used. RESULTS: Extremely high IL8 production was induced by LMP1 in time- and dose-dependent manner, where simultaneous phosphorylation of NF-κB p65 and IĸBα and transcription of NF-ĸB were observed. On the contrary, IL8 production and NF-ĸB transcription were drastically inhibited by dominant negative mutant of IĸBα. Moreover, the LMP1 mutants failed to induce IL8 production. CONCLUSION: Our findings suggest that due to CATR domains, LMP1 contributes to the progression of periodontitis via IL8 production attributable to NF-ĸB activation.

The Periodontopathic Bacterium Fusobacterium nucleatum Induced Proinflammatory Cytokine Production by Human Respiratory Epithelial Cell Lines and in the Lower Respiratory Organs in Mice.

BACKGROUND/AIMS: The most prevalent infectious disease, chronic periodontitis which leads to alveolar bone destruction and subsequent tooth loss, develops due to proinflammatory cytokine production induced by periodontopathic bacteria. Chronic obstructive pulmonary disease (COPD), a non-infectious disease, is the third leading cause of death globally. This condition exacerbates frequently, and which is attributable to proinflammatory cytokine production induced by infection by respiratory microorganisms such as Streptococcus pneumoniae. Although a positive association has recently been revealed between chronic periodontitis and COPD, how periodontitis contributes to the pathogenesis of COPD remains unclear. Therefore, we hypothesized that some periodontopathic bacteria are involved in the exacerbation of COPD through the induction of proinflammatory cytokine production by respiratory epithelial cells. In this connection, COPD develops in the airways; however, because most periodontopathic bacteria are anaerobic, they are unlikely to exhibit stable virulence in the lower respiratory organs in humans. Hence, we aimed to elucidate whether exposure to heat-inactivated periodontopathic bacteria induces proinflammatory cytokine production by several human respiratory epithelial cell lines and in the lower respiratory organs and serum in mice. METHODS: Real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA) were used to investigate in vitro induction by heat-inactivated periodontopathic bacteria and S. pneumoniae for mRNA expression and protein production of interleukin (IL)-8 and IL-6 by human respiratory epithelial cell lines. ELISA was also used to determine in vivo induction of cytokine production in the lower respiratory organs and serum of intratracheally heat-inactivated Fusobacterium nucleatum-inoculated mice. RESULTS: Some, but not all, periodontopathic bacteria, especially F. nucleatum, strongly induced IL-8 and IL-6 production by BEAS-2B bronchial epithelial cells. In addition, F. nucleatum induced IL-8 production by A549 alveolar epithelial cells as well as IL-8 and IL-6 production by Detroit 562 pharyngeal epithelial cells. Furthermore, F. nucleatum induced considerably higher cytokine production than S. pneumoniae. This was also observed in the entire lower respiratory organs and serum in mice. CONCLUSION: Exposure to increased number of F. nucleatum potentially induces proinflammatory cytokine production by human bronchial and pharyngeal epithelial cells, which may trigger exacerbation of COPD.

Methodological quality and risk-of-bias assessments in systematic reviews of treatments for peri-implantitis.

BACKGROUND AND OBJECTIVES: The purpose of the present study was to evaluate the methodological quality and risk of bias in systematic reviews (SRs) on the effectiveness of peri-implantitis treatments. MATERIAL AND METHODS: We searched four electronic databases: MEDLINE, Web of Science, Cochrane Database of Systematic Reviews, and EMBASE. Previous SRs focusing on peri-implantitis treatment published between 2010 and 2017 were identified. After literature screening, eligible SRs were qualitatively assessed using two validated instruments: Assessing the Methodological Quality of Systematic Reviews (AMSTAR2) and Risk Of Bias In Systematic reviews (ROBIS). The characteristics and findings of SRs are also reported. RESULTS: A total of 23 SRs formed the basis of this study. Of the 23, six included randomized controlled trials (RCTs) only. Overall, the AMSTAR2 assessment revealed three studies with high and six studies with low methodological quality, and all the other SRs were judged as having critically low methodological quality. ROBIS revealed only one Cochrane review with a low risk of bias and the others with a high risk of bias. In particular, the assessment of non-randomized studies (NRSIs), appropriateness of ROB assessment, and meta-analysis did not satisfy the criteria in AMSTAR2 assessment. Furthermore, there were a few SRs that interpreted and discussed the results of risk of bias (ROB) and heterogeneity assessment, together with the impact of treatment. CONCLUSIONS: Due to the lack of head-to-head comparisons conducted in RCTs, review authors need to use other sources of evidence, such as clinical control trials (CCTs), cohort studies (CS), clinical research (CR), and animal studies. The end result is the presentation of low-quality evidence, with high ROB. Several SRs conducted network meta-analysis as an alternative to head-to-head conventional meta-analysis of RCTs. We suggest that the best methods to generate, access, and assess evidence in situations where RCT evidence is lacking should be discussed on an urgent basis.

Cynaropicrin from Cynara scolymus L. suppresses Porphyromonas gingivalis LPS-induced production of inflammatory cytokines in human gingival fibroblasts and RANKL-induced osteoclast differentiation in RAW264.7 cells.

Periodontal diseases are a major public health problem affecting over half of the adult population worldwide. Lipopolysaccharide (LPS) produced by the periodontopathic bacterium Porphyromonas gingivalis induces the expression of inflammatory cytokines that promote inflammatory bone destruction. Mounting evidence supports that periodontal diseases are involved in the onset and progression of several systemic diseases, such as aspiration pneumonia and diabetes. Although treatment of periodontal diseases by removing the periodontopathic bacteria by brushing is a standard practice, it has limitations and is not effective in all cases. Therefore, a new method to replace or complement brushing is needed for the treatment of periodontal diseases. In this study, we investigated the anti-inflammatory effects of an extract from Cynara scolymus L. and its pharmacologically effective compound cynaropicrin, a sesquiterpene lactone, on human gingival fibroblasts (HGFs) stimulated by LPS and the potential anti-osteoclastogenic effects on RAW264.7 cells induced by receptor activator of NF-κB ligand (RANKL). We found that cynaropicrin inhibited IL-8 and IL-6 mRNA and protein synthesis in LPS-stimulated HGFs in a dose-dependent manner. P. gingivalis LPS-induced degradation of IκBα and phosphorylation of NF-κB p65 were also suppressed by cynaropicrin, as was LPS-stimulated NF-κB transactivation. Thus, cynaropicrin's inhibition of P. gingivalis LPS-induced IL-8 and IL-6 expression may be due to the inhibition of the NF-κB pathway. Furthermore, we showed that cynaropicrin dramatically reduced RANKL-induced osteoclast differentiation. These results suggest that cynaropicrin may be useful for preventing periodontal diseases and could prove valuable in the development of more effective preventative approaches for periodontal diseases.