Current understanding of periodontal disease pathogenesis and targets for host-modulation therapy

Psoriasis and oral health in adult United States population: a cross-sectional study

OBJECTIVES

To detect the association between psoriasis as an exposure and oral health conditions as outcomes represented by periodontal and dentition status. This was addressed by analysis of a large number of adults in the United States.

METHODS

By using The National Health and Nutrition Examination Survey datasets from 2009 to 2014, we performed a cross-sectional analysis of 11,726 participants included in our study population. For participants aged ≥ 30 years, the psoriasis status was assessed from the medical questionnaire. We used data from periodontal and oral examinations to assess the oral conditions of our participants. We examined the association between psoriasis as exposure and moderate/severe periodontitis and non-functional dentition as outcomes.

RESULTS

The weighted prevalence of psoriasis was 3%, 44% for moderate/severe periodontitis, and 20.5% for non-functional dentition. The fully adjusted model showed no significant association between psoriasis and moderate/severe periodontitis (Prevalence Ratio 1.02, 95% CI 0.9-1.2, p = 0.8). There was no statistically significant association between psoriasis and non-functional dentition except in the fully adjusted model it became statistically significant (Prevalence Ratio 0.8, 95% CI 0.7-0.9, p = 0.04).

CONCLUSION

Our results showed no association between psoriasis and periodontal or dentition status except in a fully adjusted model for non-functional dentition.

Mapping of DNA methylation-sensitive cellular processes in gingival and periodontal ligament fibroblasts in the context of periodontal tissue homeostasis

Interactions between gingival fibroblasts (GFs) and oral pathogens contribute to the chronicity of inflammation in periodontitis. Epigenetic changes in DNA methylation are involved in periodontitis pathogenesis, and recent studies indicate that DNA methyltransferase (DNMT) inhibitors may protect against epithelial barrier disruption and bone resorption. To assess the impact of DNMT inhibition on GFs, cells were cultured with decitabine (5-aza-2'-deoxycytidine, DAC) for 12 days to induce DNA hypomethylation. We observed several potentially detrimental effects of DAC on GF biological functions. First, extended treatment with DAC reduced GF proliferation and induced necrotic cell death. Second, DAC amplified Porphyromonas gingivalis- and cytokine-induced expression and secretion of the chemokine CCL20 and several matrix metalloproteinases (MMPs), including MMP1, MMP9, and MMP13. Similar pro-inflammatory effects of DAC were observed in periodontal ligament fibroblasts. Third, DAC upregulated intercellular adhesion molecule-1 (ICAM-1), which was associated with increased P. gingivalis adherence to GFs and may contribute to bacterial dissemination. Finally, analysis of DAC-induced genes identified by RNA sequencing revealed increased expression of CCL20, CCL5, CCL8, CCL13, TNF, IL1A, IL18, IL33, and CSF3, and showed that the most affected processes were related to immune and inflammatory responses. In contrast, the genes downregulated by DAC were associated with extracellular matrix and collagen fibril organization. Our observations demonstrate that studies of DNMT inhibitors provide important insights into the role of DNA methylation in cells involved in periodontitis pathogenesis. However, the therapeutic potential of hypomethylating agents in periodontal disease may be limited due to their cytotoxic effects on fibroblast populations and stimulation of pro-inflammatory pathways.

A Reciprocal Link between Oral, Gut Microbiota during Periodontitis: The Potential Role of Probiotics in Reducing Dysbiosis-Induced Inflammation

Human body is colonized by a florid microbial community of bacteria, archaea, fungi, protists, helminths, and viruses, known as microbiota, which co-evolves with the host and influences its health through all stages of its life. It is well known that oral microorganisms form highly structurally and functionally organized multi-species biofilms and establish a network of complex mutual inter-species interactions having a primary function in synergy, signaling, or antagonism. This ecological model allows the microorganisms to increase their resistance to antimicrobial agents and settle a balanced microbes-host symbiotic relationship that ensures oral and global health status in humans. The host-associated microbiome is an important factor in human health and disease. Therefore, to develop novel diagnostic, therapeutic, and preventive strategies, microbiome's functions and the reciprocal interactions every microbiome entertains with other microbial communities in the human body are being investigated. This review provides an analysis of the literature about the close connection between the two largest microbial communities in humans: the oral and the gut microbiomes. Furthermore, it focuses on how the alteration of their microbial and functional characteristics can lead to and reciprocally influence the onset of both oral and intestinal microbiome-associated illness, along with the potential role of probiotics in ameliorating inflammation and microbial dysbiosis.

With Teeth, Broken, or Fixed: The Challenges of Linking Periodontitis, Neuroepidemiology, and Biomarkers of Disease

Periodontitis is a chronic inflammatory, bacterially-driven disease of the tooth-supporting tissues that shares several risk factors and elements of host response with Alzheimer's disease and related dementias (ADRD). Epidemiological studies have identified relatively consistent associations between adverse oral health conditions and ADRD. In this issue of the journal, a large study from the UK Biobank further explores these relationships along with MRI cognitive biomarkers. Despite its strength due to the large sample size, challenges in the study of periodontitis and neuroepidemiology markers include potential sampling bias, appropriate assessment of exposures, and the possibility of reverse causality.

Salivary cortisol, dehydroepiandrosterone, and chromogranin A levels in patients with gingivitis and periodontitis and a novel biomarker for psychological stress

Introduction

This study aimed to investigate the neuroendocrine responses based on cortisol, dehydroepiandrosterone (DHEA), cortisol/DHEA ratio, and chromogranin A levels, which reflect the activity of the hypothalamic-pituitary-adrenal axis, according to the presence or absence of psychological stress in patients with gingivitis and periodontitis compared to that in healthy controls.

Methods

In total, 117 patients (60 women, mean age: 36.29 ± 19.03 years) participated in this case-control study, comprising 32 healthy controls, 49 patients with gingivitis, and 36 patients with periodontitis. We investigated the presence of psychological stress and salivary characteristics, and analyzed the stress-related biomarkers of cortisol, DHEA, cortisol/DHEA ratio, and chromogranin A in the stimulated saliva.

Results

Salivary cortisol and chromogranin A levels increased with the severity of periodontal disease; their levels were the highest in the periodontitis group and were significantly higher in the following descending order: periodontitis, gingivitis, and healthy control groups (all values of p < 0.001). Additionally, the DHEA levels and cortisol/DHEA ratio were higher in the periodontitis group than those in the healthy control group (all values of p < 0.001). A multivariate logistic regression analysis revealed that the factors predicting above-average cortisol levels were periodontitis (odds ratio [OR] = 256.829; p < 0.001), women (OR = 6.365; p = 0.004), and psychological stress (OR = 6.036; p = 0.007); those predicting above-average cortisol/DHEA ratios were periodontitis (OR = 11.436; p < 0.001), psychological stress (OR = 3.977; p = 0.003), and women (OR = 2.890; p = 0.026). Thus, periodontitis and psychological stress were significant and strong predictors of above-average cortisol levels and cortisol/DHEA ratios. In the gingivitis group, salivary cortisol levels (r = 0.381, p = 0.007) and cortisol/DHEA ratios (r = 0.479, p < 0.001) were correlated with the presence of psychological stress. In the periodontitis group, increased cortisol/DHEA ratios (r = 0.412, p = 0.013) and lowered salivary buffer capacities (r = -0.334, p = 0.047) were correlated with the presence of psychological stress.

Conclusion

Periodontitis is a multifactorial disease resulting in inflammatory tissue destruction, which differs from gingivitis and a healthy state. Differences in stress-related neuroendocrine markers were revealed based on the severity of periodontal disease. The biomarkers that could be classified according to disease severity were salivary cortisol and chromogranin A levels. Above-average cortisol levels and cortisol/DHEA ratios are significant predictors of psychological stress in patients with gingivitis and periodontitis.

Role of immune-related lncRNAs--PRKCQ-AS1 and EGOT in the regulation of IL-1β, IL-6 and IL-8 expression in human gingival fibroblasts with TNF-α stimulation

Background/purpose

It was reported that lncRNAs have an effect on immune-related diseases, however, their roles in periodontitis remain to be investigated. The aim of this study was to look for immune-related lncRNAs in periodontitis, and to preliminarily explore their function in vitro.

Materials and methods

CIBERSORT was used to analyze abundance of immune cell in the periodontal tissue. Correlation between the expression profile of lncRNAs and abundance of immune cell was calculated and immune-related lncRNAs were identified. The expressions of immune-related lncRNAs identified were validated by RT-qPCR with 15 periodontitis and 15 healthy gingival tissues. The expressions of PRKCQ-AS1 and EGOT in HGFs were detected under the stimulation of different concentrations of TNF-α (0, 10, 15, 20, 30 ng/mL) and different duration (0, 12, 24 and 48 h). Then, siRNA was used to silence PRKCQ-AS1 and EGOT in HGFs. The expression level of IL-1β, IL-6, IL-8 of the HGFs after stimulated by 15 ng/mL TNF-α, and the activation of NF-κB pathway was observed.

Results

PRKCQ-AS1 and EGOT were identified as top 2 immune-related lncRNAs in periodontal tissues. The expressions of PRKCQ-AS1 and EGOT were significantly up-regulated in inflamed periodontal tissue and in HGFs under TNF-α stimulation. After knock-down of PRKCQ-AS1 and EGOT, expression level of IL-1β, IL-6, and IL-8 in HGFs with TNF-α stimulation were decreased, and activation of NF-κB pathway was inhibited.

Conclusion

PRKCQ-AS1 and EGOT were firstly identified as immune-related lncRNAs in periodontal tissue, and they regulate the expression of IL-1β, IL-6, and IL-8 of HGFs through the NF-κB pathway.

Genotype-driven NPC1L1 and PCSK9 inhibition and reduced risk of periodontitis

AIM

Epidemiological and pre-clinical studies suggest a chemoprotective role of lipid-lowering agents in periodontitis. We tested the association of genetically proxied inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), Niemann-Pick C1-Like 1 (NPC1L1) and proprotein convertase subtilisin/kexin type 9 (PCSK9) with periodontitis.

MATERIALS AND METHODS

Genetic variants in HMGCR, NCP1L1 and PCSK9 associated with low-density lipoprotein (LDL) cholesterol in a genome-wide association study (GWAS) meta-analysis (N = 188,578) were used to proxy therapeutic inhibition of HMGCR, NPC1L1 and PCSK9. For these genetic variants, associations with periodontitis were obtained from GWAS of 17,353 cases and 28,210 controls in the GeneLifestyle Interactions in Dental Endpoints consortium. Generalized weighted least squares analysis accounted for linkage disequilibrium of genotypes to derive pooled estimates.

RESULTS

While genetically proxied HMGCR inhibition equivalent to 1 mmol/L reduction in LDL was not associated with odds of periodontitis (odds ratio [OR] = 0.92 [95% confidence interval [CI]: 0.73; 1.16]; p = .4905; false discovery rate [FDR] = 0.4905), genetically proxied NPC1L1 (OR = 0.53 [95% CI: 0.35; 0.81]; p = .0038; FDR = 0.0077) and PCSK9 (OR = 0.84 [95% CI: 0.74; 0.95]; p = .0051; FDR = 0.0077) inhibition lowered the odds of periodontitis.

CONCLUSIONS

Genetically proxied inhibition of NCP1L1 and PCSK9 was associated with lower odds of periodontitis.

Salivary secretory leukocyte protease inhibitor levels in patients with stage 3 grade C periodontitis: a comparative cross-sectional study

Secretory leukocyte protease inhibitor (SLPI) is an anti-protease that protects mucosal tissue integrity owing to its anti-microbial and immunomodulatory properties. This study aimed to investigate SLPI levels in periodontal diseases, and analyze the potential correlation with clinical periodontal parameters. Whole saliva samples were obtained from healthy (n = 24), gingivitis (n = 24) and patients with stage 3 grade C periodontitis (n = 24). SLPI was measured by ELISA and normalized by total protein. Receiver operating characteristics (ROC) curve was used for estimating the area under the curve (AUC). The normalized SLPI levels were significantly reduced in periodontitis compared with gingivitis (4.84-fold) or health (1.83-fold) and negatively correlated with periodontal parameters. The ROC curves showed a good predictor value of the SLPI for differentiation of periodontitis versus health or gingivitis (AUC ≥ 0.80). This study demonstrates that the levels of SLPI are high in periodontal health, further elevated in gingivitis, but eventually decreased in severe periodontitis beyond the former two states. This observation may have broader implications in the context of inflammatory diseases affecting the oral mucosa, as it shows that the bacterial burden is disturbing the homeostatic balances of anti-microbial and anti-protease factors in the oral cavity.

Beneficial Effects of Melatonin on Periodontitis Management: Far More Than Oral Cavity

Periodontitis as a highly prevalent chronic infection/inflammatory disease can eventually lead to tooth loss and masticatory dysfunction. It also has a negative impact on general health and largely impairs quality of life. The tissue destruction during periodontitis is mainly caused by the excessive immune-inflammatory response; hence, how to modulate the host's reaction is of profound importance for effective periodontal treatment and tissue protection. Melatonin, as an endogenous hormone exhibiting multiple biological functions such as circadian rhythm regulation, antioxidant, and anti-inflammation, has been widely used in general healthcare. Notably, the past few years have witnessed increasing evidence for the application of melatonin as an adjunctive approach in the treatment of periodontitis and periodontitis-related systemic comorbidities. The detailed underlying mechanisms and more verification from clinical practice are still lacking, however, and further investigations are highly required. Importantly, it is essential to establish standard guidelines in the near future for the clinical administration of melatonin for periodontal health and general wellbeing.

Probiotics in Periodontal and Peri-Implant Health Management: Biofilm Control, Dysbiosis Reversal, and Host Modulation

Periodontitis and peri-implantitis are microbially associated diseases of the tissues supporting the teeth and dental implants that are mediated by host inflammation and eventually lead to tooth and dental implant loss. Given the probiotics' role in biofilm control, dysbiosis reversal, and host modulation, their potential beneficial effects on the improvement of periodontitis and peri-implantitis have been recently investigated. Moreover, probiotics use has also been proposed in periodontal health management in patients undergoing fixed orthodontic therapy. Therefore, the present study aimed to review, considering the periodontal microbiome composition around teeth and dental implants in healthy and pathological conditions, the putative favorable effects of probiotics on gingivitis, periodontitis, and peri-implantitis. The secondary aim of the present narrative review was to synthesize the supporting evidence and proposed protocols for probiotics use as adjuncts in periodontitis and peri-implantitis treatment and the periodontal health management of orthodontic patients with fixed appliances. Contrasting findings from the literature may be due to the different methods, posology, and duration of probiotics prescriptions and due to the heterogeneous biological and clinical measurement methods employed. Thus, no definitive conclusions could be drawn about the effectiveness of probiotics in periodontal management, both in healthy and pathological conditions. Further studies are needed to validate probiotics for periodontal management and provide recommended protocols.

Therapeutic and Metagenomic Potential of the Biomolecular Therapies against Periodontitis and the Oral Microbiome: Current Evidence and Future Perspectives

The principles of periodontal therapy are based on the control of microbial pathogens and host factors that contribute to biofilm dysbiosis, with the aim of modulating the progression of periodontitis and periodontal tissue destruction. It is currently known how differently each individual responds to periodontal treatment, depending on both the bacterial subtypes that make up the dysbiotic biofilm and interindividual variations in the host inflammatory response. This has allowed the current variety of approaches for the management of periodontitis to be updated by defining the goals of target strategies, which consist of reducing the periodontopathogenic microbial flora and/or modulating the host-mediated response. Therefore, this review aims to update the current variety of approaches for the management of periodontitis based on recent target therapies. Recently, encouraging results have been obtained from several studies exploring the effects of some targeted therapies in the medium- and long-term. Among the most promising target therapies analyzed and explored in this review include: cell-based periodontal regeneration, mediators against bone resorption, emdogain (EMD), platelet-rich plasma, and growth factors. The reviewed evidence supports the hypothesis that the therapeutic combination of epigenetic modifications of periodontal tissues, interacting with the dysbiotic biofilm, is a key step in significantly reducing the development and progression of disease in periodontal patients and improving the therapeutic response of periodontal patients. However, although studies indicate promising results, these need to be further expanded and studied to truly realize the benefits that targeted therapies could bring in the treatment of periodontitis.

Identifying Factors Associated with Periodontal Disease Using Machine Learning

Objective

This study aimed to identify combinations of chronic conditions associated with the presence and severity of periodontal disease (PD) after accounting for a series of demographic and behavioral characteristics in a nationally representative sample of US adults.

Materials and Methods

A cross-sectional study of the 2013-2014 National Health and Nutrition Examination Survey (n = 4555). Outcome measure: PD using clinical attachment loss (measured as none, mild, moderate, or severe). The main independent variables were self-reported chronic conditions, while other covariates included demographic and behavioral variables. Classification and regression tree analysis was used to identify combinations of specific chronic conditions associated with PD and PD with higher severity. Random forest was used to identify the most important variables associated with the presence and severity of PD.

Results

The prevalence of PD was 77% among the study population. The percentage of those with PD was higher among younger and middle-aged (< 61 years old) than older (> 61 years old) adults. Age and education level were the two most important predictors for the presence and severity of PD. Other significant factors included alcohol use, type of medical insurance, sex, and non-white race. Accounting for only chronic conditions, hypertension and diabetes were the two chronic conditions associated with the presence and severity of PD.

Conclusions

Sociodemographic and behavioral factors emerged as more strongly associated with the presence and severity of PD than chronic conditions. Accounting for the co-occurrence for sociodemographic and behavioral factors will be informative for identifying people vulnerable to the development of PD.

An injectable multifunctional thermo-sensitive chitosan-based hydrogel for periodontitis therapy

Bacteria are recognized as the driving factors of periodontitis. However, excessive reactive oxygen species (ROS) can harm periodontal tissue while also causing an uncontrolled inflammatory response. Hence, eliminating excessive ROS and blocking ROS-induced abnormal inflammatory response by antioxidants are achieving remarkable results in periodontitis therapy. Moreover, influenced by the deep and irregular periodontal pockets, injectable thermo-sensitive chitosan-based hydrogels have attracted a lot of attention. This study aimed to formulate an antibacterial and antioxidant therapeutic regimen by incorporating antimicrobial peptides (Nal-P-113) and/or antioxidants (polydopamine nanoparticles, PDNPs) into chitosan-based hydrogels. The hydrogel was characterized in vitro and finally examined in rats using the experimental periodontitis model. The release kinetics showed that the hydrogel could stably release Nal-P-113 and PDNPs for up to 13 days. The scavenging activity of the hydrogel against DPPH was about 80 % and the antibacterial ratio against Streptococcus gordonii (S. gordonii), Fusobacterium nucleatum (F. nucleatum) and Porphyromonas gingivalis (P. gingivalis) was about 99 %. Importantly, it was examined that the hydrogel had the ability to prevent periodontal tissue damage. Thus, chitosan-based hydrogels may provide a basis for designing multifunctional local drug delivery biomaterials for the treatment of periodontitis.

A Biomimetic Smart Nanoplatform as “Inflammation Scavenger” for Regenerative Therapy of Periodontal Tissue

Introduction

The functional reconstruction of periodontal tissue defects remains a clinical challenge due to excessive and prolonged host response to various endogenous and exogenous pro-inflammatory stimuli. Thus, a biomimetic nanoplatform with the capability of modulating inflammatory response in a microenvironment-responsive manner is attractive for regenerative therapy of periodontal tissue.

Methods

Herein, a facile and green design of engineered bone graft materials was developed by integrating a biomimetic apatite nanocomposite with a smart-release coating, which could realize inflammatory modulation by “on-demand” delivery of the anti-inflammatory agent through a pH-sensing mechanism.

Results

In vitro and in vivo experiments demonstrated that this biocompatible nanoplatform could facilitate the clearance of reactive oxygen species in human periodontal ligament stem cells under inflammatory conditions via inhibiting the production of endogenous proinflammatory mediators, in turn contributing to the enhanced healing efficacy of periodontal tissue. Moreover, this system exhibited effective antimicrobial activity against common pathogenic bacteria in the oral cavity, which is beneficial for the elimination of exogenous pro-inflammatory factors from bacterial infection during healing of periodontal tissue.

Conclusion

The proposed strategy provides a versatile apatite nanocomposite as a promising “inflammation scavenger” and propels the development of intelligent bone graft materials for periodontal and orthopedic applications.

Complement Is Required for Microbe-Driven Induction of Th17 and Periodontitis

In both mice and humans, complement and Th17 cells have been implicated in periodontitis, an oral microbiota-driven inflammatory disease associated with systemic disorders. A recent clinical trial showed that a complement C3 inhibitor (AMY-101) causes sustainable resolution of periodontal inflammation, the main effector of tissue destruction in this oral disease. Although both complement and Th17 are required for periodontitis, it is uncertain how these immune components cooperate in disease development. In this study, we dissected the complement-Th17 relationship in the setting of ligature-induced periodontitis (LIP), a model that previously established that microbial dysbiosis drives Th17 cell expansion and periodontal bone loss. Complement was readily activated in the periodontal tissue of LIP-subjected mice but not when the mice were placed on broad-spectrum antibiotics. Microbiota-induced complement activation generated critical cytokines, IL-6 and IL-23, which are required for Th17 cell expansion. These cytokines as well as Th17 accumulation and IL-17 expression were significantly suppressed in LIP-subjected C3-deficient mice relative to wild-type controls. As IL-23 has been extensively studied in periodontitis, we focused on IL-6 and showed that LIP-induced IL-17 and bone loss required intact IL-6 receptor signaling in the periodontium. LIP-induced IL-6 was predominantly produced by gingival epithelial cells that upregulated C3a receptor upon LIP challenge. Experiments in human gingival epithelial cells showed that C3a upregulated IL-6 production in cooperation with microbial stimuli that upregulated C3a receptor expression in ERK1/2- and JNK-dependent manner. In conclusion, complement links the periodontal microbiota challenge to Th17 cell accumulation and thus integrates complement- and Th17-driven immunopathology in periodontitis.

Açaí (Euterpe oleracea Mart.) Attenuates Oxidative Stress and Alveolar Bone Damage in Experimental Periodontitis in Rats

Açaí (Euterpe oleracea Mart.) juice is rich in phenolic compounds with high antioxidant capacity. It has been observed that the use of antioxidants may be an additional strategy to nonsurgical periodontal therapy as well as to prevent alveolar bone loss. Thus, the objective of this study was to investigate the effects of açaí supplementation on experimental periodontitis in rats. Twenty male Rattus norvegicus (Wistar) rats were assigned into control, açaí, experimental periodontitis, and experimental periodontitis with açaí supplementation groups. Periodontitis was induced by placing ligatures around the lower first molars. Animals in the açaí groups received 0.01 mL/g of clarified açaí juice for 14 days by intragastric gavage. At the end of the experimental period, blood was collected to assess the reduced glutathione (GSH), Trolox equivalent antioxidant capacity (TEAC), and lipid peroxidation (TBARS) levels. Moreover, hemimandibles were analyzed by micro-computed tomography (micro-CT) for alveolar bone loss and bone quality. Açaí supplementation increased blood total antioxidant capacity and decreased lipid peroxidation. It also reduced alveolar bone loss when compared to the experimental periodontitis group. Moreover, clarified açaí per se modulated the oxidative biochemistry and bone microstructure. Thus, açaí may be considered a viable alternative for managing periodontal oxidative stress and preventing alveolar bone loss.

Biological Activity of Copaiba in Damage to the Alveolar Bone in a Model of Periodontitis Induced in Rats

Several studies have investigated the effects of natural products in the treatment of diseases. Traditional Amazonian populations commonly use copaiba due to its well-known anti-inflammatory, antibacterial, and healing properties. In this study, we aimed to investigate the effects of systemic administration of copaiba oleoresin (Copaifera reticulata Ducke) on ligature-induced periodontitis in rats. To do so, 21 adult rats were divided into three groups (n = 7 each): a control group, ligature-induced periodontitis group, and ligature-induced periodontitis group treated with copaiba oleoresin (200 mg/kg/day). The ligature remained from day 0 to 14, and the copaiba oleoresin was administered via oral gavage during the last seven days. On day 14, the animals were euthanized, and mandibles were collected for histopathological evaluation and microcomputed tomography analysis. Our data showed that the administration of copaiba considerably reduced the inflammatory profile. Moreover, copaiba oleoresin limited alveolar bone loss, increased trabecular thickness and bone-to-tissue volume ratio, and decreased the number of trabeculae compared with those of the untreated experimental periodontitis group. Our findings provide pioneering evidence that supports the potential of copaiba oleoresin in reducing periodontitis-induced alveolar bone damage in rats.

Tracking of Stem Cells from Human Exfoliated Deciduous Teeth Labeled with Molday ION Rhodamine-B during Periodontal Bone Regeneration in Rats

Background and Objectives

Chronic periodontitis can lead to alveolar bone resorption and eventually tooth loss. Stem cells from exfoliated deciduous teeth (SHED) are appropriate bone regeneration seed cells. To track the survival, migration, and differentiation of the transplanted SHED, we used super paramagnetic iron oxide particles (SPIO) Molday ION Rhodamine-B (MIRB) to label and monitor the transplanted cells while repairing periodontal bone defects.

Methods and Results

We determined an appropriate dose of MIRB for labeling SHED by examining the growth and osteogenic differentiation of labeled SHED. Finally, SHED was labeled with 25 μg Fe/ml MIRB before being transplanted into rats. Magnetic resonance imaging was used to track SHED survival and migration in vivo due to a low-intensity signal artifact caused by MIRB. HE and immunohistochemical analyses revealed that both MIRB-labeled and unlabeled SHED could promote periodontal bone regeneration. The colocalization of hNUC and MIRB demonstrated that SHED transplanted into rats could survive in vivo. Furthermore, some MIRB-positive cells expressed the osteoblast and osteocyte markers OCN and DMP1, respectively. Enzyme-linked immunosorbent assay revealed that SHED could secrete protein factors, such as IGF-1, OCN, ALP, IL-4, VEGF, and bFGF, which promote bone regeneration. Immunofluorescence staining revealed that the transplanted SHED was surrounded by a large number of host-derived Runx2- and Col II-positive cells that played important roles in the bone healing process.

Conclusions

SHED could promote periodontal bone regeneration in rats, and the survival of SHED could be tracked in vivo by labeling them with MIRB. SHED are likely to promote bone healing through both direct differentiation and paracrine mechanisms.

Whole-transcriptome analysis of periodontal tissue and construction of immune-related competitive endogenous RNA network

Background

In periodontitis, noncoding RNAs may play a regulatory role in the immune microenvironment through competitive endogenous RNA. We aimed to profile noncoding RNA expression and construct immune-related ceRNA network in periodontitis.

Methods

Five inflamed periodontal tissue and five healthy gingivae were collected for whole-transcriptome sequencing. Differential gene, functional enrichment, and protein–protein interaction network analysis were performed to explore the function of differentially expressed genes. CIBERSORTx was used to analyze level of immune cell infiltration in the periodontal tissue. An immune-related competitive endogenous RNA network was constructed and expression of key regulators in the network was validated.

Results

Compared with healthy gingiva, 200 mRNAs, 90 long noncoding RNAs, 65 microRNAs, and 518 circular RNAs were differentially expressed, and cell chemotaxis was significantly enhanced in inflamed periodontal tissue. Immune cell infiltration analysis showed that neutrophils, macrophages M1, T follicular helper cells, and naive B cells were significantly increased in periodontitis. Key regulators including JUN, FOS, THBS1, KLF2, WIF1, were identified and their expression was then validated.

Conclusion

We constructed an immune-related competitive endogenous RNA network in periodontal tissue, which provided new insights into immune homeostasis in periodontitis and laid a foundation for further study of noncoding RNAs. Key regulators in this network may be promising targets for future periodontitis treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02401-0.

Evaluation of IL-23p19/Ebi3 (IL-39) gingival crevicular fluid levels in periodontal health, gingivitis, and periodontitis

Objectives

IL-23p19/Ebi3 (IL-39) was described as a new IL-12 family member. The aim of this study is to evaluate the gingival crevicular fluid (GCF) IL-39 levels in periodontal diseases and health and to correlate them to GCF levels of IL-1β and periostin.

Materials and methods

Sixty-six adult patients were included in the study. The study design was comprised of three groups, each containing 22 individuals: the periodontally healthy (PH), gingivitis (G), and periodontitis (P) groups. The clinical periodontal parameters were recorded and GCF samples were collected from the participants. GCF interleukin (IL)-39, IL-1β, and periostin levels were examined using the enzyme-linked immunosorbent assay.

Results

GCF IL‑1β, periostin, and IL-39 levels were higher in the P and G groups than in the PH group (p < 0.001). Positive correlations were detected between all GCF biochemical parameters and clinical periodontal parameters (p < 0.05). In the multivariate generalized linear regression analysis, the P (β = 37.6, 95% CI = 22.9–52.4) and G (β = 28.4, 95% CI = 15.8–41) groups were associated with GCF IL-39 levels (p < 0.001).

Conclusion

IL-39 levels were elevated in the presence of periodontal disease paralleling the increase in IL‑1β and periostin levels. IL-39 may have a role in the periodontal inflammation process.

Statement of clinical relevance

IL-39, a new cytokine from the IL-12 family, can be a possible predictor marker of periodontal diseases.

Oxidative stress and inflammation regulation of sirtuins: New insights into common oral diseases

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD)⁺-dependent histone deacetylases, comprising seven members SIRT1-SIRT7. Sirtuins have been extensively studied in regulating ageing and age-related diseases. Sirtuins are also pivotal modulators in oxidative stress and inflammation, as they can regulate the expression and activation of downstream transcriptional factors (such as Forkhead box protein O3 (FOXO3a), nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB)) as well as antioxidant enzymes, through epigenetic modification and post-translational modification. Most importantly, studies have shown that aberrant sirtuins are involved in the pathogenesis of infectious and inflammatory oral diseases, and oral cancer. In this review, we provide a comprehensive overview of the regulatory patterns of sirtuins at multiple levels, and the essential roles of sirtuins in regulating inflammation, oxidative stress, and bone metabolism. We summarize the involvement of sirtuins in several oral diseases such as periodontitis, apical periodontitis, pulpitis, oral candidiasis, oral herpesvirus infections, dental fluorosis, and oral cancer. At last, we discuss the potential utilization of sirtuins as therapeutic targets in oral diseases.

Host Response Modulation Therapy in the Diabetes Mellitus—Periodontitis Conjuncture: A Narrative Review

The inflammatory response of the host in periodontitis is the phenomenon that underlies the onset and evolution of periodontal destructive phenomena. A number of systemic factors, such as diabetes mellitus (DM), can negatively affect the patient with periodontitis, just as the periodontal disease can aggravate the status of the DM patient. Host response modulation therapy involves the use of anti-inflammatory and anti-oxidant products aimed at resolving inflammation, stopping destructive processes, and promoting periodontal healing, all important aspects in patients with high tissue loss rates, such as diabetic patients. This paper reviews the data available in the literature on the relationship between DM and periodontitis, the main substances modulating the inflammatory response (nonsteroidal anti-inflammatory drugs, sub-antimicrobial doses of doxycycline, or omega-3 fatty acids and their products, specialized pro-resolving mediators), as well as their application in diabetic patients.

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.

Therapeutic Potential of Polyphenol and Nanoparticles Mediated Delivery in Periodontal Inflammation: A Review of Current Trends and Future Perspectives

Periodontitis is an oral inflammatory process involving the periodontium, which is mainly caused by the invasion of periodontopathogenic microorganisms that results in gingival connective tissue and alveolar bone destruction. Metabolic products of the oral pathogens and the associated host immune and inflammatory responses triggered are responsible for the local tissue destruction. Numerous studies in the past decades have demonstrated that natural polyphenols are capable of modulating the host inflammatory responses by targeting multiple inflammatory components. The proposed mechanism by which polyphenolic compounds exert their great potential is by regulating the immune cell, proinflammatory cytokines synthesis and gene expression. However, due to its low absorption and bioavailability, the beneficial effects of these substances are very limited and it hampers their use as a therapeutic agent. To address these limitations, targeted delivery systems by nanoencapsulation techniques have been explored in recent years. Nanoencapsulation of polyphenolic compounds with different carriers is an efficient and promising approach to boost their bioavailability, increase the efficiency and reduce the degradability of natural polyphenols. In this review, we focus on the effects of different polyphenolic substances in periodontal inflammation and to explore the pharmaceutical significance of polyphenol-loaded nanoparticles in controlling periodontitis, which may be useful for further enhancement of their efficacy as therapeutic agents for periodontal disease.

Critical roles for CCR2 and the therapeutic potential of cenicriviroc in periodontitis: a pre-clinical study

AIM

CCR2 plays important roles in many inflammatory and bone metabolic diseases, but its specific role in periodontitis is unknown. In the present study, we aimed to explore the role of CCR2 in the progression of periodontitis and evaluate the effect of cenicriviroc (CVC) on periodontitis.

METHODS

The expression of CCR2 was studied in patients with periodontitis and in ligation-induced murine model of periodontitis. The role of CCR2 in promoting inflammation and bone resorption in periodontitis was evaluated in Ccr2^-/- mice and wild-type mice. The effect of CVC in the prevention and treatment of periodontitis was evaluated by systemic and local medication. Micro-CT, Hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, real-time qPCR, ELISA, and flow cytometric were used for histomorphology, molecular biology and cytology analysis respectively.

RESULTS

In this study, we demonstrated that CCR2 was highly expressed in human and murine periodontitis and that CCR2 deficiency was associated with decreased inflammation, alveolar bone resorption, osteoclast number, monocyte and macrophage infiltration. Prevention and treatment with CVC significantly reduced the severity of periodontitis, regardless of whether it was administered systemically or locally.

CONCLUSION

CCR2 plays an important role in the development and progression of periodontitis and CVC is a potential drug for the prevention and treatment of periodontitis.

Mendelian randomization highlights the causal association of obesity with periodontal diseases

AIM

The underlying mechanisms connecting obesity and periodontal diseases remain unclear. This study investigates the potential causal association of obesity with periodontal diseases using Mendelian randomization (MR).

MATERIALS AND METHODS

Single-nucleotide polymorphisms of obesity traits including body mass index (BMI), waist circumference (WC), and WC adjusted for BMI (WCadjBMI) from large-scale genome-wide association studies were screened for instrumental variables. The single trait periodontitis and the combined trait comprising periodontitis and loose teeth were adopted as surrogates for periodontal diseases. Inverse-variance weighted (IVW), series of sensitivity analyses and multivariable MR were employed to determine the association of obesity with periodontal diseases.

RESULTS

IVW results showed that per 1-SD increment in BMI (odds ratio, OR = 1.115; 95% confidence interval [CI] = 1.064-1.169; p < .001) and WC (OR = 1.117; 95% CI = 1.052-1.185; p < .001), but not WCadjBMI, were significantly associated with an increased risk of periodontitis/loose teeth. Moreover, the MR estimates were consistent across other MR sensitivity analyses and multivariable MR. However, a causal association of obesity with the single trait periodontitis was not identified.

CONCLUSIONS

The presented evidence supports previous epidemiological findings by showing a potential causal association of genetic liability to obesity with periodontal diseases. The biological mechanisms underlying this association warrant further investigation.

Transcription Factor AhR, Cytokines IL-6 and IL-22 in Subjects with and without Peri-Implantitis: A Case Control-Study

Peri-implantitis is a plaque-associated condition characterized by mucosal inflammation and subsequent progressive loss of supporting bone; it is caused by bacterial biofilm, but the host response triggered by bacterial stimulation promotes the release of cells and mediators that culminate in tissue destruction. The Aryl-hydrocarbon Receptor (AhR) is associated with IL-22 production by Th22 and Th17 CD4+ Th cells. The presence of IL-6 may promote the Th22 phenotype. The present case-control study evaluated the gene expression of AhR, IL-22, and IL-6 in the peri-implant tissues of healthy and peri-implantitis patients. Tissue biopsies were collected from thirty-five volunteers (15 healthy and 20 with peri-implantitis). A real-time PCR reaction was utilized to assess the AhR, IL-22, and IL-6 gene expression levels relative to the reference gene (GAPDH). The results were analyzed using the Mann-Whitney test with a significance level of 5%. Higher levels of gene expression of AhR and IL-6 were detected in peri-implantitis tissues. The IL-22 gene expression levels did not differ between groups. In conclusion, higher gene expression levels for AhR and IL-6 were detected in the soft tissues of peri-implantitis patients. IL-22 did not vary between conditions, which may indicate the loss of the immunomodulatory role of IL-22 in periimplantitis.

A20 inhibits periodontal bone resorption and NLRP3-mediated M1 macrophage polarization

A20 is involved in inflammation and bone metabolism in periodontitis. Regulation of macrophage polarization may be an effective target for periodontitis treatment, and A20 has a regulatory role in macrophage polarization. This study aimed to explore the effects of A20 on macrophage polarization in periodontitis and the underlying mechanism. Adeno-associated virus (AAV) targeting A20 was exploited to achieve A20 knockdown or overexpression in periodontal tissues of mice with experimental periodontitis. The (AAV-A20-RNAi) +P group showed increased alveolar bone resorption when compared with PBS + P and CON305 + P groups. However, the degree of bone destruction was reduced in the (AAV-A20) +P group relative to PBS + P and CON299 + P groups. A20 knockdown resulted in enhanced inducible nitric oxide synthase (iNOS) expression and decreased CD206 expression in mice periodontal tissues. In addition, higher levels of M1 macrophage polarization markers (iNOS, CD86, TNF-α) and lower CD206 expression were found in THP-1 cells treated with lipopolysaccharide (LPS) from Porphyromonas gingivalis (P. gingivalis) (Pg. LPS) and interferon-γ (IFN-γ) when A20 was silenced. A20 overexpression showed opposite effects on macrophage polarization in vivo and in vitro. Knockdown of A20 was correlated with upregulation of the NLRP3 inflammasome pathway in mice periodontal tissues or THP-1 cells. On the contrary, A20 overexpression inhibited the NLRP3 inflammasome pathway. MCC950 suppressed M1 macrophage polarization aggravated through A20 knockdown in Pg. LPS and IFN-γ stimulated cells. Our data suggested that A20 inhibits periodontal bone resorption and NLRP3-mediated M1 macrophage polarization; A20 is expected to be a novel target for the treatment of periodontitis.

Porphyromonas gingivalis lipopolysaccharide affects the angiogenic function of endothelial progenitor cells via Akt/FoxO1 signaling

AIMS

Endothelial progenitor cells (EPCs) function as the angiogenic switch of many physiological and pathological conditions. We aimed to investigate the effects of Porphyromonas gingivalis lipopolysaccharide on the angiogenic capacity of EPCs and delineate the underlying mechanisms.

MATERIALS AND METHODS

EPCs were isolated from human umbilical blood. CCK-8 assay was undertaken to analyze the cell viability. The migration and tube formation capacity were assessed by wound healing and tube formation, respectively. The protein expression of Akt/p-Akt, endothelial nitric oxide synthase (eNOS)/p-eNOS, and Forkhead box O1 (FoxO1)/p-FoxO1 was determined by Western blot. The intracellular localization of FoxO1 was evaluated by immunofluorescent staining.

RESULTS

P. gingivalis LPS at 10 μg/ml significantly increased the viability (10.9 ± 2.9%), migration (16.3 ± 3.1%), and tube formation (38.6 ± 5.5%) of EPCs, along with increased phosphorylation of Akt, eNOS, and FoxO1. Mechanistically, Akt inhibition by specific inhibitor wortmannin and FoxO1 forced expression by adenovirus transfection in EPCs markedly attenuated the P. gingivalis LPS-induced eNOS activation, tube formation, and migration. Moreover, P. gingivalis LPS-induced phosphorylation and nuclear exclusion of FoxO1 were blunted by Akt inhibition.

CONCLUSIONS

The present study suggests that P. gingivalis LPS could affect the angiogenic function of EPCs through the Akt/FoxO1 signaling. The current findings may shed light on the clinical association of periodontitis with aberrant angiogenesis seen in atherosclerotic plaque rupture.

Effect of Green Tea on the Level of Salivary Interleukin-1 Beta in Patients with Chronic Periodontitis: A Randomized Clinical Trial

Aim

Interleukin-1 beta (IL-1β) is one of the major biomarkers involved in the pathogenesis of chronic periodontitis. The aim of this study was to evaluate the changes in salivary IL-1β concentration in patients with chronic periodontitis following daily consumption of green tea.

Methods and Materials

Thirty patients with an average age of 45.8 years suffering from chronic periodontitis were randomly assigned into 2 groups (i.e., experimental and control groups). Besides receiving phase 1 periodontal treatment (scaling and root planning (SRP)), the experimental group drank green tea for a period of 6 weeks. To measure the concentration of salivary IL-1β, saliva samples were taken from both groups at 2 time points, i.e., prior to SRP (time point 1 (T0)) and after 6 weeks (time point 2 (T1)). The nonparametric Wilcoxon test was used to examine and compare the changes in the concentration of salivary IL-1β in each group relevant to the 2 time points (T0 and T1). Data were submitted to statistical analysis.

Results

At the end of the study period, a significant reduction (P=0.0001) in the concentration of salivary IL-1β was observed in the experimental group (A). As for the control group (B), however, there was no significant change (P=0.307) in the concentration of salivary IL-1β after 6 weeks following phase 1 periodontal treatment.

Conclusion

Green tea supplementation, in addition to SRP, may reduce salivary IL-1β levels in patients with chronic periodontitis for a period of 6 weeks.

Does the use of omega-3 fatty acids as an adjunct to non-surgical periodontal therapy provide additional benefits in the treatment of periodontitis? A systematic review and meta-analysis

This review aimed to assess the impact of dietary omega-3 fatty acids as an adjunct to non-surgical periodontal treatment when compared with periodontal treatment alone on periodontal clinical parameters of periodontitis patients. We included only randomized clinical trials (RCTs) with at least 3-months follow-up of non-surgical periodontal therapy, in combination with dietary omega-3 fatty acids. The MEDLINE, EMBASE, and LILACS databases were searched for articles published up to October 2021. Random-effects meta-analyses were conducted to determine the change in clinical attachment level (CAL), probing pocket depth (PPD), bleeding on probing (BOP), and gingival index (GI) after therapy. Of the eight hundred eighty-four potentially relevant papers retrieved from the electronic databases, 10 RCTs were selected for qualitative analysis, and of these, 8 RCTs were included in meta-analysis. RCTs showed a significant PPD reduction/CAL gain associated with the use of omega-3 fatty acids. The pooled estimates revealed significant overall PPD reduction of 0.42 mm (95% CI 0.15, 0.68) and CAL gain 0.58 mm (95% CI 0.24, 0.92). In individuals with periodontitis, the use of omega-3 fatty acid dietary supplementation as an adjunct to non-surgical periodontal treatment can provide additional benefits in CAL gain and PPD reduction, compared with non-surgical periodontal treatment alone.

Relationship between periodontitis and psoriasis: A two-sample Mendelian randomization study

AIM

Observational research suggests that periodontitis affects psoriasis. However, observational studies are prone to reverse causation and confounding, which hampers drawing causal conclusions and the effect direction. We applied the Mendelian randomization (MR) method to comprehensively assess the potential bi-directional association between periodontitis and psoriasis.

MATERIALS AND METHODS

We used genetic instruments from the largest available genome-wide association study of European descent for periodontitis (17,353 cases, 28,210 controls) to investigate the relationship with psoriasis (13,229 cases, 21,543 controls), and vice versa. Causal Analysis Using Summary Effect (CAUSE) estimates and inverse variance-weighted (IVW) MR analyses were used for the primary analysis. Robust MR approaches were used for sensitivity analyses.

RESULTS

Both univariable methods, CAUSE and IVW MR analyses, did not reveal any impact of periodontitis on psoriasis (CAUSE odds ratio [OR] = 1.00, p = 1.00; IVW OR = 1.02, p = .6247), or vice versa (CAUSE OR = 1.01, p = .5135; IVW OR = 1.00, p = .7070). The null association was corroborated by pleiotropy-robust methods with ORs close to 1 and p-values >.59. Overall, MR analyses did not suggest any effect of periodontitis on psoriasis. Similarly, there was no evidence to support an effect of psoriasis on periodontitis.

CONCLUSIONS

Within the limitations of this MR study, the outcomes supported neither periodontitis affecting psoriasis nor psoriasis affecting periodontitis.

B cell depletion in patients with rheumatoid arthritis is associated with reduced IL-1β in GCF

OBJECTIVES

We evaluated the effect of B cell depletion on the clinical periodontal findings and IL-1β and MMP-8 levels of the gingival crevicular (GCF) fluid in patients with rheumatoid arthritis (RA).

MATERIALS AND METHODS

Seventy patients were included in this case-control study. Twenty patients with RA were undergoing B-cell depletion treatment. The second group of RA patients (n = 20) were undergoing non-B-cell depletion treatment with Disease-Modifying Anti-Rheumatic Drugs (DMARD). Control group, with no RA, consisted of 30 individuals. Periodontal parameters including probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), gingival index (GI), and plaque index (PI) were recorded. IL-1β and MMP-8 levels in GCF were determined using enzyme-linked immunosorbent assay. Rheumatological parameters including Disease Activity Score-28 (DAS-28), rheumatoid factor levels (RF), and anti-cyclic citrullinated peptide levels were included in the data analyses.

RESULTS

All groups were similar in PD, CAL, BOP, GI, and PI measures. GCF IL-1β levels were 1.85 ± 1.67 pg in the B-cell depletion group, 10.50 ± 13.16 pg in the DMARD group, and 34.12 ± 29.45 pg in the control group (p < 0.001). MMP-8 levels were 21.00 ± 4.23 pg in the B-cell depletion group, 8.16 ± 6.94 pg in the DMARD group, and 21.45 ± 8.67 pg in the control group (p < 0.001). DAS 28, RF, and anti-CCP were similar in RA groups.

CONCLUSIONS

GCF IL-1β levels were significantly lower in B cell depletion group, and MMP-8 levels were significantly lower in DMARD group, suggesting that rheumatoid arthritis treatments may modify biochemical parameters of GCF.

CLINICAL RELEVANCE

This study suggests that host modulation therapies in RA can reduce local production of IL-1β and MMP-8. Reduction of these inflammatory cytokines and enzymes may have a beneficial effect in controlling periodontal tissue destruction.

Modulating the Immune Response in Periodontitis

Periodontitis is a chronic inflammatory condition initiated by the accumulation of bacterial biofilm. It is highly prevalent and when left untreated can lead to tooth loss. The presence of bacterial biofilm is essential for the initiation of the inflammatory response but is not the sole initiator. Currently it is unknown which mechanisms drive the dysbiosis of the bacterial biofilm leading to the dysregulation of the inflammatory response. Other players in this equation include environmental, systemic, and genetic factors which can play a role in exacerbating the inflammatory response. Treatment of periodontal disease consists of removal of the bacterial biofilm with the goal of resolving the inflammatory response; however, this does not occur in every case. Understanding the way the inflammatory response does not return to a state of homeostasis has led investigators to consider both systemic and local pharmacological interventions. Nonetheless, a better understanding of the impact that genetics and environmental factors may have on the inflammatory response could be key to helping identify how inflammation can be modulated therefore stopping the destruction of the periodontium. In this article, we will explore the current evidence associating the microbial dysbiosis and the dysregulation of the immune response, potential mechanisms or pathways that may be targeted for the modulation of the inflammatory response, and discuss the advantages and drawbacks associated with local and systemic inflammatory modulation in the management of periodontal disease. This information will be valuable for those interested in understanding potential adjunct methods for managing periodontal diseases, but not limited to, dental professionals, clinical researchers and the public at large.

Impact of glycine and erythritol/chlorhexidine air-polishing powders on human gingival fibroblasts: an in vitro study

BACKGROUND

Supra- and subgingival air-polishing has been used in periodontitis and gingivitis therapy for years. Low-abrasive types of powders have facilitated the application in subgingival areas. In this study, the cellular effects of a glycine powder and an erythritol/chlorhexidine (CHX) powder on human gingival fibroblasts (HGF) were investigated.

METHODS

HGF were obtained from sound gingiva of three healthy donors. After 12hours and 24hours of incubation time, cell viability testing and, after 24hours and 48hours, a cell proliferation assay was conducted. Additionally, the individual components erythritol and CHX were investigated for cell viability. In vitro wound healing was monitored for 48hours and scanning electron microscopy (SEM) analysis was performed after 24hours. Statistical analysis was accomplished by ANOVA and post hoc Dunnett's and Tukey's tests (p < 0.05) were performed.

RESULTS

Erythritol/CHX powder and in a lower extent, glycine powder decreased cell viability and cell proliferation. The negative effect of erythritol/CHX was mainly based on the CHX component. In vitro wound healing was negatively influenced in both types of powders compared to control. Cell size was altered in both test groups, whereas cell morphology was affected only in the erythritol/CHX group.

CONCLUSIONS

The investigated powders for subgingival air-polishing can influence cell viability, morphology, and proliferation, as well as wound closure in vitro. These actions on fibroblasts are discernible, with the cytotoxic effect of erythritol/CHX powder being very clear and mainly due to the CHX component. Our results suggest that subgingivally applied powders can exert direct effects on gingival fibroblasts.

Pharmacological Therapies for the Management of Inflammatory Bone Resorption in Periodontal Disease: A Review of Preclinical Studies

Periodontitis, a highly prevalent multicausal chronic inflammatory and destructive disease, develops as a result of complex host-parasite interactions. Dysbiotic bacterial biofilm in contact with the gingival tissues initiates a cascade of inflammatory events, mediated and modulated by the host's immune response, which is characterized by increased expression of several inflammatory mediators such as cytokines and chemokines in the connective tissue. If periodontal disease (PD) is left untreated, it results in the destruction of the supporting tissues around the teeth, including periodontal ligament, cementum, and alveolar bone, which lead to a wide range of disabilities and poor quality of life, thus imposing significant burdens. This process depends on the differentiation and activity of osteoclasts, the cells responsible for reabsorbing the bone tissue. Therefore, the inhibition of differentiation or activity of these cells is a promising strategy for controlling bone resorption. Several pharmacological drugs that target osteoclasts and inflammatory cells with immunomodulatory and anti-inflammatory effects, such as bisphosphonates, anti-RANK-L antibody, strontium ranelate, cathepsin inhibitors, curcumin, flavonoids, specialized proresolving mediators, and probiotics, were already described to manage inflammatory bone resorption during experimental PD progression in preclinical studies. Meantime, a growing number of studies have described the beneficial effects of herbal products in inhibiting bone resorption in experimental PD. Therefore, this review summarizes the role of several pharmacological drugs used for PD prevention and treatment and highlights the targeted action of all those drugs with antiresorptive properties. In addition, our review provides a timely and critical appraisal for the scientific rationale use of the antiresorptive and immunomodulatory medications in preclinical studies, which will help to understand the basis for its clinical application.

Combined Release of Antiseptic and Antibiotic Drugs from Visible Light Polymerized Biodegradable Nanocomposite Hydrogels for Periodontitis Treatment

The in situ application of the combination of different types of drugs revolutionized the area of periodontal therapy. The purpose of this study was to develop nanocomposite hydrogel (NCHG) as a pH-sensitive drug delivery system. To achieve local applicability of the NCHG in dental practice, routinely used blue-light photopolymerization was chosen for preparation. The setting time was 60 s, which resulted in stable hydrogel structures. Universal Britton–Robinson buffer solutions were used to investigate the effect of pH in the range 4–12 on the release of drugs that can be used in the periodontal pocket. Metronidazole was released from the NCHGs within 12 h, but chlorhexidine showed a much longer elution time with strong pH dependence, which lasted more than 7 days as it was corroborated by the bactericidal effect. The biocompatibility of the NCHGs was proven by Alamar-blue test and the effectiveness of drug release in the acidic medium was also demonstrated. This fast photo-polymerizable NCHG can help to establish a locally applicable combined drug delivery system which can be loaded with the required amount of medicines and can reduce the side effects of the systemic use of drugs that have to be used in high doses to reach an ideal concentration locally.

Immunopathogenesis and distinct role of Th17 in Periodontitis: A review

BACKGROUND

Periodontitis is a multifactorial inflammatory disease mediated by the host immune response to dental plaque. Periodontitis is characterized by periodontal bone loss and loss of tooth support. Several studies have corroborated the infiltration of T lymphocytes in periodontitis and correlated the infiltration with chronic inflammation in a dysregulated T cell-mediated immune response. The complexity of the disease has prompted multiple studies aiming to understand T cell-mediated pathogenesis.

HIGHLIGHT

Recent findings have demonstrated the pivotal role of helper T cells in many autoimmune diseases, such as rheumatoid arthritis, which has been conventionally correlated with periodontal bone loss. In contrast, the roles of helper T subsets, Th1, Th2, and particularly Th17, have not been explored. Th17-mediated pathogenesis is a significant aspect of the progression and therapy of periodontitis.

CONCLUSION

In this review, we highlight the complex role of Th17 in the underlying pro-inflammatory cascades mediated by a repertoire of Th17-released molecules and their role in aggravated inflammation in periodontitis. We also summarize recent therapeutics targeting Th17 and related molecules, primarily to ameliorate inflammation and maintain periodontal care.

Enamel matrix derivative as adjunctive to non-surgical periodontal therapy: a systematic review and meta-analysis of randomized controlled trials

Objectives

To assess the potential additional benefit of the local application of enamel matrix derivative (EMD) on the clinical outcomes following non-surgical periodontal therapy (NSPT) (steps 1 and 2 periodontal therapy).

Materials and Methods

A systematic literature search was performed in several electronic databases, including Medline/PubMed, Embase, The Cochrane Register of Central Trials (CENTRAL), LILACS, and grey literature. Only randomized controlled clinical trials (RCTs) were eligible for inclusion. Clinical attachment level (CAL) change (primary outcome), probing pocket depth (PPD), and bleeding on probing (BoP) reductions (secondary outcomes) were evaluated. The Cochrane Risk of Bias tool (RoB 2.0) was used to assess the quality of the included trials. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) between test and control sites were estimated using a random-effect model for amount of mean CAL and PPD change.

Results

Six RCTs were included for the qualitative analysis, while data from 4 studies were used for meta-analysis. Overall analysis of CAL gain (3 studies) and PPD reduction (4 studies) presented WMD of 0.14 mm (p = 0.74; CI 95% − 0.66; 0.94) and 0.46 mm (p = 0.25; CI 95% − 0.33; 1.26) in favor of NSPT + EMD compared to NSPT alone respectively. Statistical heterogeneity was found to be high in both cases (I² = 79% and 87%, respectively).

Conclusions

Within their limitations, the present data indicate that the local application of EMD does not lead to additional clinical benefits after 3 to 12 months when used as an adjunctive to NSPT. However, due to the high heterogeneity among the studies, additional well-designed RCTs are needed to provide further evidence on this clinical indication for the use of EMD.

Clinical relevance

The adjunctive use of EMD to NSPT does not seem to additionally improve the clinical outcomes obtained with NSPT alone.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04474-1.

P4 Medicine as a model for precision periodontal care

Objectives

P4 Medicine is based on a proactive approach for clinical patient care incorporating the four “pillars” of prediction, prevention, personalization, and participation for patient management. The purpose of this review is to demonstrate how the concepts of P4 medicine can be incorporated into the management of periodontal diseases (particularly periodontitis) termed P4 periodontics.

Methods

This is a narrative review that used current literature to explore how P4 periodontics can be aligned with the 2018 Classification of Periodontal Diseases, current periodontal treatment paradigms, and periodontal regenerative technologies.

Results

The proposed model of P4 periodontics is highly aligned with the 2018 Classification of Periodontal Diseases and represents a logical extension of this classification into treatment paradigms. Each stage of periodontitis can be related to a holistic approach to clinical management. The role of “big data” in future P4 periodontics is discussed and the concepts of a treat-to-target focus for treatment outcomes are proposed as part of personalized periodontics. Personalized regenerative and rejuvenative periodontal therapies will refocus our thinking from risk management to regenerative solutions to manage the effects of disease and aging.

Conclusions

P4 Periodontics allows us to focus not only on early prevention and intervention but also allow for personalized late-stage reversal of the disease trajectory and the use of personalized regenerative procedures to reconstruct damaged tissues and restore them to health.

Clinical Significance

P4 Periodontics is a novel means of viewing a holistic, integrative, and proactive approach to periodontal treatment.

Interconnection of periodontal disease and comorbidities: Evidence, mechanisms, and implications

Periodontitis, a microbiome-driven inflammatory disease of the tooth-attachment apparatus, is epidemiologically linked with other disorders, including cardio-metabolic, cognitive neurodegenerative and autoimmune diseases, respiratory infections, and certain cancers. These associations may, in part, be causal, as suggested by interventional studies showing that local treatment of periodontitis reduces systemic inflammation and surrogate markers of comorbid diseases. The potential cause-and-effect connection between periodontitis and comorbidities is corroborated by studies in preclinical models of disease, which additionally provided mechanistic insights into these associations. This overview discusses recent advances in our understanding of the periodontitis-systemic disease connection, which may potentially lead to innovative therapeutic options to reduce the risk of periodontitis-linked comorbidities.

Non-surgical peri-implantitis treatment with or without systemic antibiotics; a randomized controlled clinical trial

Objectives

To assess the adjunctive effect of systemic amoxicillin (AMX) and metronidazole (MTZ) in patients receiving non‐surgical treatment (NST) for peri‐implantitis (PI).

Materials and methods

Thirty‐seven patients were randomized into an experimental group treated with NST plus AMX + MTZ (N = 18) and a control group treated with NST alone (N = 19). Clinical parameters were evaluated at 12 weeks post‐treatment. The primary outcome was the change in peri‐implant pocket depth (PIPD) from baseline to 12 weeks, while secondary outcomes included bleeding on probing (BoP), suppuration on probing (SoP), and plaque. Data analysis was performed at patient level (one target site per patient).

Results

All 37 patients completed the study. Both groups showed a significant PIPD reduction after NST. The antibiotics group showed a higher mean reduction in PIPD at 12 weeks, compared with the control group (2.28 ± 1.49 mm vs. 1.47 ± 1.95 mm), however, this difference did not reach statistical significance. There was no significant effect of various potential confounders on PIPD reduction. Neither treatment resulted in significant improvements in BoP at follow‐up; 30 of 37 (81%) target sites still had BoP after treatment. Only two implants, one in each group, exhibited a successful outcome defined as PIPD < 5 mm, and absence of BoP and SoP.

Conclusions

Non‐surgical treatment was able to reduce PIPD at implants with PI. The adjunctive use of systemic AMX and MTZ did not show statistically significant better results compared to NST alone. NST with or without antibiotics was ineffective to completely resolve inflammation around dental implants.

Inhibitory effect of roflumilast on experimental periodontitis

BACKGROUND

Phosphodiesterase-4 (PDE4) has been identified as a valid therapeutic target in several inflammatory diseases. In this study, we assessed PDE4 in gingival tissue from patients with chronic periodontitis and evaluated the therapeutic effects of the PDE4 inhibitor, roflumilast, in an experimental rat model of periodontitis.

METHODS

Gingival tissue specimens from 20 healthy subjects and 20 patients with periodontitis were collected, and the mRNA expression levels of PDE4, interleukin (IL)-1β, and IL-6 were assessed. Ninety rats were divided randomly into three groups (30 per group): non-ligature group, ligature-induced periodontitis group (L), and ligature-induced periodontitis with roflumilast administered group (5 mg/kg/d) (L+R). Rats were euthanized on days 3, 8, and 14. Alveolar bone resorption was analyzed using microcomputed tomography. Inflammation and osteoclast number were analyzed histologically. Finally, the mRNA expression levels of PDE-4, IL-1β, IL-6, tumor necrosis factor (TNF)-α, and nuclear factor kappa B (NF-κB) were assessed in the rat gingival tissue.

RESULTS

The mRNA expression levels of PDE4, IL-1β, and IL-6 in the gingiva were significantly higher in patients with periodontitis compared with healthy individuals (P <0.05). Alveolar bone loss, degree of inflammation, number of TRAP-positive multinucleated osteoclasts, and mRNA expression levels of IL-1β, IL-6, TNF-α, NF-κB, and PDE4 in the L+R group were significantly lower than those in the L group (P <0.05).

CONCLUSIONS

PDE4 expression was increased in the gingiva of patients with periodontitis. Roflumilast may decrease alveolar bone loss and the expression of inflammatory cytokines in rats with ligature-induced periodontitis.

Adjunctive probiotics after periodontal debridement versus placebo: a systematic review and meta-analysis

OBJECTIVE

To comprehensively investigate the efficacy of adjunctive probiotics compared to placebo, using conventional and novel treatment outcomes.

MATERIALS AND METHODS

Three databases (MEDLINE, EMBASE, and CENTRAL) were searched. Outcomes included percent change in the total number of deep sites before and after therapy, change in mean probing pocket depth (mm), percentage patients requiring additional therapy, risk for disease progression, and microbiological and immunological results. Meta-analysis was conducted to evaluate treatment effects wherever appropriate.

RESULTS

Ten studies were selected from 818 records. Meta-analysis showed that adjunctive probiotics had no additional benefit for percentage change of the total number of deeper sites (≥5 mm, ≥6 mm, ≥7 mm) before and after therapy. No significant difference was observed for mean probing pocket depth reduction at 3 and 6 months. Statistically significant beneficial odds ratios for need for additional therapy (OR = 0.19, 95% CI [0.07-0.56]) and risk of disease progression (OR = 0.32, 95% CI [0.14-0.73]) were observed with probiotic administration. Immunological rather than microbiological outcomes correlated more consistently with clinical findings. No adverse events were reported.

CONCLUSIONS

Adjunctive probiotics are safe in systemically healthy individuals and could offer additional patient-level benefits compared to placebo, hence its use can sometimes be justified.

Lactobacillus helveticus Prevents Periodontitis Induced by Aggregatibacter actinomycetemcomitans in Rats by Regulating β-Defensins

Objective

To study the preventive effect of Lactobacillus helveticus (L. helveticus) on periodontitis induced by Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in rats.

Methods

Eighteen 8-week-old female rats were randomly divided into three groups: Sham group, Trehalose group, and L. helveticus SBT2171 (LH2171) group. We measured the distance of the cementoenamel junction-alveolar bone crest (CEJ-ABC) to evaluate alveolar bone resorption. Hematoxylin-eosin staining was used to observe the histopathological changes of rat hemimaxillary tissues. We detected the expression of β-defensins, tumor necrosis factor-α (TNF-α), interleukin- (IL-) 1β, and IL-6 and the number of A. actinomycetemcomitans in rat gingival tissues by quantitative reverse transcriptase polymerase chain reaction. The levels of IL-1β, IL-6, and TNF-α in rat gingival tissues were also measured by enzyme-linked immunosorbent assay.

Results

Compared with the Trehalose group, the distance of CEJ-ABC was prominently reduced and alveolar bone resorption was notably improved in the LH2171 group. And the infiltration of inflammatory cells in the hemimaxillary tissue decreased obviously, periodontal fibers were arranged neatly, connective tissue small blood vessels proliferated, and the number of A. actinomycetemcomitans reduced significantly in the LH2171 group. In addition, the mRNA expression and release of inflammatory factors in the gingival tissues in the LH2171 group were notably lower than those in the Trehalose group. On the 21st and 36th day, the expression of β-defensins in the gingival tissue of the LH2171 group increased significantly.

Conclusion

L. helveticus improves alveolar bone resorption and increases the expression of β-defensins thereby inhibiting the number of A. actinomycetemcomitans and thus prevents periodontitis.

Profiling of plasma-derived exosomal RNA expression in patients with periodontitis: a pilot study

OBJECTIVE

This study aimed to profile differentially expressed (DE) exosomal RNAs in healthy subjects and periodontitis patients and compare their levels before and after treatment.

MATERIALS AND METHODS

Plasma samples from healthy subjects and patients with periodontitis (pre-/post-periodontal treatment) were collected for this case-control study. After isolation of exosomes from the plasma, the RNA was extracted and small RNA sequencing was performed (3 healthy samples, 4 pre-treatment samples, and 5 post-treatment samples). Two-way analyses were conducted according to the treatment status in the periodontitis group, unpaired analysis (grouping as pre-/post-treatment) and paired analysis (matching pre- and post-treatment in the same subject). The DE exosomal RNAs were screened by sequencing and visualized using the R software. Gene Ontology analysis was performed, and target genes were identified.

RESULTS

In both paired and unpaired analyses, two DE microRNAs (DEmiRs; miR-1304-3p and miR-200c-3p) and two DE small nucleolar RNAs (DEsnoRs; SNORD57 and SNODB1771) were common, and they were found to be downregulated during periodontitis and recovered to healthy levels after treatment. The top three target genes (NR3C1, GPR158, and CNN3) commonly regulated by DEmiRs were identified.

CONCLUSIONS

Plasma-derived exosomal miRs (miR-1304-3p and miR-200c-3p) and snoRs (SNORD57 and SNODB1771) could be valuable biomarkers for periodontitis.

Systemic Periodontal Risk Score Using an Innovative Machine Learning Strategy: An Observational Study

Early diagnosis is crucial for individuals who are susceptible to tooth-supporting tissue diseases (e.g., periodontitis) that may lead to tooth loss, so as to prevent systemic implications and maintain quality of life. The aim of this study was to propose a personalized explainable machine learning algorithm, solely based on non-invasive predictors that can easily be collected in a clinic, to identify subjects at risk of developing periodontal diseases. To this end, the individual data and periodontal health of 532 subjects was assessed. A machine learning pipeline combining a feature selection step, multilayer perceptron, and SHapley Additive exPlanations (SHAP) explainability, was used to build the algorithm. The prediction scores for healthy periodontium and periodontitis gave final F1-scores of 0.74 and 0.68, respectively, while gingival inflammation was harder to predict (F1-score of 0.32). Age, body mass index, smoking habits, systemic pathologies, diet, alcohol, educational level, and hormonal status were found to be the most contributive variables for periodontal health prediction. The algorithm clearly shows different risk profiles before and after 35 years of age and suggests transition ages in the predisposition to developing gingival inflammation or periodontitis. This innovative approach to systemic periodontal disease risk profiles, combining both ML and up-to-date explainability algorithms, paves the way for new periodontal health prediction strategies.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.