Polymicrobial communities in periodontal disease: Their quasi-organismal nature and dialogue with the host

Oral bacteriophages and their potential as adjunctive treatments for periodontitis: a narrative review

Background

There is no specific cure for periodontitis and treatment is symptomatic, primarily by physical removal of the subgingival plaque biofilm. Current non-surgical periodontal therapy becomes less effective as the periodontal pocket depth increases and as such new adjunctive treatments are required. The development of antibiotic resistance has driven a recent resurgence of interest in bacteriophage therapy.

Methods

Here we review the published literature with a focus on the subgingival phageome, key oral pathobionts and the dysbiotic nature of periodontitis leading to the emergence of synergistic, proteolytic and inflammophilic bacterial species in subgingival plaque. We discuss the opportunities available, the barriers and the steps needed to develop bacteriophage therapy as an adjunctive treatment for periodontitis.

Results

The oral phageome (or virome) is diverse, featuring abundant bacteriophage, that could target key subgingival bacteria. Yet to date few bacteriophages have been isolated and characterised from oral bacterial species, although many more have been predicted by genomic analyses. Bacteriophage therapy has yet to be tested against chronic diseases that are caused by dysbiosis of the endogenous microbial communities.

Conclusion

To be effective as an adjunctive treatment for periodontitis, bacteriophage therapy must cause the collapse of the dysbiotic bacterial community, thereby resolving inflammation and enabling the reestablishment of a health-associated mutualistic subgingival bacterial community. The isolation and characterisation of novel oral bacteriophage is an essential first step in this process.

Hyperuricemia Exacerbates Experimental Periodontitis via Uric Acid-Induced Periodontal Inflammation and Oxidative Stress

AIM

To investigate the effects of hyperuricemia on periodontitis and the underlying mechanisms by establishing combined animal and cell models.

METHODS

A hyperuricemia mouse model was established by potassium oxonate injection, with sodium carboxymethylcellulose treatment serving as controls. Both models were treated with or without periodontitis induction (n = 10/group). RAW264.7 macrophages and THP-1-derived macrophages were stimulated with Porphyromonas gingivalis-lipopolysaccharide in the presence of normal or excessive concentrations of uric acid. Allopurinol intervention was applied to both animal and cell models. Periodontal destruction was measured by micro-computed tomography and histology. The immune response and oxidative stress in the periodontium and macrophages were assessed using various methods including immunohistochemistry, quantitative PCR, western blotting, flow cytometry and multiplex cytokine assays.

RESULTS

Potassium oxonate successfully induced hyperuricemia without affecting serum glucose/lipid levels or xanthine oxidoreductase activity. In mice with periodontitis, hyperuricemia exacerbated alveolar bone loss and the presence of osteoclasts and M1 macrophages. Mechanistically, hyperuricemia promoted NLRP3 inflammasome activation, disrupted the inflammatory cytokine response and exacerbated oxidative stress both in the periodontium and in vitro. Allopurinol treatment reversed all relevant changes in both mice and macrophages.

CONCLUSION

Hyperuricemia exacerbates periodontitis possibly via uric acid-induced periodontal inflammation and oxidative stress.

Meteorin-like levels of oral fluids in periodontal health and diseases: a comparative cross-sectional study

OBJECTIVES

Cytokines are critical role in the pathogenesis of periodontal diseases. Meteorin-like (Metrnl), a protein released in the oral mucosa, is a novel cytokine associated with various inflammatory diseases. This study aimed to evaluate levels of salivary and gingival crevicular fluid (GCF), interleukin - 1 beta (IL-1β), interleukin - 10 (IL-10), and Metrnl in periodontal disease.

MATERIALS AND METHODS

It was formed three groups of 20 individuals each: the healthy, gingivitis, and periodontitis (Stage III, Grades A and B) groups. The enzyme-linked immunosorbent assay method measured IL-1β, IL-10, and Metrnl levels in salivary and GCF samples. Clinical periodontal measurement including probing pocket depth (PD), clinical attachment loss (CAL), plaque index (PI), gingival index (GI) and percentage of bleeding on probing (%BOP); and biochemical parameters were evaluated using statistical analysis.

RESULTS

Salivary concentrations and GCF total amount of IL-1β were significantly higher in the periodontal disease groups (p < 0.001). There was no significant difference among the groups in either salivary concentrations or GCF total amount of IL-10 (p > 0.05). Salivary Metrnl concentrations were significantly lower in the periodontitis group (p = 0.002). Salivary Metrnl concentrations had significant negative correlations with %BOP, PD, and CAL (p < 0.05). GCF total amount of Metrnl had significant negative correlations with GCF total amount of IL-1β (p = 0.03). The receiver operating characteristics curve showed: area under the curve (AUC) = 0.731 for salivary Metrnl concentrations to discriminate periodontitis from periodontal health and gingivitis.

CONCLUSION

Based on the findings of this study, Metrnl, as an immunoregulatory cytokine, may have an important relationship with periodontitis. Additional studies are needed to fully elucidate the functional effect of Metrnl in periodontal disease.

CLINICAL RELEVANCE

Background In knock-out experimental studies, it has been reported that Metrnl acts as an inflammation-related immunoregulatory cytokine. The findings relating it to inflammatory diseases support the idea that Metrnl may play a role in the pathogenesis of a variety of inflammatory diseases.

ADDED VALUE OF THIS STUDY

Although Metrnl is a protein abundantly secreted in the oral mucosa, to the authors' knowledge there has been no study evaluating it in gingivitis and periodontitis, inflammatory diseases. In this study, the levels of Metrnl in oral fluids, such as GCF and saliva, were examined in the presence of different periodontal diseases.

CLINICAL IMPLICATIONS

Metrnl can be useful in distinguishing periodontal destruction from periodontal health.

The efficacy of antimicrobial therapies in the treatment of mixed biofilms formed between Candida albicans and Porphyromonas gingivalis during epithelial cell infection in the aspiration pneumonia model

Aspiration pneumonia is a serious respiratory condition, which is particularly prevalent in patients with dysphagia, neurological disorders, or those undergoing surgical interventions. The formation of multispecies biofilms in the oral cavity, involving the bacterial periodontopathogen Porphyromonas gingivalis and the opportunistic pathogenic fungus Candida albicans, may also be related to the development of this serious disease, contributing also to the resistance to standard antimicrobial treatment. Therefore, this research aimed to evaluate the efficacy of selected antibiotics‒levofloxacin, metronidazole, meropenem, vancomycin‒and antifungal agents‒amphotericin B, caspofungin, and fluconazole‒on these mixed biofilms in the aspiration pneumonia model. While metronidazole and levofloxacin effectively inhibited bacterial viability in the mixed biofilms, lower doses increased release of bacterial proteases. In the conditions of mixed biofilms meropenem and vancomycin showed reduced efficacy, requiring significantly higher doses to achieve similar effect in mixed biofilms as in single bacterial cultures. Treatment with antifungals revealed that amphotericin B significantly impacted fungal cell viability within mixed biofilms, and this effect was enhanced when the antifungal drug was applied in the presence of P. gingivalis. Caspofungin and fluconazole showed variable efficacy, with caspofungin being more effective against C. albicans cells within biofilm.These findings indicated that due to the mutual microbial protection in the mixed-species biofilm, P. gingivalis retained its virulence despite increasing antibiotic doses. However, no excessive benefit of mixed biofilms was observed for C. albicans in the presence of antifungals, indicating the minor importance of yeasts in aspiration pneumonia development and their protective role for other pathogens in mixed-species infection.

New Advances in Periodontal Functional Materials Based on Antibacterial, Anti-Inflammatory, and Tissue Regeneration Strategies

With the global population aging, awareness of oral health is rising. Periodontitis, a widespread bacterial infectious disease, is gaining attention. Current novel biomaterials address key clinical issues like bacterial infection, gum inflammation, tooth loosening, and loss, focusing on antibacterial, anti-inflammatory, and tissue regeneration properties. However, strategies that integrate the advantages of these biomaterials to achieve synergistic therapeutic effects by clearing oral biofilms, inhibiting inflammation activation, and restoring periodontal soft and hard tissue functions remain very limited. Recent studies highlight the link between periodontitis and systemic diseases, underscoring the complexity of the periodontal disease. There is an urgent need to find comprehensive treatment plans that address clinical requirements. Whether by integrating new biomaterials to enhance existing periodontal treatments or by developing novel approaches to replace traditional therapies, these efforts will drive advancements in periodontitis treatment. Therefore, this review compares novel biomaterials with traditional treatments. It highlights the design concepts and mechanisms of these functional materials, focusing on their antibacterial, anti-inflammatory, and tissue regeneration properties, and discusses the importance of developing comprehensive treatment strategies. This review aims to provide guidance for emerging periodontitis research and to promote the development of precise and efficient treatment strategies.

Microbiome analysis in individuals with human papillomavirus oral infection

Microbiome gained attention as a cofactor in cancers originating from epithelial tissues. High-risk (hr)HPV infection causes oropharyngeal squamous cell carcinoma but only in a fraction of hrHPV+ individuals, suggesting that other factors play a role in cancer development. We investigated oral microbiome in cancer-free subjects harboring hrHPV oral infection (n = 33) and matched HPV- controls (n = 30). DNA purified from oral rinse-and-gargles of HIV-infected (HIV+) and HIV-uninfected (HIV-) individuals were used for 16S rRNA gene V3-V4 region amplification and sequencing. Analysis of differential microbial abundance and differential pathway abundance was performed, separately for HIV+ and HIV- individuals. Significant differences in alpha (Chao-1 and Shannon indices) and beta diversity (unweighted UniFrac distance) were observed between hrHPV+ and HPV-negative subjects, but only for the HIV- individuals. Infection by hrHPVs was associated with significant changes in the abundance of Saccharibacteria in HIV+ and Gracilibacteria in HIV- subjects. At the genus level, the greatest change in HIV+ individuals was observed for Bulleidia, which was significantly enriched in hrHPV+ subjects. In HIV- individuals, those hrHPV+ showed a significant enrichment of Parvimonas and depletion of Alloscardovia. Our data suggest a possible interplay between hrHPV infection and oral microbiome, which may vary with the HIV status.

Prevalence of the oral pathogen Filifactor alocis and its FtxA toxin related to clinical parameters and presence of Aggregatibacter actinomycetemcomitans

The Gram-positive organism Filifactor alocis is implicated in multiple oral diseases including periodontitis, and approximately 50% of known strains encode and produce a recently identified repeat-in-toxin (RTX) protein, FtxA, partly homologous to the Aggregatibacter actinomycetemcomitans leukotoxin. By assessing a longitudinal Ghanaian study population of adolescents, we recently identified a possible correlation between F. alocis levels, ftxA gene carriage, and progression of clinical attachment loss (CAL). To extend knowledge on the possible significance of F. alocis and its FtxA in periodontal disease, we have in the present work analyzed saliva samples in an independent cohort of periodontitis (n=156), collected at two private periodontal specialist practices in Perth, Western Australia. The present results corroborate that high loads of F. alocis and the presence of its ftxA gene together are associated with parameters of periodontal tissue destruction and severity. Moreover, among the individuals carrying A. actinomycetemcomitans, a majority also exhibited an ftxA-positive F. alocis, supporting the notion of the synergistic behavior of these two species. This emphasizes that F. alocis and its ftxA are involved in the pathogenesis of periodontitis and may have ecological roles, with diagnostic and prognostic implications for the disease.

Advancing oral immunology for improving oral health

Although substantial progress has been made in dentistry in terms of diagnosis and therapy, current treatment methods in periodontology, orthodontics, endodontics, and oral and maxillofacial surgery, nevertheless, suffer from numerous limitations, some of which are associated with a dramatic reduction in the quality of life. Many general mechanisms of inflammation and immunity also apply to the oral cavity and oral diseases. Nonetheless, there are special features here that are attributable, on the one hand, to developmental biology and, on the other hand, to the specific anatomical situation, which is characterized by a close spatial relationship of soft and hard tissues, exposure to oral microbiota, and to a rapid changing external environment. Currently, a comprehensive and overarching understanding is lacking about how the immune system functions in oral tissues (oral immunology) and how oral immune responses contribute to oral health and disease. Since advances in translational immunology have created a game-changing shift in therapy in rheumatology, allergic diseases, inflammatory bowel disease, and oncology in recent years, it is reasonable to assume that a better understanding of oral immunology might lead to practice-changing diagnostic procedures and therapies in dentistry and thereby also profoundly improve oral health in general.

Gingipains protect Porphyromonas gingivalis from macrophage-mediated phagocytic clearance

Porphyromonas gingivalis (Pg) is a keystone pathogen in periodontitis, a highly prevalent disease manifested by chronic inflammation of the periodontium, alveolar bone resorption and tooth loss. During periodontitis pathobionts such as Pg can enter the bloodstream and growing evidence correlates periodontitis with increased risk of cardiovascular and neurodegenerative diseases. However, the mechanism by which immune cells respond to Pg challenge in vivo remains elusive. Pg produce aggressive proteolytic virulence factors termed gingipains which not only provide nutrients necessary for bacterial growth, but also subvert the host immune response, facilitating bacterial survival. Using transgenic zebrafish with fluorescently labelled macrophages and neutrophils, the role of gingipains in bacterial survival and interaction with phagocytes during systemic and local infection was examined. In contrast to the wild-type (W83) Pg, isogenic gingipain-null (ΔK/R-ab) or wild-type Pg treated with gingipain inhibitors caused less zebrafish mortality, bacteria were rapidly phagocytosed, acidified in phagosomes and eradicated when systemically injected, showing that gingipains are instrumental in preventing phagocytosis and intracellular killing of Pg by innate immune cells. Moreover, Pg were predominantly phagocytosed by macrophages, and gingipain depletion/inactivation increased bacterial phagocytosis when bacteria were injected either systemically or locally in the otic vesicle, with less bacteria internalised by neutrophils. This phenomenon was Pg-specific as Fusobacterium nucleatum caused neutrophil recruitment that then effectively phagocytosed these bacteria. These data demonstrate the important role of phagocytes, especially macrophages, in combating Pg infection and highlight the crucial protective role of gingipains in subverting the innate immune response. This study also emphasizes the advantages of using zebrafish to study interactions of Pg with phagocytes in vivo in real-time, providing a valuable experimental system for testing new therapeutic strategies aimed at reducing periodontal-associated systemic or neurodegenerative disease.

Inflammation and mechanical force-induced bone remodeling

Periodontitis arises from imbalanced host-microbe interactions, leading to dysbiosis and destructive inflammation. The host's innate and adaptive immune responses produce pro-inflammatory mediators that stimulate destructive events, which cause loss of alveolar bone and connective tissue attachment. There is no consensus on the factors that lead to a conversion from gingivitis to periodontitis, but one possibility is the proximity of the inflammation to the bone, which promotes bone resorption and inhibits subsequent bone formation during coupled bone formation. Conversely, orthodontic tooth movement is triggered by the mechanical force applied to the tooth, resulting in bone resorption on the compression side and new bone formation on the tension side. However, the environment around orthodontic brackets readily retains dental plaque and may contribute to inflammation and bone remodeling. The immune, epithelial, stromal, endothelial and bone cells of the host play an important role in setting the stage for bone remodeling that occurs in both periodontitis and orthodontic tooth movement. Recent advancements in single-cell RNA sequencing have provided new insights into the roles and interactions of different cell types in response to challenges. In this review, we meticulously examine the functions of key cell types such as keratinocytes, leukocytes, stromal cells, osteocytes, osteoblasts, and osteoclasts involved in inflammation- and mechanical force-driven bone remodeling. Moreover, we explore the combined effects of these two conditions: mechanical force-induced bone remodeling combined with periodontal disease (chronic inflammation) and periodontally accelerated osteogenic orthodontics (acute transient inflammation). This comprehensive review enhances our understanding of inflammation- and mechanical force-induced bone remodeling.

Dynamic Covalent Prodrug Nanonetworks via Reaction-Induced Self-Assembly for Periodontitis Treatment

Periodontitis is characterized by dysbiotic biofilms, gingival inflammation, and bone resorption, highlighting the urgent need for a comprehensive approach to drug combination therapy. In this study, we introduce dynamic covalent nanonetworks (dcNNWs) synthesized through a one-pot, four-component reaction-induced self-assembly method using polyamines, 2-formylphenylboronic acid, epigallocatechin gallate, and alendronate. The formation of iminoboronate bonds drives the creation of dcNNWs, allowing controlled release in the periodontitis microenvironment. The inclusion of catechol and bisphosphonate imparts exceptional bioadhesive properties to the dcNNWs, enhancing their efficacy in preventing pathogenic bacterial biofilm formation and eliminating mature biofilms. Moreover, the dcNNWs efficiently absorb pathogen-associated molecular patterns and scavenge excess reactive oxygen species, regulating the local immune response and demonstrating anti-inflammatory effects. Additionally, the released polyphenol and alendronate from the dcNNWs alleviated inflammation and enhanced osteogenesis significantly. The detailed synergistic effects of dcNNWs in biofilm eradication, anti-inflammation, and bone remodeling, with minimal impact on healthy tissues, are confirmed in a rat model of periodontitis. With a facile synthesis process, excellent synergistic effects in periodontitis treatment, and biocompatibility, our dcNNWs present a promising and translational solution for the effective management of periodontitis.

Patient awareness of the association between periodontal and systemic diseases in an academic setting

BACKGROUND

Periodontal diseases (PD) have been increasingly associated with several systemic conditions such as cardiovascular disease (CVD), diabetes mellitus (DM), rheumatoid arthritis (RA), and Alzheimer's disease (AD). This study aimed to gain insight into patients' awareness of the association between PD and systemic diseases.

METHODS

A survey was developed to analyze patient awareness of the association between PD and systemic diseases. Descriptive and categorical variables were summarized with counts and percentages. Chi-squared tests were used to evaluate differences between variables. A linear logistical regression model was used to assess the simultaneous, independent association between each variable.

RESULTS

Data from 161 completed surveys were analyzed. The majority of the participants (61.49%) reported awareness of symptoms of PD, but only 36.36% identified all its major symptoms. Individuals reporting awareness of the association between PD and systemic diseases was 48.4%, 31.7%, 14.9%, and 9.9% for CVD, DM, RA, and AD, respectively. Patients aged ≥51 years and males were more aware of the association between PD and CVD. Increased awareness of an association between PD and DM was observed among patients who had a higher frequency of dental visits and those with a self-reported history of DM.

CONCLUSIONS

This study provides insight that, even with the vast amount of scientific knowledge on the inter-relationships that exist between PD and systemic diseases, most patients are still unaware of these associations. This research identified that improvement of health literacy surrounding PD, their symptoms, and their association with systemic diseases may be warranted.

Periodontal Molecular Diagnostics: State of Knowledge and Future Prospects for Clinical Application

Periodontitis leads to immunologically mediated loss of periodontium and, if untreated, can result in tooth loss. Periodontal diseases are the most prevalent in the world and have a very strong impact on patients' well-being and general health. Their treatment generates enormous costs. Given the above, precise, prompt, and predictive diagnosis of periodontal disease is of paramount importance for clinicians. The aim of the study was to summarize the state-of-the-art knowledge of molecular periodontal diagnostics and the utility of its clinical application. There is a great need to have diagnostic tests that not only describe the periodontal destruction that has occurred in the tissues but also allow clinicians to detect disease at a subclinical level before the changes occur. A test that would enable clinicians to follow the course of the disease and detect areas prone to exacerbation could be used to evaluate the effectiveness of ongoing periodontal therapies. Unfortunately, there is no such diagnostic method yet. A hopeful prospect is molecular diagnostics. There are numerous studies on biomarkers of periodontal disease. Point-of-care tests are also emerging. There are possibilities for processing large biological datasets (omics data). However, all of the above have a minor role in the overall single-patient diagnostics process. Despite advances in microbiological, molecular, and genetic research, the basis of periodontal diagnosis is still clinical examination enriched by the evaluation of radiological images.

Mesaconate from Bacillus subtilis R0179 Supernatant Attenuates Periodontitis by Inhibiting Porphyromonas gingivalis in Mice

AIMS

This research sought to assess the efficacy of Bacillus subtilis (B. subtilis) R0179 and explore potential metabolites in mitigating experimental periodontitis in mice induced by Porphyromonas gingivalis (P. gingivalis) ATCC 33277.

METHODS

B. subtilis R0179 was administered to 8-week-old male C57BL/6J mice with periodontitis. Oral load of P. gingivalis ATCC 33277 and periodontal tissue loss were quantified. The cell-free supernatant (CFS) was separated to assess its anti-P. gingivalis effect. Proteomic and metabolomic analyses identified potential antibacterial components in the CFS, further evaluated for anti-P. gingivalis effects.

RESULTS

B. subtilis R0179 significantly reduced P. gingivalis ATCC 33277 levels and mitigated periodontal tissue loss in mice. The CFS, rather than inactivated B. subtilis R0179 cells, exhibited antibacterial activity. Proteomic and metabolomic analyses identified mesaconate and citraconate as key antibacterial agents. Disk diffusion assays confirmed the efficacy of mesaconate against P. gingivalis, while citraconate had no effect. Mesaconate showed a dose-dependent reduction in P. gingivalis ATCC 33277 population and periodontal tissue loss in mice.

CONCLUSION

These findings highlight B. subtilis R0179 and its metabolite mesaconate as promising candidates for therapeutic development against periodontitis by inhibiting P. gingivalis ATCC 33277 effectively.

Beneficial effects of non-invasive physical plasma on human periodontal ligament cells in vitro

Introduction

Periodontitis is a chronic inflammatory disease of the periodontium that can lead to the loss of affected teeth if left untreated. It is induced by a multifactorial process centered on microbial pathogens such as Fusobacterium nucleatum (F.n.). Non-invasive physical plasma (NIPP), a highly reactive gas, has become a focus of research, not only for its hemostatic, proliferation-enhancing and apoptotic properties, but also for its antimicrobial potential. The objective of this study was to examine the impact of NIPP on human periodontal ligament (PDL) cells that had been induced into a state of periodontal infection in vitro.

Methods

Initially, the solitary effect of NIPP was evaluated by measuring temperature and pH and analyzing reactive oxygen species (ROS). Additionally, DAPI and phalloidin staining were employed to investigate possible cytotoxic effects. The cells were pre-incubated with F.n. and treated with NIPP after 24 hours. Interleukin (IL)-6 and IL-8 were analyzed at mRNA and protein levels, respectively, by real-time PCR and ELISA.

Results

NIPP alone had no significant effect on PDL cells. However, the F.n.-induced upregulation of IL-6 and IL-8 was counteracted by NIPP.

Discussion

Thus, the utilization of NIPP may be regarded as a promising therapeutic strategy for the treatment of periodontal diseases.

CD47 and thrombospondin-1 contribute to immune evasion by Porphyromonas gingivalis

Porphyromonas gingivalis is a gram-negative anaerobic bacterium linked to periodontal disease. Remarkably, P. gingivalis thrives in an inflamed environment rich in activated neutrophils. Toll-like receptor 2 (TLR2) recognition is required for P. gingivalis to evade innate immune killing; however, the mechanisms through which P. gingivalis uncouples host inflammation from bactericidal activity are only partially known. Since integrin activation and alternative signaling are implicated in P. gingivalis TLR2-mediated immune escape, we explored the role of CD47, a widely expressed integrin-associated protein known to suppress phagocytosis and implicated as an interacting partner with other innate immune receptors. We found that CD47 associates with TLR2, and blocking CD47 leads to decreased intracellular P. gingivalis survival in macrophages in a manner dependent on the bacterial major fimbria. In vivo, CD47 knock-out mice cleared P. gingivalis more efficiently than wild-type mice. Next, we found increased expression and secretion of the CD47 ligand thrombospondin-1 (TSP-1) following P. gingivalis infection. Secreted TSP-1 broadly protected P. gingivalis and other periodontitis-associated bacterial species from neutrophil bactericidal activity. Therefore, CD47-TLR2 cosignaling in response to P. gingivalis induces TSP-1 that in turn suppresses neutrophil activity, an effect that can explain how species such as P. gingivalis survive in an inflamed environment and cause dysbiosis.

Microbial Dynamics in Periodontal Regeneration: Understanding Microbiome Shifts and the Role of Antifouling and Bactericidal Materials: A Narrative Review

Periodontal regeneration is a multifaceted therapeutic approach to restore the tooth-supporting structures lost due to periodontal diseases. This manuscript explores the intricate interactions between regenerative therapies and the oral microbiome, emphasizing the critical role of microbial balance in achieving long-term success. While guided tissue regeneration (GTR), bone grafting, and soft tissue grafting offer promising outcomes in terms of tissue regeneration, these procedures can inadvertently alter the oral microbial ecosystem, potentially leading to dysbiosis or pathogenic recolonization. Different grafting materials, including autografts, allografts, xenografts, and alloplasts, influence microbial shifts, with variations in the healing timeline and microbial stabilization. Biologics and antimicrobials, such as enamel matrix derivatives (EMD) and sub-antimicrobial dose doxycycline (SDD), play a key role in promoting microbial homeostasis by supporting tissue repair and reducing pathogenic bacteria. Emerging strategies, such as enzyme-based therapies and antifouling materials, aim to disrupt biofilm formation and enhance the effectiveness of periodontal treatments. Understanding these microbial dynamics is essential for optimizing regenerative therapies and improving patient outcomes. The future of periodontal therapy lies in the development of advanced materials and strategies that not only restore lost tissues but also stabilize the oral microbiome, ultimately leading to long-term periodontal health.

The role of the oral microbiota in the causal effect of adjunctive antibiotics on clinical outcomes in stage III-IV periodontitis patients

BACKGROUND

Periodontitis, a prevalent chronic inflammatory disease, offers insights into the broader landscape of chronic inflammatory conditions. The progression and treatment outcomes of periodontitis are closely related to the oral microbiota's composition. Adjunctive systemic Amoxicillin 500 mg and Metronidazole 400 mg, often prescribed thrice daily for 7 days to enhance periodontal therapy's efficacy, have lasting effects on the oral microbiome. However, the precise mechanism through which the oral microbiome influences clinical outcomes in periodontitis patients remains debated. This investigation explores the pivotal role of the oral microbiome's composition in mediating the outcomes of adjunctive systemic antibiotic treatment.

METHODS

Subgingival plaque samples from 10 periodontally healthy and 163 periodontitis patients from a randomized clinical trial on periodontal therapy were analyzed. Patients received either adjunctive amoxicillin/metronidazole or a placebo after mechanical periodontal treatment. Microbial samples were collected at various intervals up to 26 months post-therapy. Using topic models, we identified microbial communities associated with normobiotic and dysbiotic states, validated with 86 external and 40 internal samples. Logistic regression models evaluated the association between these microbial communities and clinical periodontitis parameters. A Directed Acyclic Graph (DAG) determined the mediating role of oral microbiota in the causal path of antibiotic treatment effects on clinical outcomes.

RESULTS

We identified clear distinctions between dysbiotic and normobiotic microbial communities, differentiating healthy from periodontitis subjects. Dysbiotic states consistently associated with below median %Pocket Probing Depth ≥ 5 mm (OR = 1.26, 95% CI [1.14-1.42]) and %Bleeding on Probing (OR = 1.09, 95% CI [1.00-1.18]). Factors like microbial response to treatment, smoking, and age were predictors of clinical attachment loss progression, whereas sex and antibiotic treatment were not. Further, we showed that the oral microbial treatment response plays a crucial role in the causal effect of antibiotic treatment on clinical treatment outcomes.

CONCLUSIONS

The shift towards a normobiotic subgingival microbiome, primarily induced by adjunctive antibiotics, underscores the potential for microbiome-targeted interventions to enhance therapeutic efficacy in chronic inflammatory conditions. This study reaffirms the importance of understanding the oral microbiome's role in periodontal health and paves the way for future research exploring personalized treatment strategies based on individual microbiome profiles. Video Abstract.

Differences in maternal subgingival microbiome between preterm and term births: The MOHEPI study

AIM

Periodontitis is a potential risk factor for preterm birth (PTB) in women; however, the causal relationship or the exact mechanism remain unknown. This study aimed to compare the oral microbiome features of mothers with full-term birth (FTB) with those who had preterm delivery.

METHODS

This study prospectively enrolled 60 women (30 mothers with PTB and 30 mothers with FTB), and subgingival plaque samples were collected and analysed by metagenomic 16S rDNA sequencing. Clinical measurements, including periodontal probing depth, clinical attachment level, modified gingival index (mGI) and plaque index, were performed to determine the periodontal state of the participants. Medical and obstetric data were collected as well.

RESULTS

Among the periodontal measurements, mGI score, reflecting the level of gingival inflammation, exhibited a statistically significant association with PTB (adjusted odds ratio 2.705, 95% confidence interval 1.074-6.811, p = .035). When subgroup analysis was conducted based on mean mGI scores (mGI ≥ 2, high inflammation [HI] versus mGI < 2, low inflammation [LI]), microbiome analysis revealed clear distinctions in microbial compositions between PTB and FTB mothers in both the HI and LI groups. Especially in the HI group, alpha diversity exhibited a decreasing trend in PTB mothers compared to FTB mothers. Beta diversity also revealed significant differences between the two groups. In Linear Discriminant Analysis Effect Size analysis, certain anaerobic taxa, including the genera Spirochaetes, Treponema and Porphyromonas, were relatively abundant in the FTB/HI group, whereas the PTB/HI group showed a high abundance of the order Actinomycetales. Network analysis showed that the FTB/HI had relatively stronger connectivity in microbial composition than the PTB/HI group. Dysbiosis ratio of plaque microbiome, in terms of periodontitis, was significantly lower in PTB/HI group compared to FTB/HI group.

CONCLUSION

The compositions of maternal subgingival microbiomes differed between PTB and FTB mothers in both the high and low levels of gingival inflammation groups. In the presence of high level of gingival inflammation, dysbiosis in plaque microbiome, in terms of periodontitis, was decreased in PTB mothers compared to FTB mothers.

Periodontal pathogen Aggregatibacter actinomycetemcomitans JP2 correlates with colonic leukocytes decrease and gut microbiome imbalance in mice

AIM

Evidence suggests that translocation of oral pathogens through the oral-gut axis may induce intestinal dysbiosis. This study aimed to evaluate the impact of a highly leukotoxic Aggregatibacter actinomycetemcomitans (Aa) strain on the gut microbiota, intestinal mucosal integrity and immune system in healthy mice.

METHODS

Eight-week-old male C57BL6 mice were divided into control (n = 16) and JP2 groups (n = 19), which received intragastric gavage with PBS and with a suspension of Aa JP2 (HK921), respectively, twice a week for 4 weeks. Colonic lamina propria, fecal material, serum, gingival tissues, and mandibles were obtained for analyses of leukocyte populations, inflammatory mediators, mucosal integrity, alveolar bone loss, and gut microbiota. Differences between groups for these parameters were examined by non-parametric tests.

RESULTS

The gut microbial richness and the number of colonic macrophages, neutrophils, and monocytes were significantly lower in Aa JP2-infected mice than in controls (p < .05). In contrast, infected animals showed higher abundance of Clostridiaceae, Lactobacillus taiwanensis, Helicobacter rodentium, higher levels of IL-6 expression in colonic tissues, and higher splenic MPO activity than controls (p < .05). No differences in tight junction expression, serum endotoxin levels, and colonic inflammatory cytokines were observed between groups. Infected animals presented also slightly more alveolar bone loss and gingival IL-6 levels than controls (p < .05).

CONCLUSION

Based on this model, intragastric administration of Aa JP2 is associated with changes in the gut ecosystem of healthy hosts, characterized by less live/recruited myeloid cells, enrichment of the gut microbiota with pathobionts and decrease in commensals. Negligible levels of colonic pro-inflammatory cytokines, and no signs of mucosal barrier disruption were related to these changes.

Glycolanguage of the oral microbiota

The oral cavity harbors a diverse and dynamic bacterial biofilm community which is pivotal to oral health maintenance and, if turning dysbiotic, can contribute to various diseases. Glycans as unsurpassed carriers of biological information are participating in underlying processes that shape oral health and disease. Bacterial glycoinfrastructure-encompassing compounds as diverse as glycoproteins, lipopolysaccharides (LPSs), cell wall glycopolymers, and exopolysaccharides-is well known to influence bacterial fitness, with direct effects on bacterial physiology, immunogenicity, lifestyle, and interaction and colonization capabilities. Thus, understanding oral bacterias' glycoinfrastructure and encoded glycolanguage is key to elucidating their pathogenicity mechanisms and developing targeted strategies for therapeutic intervention. Driven by their known immunological role, most research in oral glycobiology has been directed onto LPSs, whereas, recently, glycoproteins have been gaining increased interest. This review draws a multifaceted picture of the glycolanguage, with a focus on glycoproteins, manifested in prominent oral bacteria, such as streptococci, Porphyromonas gingivalis, Tannerella forsythia, and Fusobacterium nucleatum. We first define the characteristics of the different glycoconjugate classes and then summarize the current status of knowledge of the structural diversity of glycoconjugates produced by oral bacteria, describe governing biosynthetic pathways, and list biological roles of these energetically costly compounds. Additionally, we highlight emerging research on the unraveling impact of oral glycoinfrastructure on dental caries, periodontitis, and systemic conditions. By integrating current knowledge and identifying knowledge gaps, this review underscores the importance of studying the glycolanguage oral bacteria speak to advance our understanding of oral microbiology and develop novel antimicrobials.

Oral Lactobacillus zeae exacerbates the pathological manifestation of periodontitis in a mouse model

INTRODUCTION

The worldwide prevalence of periodontitis is considerably high, and its pathogenic mechanisms must be investigated and understood in order to improve clinical treatment outcomes and reduce the disease prevalence and burden. The exacerbation of the host immune system induced by oral microbial dysbiosis and the subsequent tissue destruction are the hallmarks of the periodontitis. However, the oral bacteria involved in periodontitis are not fully understood. We used the Oxford Nanopore Technologies (ONT) sequencing system to analyze metagenomic information in subgingival dental plaque from periodontitis and non-periodontitis patients. The number of Lactobacillus zeae (L. zeae) in the periodontitis patients was 17.55-fold higher than in the non-periodontitis patients, suggesting that L. zeae is a novel periodontitis-associated pathogen. Although several Lactobacillus species are used in vivo as probiotics to treat periodontitis and compete with Porphyromonas gingivalis (P. gingivalis), the roles of L. zeae in periodontitis progression, and the relationship between L. zeae and P. gingivalis needs to be investigated.

METHODS

Both L. zeae and P. gingivalis were inoculated in the ligature-implant site of periodontitis mice. We collected mouse gingival crevicular fluid to analyze inflammatory cytokine secretion using a multiplex assay. Intact or sliced mouse maxilla tissue was used for micro-computed tomography analysis or hematoxylin and eosin staining, immunohistochemistry, and tartrate-resistant acid phosphatase staining to evaluate alveolar bone loss, neutrophil infiltration, and osteoclast activation, respectively.

RESULTS

We observed that L. zeae competed with P. gingivalis, and it increased inflammatory cytokine secretion at the ligature-implant site. Similar to P. gingivalis, L. zeae promoted ligature-induced neutrophile infiltration, osteoclast activation, and alveolar bone loss.

DISCUSSION

We, therefore, concluded that L. zeae accelerated the progression of periodontitis in the ligature-induced periodontitis mouse model.

Toward Digital Periodontal Health: Recent Advances and Future Perspectives

Periodontal diseases, ranging from gingivitis to periodontitis, are prevalent oral diseases affecting over 50% of the global population. These diseases arise from infections and inflammation of the gums and supporting bones, significantly impacting oral health. The established link between periodontal diseases and systemic diseases, such as cardiovascular diseases, underscores their importance as a public health concern. Consequently, the early detection and prevention of periodontal diseases have become critical objectives in healthcare, particularly through the integration of advanced artificial intelligence (AI) technologies. This paper aims to bridge the gap between clinical practices and cutting-edge technologies by providing a comprehensive review of current research. We examine the identification of causative factors, disease progression, and the role of AI in enhancing early detection and treatment. Our goal is to underscore the importance of early intervention in improving patient outcomes and to stimulate further interest among researchers, bioengineers, and AI specialists in the ongoing exploration of AI applications in periodontal disease diagnosis.

The association between periodontal microbial biomarkers and primary therapy outcome

OBJECTIVE

This study aims to analyse the association between the baseline microbial load of selected periodontopathogenic bacteria collected from gingival crevicular fluid (GCF) and the primary outcome of steps I and II therapy.

MATERIALS AND METHODS

222 patients with stage III periodontitis were included into this retrospective analysis that received steps 1 and 2 periodontal therapy without adjunctive systemic antibiotics. Baseline GCF samples were quantitatively analysed using ELISA-based kits for levels of periodontopathogens (Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Treponema denticola (Td), and Tannerella forsythia (Tf)) and associated with the primary therapy outcome using a "treat-to-target" therapy endpoint (TE) defined as ≤ 4 sites with PD ≥ 5 mm six months after therapy.

RESULTS

38.2% of the patients achieved TE. Patients failing to achieve TE revealed significantly increased levels of Pg, Fn, and Tf at baseline (Pg: p = 0.010, Fn: p = 0.008 Tf: p = 0.004). Multivariate binary logistic regression adjusted for sex, mean probing depth, diabetes, and current smoking status showed an independent relationship between Tf and the TE (aOR 2.570, p = 0.023).

CONCLUSION

Increased microbial load is associated with decreased responsiveness to therapy. The findings suggest that specifically baseline Tf levels are associated with poorer treatment outcomes and might improve the accuracy of periodontal diagnosis.

CLINICAL RELEVANCE

The findings of this study support the concept of a critical biomass that is sufficient to induce and maintain an immune response within the periodontal pocket, which ultimately leads to irreversible tissue destruction. However, calculating this level in advance may serve as an early indicator for intervention.

KEY FINDING

Baseline Tannerella forsythia levels are associated with poorer treatment outcome.

Meta-analysis of oral microbiome reveals sex-based diversity in biofilms during periodontitis

Sex is an often overlooked, yet compulsory, biological variable when performing biomedical research. Periodontitis is a common yet progressively debilitating chronic inflammatory disorder affecting the tissues supporting teeth that ultimately leads to tooth loss if left untreated. The incidence of periodontitis is sex biased, with increased prevalence in males compared with females but with unknown etiology. We performed a sex-specific meta-analysis using publicly available oral microbiome data from different sampling sites of patients with periodontitis and periodontally healthy controls; sex balance was established for each periodontal health condition. Our results show sex-based diversity in oral biofilms of individuals with periodontitis but not in their saliva, with increased abundance of several periodontal pathogens in subgingival plaques from females compared with males. We devised a quantitative measure, uniquely defined as the Microsexome Index (MSI), which indicates that sexual dimorphism in subgingival bacterial composition is a distinct feature of reduced microbial diversity during periodontitis but not under healthy conditions. In addition, we found that smoking exacerbates microsexome diversity in supragingival biofilms, particularly during periodontitis. Taken together, we provide insights regarding sex-based diversity in periodontitis, a disease with multiorgan associations, and provide the rationale for further mechanistic, diagnostic, and therapeutic studies.

Periodontitis prevalence and acceleration of biological aging: Insights from NHANES 2009-2014 and Mendelian randomization study

AIM

This study aimed to investigate the association of periodontitis with biological aging and to assess potential causality using Mendelian randomization (MR).

METHODS

A cross-sectional study with 9558 participants from the National Health and Nutrition Examination Survey (2009-2014) was conducted. Age acceleration (BioAgeAccel and PhenoAgeAccel) was calculated from clinical biomarkers and their discrepancies with chronological age. Two-sample MR analysis was performed using data from a large-scale genome-wide association study and UK Biobank.

RESULTS

Periodontitis was associated with increased biological aging, with 0.57-year (95% CI: 0.28-0.86, p < .001) increases in BioAgeAccel and 0.41-year (95% CI: 0.04-0.78, p = .034) increases in PhenoAgeAccel. Subgroup analysis found significantly stronger associations in males for BioAgeAccele (PINTERACTION = .006), and pronounced associations in young adults (pinteraction = .023), individuals with normal body mass index (pinteraction = .015), and current smokers (pinteraction = .016) for PehonAgeAccel. MR analysis did not provide strong evidence for a causal effect of periodontitis on biological aging (BioAgeAccel: IVW β = 0.008, 95% CI: -0.018 to 0.034, p = .553 and PhenoAgeAccel: IVW β = 0.016, 95% CI: -0.042 to 0.074, p = .585).

CONCLUSION

This study identified the association of periodontitis and its severity with accelerated aging, suggesting periodontal health could be a possible method in personalized preventive and therapeutic strategies of biological aging.

Red-complex bacteria exhibit distinctly different interactions with human periodontal ligament stromal cells compared to Fusobacterium nucleatum

OBJECTIVE

The red-complex bacteria Porphyromonas gingivalis and Tannerella forsythia together with Fusobacterium nucleatum are essential players in periodontitis. This study investigated the bacterial interplay with human periodontal ligament mesenchymal stromal cells (hPDL-MSCs) which act in the acute phase of periodontal infection.

DESIGN

The capability of the bacteria to induce an inflammatory response as well as their viability, cellular adhesion and invasion were analyzed upon mono- and co-infections of hPDL-MSCs to delineate potential synergistic or antagonistic effects. The expression level and concentration of interleukin (IL)-6, IL-8 and monocyte chemoattractant protein (MCP)-1 were measured using qRT-PCR and ELISA. Viability, invasion, and adhesion were determined quantitatively using agar plate culture and qualitatively by confocal microscopy.

RESULTS

Viability of P. gingivalis and T. forsythia but not F. nucleatum was preserved in the presence of hPDL-MSCs, even in an oxygenated environment. F. nucleatum significantly increased the expression and concentration of IL-6, IL-8 and MCP-1 in hPDL-MSCs, while T. forsythia and P. gingivalis caused only a minimal inflammatory response. Co-infections in different combinations had no effect on the inflammatory response. Moreover, P. gingivalis mitigated the increase in cytokine levels elicited by F. nucleatum. Both red-complex bacteria adhered to and invaded hPDL-MSCs in greater numbers than F. nucleatum, with only a minor effect of co-infections.

CONCLUSIONS

Oral bacteria of different pathogenicity status interact differently with hPDL-MSCs. The data support P. gingivalis' capability to manipulate the inflammatory host response. Further research is necessary to obtain a comprehensive picture of the role of hPDL-MSCs in more complex oral biofilms.

Periodontal disease and emerging point-of-care technologies for its diagnosis

Periodontal disease (PD), a chronic inflammatory disorder that damages the tooth and its supporting components, is a common global oral health problem. Understanding the intricacies of these disorders, from gingivitis to severe PD, is critical for efficient treatment, diagnosis, and prevention in dental care. Periodontal biosensors and biomarkers are critical in improving oral health diagnostic skills. Clinicians may accomplish early identification, tailored therapy, and efficient tracking of periodontal diseases by using these technologies, ushering in a new age of accurate oral healthcare. Traditional periodontitis diagnostic methods frequently rely on physical probing and visual examinations, necessitating the development of point-of-care (POC) devices. As periodontal disorders necessitate more precise and rapid diagnosis, incorporating novel innovations in biosensors and biomarkers becomes increasingly crucial. These innovations improve our capacity to diagnose, monitor, and adapt periodontal therapies, bringing in the next phase of customized and effective dental healthcare. The review discusses the characteristics and stages of PD, clinical treatment techniques, prominent biomarkers and infection-associated factors that may be employed to determine PD, biomedical sensing, and POC appliances that have been created so far to diagnose stages of PD and its progression profile, as well as predicting future developments in this field.

A Flagellin-Adjuvanted Trivalent Mucosal Vaccine Targeting Key Periodontopathic Bacteria

Periodontal disease (PD) is caused by microbial dysbiosis and accompanying adverse inflammatory responses. Due to its high incidence and association with various systemic diseases, disease-modifying treatments that modulate dysbiosis serve as promising therapeutic approaches. In this study, to simulate the pathophysiological situation, we established a "temporary ligature plus oral infection model" that incorporates a temporary silk ligature and oral infection with a cocktail of live Tannerella forsythia (Tf), Pophyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn) in mice and tested the efficacy of a new trivalent mucosal vaccine. It has been reported that Tf, a red complex pathogen, amplifies periodontitis severity by interacting with periodontopathic bacteria such as Pg and Fn. Here, we developed a recombinant mucosal vaccine targeting a surface-associated protein, BspA, of Tf by genetically combining truncated BspA with built-in adjuvant flagellin (FlaB). To simultaneously induce Tf-, Pg-, and Fn-specific immune responses, it was formulated as a trivalent mucosal vaccine containing Tf-FlaB-tBspA (BtB), Pg-Hgp44-FlaB (HB), and Fn-FlaB-tFomA (BtA). Intranasal immunization with the trivalent mucosal vaccine (BtB + HB + BtA) prevented alveolar bone loss and gingival proinflammatory cytokine production. Vaccinated mice exhibited significant induction of Tf-tBspA-, Pg-Hgp44-, and Fn-tFomA-specific IgG and IgA responses in the serum and saliva, respectively. The anti-sera and anti-saliva efficiently inhibited epithelial cell invasion by Tf and Pg and interfered with biofilm formation by Fn. The flagellin-adjuvanted trivalent mucosal vaccine offers a novel method for modulating dysbiotic bacteria associated with periodontitis. This approach leverages the adjuvant properties of flagellin to enhance the immune response, aiming to restore a balanced microbial environment and improve periodontal health.

HAMLET, a human milk protein-lipid complex, modulates amoxicillin induced changes in an ex vivo biofilm model of the oral microbiome

Challenges from infections caused by biofilms and antimicrobial resistance highlight the need for novel antimicrobials that work in conjunction with antibiotics and minimize resistance risk. In this study we investigated the composite effect of HAMLET (human alpha-lactalbumin made lethal to tumor cells), a human milk protein-lipid complex and amoxicillin on microbial ecology using an ex vivo oral biofilm model with pooled saliva samples. HAMLET was chosen due to its multi-targeted antimicrobial mechanism, together with its synergistic effect with antibiotics on single species pathogens, and low risk of resistance development. The combination of HAMLET and low concentrations of amoxicillin significantly reduced biofilm viability, while each of them alone had little or no impact. Using a whole metagenomics approach, we found that the combination promoted a remarkable shift in overall microbial composition compared to the untreated samples. A large proportion of the bacterial species in the combined treatment were Lactobacillus crispatus, a species with probiotic effects, whereas it was only detected in a minor fraction in untreated samples. Although resistome analysis indicated no major shifts in alpha-diversity, the results showed the presence of TEM beta-lactamase genes in low proportions in all treated samples but absence in untreated samples. Our study illustrates HAMLET's capability to alter the effects of amoxicillin on the oral microbiome and potentially favor the growth of selected probiotic bacteria when in combination. The findings extend previous knowledge on the combined effects of HAMLET and antibiotics against target pathogens to include potential modulatory effects on polymicrobial biofilms of human origin.

Identification of keystone taxa in root canals and periapical lesions of post-treatment endodontic infections: Next generation microbiome research

AIM

The aim of this study was to analyse and compare the microbiome present in root canals and periapical lesions of teeth with post-treatment infections, and to identify the presence of keystone taxa in both habitats using next-generation sequencing analysis.

METHODOLOGY

Apices and periapical lesions of patients with post-treatment apical periodontitis were surgically extracted. Specimens were cryo-pulverized, bacterial DNA was extracted, and the V3-V4 hypervariable regions of the 16S rRNA gene were sequenced using the Illumina Miseq platform. Bioinformatic analysis was carried out with Mothur software, whilst diversity indices were obtained using operational taxonomic units (OTUs). The diversity indices were compared with the Kruskal-Wallis test, and community composition differences were explored with Permutational Multivariate Analysis of Variance (PERMANOVA). A bacterial functional study was performed with the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis. Co-occurrence network analyses were performed using the Sparse Correlations for Compositional data (SparCC). Eigencentrality, clr-based abundance and ubiquitousness were applied to infer keystone taxa. P values <.05 were considered statistically significant.

RESULTS

Thirty-two apices and thirty-nine periapical lesions were sequenced and analysed. A similar alpha-diversity (p < .05) and community composition (p = .91) was observed for apices and lesion samples. The most abundant OTUs identified amongst all samples included Fusobacterium nucleatum, Prevotella loescheii, Streptococcus intermedius, Porphyromonas gingivalis, Parvimonas micra, Synergistetes bacterium, Tannerella forsythia and Peptostreptococcus stomatis. The metabolic pathways with >0.81% abundances included membrane transport, genetic information processing and metabolic pathways. F. nucleatum was identified as a keystone taxon as it showed ubiquitousness, an eigenvector centrality value of 0.83 and a clr-based abundance >4.

CONCLUSIONS

The microbiome in apices and periapical lesions of post-treatment endodontic infections showed a similar diversity and taxonomic composition. Co-occurrence network analyses at OTU level identified F. nucleatum as a keystone taxon candidate in these infections.

An update on periodontal inflammation and bone loss

Periodontal disease is a chronic inflammatory condition that affects the supporting structures of the teeth, including the periodontal ligament and alveolar bone. Periodontal disease is due to an immune response that stimulates gingivitis and periodontitis, and its systemic consequences. This immune response is triggered by bacteria and may be modulated by environmental conditions such as smoking or systemic disease. Recent advances in single cell RNA-seq (scRNA-seq) and in vivo animal studies have provided new insight into the immune response triggered by bacteria that causes periodontitis and gingivitis. Dysbiosis, which constitutes a change in the bacterial composition of the microbiome, is a key factor in the initiation and progression of periodontitis. The host immune response to dysbiosis involves the activation of various cell types, including keratinocytes, stromal cells, neutrophils, monocytes/macrophages, dendritic cells and several lymphocyte subsets, which release pro-inflammatory cytokines and chemokines. Periodontal disease has been implicated in contributing to the pathogenesis of several systemic conditions, including diabetes, rheumatoid arthritis, cardiovascular disease and Alzheimer's disease. Understanding the complex interplay between the oral microbiome and the host immune response is critical for the development of new therapeutic strategies for the prevention and treatment of periodontitis and its systemic consequences.

The association between halitosis and periodontitis: a systematic review and meta-analysis

OBJECTIVES

The purpose of this systemic review and meta-analysis was to explore the association between halitosis and periodontitis in observational studies.

MATERIALS AND METHODS

A systematic search covered PubMed, Web of Science, Embase, Scopus, and Cochrane Library until August 18, 2023. Nine observational studies (585 cases, 1591 controls) were analyzed using Stata 17, with odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses considered halitosis assessment methods.

RESULTS

The review found a positive association between halitosis and periodontitis. Significant differences were observed with organoleptic test (OR = 4.05, 95% CI: 1.76, 9.30, p < 0.01) and volatile sulfur compound readings (OR = 4.52, 95% CI: 1.89, 10.83, p < 0.01).

CONCLUSIONS

A positive association was observed between halitosis and periodontitis, supported by significant differences in both organoleptic and volatile sulfur compound readings. However, conclusive findings are limited by statistical heterogeneity, emphasizing the need for additional research.

CLINICAL RELEVANCE

Understanding the halitosis and periodontitis association is clinically significant, informing potential interventions for improved oral health. Further research is vital to refine understanding and guide effective clinical strategies, acknowledging the limitations in current findings.

In-vitro effects of novel periodontal scalers with a planar ultrasonic piezoelectric transducer on periodontal biofilm removal, dentine surface roughness, and periodontal ligament fibroblasts adhesion

OBJECTIVES

To compare ultrasonic scaler prototypes based on a planar piezoelectric transducer with different working frequencies featuring a titanium (Ti-20, Ti-28, and Ti-40) or stainless steel (SS-28) instrument, with a commercially available scaler (com-29) in terms of biofilm removal and reformation, dentine surface roughness and adhesion of periodontal fibroblasts.

MATERIALS AND METHODS

A periodontal multi-species biofilm was formed on specimens with dentine slices. Thereafter specimens were instrumented with scalers in a periodontal pocket model or left untreated (control). The remaining biofilms were quantified and allowed to reform on instrumented dentine slices. In addition, fibroblasts were seeded for attachment evaluation after 72 h of incubation. Dentine surface roughness was analyzed before and after instrumentation.

RESULTS

All tested instruments reduced the colony-forming unit (cfu) counts by about 3 to 4 log10 and the biofilm quantity (each p < 0.01 vs. control), but with no statistically significant difference between the instrumented groups. After 24-hour biofilm reformation, no differences in cfu counts were observed between any groups, but the biofilm quantity was about 50% in all instrumented groups compared to the control. The attachment of fibroblasts on instrumented dentine was significantly higher than on untreated dentine (p < 0.05), with the exception of Ti-20. The dentine surface roughness was not affected by any instrumentation.

CONCLUSIONS

The planar piezoelectric scaler prototypes are able to efficiently remove biofilm without dentine surface alterations, regardless of the operating frequency or instrument material.

CLINICAL RELEVANCE

Ultrasonic scalers based on a planar piezoelectric transducer might be an alternative to currently available ultrasonic scalers.

The polymicrobial pathogenicity of Porphyromonas gingivalis

Accumulating microbiome data and mechanistic studies in vitro and in vivo have refined our understanding of the oral microbiota as a functionally integrated polymicrobial community. Emergent properties of these communities are driven to a large extent by interspecies communication which can be based on physical association, secreted small molecules or nutritional exchange. Porphyromonas gingivalis is a consensus periodontal pathogen; however, virulence is only expressed in the context of a polymicrobial community. Multivalent fimbriae mediate attachment to other oral species which can initiate a distinct transcriptional program in both constituents of the binding pair. P. gingivalis also responds to small molecules and nutritional cues produced by partner organisms. Physiological interdependence forms the basis of complex networks of cooperating organisms which begin to resemble an organismal entity exhibiting a spectrum of pathogenic potential.

A retrospective analysis of the role of age and sex in outcomes of non-surgical periodontal therapy at a single academic dental center

The present study examined the role of age and sex in the outcomes of non-surgical periodontal therapy (NSPT). De-identified demographic and periodontal characteristics of patients who presented for baseline periodontal evaluation, NSPT, and periodontal re-evaluation were abstracted from electronic health records. Independent associations of age and sex with severe periodontitis defined as ≥ 5 mm clinical attachment loss (CAL) and ≥ 6 mm probing depth (PD) were determined using multinomial logistic regression. The null hypothesis was rejected at α < 0.05. A total of 2866 eligible subjects were included in the analysis. Significantly lower odds of CAL ≤ 4 mm than CAL ≥ 5 mm (reference) were observed in adults aged 35-64 (odds ratio, OR, 0.19; 95% confidence interval, CI 0.13, 0.29) and ≥ 65 years (OR 0.13; 95% CI 0.07, 0.25) compared to those aged 18-34 years. Odds of PD < 4 mm versus PD ≥ 6 mm (reference) were lower in adults aged 35-64 years than those aged 18-34 years (OR 0.71; 95% CI 0.55, 0.90) and higher in females compared to males (OR 1.67; 95% CI 1.14, 2.44). These results suggest more compromised post-NSPT outcomes in older adults and males compared to the respective populations and highlight the need for personalized therapeutic strategies in these populations.

Exploring the Potential Consortium of Migraine and Periodontitis

Objectives

Various researches have shown periodontitis to share common pathophysiological pathways with systemic diseases such as diabetes, cardiovascular diseases, and osteoporosis and recently neurological disorders. This article provides a narrative review summarizing the various linking mechanisms and the nature of association between two multifactorial diseases-periodontitis and migraine.

Materials and Methods

A literature search was performed for articles related to periodontitis and migraine up till the year 2023 which yielded totally 14 articles. There were only three randomized controlled clinical trials; therefore, we were unable to conduct a systematic review and focused on a narrative review. The keywords searched were "migraine", "periodontitis" and "biomarkers" in PubMed/Medline, Web of Science, and Embase databases. Any article related to the association of periodontitis and migraine and the dental management of subjects with headache disorders were included and studies with migraine and other dental diseases were excluded.

Results

It is found that the occurrence of periodontitis and migraine are associated with each other. There is reasonable evidence to believe that periodontitis and migraine are linked by direct and indirect mechanisms which can eventually lead to chronic inflammatory conditions like periodontitis worsening neurovascular conditions such as migraine. However, upon detailed analysis it was found that the strength of association is weak owing to the presences of various common confounding and risk factors.

Conclusions

The association between periodontitis and migraine cannot be denied, however, not all the criteria are fulfilled while examining the nature of association and future long-term studies are required to prove the same. Clinical Relevance. Various studies have reported poor periodontal health in patients with migraine. The risk of exacerbation of migraine also increases in subject undergoing dental therapy if the triggering factors are manipulated. Hence, knowing the precise pathophysiologic mechanisms linking both the diseases would be favorable in planning treatment protocols for subjects with migraine.

Differential Response of Human Dendritic Cells upon Stimulation with Encapsulated or Non-Encapsulated Isogenic Strains of Porphyromonas gingivalis

During periodontitis, the extracellular capsule of Porphyromonas gingivalis favors alveolar bone loss by inducing Th1 and Th17 patterns of lymphocyte response in the infected periodontium. Dendritic cells recognize bacterial antigens and present them to T lymphocytes, defining their activation and polarization. Thus, dendritic cells could be involved in the Th1 and Th17 response induced against the P. gingivalis capsule. Herein, monocyte-derived dendritic cells were obtained from healthy individuals and then stimulated with different encapsulated strains of P. gingivalis or two non-encapsulated isogenic mutants. Dendritic cell differentiation and maturation were analyzed by flow cytometry. The mRNA expression levels for distinct Th1-, Th17-, or T-regulatory-related cytokines and transcription factors, as well as TLR2 and TLR4, were assessed by qPCR. In addition, the production of IL-1β, IL-6, IL-23, and TNF-α was analyzed by ELISA. The encapsulated strains and non-encapsulated mutants of P. gingivalis induced dendritic cell maturation to a similar extent; however, the pattern of dendritic cell response was different. In particular, the encapsulated strains of P. gingivalis induced higher expression of IRF4 and NOTCH2 and production of IL-1β, IL-6, IL-23, and TNF-α compared with the non-encapsulated mutants, and thus, they showed an increased capacity to trigger Th1 and Th17-type responses in human dendritic cells.

Advances in periodontal biomarkers

Due to technologic advancements, periodontology has witnessed a boost in biomarker research over the past three decades. Indeed, with the aid of omics, our understanding of the healthy periodontium, pathogenesis of periodontal diseases, and healing after periodontal treatment has improved significantly. Yet, the traditional methods, periodontal probing and radiographies, remain the most common methods to diagnose periodontal disease and monitor treatment. Although these approaches can produce reliable diagnostic outcomes, they generally detect disease only after significant tissue degradation thus making treatment outcome highly uncertain. Accordingly, laboratories worldwide have collaborated with clinicians to design accurate, rapid and cost-effective biomarkers for periodontal disease diagnosis. Despite these efforts, biomarkers that can be widely used in early disease diagnosis and for treatment outcome prediction are far from daily use. The aim of this chapter is to give a general overview on periodontal health and diseases, and review recent advancements in periodontal biomarker research. A second aim will discuss the strengths and limitations of translating periodontal biomarker research to clinical practice. Genetic biomarkers of periodontitis are not discussed as the available confirmatory data is scarce.

Oral bacteria accelerate pancreatic cancer development in mice

OBJECTIVE

Epidemiological studies highlight an association between pancreatic ductal adenocarcinoma (PDAC) and oral carriage of the anaerobic bacterium Porphyromonas gingivalis, a species highly linked to periodontal disease. We analysed the potential for P. gingivalis to promote pancreatic cancer development in an animal model and probed underlying mechanisms.

DESIGN

We tracked P. gingivalis bacterial translocation from the oral cavity to the pancreas following administration to mice. To dissect the role of P. gingivalis in PDAC development, we administered bacteria to a genetically engineered mouse PDAC model consisting of inducible acinar cell expression of mutant Kras (Kras +/LSL-G12D; Ptf1a-CreER, iKC mice). These mice were used to study the cooperative effects of Kras mutation and P. gingivalis on the progression of pancreatic intraepithelial neoplasia (PanIN) to PDAC. The direct effects of P. gingivalis on acinar cells and PDAC cell lines were studied in vitro.

RESULTS

P. gingivalis migrated from the oral cavity to the pancreas in mice and can be detected in human PanIN lesions. Repetitive P. gingivalis administration to wild-type mice induced pancreatic acinar-to-ductal metaplasia (ADM), and altered the composition of the intrapancreatic microbiome. In iKC mice, P. gingivalis accelerated PanIN to PDAC progression. In vitro, P. gingivalis infection induced acinar cell ADM markers SOX9 and CK19, and intracellular bacteria protected PDAC cells from reactive oxygen species-mediated cell death resulting from nutrient stress.

CONCLUSION

Taken together, our findings demonstrate a causal role for P. gingivalis in pancreatic cancer development in mice.

A Mendelian randomization study on the association of bone mineral density with periodontitis

OBJECTIVE

Observational studies indicated that individuals with osteoporosis could be at an increased risk of periodontitis. This study aimed to investigate whether there is a causal association of bone mineral density (BMD) with periodontitis using Mendelian randomization (MR).

MATERIALS AND METHODS

Summary statistics were sourced from genome-wide association study on BMD measured at different skeletal sites, including estimated heel BMD (eBMD, N = 426,824), forearm BMD (FA-BMD, N = 8143), femoral neck BMD (FN-BMD, N = 32,735), and lumbar spine BMD (LS-BMD, N = 28,498). Genetic variants of periodontitis (N = 45,563) and loose teeth (N = 461,031) were used as outcome surrogates. Inverse variance weighted meta-analysis (IVW) was adopted as main analyses. Other sensitivity MR approaches were used to boost power and account for pleiotropy.

RESULTS

IVW results suggested no evidence for a causal association of any phenotypes of BMD with periodontitis (eBMD, odds ratio [OR] = 0.984, 95% confidence interval [CI] = 0.885-1.083; FA-BMD, OR = 1.028, 95%CI = 0.864-1.193; FN-BMD, OR = 1.033, 95%CI = 0.896-1.169; LS-BMD, OR = 0.991, 95%CI =0.878-1.103; all P > 0.65). Such null associations were consistent through other sensitivity MR approaches. Similarly, no significant causal effects of BMD on loose teeth were found.

CONCLUSIONS

Within the limitation of the study, our MR estimates suggested that a decreased BMD is unlikely to substantially increase the risk of periodontitis.

Hemophore-like proteins of the HmuY family in the oral and gut microbiome: unraveling the mystery of their evolution

SUMMARY

Heme (iron protoporphyrin IX, FePPIX) is the main source of iron and PPIX for host-associated pathogenic bacteria, including members of the Bacteroidota (formerly Bacteroidetes) phylum. Porphyromonas gingivalis, a keystone oral pathogen, uses a unique heme uptake (Hmu) system, comprising a hemophore-like protein, designated as the first member of the novel HmuY family. Compared to classical, secreted hemophores utilized by Gram-negative bacteria or near-iron transporter domain-based hemophores utilized by Gram-positive bacteria, the HmuY family comprises structurally similar proteins that have undergone diversification during evolution. The best characterized are P. gingivalis HmuY and its homologs from Tannerella forsythia (Tfo), Prevotella intermedia (PinO and PinA), Bacteroides vulgatus (Bvu), and Bacteroides fragilis (BfrA, BfrB, and BfrC). In contrast to the two histidine residues coordinating heme iron in P. gingivalis HmuY, Tfo, PinO, PinA, Bvu, and BfrA preferentially use two methionine residues. Interestingly, BfrB, despite conserved methionine residue, binds the PPIX ring without iron coordination. BfrC binds neither heme nor PPIX in keeping with the lack of conserved histidine or methionine residues used by other members of the HmuY family. HmuY competes for heme binding and heme sequestration from host hemoproteins with other members of the HmuY family to increase P. gingivalis competitiveness. The participation of HmuY in the host immune response confirms its relevance in relation to the survival of P. gingivalis and its ability to induce dysbiosis not only in the oral microbiome but also in the gut microbiome or other host niches, leading to local injuries and involvement in comorbidities.

Antimicrobial efficacy of antiplaque agents of common toothpastes against Porphyromonas gingivalis and Streptococcus oralis: An in vitro study

Background

This study was designed to evaluate the antimicrobial activity of common gum protection and antiplaque toothpastes against Porphyromonas gingivalis (P. gingivalis) and Streptococcus oralis (S. oralis) as important periodontal pathogens.

Materials and Methods

This experimental study investigated the antimicrobial activity of 15 commonly used toothpastes from different companies on the two common types of periopathogens, S. oralis and P. gingivalis . The antimicrobial activity of toothpaste was evaluated at three concentrations of 100%, 50%, and 25% and analyzed by agar well diffusion plate method and zone of inhibition. The obtained data were compared and statistically analyzed by SPSS software using one-way ANOVA and the least significant difference post hoc tests (α = 0.05).

Results

One-way ANOVA showed that the mean diameter of the two-bacterial zone of inhibition was significantly different at 100%, 50%, and 25% concentrations of toothpastes (P < 0.001). In general, the mean diameter of the zone of inhibition was greater at 100% concentration than the other two concentrations in all toothpastes. The highest zone of inhibition of the S. oralis was in the toothpastes containing tin. Further, the highest zone of inhibition of P. gingivalis was found in the triclosan-containing toothpastes.

Conclusion

Toothpastes containing triclosan had the most antimicrobial activity against P. gingivalis . Moreover, toothpastes containing tin compounds had the most antimicrobial effect against S. oralis .

Porphyromonas gingivalis aggravates colitis via a gut microbiota-linoleic acid metabolism-Th17/Treg cell balance axis

Periodontitis is closely related to inflammatory bowel disease (IBD). An excessive and non-self-limiting immune response to the dysbiotic microbiome characterizes the two. However, the underlying mechanisms that overlap still need to be clarified. We demonstrate that the critical periodontal pathogen Porphyromonas gingivalis (Pg) aggravates intestinal inflammation and Th17/Treg cell imbalance in a gut microbiota-dependent manner. Specifically, metagenomic and metabolomic analyses shows that oral administration of Pg increases levels of the Bacteroides phylum but decreases levels of the Firmicutes, Verrucomicrobia, and Actinobacteria phyla. Nevertheless, it suppresses the linoleic acid (LA) pathway in the gut microbiota, which was the target metabolite that determines the degree of inflammation and functions as an aryl hydrocarbon receptor (AHR) ligand to suppress Th17 differentiation while promoting Treg cell differentiation via the phosphorylation of Stat1 at Ser727. Therapeutically restoring LA levels in colitis mice challenged with Pg exerts anti-colitis effects by decreasing the Th17/Treg cell ratio in an AHR-dependent manner. Our study suggests that Pg aggravates colitis via a gut microbiota-LA metabolism-Th17/Treg cell balance axis, providing a potential therapeutically modifiable target for IBD patients with periodontitis.

Aggregatibacter actinomycetemcomitans Cytolethal Distending Toxin Induces Cellugyrin-(Synaptogyrin 2) Dependent Cellular Senescence in Oral Keratinocytes

Recently, we reported that oral-epithelial cells (OE) are unique in their response to Aggregatibacter actinomycetemcomitans cytolethal distending toxin (Cdt) in that cell cycle arrest (G2/M) occurs without leading to apoptosis. We now demonstrate that Cdt-induced cell cycle arrest in OE has a duration of at least 7 days with no change in viability. Moreover, toxin-treated OE develops a new phenotype consistent with cellular senescence; this includes increased senescence-associated β-galactosidase (SA-β-gal) activity and accumulation of the lipopigment, lipofuscin. Moreover, the cells exhibit a secretory profile associated with cellular senescence known as the senescence-associated secretory phenotype (SASP), which includes IL-6, IL-8 and RANKL. Another unique feature of Cdt-induced OE senescence is disruption of barrier function, as shown by loss of transepithelial electrical resistance and confocal microscopic assessment of primary gingival keratinocyte structure. Finally, we demonstrate that Cdt-induced senescence is dependent upon the host cell protein cellugyrin, a homologue of the synaptic vesicle protein synaptogyrin. Collectively, these observations point to a novel pathogenic outcome in oral epithelium that we propose contributes to both A. actinomycetemcomitans infection and periodontal disease progression.

Oral microbiome associated with differential ratios of Porphyromonas gingivalis and Streptococcus cristatus

Periodontitis has recently been defined as a dysbiotic disease caused by an imbalanced oral microbiota. The transition from commensal microbial communities to periodontitis-associated ones requires colonization by specific pathogens, including Porphyromonas gingivalis. We previously reported an antagonistic relationship between Streptococcus cristatus and P. gingivalis. To determine the role of S. cristatus in altering the interactions of P. gingivalis with other oral bacteria in a complex context, we collected dental plaque samples from patients with periodontitis and assigned them to two groups based on the ratios of S. cristatus and P. gingivalis. We then characterized the microbial profiles of the dental plaque samples using shotgun metagenomic sequencing and compared the oral microbial composition and functional capabilities of the group with high S. cristatus-P. gingivalis ratios with the low ratio group. Taxonomic annotation revealed significant differences in the microbial composition at both the genus and species levels between the low and high S. cristatus-P. gingivalis ratio groups. Notably, a higher microbial diversity was observed in the samples with low S. cristatus-P. gingivalis ratios. Furthermore, the antibiotic resistance gene profiles of the two groups were also distinct, with a significantly increased abundance of the genes in the dental plaque samples with low S. cristatus-P. gingivalis ratios. It, therefore, indicates that the S. cristatus-P. gingivalis ratios influenced the virulence potential of the oral microbiome. Our work shows that enhancing the S. cristatus-P. gingivalis ratio in oral microbial communities can be an attractive approach for revising the dysbiotic oral microbiome.IMPORTANCEPeriodontitis, one of the most common chronic diseases, is linked to several systemic diseases, such as cardiovascular disease and diabetes. Although Porphyromonas gingivalis is a keystone pathogen that causes periodontitis, its levels, interactions with accessory bacteria and pathobionts in the oral microbiome, and its association with the pathogenic potential of the microbial communities are still not well understood. In this study, we revealed the role of Streptococcus cristatus and the ratios of S. cristatus and P. gingivalis in modulating the oral microbiome to facilitate a deeper understanding of periodontitis and its progression. The study has important clinical implications as it laid a foundation for developing novel non-antibiotic therapies against P. gingivalis and improving the efficiency of periodontal treatments.

Role of LL-37 in Oral Bacterial DNA Accumulation in Dental Plaque

Dental plaque, a highly structured polymicrobial biofilm, persistently forms in the oral cavity and is a common problem affecting oral health. The role of oral defense factors in either collaborating or disrupting host-microbiome interactions remains insufficiently elucidated. This study aims to explore the role of LL-37, a critical antimicrobial peptide in the oral cavity, in dental plaque formation. Through immunostaining dental plaque specimens, we observed that LL-37 and DNA colocalized in the samples, appearing as condensed clusters. In vitro experiments revealed that LL-37 binds rapidly to oral bacterial DNA, forming high molecular weight, DNase-resistant complexes. This interaction results in LL-37 losing its inherent antibacterial activity. Further, upon the addition of LL-37, we observed a visible increase in the precipitation of bacterial DNA. We also discovered a significant correlation between the levels of the DNA-LL-37 complex and LL-37 within dental plaque specimens, demonstrating the ubiquity of the complex within the biofilm. By using immunostaining on dental plaque specimens, we could determine that the DNA-LL-37 complex was present as condensed clusters and small bacterial cell-like structures. This suggests that LL-37 immediately associates with the released bacterial DNA to form complexes that subsequently diffuse. We also demonstrated that the complexes exhibited similar Toll-like receptor 9-stimulating activities across different bacterial species, including Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia, and Streptococcus salivarius. However, these complexes prompted dissimilar activities, such as the production of IL-1β in monocytic cells via both NLRP3 pathway-dependent and pathway-independent mechanisms. This study, therefore, reveals the adverse role of LL-37 in dental plaque, where it binds bacterial DNA to form complexes that may precipitate to behave like an extracellular matrix. Furthermore, the unveiled stimulating properties and species-dependent activities of the oral bacterial DNA-LL-37 complexes enrich our understanding of dental plaque pathogenicity and periodontal innate immune responses.

IL-39 and IL-35 gingival crevicular fluid levels in diabetic patients with generalized periodontitis

OBJECTIVES

This research was performed to investigate if there is a role for IL-39 in immunopathogenesis of both systemically healthy and diabetic periodontitis patients. Additionally, to explore if we can consider IL-39 and IL-35 as biomarkers for periodontitis activity.

MATERIALS AND METHODS

A total of 38 periodontitis patients and 19 control volunteers were included in our study. The periodontitis patients were divided equally into (Group I), 19 patients with stage III grade C periodontitis with diabetes mellitus and (Group II), 19 patients with stage III grade B periodontitis and systemically healthy. Gingival crevicular fluid levels of each interleukin were measured pre- and postoperatively for all periodontitis patients as well as control subjects using ELISA.

RESULTS

Our study results showed that the highest level for IL-39 was in diabetic periodontitis patients that decreased significantly postoperatively. However, the highest level for IL-35 was revealed in control group while the lowest value was registered in diabetic periodontitis patients and statistically increased after periodontal treatment.

CONCLUSIONS

Based on the results of our research, both investigated biomarkers may have a potent role in pathogenesis of periodontitis.

CLINICAL RELEVANCE

We could consider both interleukins as accurate diagnostic markers for periodontitis patients, regardless of diabetes mellitus association, as well as promising markers that can aid in the prevention and treatment of periodontitis patients worldwide.

Biomaterials Functionalized with Inflammasome Inhibitors-Premises and Perspectives

This review aimed at searching literature for data regarding the inflammasomes' involvement in the pathogenesis of oral diseases (mainly periodontitis) and general pathologies, including approaches to control inflammasome-related pathogenic mechanisms. The inflammasomes are part of the innate immune response that activates inflammatory caspases by canonical and noncanonical pathways, to control the activity of Gasdermin D. Once an inflammasome is activated, pro-inflammatory cytokines, such as interleukins, are released. Thus, inflammasomes are involved in inflammatory, autoimmune and autoinflammatory diseases. The review also investigated novel therapies based on the use of phytochemicals and pharmaceutical substances for inhibiting inflammasome activity. Pharmaceutical substances can control the inflammasomes by three mechanisms: inhibiting the intracellular signaling pathways (Allopurinol and SS-31), blocking inflammasome components (VX-765, Emricasan and VX-740), and inhibiting cytokines mediated by the inflammasomes (Canakinumab, Anakinra and Rilonacept). Moreover, phytochemicals inhibit the inflammasomes by neutralizing reactive oxygen species. Biomaterials functionalized by the adsorption of therapeutic agents onto different nanomaterials could represent future research directions to facilitate multimodal and sequential treatment in oral pathologies.

Chronological analysis of periodontal bone loss in experimental periodontitis in mice

OBJECTIVES

Periodontal disease is understood to be a result of dysbiotic interactions between the host and the biofilm, causing a unique reaction for each individual, which in turn characterizes their susceptibility. The objective of this study was to chronologically evaluate periodontal tissue destruction induced by systemic bacterial challenge in known susceptible (BALB/c) and resistant (C57BL/6) mouse lineages.

MATERIAL AND METHODS

Animals, 6-8 weeks old, were allocated into three experimental groups: Negative control (C), Gavage with sterile carboxymethyl cellulose 2%-without bacteria (Sham), and Gavage with carboxymethyl cellulose 2% + Porphyromonas gingivalis (Pg-W83). Before infection, all animals received antibiotic treatment (sulfamethoxazole/trimethoprim, 400/80 mg/5 mL) for 7 days, followed by 3 days of rest. Microbial challenge was performed 3 times per week for 1, 2, or 3 weeks. After that, the animals were kept until the completion of 42 days of experiments, when they were euthanized. The alveolar bone microarchitecture was assessed by computed microtomography.

RESULTS

Both C57BL/6 and BALB/c mice exhibited significant bone volume loss and lower trabecular thickness as well as greater bone porosity compared to the (C) and (Sham) groups after 1 week of microbial challenge (p < .001). When comparing only the gavage groups regarding disease implantation, time and lineage, it was possible to observe that within 1 week of induction the disease was more established in BALB/c than in C57BL/6 (p < .05).

CONCLUSIONS

Our results reflected that after 1 week of microbial challenge, there was evidence of alveolar bone loss for both lineages, with the loss observed in BALB/c mice being more pronounced.