Impact of periodontal therapy on the subgingival microbiota of severe periodontitis: comparison between good responders and individuals with refractory periodontitis using the human oral microbe identification microarray

Dydrogesterone alleviates periodontitis in perimenopausal women undergoing periodontal therapy by decreasing inflammation and mediating oral microbiota

OBJECTIVE

Dydrogesterone (DG), a synthetic isomer of progesterone, plays a potential regulatory role in the periodontal environment. The aim of this study was to investigate the potential effects of DG on periodontitis under periodontal therapy (PT) and the underlying mechanisms related to oral microbiota.

METHODS

As a cohort study, perimenopausal women with periodontitis and abnormal uterine bleeding associated with ovulatory dysfunction were screened. A total of 30 women received PT (PT group) and 30 women received PT and oral DG 10 mg twice/day for 10 days/month (PT + DG group). At baseline and 3 months after treatment, pocket probing depth (PPD), bleeding index (BI), bleeding on probing (BOP), plaque index, CRP, IL-6, and TNF-α were measured. Additionally, 16S rDNA sequencing was performed to determine the characteristics of oral microbiota, mainly in terms of abundance, diversity, composition, and community structure.

RESULTS

Three months after treatment, the levels of PPD, BI, and BOP, as well as the levels of CRP, IL-6, and TNF-α in gingival crevicular fluid were significantly lower in the PT + DG group than those in the PT group. After treatment, a relatively lower microbial abundance, and some differences in microbial composition were revealed between the PT and PT + DG groups. At the genus level, significantly fewer Escherichia-Shigella, Porphyromonas, and Absconditabacteriales (SR1), and more Lactobacillus, Gordonia, Bifidobacterium, and Oribacterium were found in the PT group than in the PT + DG group.

CONCLUSIONS

DG enhances the effect of PT on inhibiting inflammatory response in women with periodontitis by mediating oral microbiota.

Viable but non-cultivable state in oral microbiota: a critical review of an underexplored microbial survival strategy

The viable but non-cultivable (VBNC) state and persister cells, two dormancy phenomena in bacteria, differ in various aspects. The entry of bacteria into the VBNC state as a survival strategy under stressful conditions has gained increasing attention in recent years, largely due to the higher tolerance of VBNC cells to antibiotics and antimicrobials resulting from their low metabolic activity. The oral cavity favors biofilm growth in dental hard tissues, resulting in tooth decay and periodontitis. Despite advances in VBNC state detection in the food industry and environment, the entry capability of oral bacteria into the VBNC state remains poorly documented. Furthermore, the VBNC state has recently been observed in oral pathogens, including Porphyromonas gingivalis, which shows potential relevance in chronic systemic infections, Enterococcus faecalis, an important taxon in endodontic infections, and Helicobacter pylori, which exhibits transient presence in the oral cavity. Further research could create opportunities to develop novel therapeutic strategies to control oral pathogens. The inability of conventional culture-based methods to identify VBNC bacteria and the metabolic reactivation of dormant cells to restore susceptibility to therapies highlights a notable gap in anti-VBNC state strategies. The lack of targeted approaches tested for efficacy against VBNC bacteria underscores the need to develop novel detection methods. This review discusses the VBNC state, its importance in public health, and diagnostic techniques, with a special focus on the VBNC state in oral bacteria.

Polypeptide of Inonotus hispidus extracts alleviates periodontitis through suppressing inflammatory bone loss

This study aimed to characterize and evaluate the effects of a novel polypeptide isolated from Inonotus hispidus (IH) against periodontitis. The polypeptides extracted and purified from the fruiting body of IH had a uniform molar mass, including 23 types of peptides. IH polypeptide (IHP) exerted antimicrobial activity against Porphyromonas gingivalis (P. gingivalis) by damaging the cell walls and membranes of microorganisms, disturbing energy metabolism, and regulating the expression of virulence factors. IHP significantly inhibited inflammation in lipopolysaccharides (LPS)-stimulated Raw264.7 cells evidenced by the regulation of inflammatory cytokine levels. In rats with ligature-induced periodontitis, IHP treatment ameliorated alveolar bone destruction and preserved the balance between oral flora and gut microbes. The interaction between oral and intestinal flora possibly affected the relevant metabolites. Proteomics combined with confirmation experiment revealed that the β-catenin/ nuclear factor-kappa B (NF-κB) signaling may be involved in IHP-mediated anti-periodontitis in rats, which helps reduce the secretion of pro-inflammatory factors and inhibit inflammatory osteoclastic response in the periodontal tissue. Additionally, IHP improved clinical parameters, including the plaque index (PLI), pocket depth (PD), bleeding on probing (BOP), and average probing depth in individuals with periodontitis. These findings augment the understanding of the potential role of IHP in treating periodontitis.

Salivary microbiota reflecting changes in subgingival microbiota

The purpose of this study was to determine whether subgingival microbial changes according to the severity of periodontal disease and following the non-surgical periodontal treatment of periodontitis are reflected in the saliva microbiota. Subgingival and saliva samples were collected from 7 periodontally healthy controls, 14 patients with gingivitis, 12 with moderate periodontitis, and 18 with severe periodontitis. Among subjects who received treatment, seven moderate and seven severe periodontitis patients were selected for post-treatment microbial analysis, and their samples were analyzed at baseline and 6 months after treatment. The V3 and V4 regions of the 16S rRNA gene were sequenced, and correlations of the relative abundance of phyla and health- or periodontitis-dominant species between subgingival plaque and saliva samples were analyzed using Spearman signed-rank tests. Alpha diversity was higher in saliva than subgingival plaque samples, and beta diversity was significantly different between the two samples. However, levels of phyla and most health- or periodontitis-dominant species in salivary microbiota were significantly correlated with those in subgingival plaque. The improvement in clinical parameters following treatment was accompanied by a microbial shift not only in subgingival plaque but also in saliva. The abundance of 2 phyla including Bacteroidetes, 6 genera including Porphyromonas and Treponema, and 11 species including Porphyromonas gingivalis, Tannerella forsythia, and Filifactor alocis was significantly reduced in saliva following treatment. These results indicate that the salivary microbiota can reflect changes in the subgingival microbiota, suggesting that saliva can be used as a diagnostic tool to monitor the periodontal health status of individuals.

IMPORTANCE

The salivary microbiota has attracted increasing attention as a promising method for monitoring periodontal disease. With regard to the pathogenesis of periodontal disease, however, subgingival plaque microbiota is the dominant etiological factor. Although it has been established that periodontopathogenic bacteria exist in saliva and their distribution differs, depending on the severity of the disease, it is necessary to analyze the extent to which the salivary microbiota reflects the subgingival microbiota. This study explored whether subgingival microbial changes according to the severity of periodontal disease and following the non-surgical periodontal treatment of periodontitis are reflected in the saliva microbiota and concluded that the salivary microbiota can reflect changes in the subgingival microbiota. Saliva can be used as a diagnostic tool to monitor the periodontal health status of individuals.

Assessing oral and toothbrush microbial profiles among high-altitude individuals with and without periodontal disease: a case-control study

BACKGROUND

Periodontitis is the sixth-most common disease worldwide. The oral microbiome composition and its association with Periodontal disease (PD) have been largely explored; however, limited studies have explored the microbial profiles of both oral and toothbrushes in patients with PD. Thus, this study aimed to ascertain the oral and toothbrushes microbial composition in high-altitude populations, hypothesizing that their correlation with periodontal health would differ from those at lower altitudes, potentially indicating links between environmental factors, microbial colonization patterns, and periodontal health in distinct geographic contexts.

METHODS

In the present study, we enrolled 35 individuals including 21 healthy and 14 diagnosed with PD from the Lhasa region of Tibet, China. Saliva and toothbrush samples were collected from each participant to assess the association between toothbrush usage and oral microbiome with PD using 16 S rRNA gene-specific V3-V4 regions sequencing. To assess the oral and toothbrush microbiome composition and diversity and its possible link to PD.

RESULTS

Significantly higher Alpha diversity (Shannon index) was observed between the PD group and PD toothbrushes (p = 0.00021) and between the PD group and Healthy toothbrushes (p = 0.00041). The predominant species were Proteobacteria, Bacteroidota, Firmicutes, Actinobacteria, and Fusobacteria, with genera Pseudomonas, Veillonella, Neisseria, Acinetobacter, and Haemophilus. In addition, PICRUST2 analysis unveiled 44 significant pathways differentiating the disease and healthy groups, along with 29 pathways showing significant differences between their respective toothbrush microbial profiles. The distinct oral and toothbrush microbial composition among high-altitude populations suggests potential adaptations to the challenges of high-altitude environments.

CONCLUSION

This study emphasizes the importance of tailored dental care strategies, accounting for altitude and racial factors, to effectively manage periodontal health in these communities. Further research is warranted to investigate the specific microbial mechanisms and develop targeted interventions for optimizing oral health in populations across varying altitudes.

Association between Oral Microbiome and Gastroesophageal Reflux Severity

Background/Objectives: Gastroesophageal reflux disease (GORD) is caused by gastric contents refluxing back into the oesophagus and oral cavity. It can lead to injuries to the mucosa in the form of erosion and ulcers. Our past research have shown acid reflux severity and disease progression is associated with alternations in the microbiota of the distal oesophagus. The aim of this study was to explore whether changes in the oral microbiota occurred in GORD patients and establish any associations with reflux severity. Methods: Fresh mouthwash samples were collected from 58 patients experiencing reflux symptoms referred for 24 h pH monitoring. The participants were categorised into three groups based on their DeMeester scores: Normal (<14.72), Mild (14.2-50), and Moderate/severe (>51). Microorganism identity and diversity were generated using hypervariable tag sequencing and analysing the V1-V3 region of the 16S rRNA gene. Results: No differences in microbiota diversity were found in oral microbiota between groups using the Chiao1 diversity index and Shannon diversity index. Microbiota in the Mild group showed reductions in Rothia dentocariosa and Lautropia, while Moryella and Clostridiales_1 were increased compared with the Normal group. In the Moderate/severe group, the abundance of Rothia aeria was reduced compared with the Normal group, while Schwartzia, Rs_045, Paludibacter, S. satelles, Treponema, and T. socranskii all had increased abundance. The abundance of Prevotella pallens was higher in the Mild group compared with Moderate/severe, while S. satelles and Paludibacter abundances were lower. Conclusions: Our study shows the oral microbiome show significant differences between acid reflux severity groups, as categorised by DeMeester score.

Microbial diagnostics in periodontal diseases

Microbial analytical methods have been instrumental in elucidating the complex microbial etiology of periodontal diseases, by shaping our understanding of subgingival community dynamics. Certain pathobionts can orchestrate the establishment of dysbiotic communities that can subvert the host immune system, triggering inflammation and tissue destruction. Yet, diagnosis and management of periodontal conditions still rely on clinical and radiographic examinations, overlooking the well-established microbial etiology. This review summarizes the chronological emergence of periodontal etiological models and the co-evolution with technological advances in microbial detection. We additionally review the microbial analytical approaches currently accessible to clinicians, highlighting their value in broadening the periodontal assessment. The epidemiological importance of obtaining culture-based antimicrobial susceptibility profiles of periodontal taxa for antibiotic resistance surveillance is also underscored, together with clinically relevant analytical approaches to guide antibiotherapy choices, when necessary. Furthermore, the importance of 16S-based community and shotgun metagenomic profiling is discussed in outlining dysbiotic microbial signatures. Because dysbiosis precedes periodontal damage, biomarker identification offers early diagnostic possibilities to forestall disease relapses during maintenance. Altogether, this review highlights the underutilized potential of clinical microbiology in periodontology, spotlighting the clinical areas most conductive to its diagnostic implementation for enhancing prevention, treatment predictability, and addressing global antibiotic resistance.

Subgingival microbial changes in Down Syndrome adults with periodontitis after chlorhexidine adjunct non-surgical therapy and monthly recalls-A 12-month case series study

OBJECTIVES

Down Syndrome (DS) adults are at risk for periodontitis. Previous reports indicated difficulties in periodontopathogen reduction or eradication in DS individuals after periodontal treatment. This case series follows the subgingival microbial changes in adult DS individuals with periodontitis who received chlorhexidine adjunct non-surgical therapy plus 12-month recalls.

METHODS

Twenty periodontitis DS participants (7 females; 25.5 ± 5.6 years of age; 3 with generalized periodontitis) partook in a study involving non-surgical mechanical periodontal therapy, twice daily chlorhexidine gel toothbrushing, chlorhexidine mouthwash, and monthly recalls. The subgingival microbiota profile was followed at baseline, 6-, and 12-months post-operation.

RESULTS

Desulfobulbus, Saccharibacteria (TM7), Tannerella, and Porphyromonas were the major subgingival genera in this DS cohort. Favorable chlorhexidine adjunct non-surgical treatment outcomes were observed, with the relative abundance of Desulfobulbus sp. HMT 041, Saccharibacteria (TM7) [G-1] bacterium HMT 346 or 349, and Tannerella forsythia significantly reduced at the end of the study, but no significant reduction of Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans could be observed. Relative abundance of Desulfobulbus sp. HMT 041 and T. forsythia were also found to be significantly associated with plaque, bleeding on probing, and probing pocket depth (PPD, in mm) at a site level, while the relative abundance of Halomonas pacifica was negatively associated with PPD.

CONCLUSIONS

Successful chlorhexidine adjunct non-surgical treatment with hygiene care was accompanied by a subgingival microbial shift involving certain periodontopathogenic species, except P. gingivalis and A. actinomycetemcomitans. Further investigations are required to clarify the mechanism underpinning the unchanged relative abundance of the above two pathogens despite favorable clinical responses.

CLINICAL SIGNIFICANCE

DS adults face challenges achieving optimal home care or hygiene for periodontal healing and disease prevention. Chemical adjunct mechanical periodontal therapy plus regular recalls appeared promising clinically and microbiologically, with subgingival periodontopathogenic species reduction. The persistence of A. actinomycetemcomitans and P. gingivalis in subgingival niches post-treatment warrants further investigation.

Metagenomic analysis of healthy and diseased peri-implant microbiome under different periodontal conditions: a cross-sectional study

BACKGROUND

Peri-implantitis is a polybacterial infection that can lead to the failure of dental implant rehabilitation. This study aimed to profile the microbiome of the peri-implant plaque and estimate the effect of periodontitis on it among 40 Chinese participants with dental implant prostheses and presenting with varying peri-implant and periodontal health states.

METHODS

Submucosal plaque samples were collected from four distinct clinical categories based on both their implant and periodontal health status at sampling point. Clinical examinations of dental implant and remaining teeth were carried out. Metagenomic analysis was then performed.

RESULTS

The microbiome of the peri-implantitis sites differed from that of healthy implant sites, both taxonomically and functionally. Moreover, the predominant species in peri-implantitis sites were slightly affected by the presence of periodontitis. T. forsythia, P. gingivalis, T. denticola, and P. endodontalis were consistently associated with peri-implantitis and inflammatory clinical parameters regardless of the presence of periodontitis. Prevotella spp. and P. endodontalis showed significant differences in the peri-implantitis cohorts under different periodontal conditions. The most distinguishing function between diseased and healthy implants is related to flagellar assembly, which plays an important role in epithelial cell invasion.

CONCLUSIONS

The composition of the peri-implant microbiome varied in the diseased and healthy states of implants and is affected by individual periodontal conditions. Based on their correlations with clinical parameters, certain species are associated with disease and healthy implants. Flagellar assembly may play a vital role in the process of peri-implantitis.

Periodontal disease in down syndrome: Predisposing factors and potential non-surgical therapeutic approaches

BACKGROUND

Periodontal diseases (PDs) have been documented to be significantly more prevalent and severe in patients with Down syndrome (DS). Different immunological and microbiological factors contributed to predisposing these patients to progressive and recurrent PDs.

AIM

The aim of this review was to investigate the altered immunological responses and oral microbiota disorders as well as focus on adjunctive non-surgical methods for the treatment of PDs and its applicability in patients with DS.

MATERIAL AND METHODS

A literature review was conducted addressing the following topics: (1) the altered immunological responses, (2) orofacial disorders related to DS patients, (3) oral microbiota changing, and (4) adjunctive non-surgical treatment and its efficacy in patients with DS.

RESULTS

Due to the early onset of PDs in children with DS, the need for prompt and effective treatment in these patients is essential.

DISCUSSION AND CONCLUSION

So, investigating underlying factors may open a new window to better understand the pathology of PDs in DS people and thus, find better strategies for treatment in such group. Although non-surgical treatments such as photodynamic therapy and probiotic consumption represented acceptable outcomes in different examined patients without DS, data about the application of these convenience and no need for local anesthesia methods in patients with DS is limited.

Organotypic model of the gingiva for studying bacterial and viral pathogens implicated in periodontitis

Background

Three-dimensional (3D) tissue models bridge the gap between conventional two-dimensional cell cultures and animal models. The aim of this study was to develop an organotypic 3D gingival (OTG) model to provide a tool to investigate bacterial and viral pathogens in periodontitis.

Methods

The OTG model composed of gingival fibroblasts (GFs) and telomerase-immortalized gingival keratinocytes (TIGKs) was constructed and applied to study infections by Porphyromonas gingivalis and herpes simplex virus 1 (HSV-1). Immunohistochemical staining, confocal microscopy, qPCR, titration techniques, and colony-forming unit counts were applied to interrogate epithelial markers expression, monitor P. gingivalis and HSV-1 presence, and evaluate the immune response along with the efficiency of antimicrobial drugs.

Results

The OTG model resembled the morphology of the human gingiva. During infection, both pathogens penetrated deep into the tissue and persisted for a few days with P. gingivalis also forming a biofilm on the cell surface. The infection triggered the expression of inflammatory mediators in cells and both pathogens were efficiently eliminated by specific antimicrobials.

Conclusions

Presented OTG model constitutes a simple and convenient tool to study the interaction between bacterial and viral pathogens within the gingival tissue, including penetration, persistence and biofilm formation. It is also suitable to examine the efficiency of antimicrobial drugs.

Comparison of the main pathogenic microorganisms of various common oral diseases in children and adults

The microorganisms in the human body gradually change and maintain a dynamic balance with the development of physiology and pathology. Oral microbiota is one of the most important microbiota in human body. It is not only closely related to the occurrence and development of oral diseases, but also plays an important role in the overall health. In childhood, the population of oral microorganisms is relatively small, but with the growth of age and tooth development, the species and quantity of oral microorganisms are gradually increasing. Different oral diseases also have their corresponding main microorganisms, and these dominant microorganisms change at different stages of the disease. In this review, we summarized and compared the main pathogenic microorganisms of several common oral diseases in children and adults. In addition, the possible association and difference between adults and children of the main pathogenic microorganisms in different stages of the same or different diseases are also discussed in order to provide research data for the development and diagnosis of common oral diseases in children and adults.

Oral microbiota in human health and disease: A perspective

The evolution of medical knowledge about oral microbiota has increased awareness of its important role for the entire human body health. A wide range of microbial species colonizing the oral cavity interact both with each other and with their host through complex pathways. Usually, these interactions lead to a harmonious coexistence (i.e. eubiosis). However, several factors - including diet, poor oral hygiene, tobacco smoking, and certain medications, among others - can disrupt this weak homeostatic balance (i.e. dysbiosis) with potential implications on both oral (i.e. development of caries and periodontal disease) and systemic health. This article is thus aimed at providing an overview on the importance of oral microbiota in mediating several physiological and pathological conditions affecting human health. In this context, strategies based on oral hygiene and diet as well as the role of probiotics supplementation are discussed.

Differential analysis of culturable and unculturable subgingival target microorganisms according to the stages of periodontitis

OBJECTIVES

Culturable and unculturable microorganisms have been associated with periodontitis. Their differential proportions and composition have not been evaluated by their severity and complexity defined by stages in the 2018 AAP-EEP classification.

METHODS

One hundred eighty subgingival biofilm samples were collected in Spain and Colombia from subjects categorized as health/gingivitis: periodontitis stages I/II periodontitis stages III/IV. Target culturable microorganisms (Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Treponema denticola, and Eubacterium nodatum) and target unculturable microorganisms (Filifactor alocis, Eubacterium saphenum, Eubacterium brachy, Desulfobulbus oralis) were evaluated by quantitative PCR analysis. In addition, their differences and association with periodontal status were analyzed by ANCOVA and logistic regression models once adjusted to age, current smoking, and country.

RESULTS

P. gingivalis was significantly associated with periodontitis stages I/II, OR 2.44 (CI 95% 1.08-5.47) and stages III/V, OR 6.43 (CI 95% 2.43-16.9). T forsythia, OR 7.53 (CI 95% 2.07-27.4); D. oralis, OR 5.99 (CI 95% 2.71-13.23); F. alocis, OR 10.9 (CI 95% 4.56-23.2); E. brachy, 3.57 (CI 95% 1.40-9.11); and E. saphenum, 4.85 (CI 95% 1.99-11.7) were significantly associated only with stages III/IV periodontitis. P. gingivalis evidenced significant differences with the increase in the severity of the periodontal lesion: 2.97 colony forming unit (CFU)/μL (CI 95% 2.32-3.54) health/gingivitis, and 4.66 CFU/μL (CI 95% 4.03-5.30) and 5.90 CFU/μL (CI 95% 5.20-6.48) in stages I/II and III/IV respectively (p < 0.0001). Unculturable microorganisms only evidenced differences in concentration in stages III/IV compared with health-gingivitis (p ≤ 0.001).

CONCLUSION

Culturable and unculturable are strongly associated with stages III/IV periodontitis. Classic culturable microorganisms are more sensitive to differentiate between stages of periodontitis in the quantitative analysis.

CLINICAL RELEVANCE

Future interventional studies of periodontal disease should include Filifactor alocis, Eubacterium saphenum, Eubacterium brachy, and Desulfobulbus oralis as possible markers of therapy response and as indicators of progressive disease.

Non-Surgical Periodontal Treatment Impact on Subgingival Microbiome and Intra-Oral Halitosis

The purpose of this study was to characterize and compare subgingival microbiome before and after periodontal treatment to learn if any changes of the subgingival microbiome were reflected in intra-oral halitosis. We tested the hypothesis that intra-oral halitosis (Volatile sulfur compounds levels) correlates with corresponding subgingival bacterial levels before and after periodontal treatment. Twenty patients with generalized periodontitis completed the study. Subgingival plaque samples were collected at baseline and 6-8 weeks after nonsurgical periodontal therapy. Full-mouth periodontal status assessed probing depth (PD), clinical attachment loss (CAL), gingival recession (REC), bleeding on probing (BoP), PISA and PESA. Halitosis assessment was made using a volatile sulfur compounds (VSC) detector device. Periodontal measures were regressed across VSC values using adjusted multivariate linear analysis. The subgingival microbiome was characterized by sequencing on an Illumina platform. From a sample of 20 patients referred to periodontal treatment, 70% were females (n = 14), with a mean age of 56.6 (±10.3) years; full-mouth records of PD, CAL, BOP (%) allowed to classify the stage and grade of periodontitis, with 45% (n = 9) of the sample having Periodontitis Stage IV grade C and 95% (n = 19) had generalized periodontitis. The correlation of bacterial variation with VSCs measured in the periodontal diagnosis and in the reassessment after treatment were evaluated. Fusobacterium nucleatum, Capnocytophaga gingivalis and Campylobacter showaei showed correlation with the reduction of VSC after periodontal treatment (p-value = 0.044; 0.047 and 0.004, respectively). Capnocytophaga sputigena had a significant reverse correlation between VSCs variation from diagnosis (baseline) and after treatment. Microbial diversity was high in the subgingival plaque on periodontitis and intra-oral halitosis participants of the study. Furthermore, there were correlations between subgingival plaque composition and VSC counting after periodontal treatment. The subgingival microbiome can offer important clues in the investigation of the pathogenesis and treatment of halitosis.

Antimicrobial Chemotherapy for Recalcitrant Severe Human Periodontitis

This study evaluated a combined systemic and topical anti-infective periodontal treatment of 35 adults who had experienced ongoing periodontal breakdown following conventional surgical periodontics. The prescribed anti-infective therapy, based on microbiological testing, consisted of a single course of metronidazole plus ciprofloxacin (23 patients), metronidazole plus amoxicillin/clavulanic acid (10 patients), and metronidazole plus ciprofloxacin followed by metronidazole plus amoxicillin/clavulanic acid (2 patients). In addition, the study patients received 0.1% povidone-iodine subgingival disinfection during non-surgical root debridement and daily patient administered oral irrigation with 0.1% sodium hypochlorite. At 1 and 5 years post-treatment, all study patients showed gains in clinical periodontal attachment with no further attachment loss, and significant decreases in pocket probing depth, bleeding on probing, and subgingival temperature. The greatest disease resolution occurred in patients who at baseline harbored predominantly major periodontal pathogens which post-antibiotics became non-detectable and substituted by non-periodontopathic viridans streptococci. The personalized and minimally invasive anti-infective treatment regimen described here controlled periodontitis disease activity and markedly improved the clinical and microbiological status of the refractory periodontitis patients.

Periodontal microbiology and microbial etiology of periodontal diseases: Historical concepts and contemporary perspectives

This narrative review summarizes the collective knowledge on periodontal microbiology, through a historical timeline that highlights the European contribution in the global field. The etiological concepts on periodontal disease culminate to the ecological plaque hypothesis and its dysbiosis-centered interpretation. Reference is made to anerobic microbiology and to the discovery of select periodontal pathogens and their virulence factors, as well as to biofilms. The evolution of contemporary molecular methods and high-throughput platforms is highlighted in appreciating the breadth and depth of the periodontal microbiome. Finally clinical microbiology is brought into perspective with the contribution of different microbial species in periodontal diagnosis, the combination of microbial and host biomarkers for this purpose, and the use of antimicrobials in the treatment of the disease.

SIRT6-regulated macrophage efferocytosis epigenetically controls inflammation resolution of diabetic periodontitis

Rationale: Diabetes exacerbates the prevalence and severity of periodontitis, leading to severe periodontal destruction and ultimately tooth loss. Delayed resolution of inflammation is a major contributor to diabetic periodontitis (DP) pathogenesis, but the underlying mechanisms of this imbalanced immune homeostasis remain unclear. Methods: We collected periodontium from periodontitis with or without diabetes to confirm the dysfunctional neutrophils and macrophages in aggravated inflammatory damage and impaired inflammation resolution. Our in vitro experiments confirmed that SIRT6 inhibited macrophage efferocytosis by restraining miR-216a-5p-216b-5p-217 cluster maturation through ''non-canonical'' microprocessor complex (RNA pulldown, RIP, immunostaining, CHIP, Luciferase assays, and FISH). Moreover, we constructed m6SKO mice that underwent LIP-induced periodontitis to explore the in vitro and in vivo effect of SIRT6 on macrophage efferocytosis. Finally, antagomiR-217, a miRNA antagonism, was delivered into the periodontium to treat LIP-induced diabetic periodontitis. Results: We discovered that insufficient SIRT6 as a histone deacetylase in macrophages led to unresolved inflammation and aggravated periodontitis in both human and mouse DP with accumulated apoptotic neutrophil (AN) and higher generation of neutrophil extracellular traps. Mechanistically, we validated that macrophage underwent high glucose stimulation resulting in disturbance of the SIRT6-miR-216/217 axis that triggered impeded efferocytosis of AN through targeting the DEL-1/CD36 axis directly. Furthermore, we demonstrated the inhibitory role of SIRT6 for MIR217HG transcription and identified a non-canonical action of microprocessor that SIRT6 epigenetically hindered the splicing of the primary miR-216/217 via the complex of hnRNPA2B1, DGCR8, and Drosha. Notably, by constructing myeloid-specific deletion of SIRT6 mice and locally delivering antagomir-217 in DP models, we strengthened the in vivo effect of this axis in regulating macrophage efferocytosis and inflammation resolution in DP. Conclusions: Our findings delineated the emerging role of SIRT6 in mediating metabolic dysfunction-associated inflammation, and therapeutically targeting this regulatory axis might be a promising strategy for treating diabetes-associated inflammatory diseases.

Prevotella genus and its related NOD-like receptor signaling pathway in young males with stage III periodontitis

Background

As periodontitis progresses, the oral microbiota community changes dynamically. In this study, we evaluated the dominant bacteria and their roles in the potential pathway in young males with stage III periodontitis.

Methods

16S rRNA sequencing was performed to evaluate variations in the composition of oral bacteria between males with stage I and III periodontitis and identify the dominant bacteria of each group. Function prediction was obtained based on 16S rRNA sequencing data. The inhibitor of the predominant pathway for stage III periodontitis was used to investigate the role of the dominant bacteria in periodontitis in vivo and in vitro.

Results

Chao1 index, Observed Species and Phylogenetic Diversity (PD) whole tree values were significantly higher in the stage III periodontitis group. β-diversity suggested that samples could be divided according to the stages of periodontitis. The dominant bacteria in stage III periodontitis were Prevotella, Prevotella_7, and Dialister, whereas that in stage I periodontitis was Cardiobacterium. KEGG analysis predicted that variations in the oral microbiome may be related to the NOD-like receptor signaling pathway. The inhibitor of this pathway, NOD-IN-1, decreased P. intermedia -induced Tnf-α mRNA expression and increased P. intermedia -induced Il-6 mRNA expression, consistent with the ELISA results. Immunohistochemistry confirmed the down-regulation of TNF-α and IL-6 expressions by NOD-IN-1 in P. intermedia-induced periodontitis.

Conclusion

The composition of the oral bacteria in young males varied according to the stage of periodontitis. The species richness of oral microtia was greater in young males with stage III periodontitis than those with stage I periodontitis. Prevotella was the dominant bacteria in young males with stage III periodontitis, and inhibition of the NOD-like receptor signaling pathway can decrease the periodontal inflammation induced by P. intermedia.

The human microbiome in disease and pathology

This narrative review seeks to examine the relationships between bacterial microbiomes and infectious disease. This is achieved by detailing how different human host microbiomes develop and function, from the earliest infant acquisitions of maternal and environmental species through to the full development of microbiomes by adulthood. Communication between bacterial species or communities of species within and outside of the microbiome is a factor in both maintenance of homeostasis and management of threats from the external environment. Dysbiosis of this homeostasis is key to understanding the development of disease states. Several microbiomes and the microbiota within are used as prime examples of how changes in species composition, particularly at the phylum level, leads to such diverse conditions as inflammatory bowel disease (IBD), type 2 diabetes, psoriasis, Parkinson's disease, reflux oesophagitis and others. The review examines spatial relationships between microbiomes to understand how dysbiosis in the gut microbiome in particular can influence diseases in distant host sites via routes such as the gut-lung, gut-skin and gut-brain axes. Microbiome interaction with host processes such as adaptive immunity is increasingly identified as critical to developing the capacity of the immune system to react to pathogens. Dysbiosis of essential bacteria involved in modification of host substrates such as bile acid components can result in development of Crohn's disease, small intestine bacterial overgrowth, hepatic cancer and obesity. Interactions between microbiomes in distantly located sites are being increasingly being identified, resulting in a 'whole of body' effect by the combined host microbiome.

Analysis of subgingival micro-organisms based on multi-omics and Treg/Th17 balance in type 2 diabetes with/without periodontitis

Type 2 diabetes mellitus (T2DM) and periodontitis are common and interrelated diseases, resulting in altered host response microbiota. The subgingival micro-organisms play a key role in periodontitis pathogenesis. To assess the shift of subgingival microbiome and metabolome in T2DM, we performed an analysis of the subgingival microbiome in patients with T2DM (n = 20) compared with non-diabetes (ND) subjects (n = 21). Furthermore, patients were subdivided into 10 T2DM with periodontitis (DP), 10 T2DM without periodontitis (DNP), 10 periodontitis (P), and 11 healthy control (H) groups. 16SrRNA gene sequencing combined with ultra high-performance liquid chromatography-mass spectrometry (UHPLC-MS) based metabolomics was performed in all participants. T lymphocyte immunity was analyzed by flow cytometry. Furthermore, the network relationship among subgingival micro-organisms, metabolites, blood glucose level, and T lymphocyte immunity were analyzed. The results showed that the difference of the subgingival microbiome from healthy to periodontitis status was less prominent in T2DM compared with ND, though the clinical signs of disease were similar. The bacteria Eubacterium nodatum group, Filifactor, Fretibacterium, Peptostreptococcus, and Desulfovibrio, amongst others, may be important in the pathopoiesia of periodontitis in the T2DM state. In addition, some dominant bacteria showed network relationships. The Treg/Th17 ratio was lower in the DP and DNP groups than in the P and H groups-though that of P was lower than for H. The percentage of CD4+/CD8+ PD1 and CD8+ PDL1 was higher in the DP and DNP groups than in the H group; the percentage of CD8+ PDL1 was higher in the DP than P groups. Subgingival micro-organisms in periodontitis had a significant metabolic shift in terms of their signature metabolites. Butyrate metabolism and phenylalanine metabolism may play a role in the pathogenesis of periodontitis with/without T2DM. Specifically, biphenyl degradation, tryptophan metabolism, and the two-component system may play important roles in periodontitis with T2DM. Lastly, the network relationship among subgingival micro-organisms, metabolites, blood glucose level, and T lymphocyte immunity were unbalanced. This study identified the changes in the subgingival microbiome associated with periodontitis in T2DM, as well as the associated network between bacterial flora, metabolism dysbiosis, and immune regulation.

Lipopolysaccharide from Porphyromonas gingivalis, but Not from Porphyromonas endodontalis, Induces Macrophage M1 Profile

Apical Lesions of Endodontic Origin (ALEO) are initiated by polymicrobial endodontic canal infection. Porphyromonas gingivalis (Pg) and Porphyromonas endodontalis (Pe) lipopolysaccharides (LPS) can induce a pro-inflammatory macrophage response through their recognition by TLR2 and TLR4. However, polarization responses induced by Pg and/or Pe LPS in macrophages are not fully understood. We aimed to characterize the polarization profiles of macrophages differentiated from THP-1 cells following Pg and/or Pe LPS stimulation from reference strain and clinical isolates. A modified LPS purification protocol was implemented and the electrophoretic LPS profiles were characterized. THP-1 human monocytes differentiated to macrophages were stimulated with Pg and Pe LPS. Polarization profiles were characterized through cell surface markers and secreted cytokines levels after 24 h of stimulation. TLR2 and TLR4 cell surfaces and transcriptional levels were determined after 24 or 2 h of LPS stimulation, respectively. LPS from Pg induced a predominant M1 profile in macrophages evidenced by changes in the expression of the surface marker CD64 and pro-inflammatory cytokine profiles, TNF-α, IL-1β, IL-6, and IL-12. Pe LPS was unable to induce a significant response. TLR2 and TLR4 expressions were neither modified by Pg or Pe LPS. Pg LPS, but not Pe LPS, induced a macrophage M1 Profile.

Metronidazole enhances killing of Porphyromonas gingivalis by human PMNs

Background and objectives

Periodontitis affects the supporting structures of the teeth as a result of the interactions between the subgingival biofilm and the host immune system. Periodontal therapy in severe forms of periodontitis often utilizes antimicrobial agents with some potential to improve host defense responses. In the present study, we investigated the in vitro effect of metronidazole (MTZ) at concentrations achievable in the periodontal pocket on PMN activation and PMN mediated killing of Porphyromonas gingivalis.

Materials and methods

Flow cytometry based assays were used to measure the impact of MTZ on PMN degranulation, neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) release and phagocytosis in response to the keystone oral pathogen P. gingivalis. Functional assays for PMN mediated killing of P. gingivalis and reactive oxygen species (ROS) production in PMN were also carried out.

Results

We demonstrate that PMNs pretreated with MTZ (2 μg/ml or 50 μg/ml) displayed enhanced killing of P. gingivalis compared to untreated PMNs. At concentrations achieved physiologically in the periodontal pocket, MTZ induced PMN surface expression of two activation markers (CD66 and CD63). MTZ did not alter P. gingivalis-induced NETosis, but suppressed P. gingivalis-induced ROS production and phagocytosis.

Conclusion

MTZ displays a positive interaction with PMNs to potentiate PMN mediated killing of P. gingivalis and may therefore contribute to its beneficial effects in the treatment of periodontitis initiated by P. gingivalis infections including those refractory to conventional treatment.

Effectiveness of the Human Oral Microbe Identification Microarray in Identifying Periodontal Pathogens: A Systematic Review

The aim of this review was to investigate the effectiveness of the Human Oral Microbe Identification Microarray (HOMIM) in identifying and quantifying bacterial species of the oral microbiome in periodontal disease. The search for articles was conducted in CENTRAL, CINAHL, MEDLINE and EMBASE by two reviewers, and included articles published in English between January 1990 and December 2021. The selected articles were human observational studies in adults between 18 and 65 years, presenting specific predefined keywords. Articles were initially selected by title and abstract; articles that met the inclusion criteria were analyzed for methodological quality using a detailed checklist for quality assessment. Data were extracted and reported using the PRISMA tool. The study design, sample, follow-up period, collection and microbial analysis methods, statistical treatment, results and discussion were quality assessed and risk of bias was evaluated using the Cochrane Risk-of-Bias tool. A narrative synthesis approach was used to synthesize and interpret the extracted data. From the initial search, 2931 articles were retrieved; 51 of these were then selected after screening by title and abstract. Subsequently, 8 articles met the inclusion after full-text reading and were classed according to methodological quality as high (2), moderate (3) or low (3). Studies included in this review were of high and medium quality. Data from the Human Oral Microbe Identification Microarray (HOMIM) provide much more robust results, showing major shifts between periodontal health and periodontal disease. Compared to earlier techniques such as Denaturing Gradient Gel Electrophoresis (DGGE), HOMIM represents a more effective approach for quantification due to its high sensitivity; thus, it is able to identify a high prevalence of periodontal pathogens and novel species in low abundance. The literature provides moderate evidence that the Human Oral Microbe Identification Microarray (HOMIM) is more effective in identifying and quantifying bacterial species of the oral microbiome in periodontal disease, compared to earlier molecular and non-molecular methods such as Denaturing Gradient Gel Electrophoresis (DGGE) and a culture-based approach with phenotypic tests.

Can metagenomics unravel the impact of oral bacteriome in human diseases?

Oral microbial ecosystems are vital in maintaining the health of the oral cavity and the entire body. Oral microbiota is associated with the progression of oral diseases such as dental caries, periodontal diseases, head and neck cancer, and several systemic diseases such as cardiovascular disease, rheumatoid arthritis, adverse pregnancy outcomes, diabetes, lung infection, colorectal cancer, and pancreatic cancer. Buccal mucosa, tongue dorsum, hard palate, saliva, palatine tonsils, throat, keratinized gingiva, supra-gingival plaque, subgingival plaque, dentures, and lips are microbial habitats of the oral cavity. Porphyromonas gingivalis may have a role in the development of periodontal diseases, oral cancer, diabetes, and atherosclerotic disease. Fusobacterium nucleatum showed a higher abundance in periodontal diseases, oral and colon cancer, adverse pregnancy outcomes, diabetes, and rheumatoid arthritis. The higher abundance of Prevotella intermedia is typical in periodontal diseases, rheumatoid arthritis, and adverse pregnancy outcome. S. salivarius displayed higher abundance in both dental caries and OSCC. Oral bacteria may influence systemic diseases through inflammation by releasing pro inflammatory cytokines. Identification of oral bacteria using culture-dependent approaches and next-generation sequencing-based metagenomic approaches is believed to significantly identify the therapeutic targets and non-invasive diagnostic indicators in different human diseases. Oral bacteria in saliva could be exploited as a non-invasive diagnostic indicator for the early detection of oral and systemic disorders. Other therapeutic approaches such as the use of probiotics, green tea polyphenol, cold atmospheric plasma (CAP) therapy, antimicrobial photodynamic therapy, and antimicrobial peptides are used to inhibit the growth of biofilm formation by oral bacteria.

An In Vitro Pilot Study on the Effects of Silver Diamine Fluoride on Periodontal Pathogens and Three-Dimensional Scaffolds of Human Fibroblasts and Epithelial Cells

Objective

The aims of this study were to investigate the antibacterial and cytotoxic effects of silver diamine fluoride (SDF) on periodontal pathogens and human skin constructs, respectively.

Background

SDF has been proven to have bactericidal effects on cariogenic bacteria. No studies to date evaluated the bactericidal effects of SDF on periodontal pathogens nor its effect on epithelium and fibroblasts.

Methods

Streptococcus mutans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans were cultured in monospecies biofilms, exposed to increasing concentrations of SDF and inoculated on agar plates to assess viability. Human gingival fibroblasts in 2D cultures were exposed to 1 μL of 0.394% of SDF and viewed using real-time imaging. Finally, SDF was applied to human, 3D tissue scaffolds of fibroblasts and keratinocytes, and termed human skin equivalents (HSE). A clinical dose of 38% SDF was applied, and HSE were cultured for 12 hours, 1, 3, 5, and 10 days. The tissue was observed clinically and histologically with hematoxylin and eosin staining and TUNEL.

Results

S. mutans and A. actinomycetemcomitans growth was completely inhibited using all dilutions of SDF, whereas P. gingivalis was still viable with 0.197% and 0.098% of SDF. Single-layer fibroblasts experienced immediate necrosis upon contact with SDF. Application of SDF to HSE showed maturation of a whitish lesion within 24 hours, followed by pigmented, crusted tissue after 3 days. Histological evaluation of treated tissues showed apoptotic cells in the epithelium and upper half of the connective tissue.

Conclusion

Our data suggest that SDF has bactericidal properties against two periodontal pathogens: P. gingivalis and A. actinomycetemcomitans. SDF caused immediate necrosis of monolayer fibroblasts, but does not extend to the full extent of layered fibroblasts in HSE.

Comparison of the oral microbial composition between healthy individuals and periodontitis patients in different oral sampling sites using 16S metagenome profiling

Purpose

The purpose of this study was to compare the microbial composition of 3 types of oral samples through 16S metagenomic sequencing to determine how to resolve some sampling issues that occur during the collection of sub-gingival plaque samples.

Methods

In total, 20 subjects were recruited. In both the healthy and periodontitis groups, samples of saliva and supra-gingival plaque were collected. Additionally, in the periodontitis group, sub-gingival plaque samples were collected from the deepest periodontal pocket. After DNA extraction from each sample, polymerase chain reaction amplification was performed on the V3-V4 hypervariable region on the 16S rRNA gene, followed by metagenomic sequencing and a bioinformatics analysis.

Results

When comparing the healthy and periodontitis groups in terms of alpha-diversity, the saliva samples demonstrated much more substantial differences in bacterial diversity than the supra-gingival plaque samples. Moreover, in a comparison between the samples in the case group, the diversity score of the saliva samples was higher than that of the supra-gingival plaque samples, and it was similar to that of the sub-gingival plaque samples. In the beta-diversity analysis, the sub-gingival plaque samples exhibited a clustering pattern similar to that of the periodontitis group. Bacterial relative abundance analysis at the species level indicated lower relative frequencies of bacteria in the healthy group than in the periodontitis group. A statistically significant difference in frequency was observed in the saliva samples for specific pathogenic species (Porphyromonas gingivalis, Treponema denticola, and Prevotella intermedia). The saliva samples exhibited a similar relative richness of bacterial communities to that of sub-gingival plaque samples.

Conclusions

In this 16S oral microbiome study, we confirmed that saliva samples had a microbial composition that was more similar to that of sub-gingival plaque samples than to that of supra-gingival plaque samples within the periodontitis group.

Direct current exerts electricidal and bioelectric effects on Porphyromonas gingivalis biofilms partially via promoting oxidative stress and antibiotic transport

Low electric current can inhibit certain microbial biofilms and enhance the efficacy of antimicrobials against them. This study investigated the electricidal and bioelectric effects of direct current (DC) against Porphyromonas gingivalis biofilms as well as the underlying mechanisms. Here, we firstly showed that DC significantly suppressed biofilm formation of P. gingivalis in time- and intensity-dependent manners, and markedly inhibited preformed P. gingivalis biofilms. Moreover, DC enhanced the killing efficacy of metronidazole (MTZ) and amoxicillin with clavulanate potassium (AMC) against the biofilms. Notably, DC-treated biofilms displayed upregulated intracellular ROS and expression of ROS related genes (sod, feoB, and oxyR) as well as porin gene. Interestingly, DC-induced killing of biofilms was partially reversed by ROS scavenger N-dimethylthiourea (DMTU), and the synergistic effect of DC with MTZ/AMC was weakened by small interfering RNA of porin gene (si-Porin). In conclusion, DC can exert electricidal and bioelectric effects against P. gingivalis biofilms partially via promotion of oxidative stress and antibiotic transport, which offers a promising approach for effective management of periodontitis.

Potential Roles of the Free Salivary Microbiome Dysbiosis in Periodontal Diseases

Saliva is a vital mediator in the oral cavity. The dysbiosis of free bacteria in saliva might be related to the onset, development, prognosis, and recurrence of periodontal diseases, but this potential relationship is still unclear. The objective of this study was to investigate the potential roles of the free salivary microbiome in different periodontal statuses, their reaction to nonsurgical periodontal therapy, and differences between diseased individuals after treatment and healthy persons. We recruited 15 healthy individuals, 15 individuals with gingivitis, and 15 individuals with stage I/II generalized periodontitis. A total of 90 unstimulated whole saliva samples were collected and sequenced using full-length bacterial 16S rRNA gene sequencing. We found that as the severity of disease increased, from healthy to gingivitis and periodontitis, the degree of dysbiosis also increased. A higher abundance of Prevotella intermedia and Catonella morbi and a lower abundance of Porphyromonas pasteri, Prevotella nanceiensis, and Haemophilus parainfluenzae might be biomarkers of periodontitis, with an area under curve (AUC) reaching 0.9733. When patients received supragingival scaling, there were more pathogens related to recolonization in the saliva of periodontitis patients than in healthy persons. Even after effective nonsurgical periodontal therapy, individuals with periodontitis displayed a more dysbiotic and pathogenic microbial community in their saliva than healthy individuals. Therefore, the gradual transition in the entire salivary microbial community from healthy to diseased includes a gradual shift to dysbiosis. Free salivary pathogens might play an important role in the recolonization of bacteria as well as the prognosis and recurrence of periodontal diseases.

Non-surgical treatment for periodontitis and peri-implantitis: longitudinal clinical and bacteriological findings-A case report with a 7-year follow-up evaluation

The aim of this report is to show that periodontitis and peri-implantitis with horizontal bone resorption in a 68-year-old male patient were successfully treated by non-surgical treatment. Scaling with an ultrasonic device was performed for moderate periodontitis around the mandibular left first premolar and moderate peri-implantitis around the maxillary right molar implants. Root planing with a metal curette was performed for the periodontal site, and debridement with a plastic curette was performed for the peri-implant site. A month after treatment, probing depth decreased from 5 to 2 mm at the periodontal site and 8 to 3 mm at the peri-implant site. The investigation of bacterial composition by sequencing the 16S rRNA gene amplicons showed that the composition similarly changed at both sites, 5 years after treatment; the change reflected the typical recovery of periodontitis. The clinical condition was maintained for 7 years after treatment at both sites. This was a successful case of non-surgical treatment for peri-implantitis with horizontal bone resorption, promoting recovery of the microbiota from dysbiotic shift.

Structure and Function of Oral Microbial Community in Periodontitis Based on Integrated Data

Objective

Microorganisms play a key role in the initiation and progression of periodontal disease. Research studies have focused on seeking specific microorganisms for diagnosing and monitoring the outcome of periodontitis treatment. Large samples may help to discover novel potential biomarkers and capture the common characteristics among different periodontitis patients. This study examines how to screen and merge high-quality periodontitis-related sequence datasets from several similar projects to analyze and mine the potential information comprehensively.

Methods

In all, 943 subgingival samples from nine publications were included based on predetermined screening criteria. A uniform pipeline (QIIME2) was applied to clean the raw sequence datasets and merge them together. Microbial structure, biomarkers, and correlation network were explored between periodontitis and healthy individuals. The microbiota patterns at different periodontal pocket depths were described. Additionally, potential microbial functions and metabolic pathways were predicted using PICRUSt to assess the differences between health and periodontitis.

Results

The subgingival microbial communities and functions in subjects with periodontitis were significantly different from those in healthy subjects. Treponema, TG5, Desulfobulbus, Catonella, Bacteroides, Aggregatibacter, Peptostreptococcus, and Eikenella were periodontitis biomarkers, while Veillonella, Corynebacterium, Neisseria, Rothia, Paludibacter, Capnocytophaga, and Kingella were signature of healthy periodontium. With the variation of pocket depth from shallow to deep pocket, the proportion of Spirochaetes, Bacteroidetes, TM7, and Fusobacteria increased, whereas that of Proteobacteria and Actinobacteria decreased. Synergistic relationships were observed among different pathobionts and negative relationships were noted between periodontal pathobionts and healthy microbiota.

Conclusion

This study shows significant differences in the oral microbial community and potential metabolic pathways between the periodontitis and healthy groups. Our integrated analysis provides potential biomarkers and directions for in-depth research. Moreover, a new method for integrating similar sequence data is shown here that can be applied to other microbial-related areas.

Gemella haemolysans inhibits the growth of the periodontal pathogen Porphyromonas gingivalis

The oral microbiome plays an important role in the human microbial community and in maintaining the health of an individual. Imbalances in the oral microbiome may contribute to oral and systemic diseases. The progression of periodontal disease is closely related to the growth of bacteria, such as Porphyromonas gingivalis, in the oral cavity. However, the pathogen growth mechanism specific to periodontal disease remains unknown. This study aimed to identify bacteria associated with periodontal health by focusing on hemolytic bacteria. Unstimulated saliva samples were collected from ten periodontitis patients and five healthy subjects to detect and identify the presence of hemolytic bacteria. The saliva of healthy subjects contained a higher proportion of G. haemolysans than saliva samples from patients with periodontitis. Growth inhibition assays indicated that the protein components contained in the culture supernatant of G. haemolysans directly suppressed the growth of P. gingivalis. This study shows that the presence of G. haemolysans in saliva is associated with periodontal health and that it inhibits the growth of P. gingivalis in vitro.

Resolving the Contradictory Functions of Lysine Decarboxylase and Butyrate in Periodontal and Intestinal Diseases

Periodontal disease is a common, bacterially mediated health problem worldwide. Mastication (chewing) repeatedly traumatizes the gingiva and periodontium, causing traces of inflammatory exudate, gingival crevicular fluid (GCF), to appear in crevices between the teeth and gingiva. Inadequate tooth cleaning causes a dentally adherent microbial biofilm composed of commensal salivary bacteria to appear around these crevices where many bacteria grow better on GCF than in saliva. We reported that lysine decarboxylase (Ldc) from Eikenella corrodens depletes the GCF of lysine by converting it to cadaverine and carbon dioxide. Lysine is an amino acid essential for the integrity and continuous renewal of dentally attached epithelium acting as a barrier to microbial products. Unless removed regularly by oral hygiene, bacterial products invade the lysine-deprived dental attachment where they stimulate inflammation that enhances GCF exudation. Cadaverine increases and supports the development of a butyrate-producing microbiome that utilizes the increased GCF substrates to slowly destroy the periodontium (dysbiosis). A long-standing paradox is that acid-induced Ldc and butyrate production support a commensal (probiotic) microbiome in the intestine. Here, we describe how the different physiologies of the respective tissues explain how the different Ldc and butyrate functions impact the progression and control of these two chronic diseases.

Citizen-science based study of the oral microbiome in Cystic fibrosis and matched controls reveals major differences in diversity and abundance of bacterial and fungal species

Introduction: Cystic fibrosis (CF) is an autosomal genetic disease, associated with the production of excessively thick mucosa and with life-threatening chronic lung infections. The microbiota of the oral cavity can act as a reservoir or as a barrier for infectious microorganisms that can colonize the lungs. However, the specific composition of the oral microbiome in CF is poorly understood.Methods: In collaboration with CF associations in Spain, we collected oral rinse samples from 31 CF persons (age range 7-47) and matched controls, and then performed 16S rRNA metabarcoding and high-throughput sequencing, combined with culture and proteomics-based identification of fungi to survey the bacterial and fungal oral microbiome.Results: We found that CF is associated with less diverse oral microbiomes, which were characterized by higher prevalence of Candida albicans and differential abundances of a number of bacterial taxa that have implications in both the connection to lung infections in CF, as well as potential oral health concerns, particularly periodontitis and dental caries.Conclusion: Overall, our study provides a first global snapshot of the oral microbiome in CF. Future studies are required to establish the relationships between the composition of the oral and lung microbiomes in CF.

The prevalence of novel periodontal pathogens and bacterial complexes in Stage II generalized periodontitis based on 16S rRNA next generation sequencing

Objective:

To define the subgingival microbial profile associated with Stage II generalized periodontitis using next-generation sequencing and to determine the relative abundance of novel periodontal pathogens and bacterial complexes.

Methodology:

Subgingival biofilm samples were collected from 80 subjects diagnosed with Stage II generalized periodontitis. Bacterial DNA was extracted, and 16S rRNA-based bacterial profiling via next-generation sequencing was carried out. The bacterial composition and diversity of microbial communities based on the age and sex of the patients were analyzed. The bacterial species were organized into groups: bacterial complexes (red, orange, purple, yellow, and green), novel periodontal pathogens, periodontal health-related species, and unclassified periodontal species. The results were analyzed and statistically evaluated.

Results:

The highest number of bacteria belonged to the phylum Bacteroidetes and Firmicutes. In terms of relative abundance, the orange complex represented 18.99%, novel bacterial species (Fretibacterium spp. and Saccharibacteria spp.) comprised 17.34%, periodontal health-related species accounted for 16.75% and unclassified periodontal species represented (Leptotrichia spp. and Selenomonas spp.) 15.61%. Novel periodontal pathogens had outweighed the periodontal disease-related red complex (5.3%). The one-sample z-test performed was statistically significant at p<0.05. The Beta diversity based on the unweighted UniFrac distance at the species level demonstrated a total variance of 15.77% based on age and 39.19% on sex, which was not statistically significant.

Conclusion:

The bacterial species corresponding to the disease-related orange complex and novel periodontal pathogens are predominant in Stage II generalized periodontitis.

Molecular subgroup of periodontitis revealed by integrated analysis of the microbiome and metabolome in a cross-sectional observational study

Background: Periodontitis (PT) is a multifactorial, chronic inflammatory disease that can have heterogeneous clinical presentations. The oral microbiome and its metabolites have been implicated as the causes and regulators of PT pathogenesis. In this study, we assessed the oral microbiome and its metabolome in PT patients to clarify the interactions between the microbiome and its metabolites.Methods: A total of 112 subjects were recruited. Buccal and supragingival samples were collected for microbiome analysis. Saliva samples were collected for metabolomic analyses. Microbiome and metabolome data were analyzed and further integrated for combined analysis using various bioinformatics approaches.Results: Oral metabolomic analysis identified 28 metabolites distinguishing the healthy (H) and PT groups. PT group were further clustered into two subgroups (PT_G1 and PT_G2) depending on metabolite profiles. Oral microbiome analysis revealed discriminatory bacterial species in the H, PT_G1, and PT_G2 microbiota. Interestingly, PT_G2 had significantly higher concentration of short chain fatty acids and higher abundance of pathogenic bacteria. Integrated analysis of the microbiome and metabolome showed close association.Conclusion: Our results provide evidence of a close interplay between the oral microbiome and metabolome. Multi-omics approach including microbiome and microbe-associated metabolites may serve as diagnostic biomarkers and enhance treatment prediction in periodontal disease.

Isolation and Description of Catonella massiliensis sp. nov., a Novel Catonella Species, Isolated from a Stable Periodontitis Subject

The genus Catonella currently counts a unique species, C. morbi, isolated from periodontal pockets and associated with periodontitis and endodontic infections. This study contributed to the taxonomical and clinical knowledge of this genus by describing a novel species isolated from a saliva sample from a man in clinical gingival health following successful treatment of periodontitis. Morphological and chemotaxonomic characteristics were investigated using different growth conditions, pH, and temperature. Cellular fatty acid methyl ester (FAME) analysis was conducted by gas chromatography/mass spectrometry (GC/MS). Phylogenetic analysis based on 16S rRNA, orthologous average nucleotide identity (OrthoANI), and digital DNA-DNA hybridization (dDDH) relatedness were performed. Strain Marseille-Q4567^T was found to be an anaerobic and non-spore-forming rod-shaped bacterium that grew at 28–41.5 °C (optimum 37 °C), pH 6.5–8.5 (optimum pH 7.5), and 5–10 g/L of NaCl (optimum 5 g/L). The predominant cellular fatty acid was C16:0 (64.2%), followed by unsaturated structures C18:1n9 (12.5%) and C18:2n6 (7.8%). Based on 16S rRNA sequence comparison, the closest phylogenetic neighbor was C. morbi ATCC 51271^T (98.23% similarity). The OrthoANI and dDDH values between strain Q4567^T and C. morbi ATCC 51271^T were respectively 79.43% and 23.8%. Therefore, we concluded that strain Marseille-Q4567^T represents a novel species of the genus Catonella, for which the name Catonella massiliensis sp. nov. is proposed (= CSUR Q4567).

Combination effect of laser diode for photodynamic therapy with doxycycline on a wistar rat model of periodontitis

Background

Periodontitis is a chronic inflammatory disease characterized by progressive damage on the structure of tooth-supporting tissues. The aim of the study is determining the combination photodynamic effect of diode laser 405 nm treatments and the administration of doxycycline 0.1% within 1, 3, 5, and 7 days on a Wistar rat model of periodontitis.

Methods

Samples were induced with Porphyromonas gingivalis ATCC33277 to allow periodontitis development and were treated with combination of doxycycline and laser diode, then statistical analysis was carried out (One-Way ANOVA test and the post-hoc Duncan test; Kruskal–Wallis test and Mann–Whitney follow-up test for non-parametric data). Samples were divided into five groups, laser exposure used was 405-nm diode laser with energy density of 8 J/cm². The expression level of histomorphometric was calculated by measuring the number of macrophages, lymphocytes, fibroblasts and the distance between the CEJ-AV.

Results

The results showed that the combination treatment of doxycycline and laser exposure yielded immunomodulatory effects. The expression level of fibroblast and the distance between CEJ-AV bone showed that the combination of doxycycline and laser therapy exerted healing effect in rat models of periodontitis on day 5 and 7.

Conclusion

The combination of doxycycline 0.1% and diode laser therapy provides a healing effect in rats models of periodontitis.

Streptococci in the Subgingival Biofilm and Periodontal Therapy

Purpose: The aim of this study was to verify how the prevalence of viridans-streptococci is changed by two appointments of professional prophylaxis and after the subgingival instrumentation via scaling and root planing (SRP). Material and Methods: Samples of the subgingival biofilm were collected from 19 individuals with periodontitis receiving two appointments of professional prophylaxis and SRP before and after the treatment procedures and the presence of viridans-streptococci was analysed by microbiological cultivation. Non-parametric statistical testing using Friedman/Wilcoxon tests and chi-square testing was used for statistical analysis. Results: No statistically significant changes over time were found for the mutans-group. The prevalence of Streptococcus mitis decreased after two appointments of professional prophylaxis (p = 0.013). The prevalence of S. mitis decreased again after SRP (p <0.001). The prevalence of Streptococcus anginosus decreased after two appointments of professional prophylaxis (p = 0.002). After SRP five positive results for S. anginosus were detected (p = 0.026). For Streptococcus oralis and Streptococcus gordonii tendencies to statistical significance were found. The number of positive results for S. oralis increased after the first appointment of professional oral prophylaxis (p = 0.055). The number of positive results for S. gordonii increased after the first appointment of professional oral prophylaxis (p = 0.055). Conclusion: The step-wise periodontal therapy influences the prevalence of viridans-streptococci, especially S. mitis and S. anginosus. No tremendous increase of streptococci especially related to the carious process occurs in the subgingival biofilm. Clinical Relevance: The study reveals knowledge on changes of the composition of the subgingival biofilm due to different steps of periodontal therapy.

Subgingival microbiota in overweight and obese young adults with no destructive periodontal disease

BACKGROUND

This study analyzed the levels of a specific group of periodontal health/disease-related oral bacteria in the subgingival biofilm of young adults with overweight (OW) and obesity (OB), and no destructive periodontal disease.

METHODS

Full-mouth periodontal assessment and subgingival biofilm sampling were performed in individuals with normal weight (NW) (BMI [body mass index] ≥18.5 to ≤24.9 kg/m² ; n = 29), OW (BMI ≥25 to ≤29.9 kg/m² ; n = 26), or OB (BMI ≥30 kg/m² ; n = 22). BMI, waist (WC) and hip (HC) circumferences, and waist-hip ratio (WHR) were established for every individual. Biofilm samples were analyzed by checkerboard. Spearman coefficient, linear, and logistic regression analyses were obtained.

RESULTS

Gingivitis was detected in 45% NW, 65% OW, and 73% OB individuals. NW patients presented significantly less calculus and supragingival biofilm than OB. OW, and OB individuals had significantly higher levels of Porphyromonas gingivalis and Tannerella forsythia than NW patients (P <0.05). Treponema denticola correlated with BMI (rho = 0.31), WC (rho = 0.28), and HC (rho = 0.29), P≤0.01. Linear regression analysis showed significant (P <0.05) positive associations between BMI, WC, HC, and WHR indicators and Prevotella spp., Lactobacillus spp., V. parvula, and A. actinomycetemcomitans (Aa); negative associations were found between Capnocytophaga spp., WC, and HC (β = -0.29 and β = -0.37, respectively; P <0.01). However, the interaction of Prevotella spp. and T. forsythia decreased the likelihood of an individual to be diagnosed as OW/OB (OR 0.183 [95% CI, 0.062-0.540]).

CONCLUSIONS

Few periodontal pathogens differed in levels between NW and OW/OB individuals without destructive periodontal disease. Moreover, Aa, T. denticola, and Prevotella spp. were associated with clinical parameters of obesity.

Oral microbiome in down syndrome and its implications on oral health

Introduction: The oral cavity harbors an abundant and diverse microbial community (i.e. the microbiome), whose composition and roles in health and disease have been the focus of intense research. Down syndrome (DS) is associated with particular characteristics in the oral cavity, and with a lower incidence of caries and higher incidence of periodontitis and gingivitis compared to control populations. However, the overall composition of the oral microbiome in DS and how it varies with diverse factors like host age or the pH within the mouth are still poorly understood. Methods: Using a Citizen-Science approach in collaboration with DS associations in Spain, we performed 16S rRNA metabarcoding and high-throughput sequencing, combined with culture and proteomics-based identification of fungi to survey the bacterial and fungal oral microbiome in 27 DS persons (age range 7–55) and control samples matched by geographical distribution, age range, and gender.

Results: We found that DS is associated with low salivary pH and less diverse oral microbiomes, which were characterized by lower levels of Alloprevotella, Atopobium, Candidatus Saccharimonas, and higher amounts of Kingella, Staphylococcus, Gemella, Cardiobacterium, Rothia, Actinobacillus, and greater prevalence of Candida.

Conclusion: Altogether, our study provides a first global snapshot of the oral microbiome in DS. Future studies are required to establish whether the observed differences are related to differential pathology in the oral cavity in DS.

Understanding the microbial components of periodontal diseases and periodontal treatment-induced microbiological shifts

In the mid-1960s the microbial aetiology of periodontal diseases was introduced based on classical experimental gingivitis studies . Since then, numerous studies have addressed the fundamental role that oral microbiota plays in the initiation and progression of periodontal diseases. Recent advances in laboratory identification techniques have contributed to a better understanding of the complexity of the oral microbiome in both health and disease. Modern culture-independent methods such as human oral microbial identification microarray and next-generation sequencing have been used to identify a wide variety of microbial taxa residing in the gingival sulcus and the periodontal pocket. The first theory of the 'non-specific plaque' hypothesis gave rise to the 'ecological plaque' hypothesis and more recently to the 'polymicrobial synergy and dysbiosis hypothesis'. Periodontitis is now considered to be a multimicrobial inflammatory disease in which the various bacterial species within the dental biofilm are in a dysbiotic state and this imbalance favours the establishment of chronic inflammatory conditions and ultimately the destruction of tooth-supporting tissues. Apart from the known putative periodontal pathogens, the whole biofilm community is now considered to play a role in the establishment of inflammation and the initiation and progression of periodontitis in a susceptible host. Treatment is unlikely to eliminate putative pathogens but, when it is thoroughly performed it has the potential to establish a healthy ecosystem by altering the microbial community in numbers and composition and also contribute to the maturation of the host immune response.

Dysbiosis of Oral Microbiota Associated with Palmoplantar Pustulosis

BACKGROUND

Dysbiosis of oral microbiota is implicated not only in oral inflammatory lesions, but also in a variety of extraoral diseases. The etiology of palmoplantar pustulosis (PPP) remains unclear; however, it has been suggested that chronic inflammation caused by periodontopathic bacterial infection may play a role.

OBJECTIVES/METHODS

To determine whether patients with PPP have altered diversity and composition of oral microbiota, we conducted the 16S rDNA analysis using saliva samples collected from 21 outpatients with PPP and 10 healthy individuals.

RESULTS

We found that the proportion of bacteria in the phylum Proteobacteria was significantly lower in PPP patients (p = 0.025). At the genus level, patients with PPP had a significantly lower abundance of Neisseria (p = 0.014), which best accounted for the observed decrease in Proteobacteria. We also identified multiple minor genera and species that were represented at a significantly higher level in the PPP group, several of which have been associated with periodontal diseases.

CONCLUSION

Our results suggest a possible link between PPP and dysbiosis of oral microbiota, particularly the lower abundance of Neisseria, the most predominant genus of Proteobacteria in healthy oral microbiota. Probiotics that improves oral dysbiosis may be beneficial for patients with PPP as an adjunctive therapy.

Antibiotic Resistance of Human Periodontal Pathogen Parvimonas micra Over 10 Years

Changes were evaluated over 10 years in the in vitro resistance of human periodontopathic strains of Parvimonas micra to four antibiotics. Subgingival biofilms culture positive for P. micra from 300 United States adults with severe periodontitis in 2006, and from a similar group of 300 patients in 2016, were plated onto anaerobically incubated enriched Brucella blood agar alone, or supplemented with either doxycycline (4 mg/L), clindamycin (4 mg/L), amoxicillin (8 mg/L), or metronidazole (16 mg/L). P. micra growth on antibiotic-supplemented media indicated in vitro resistance to the evaluated antibiotic concentration. P. micra resistance was significantly more frequent among patients in 2016, as compared to 2006, for doxycycline (11.3% vs. 0.3% patients; 37.7-fold increase), and clindamycin (47.3% vs. 2.0% patients; 23.7-fold increase) (both p < 0.001), whereas resistance to amoxicillin (2.3% vs. 1.0% patients) and metronidazole (0% vs. 0.3% patients) remained low and statistically unchanged between the two patient groups (p-values > 0.05). No P. micra isolates in 2006 or 2016 were jointly resistant in vitro to both amoxicillin and metronidazole. The alarming increases in subgingival P. micra resistance to doxycycline and clindamycin raise serious questions about the empiric use of these antibiotics, either locally or systemically, in the treatment of United States periodontitis patients harboring subgingival P. micra.

Microbiome changes in young periodontitis patients treated with adjunctive metronidazole and amoxicillin

BACKGROUND

To our knowledge, to date, no studies have comprehensively assessed the changes occurring in the subgingival microbiome of young patients with periodontitis treated by means of mechanical and antibiotic therapy. Thus, this study aimed to use next-generation sequencing to evaluate the subgingival microbial composition of young patients with severe periodontitis treated with scaling and root planing and systemic metronidazole and amoxicillin.

METHODS

Subgingival samples from healthy individuals and shallow and deep sites from periodontitis patients were individually collected at baseline and 90 days post-treatment. The samples were analyzed using 16S rRNA-gene sequencing (MiSeq-Illumina) and QIIME pipeline. Differences between groups for the microbiological data were determined using principal coordinate analysis (PCoA), linear mixed models, and the PERMANOVA test.

RESULTS

One hundred samples were collected from 10 periodontitis patients and seven healthy individuals. PCoA analysis revealed significant partitioning between pre-and post-treatment samples. No major differences in the composition of the subgingival microbiota were observed between shallow and deep sites, at baseline or at 90-days post-treatment, and the microbiome of both site categories after treatment moved closer in similarity to that observed in periodontal health. Treatment significantly improved all clinical parameters and reduced the relative abundance of classical periodontal pathogens and of Fretibacterium fastidiosum, Eubacterium saphenum, Porphyromonas endodontalis, Treponema medium, Synergistetes, TM7, and Treponema spp, and increased that of Actinomyces, Rothia, Haemophilus, Corynebacterium, and Streptococci spp.

CONCLUSION

Mechanical treatment associated with metronidazole and amoxicillin promoted a beneficial change in the microbiome of young individuals with severe periodontitis.

An injectable hydrogel-formulated inhibitor of prolyl-4-hydroxylase promotes T regulatory cell recruitment and enhances alveolar bone regeneration during resolution of experimental periodontitis

The hypoxia-inducible factor 1α (HIF-1α) is critically involved in tissue regeneration. Hence, the pharmacological prevention of HIF-1α degradation by prolyl hydroxylase (PHD) under normoxic conditions is emerging as a promising option in regenerative medicine. Using a mouse model of ligature-induced periodontitis and resolution, we tested the ability of an injectable hydrogel-formulated PHD inhibitor, 1,4-dihydrophenonthrolin-4-one-3-carboxylic acid (1,4-DPCA/hydrogel), to promote regeneration of alveolar bone lost owing to experimental periodontitis. Mice injected subcutaneously with 1,4-DPCA/hydrogel at the onset of periodontitis resolution displayed significantly increased gingival HIF-1α protein levels and bone regeneration, as compared to mice treated with vehicle control. The 1,4-DPCA/hydrogel-induced increase in bone regeneration was associated with elevated expression of osteogenic genes, decreased expression of pro-inflammatory cytokine genes, and increased abundance of FOXP3⁺ T regulatory (Treg) cells in the periodontal tissue. The enhancing effect of 1,4-DPCA/hydrogel on Treg cell accumulation and bone regeneration was reversed by AMD3100, an antagonist of the chemokine receptor CXCR4 that mediates Treg cell recruitment. In conclusion, the administration of 1,4-DPCA/hydrogel at the onset of periodontitis resolution promotes CXCR4-dependent accumulation of Treg cells and alveolar bone regeneration, suggesting a novel approach for regaining bone lost due to periodontitis.

Differences in the periodontal microbiome of successfully treated and persistent aggressive periodontitis

AIMS

The primary aim of this investigation was to analyse the periodontal microbiome in patients with aggressive periodontitis (AgP) following treatment.

METHODS

Sixty-six AgP patients were recalled on average 7 years after completion of active periodontal treatment and had subgingival plaque samples collected and processed for 16S rRNA gene sequencing analyses.

RESULTS

Of 66 participants, 52 showed persistent periodontal disease, while 13 participants were considered as "successfully treated AgP" (no probing pocket depths >4 mm) and 1 was fully edentulous. Genera associated with persistent generalized disease included Actinomyces, Alloprevotella, Capnocytophaga, Filifactor, Fretibacterium, Fusobacterium, Leptotrichia, Mogibacterium, Saccharibacteria [G-1], Selenomonas and Treponema. "Successfully treated" patients harboured higher proportions of Haemophilus, Rothia, and Lautropia and of Corynebacterium, Streptococcus and Peptidiphaga genera. Overall, patients with persistent generalized AgP (GAgP) revealed higher alpha diversity compared to persistent localized AgP (LAgP) and stable patients (p < .001). Beta diversity analyses revealed significant differences only between stable and persistent GAgP groups (p = .004).

CONCLUSION

Patients with persistent AgP showed a more dysbiotic subgingival biofilm than those who have been successfully treated. It remains to be established whether such differences were predisposing to disease activity or were a result of a dysbiotic change associated with disease recurrence in the presence of sub-standard supportive periodontal therapy or other patient-related factors.

Microbiology of molar-incisor hypomineralization lesions. A pilot study

Objective: An insufficient mineralization (hypomineralization) in the teeth during the maturation stage of amelogenesis cause defects in 3–44% of children. Here, we describe for the first time the microbiota associated with these defects and compared it to healthy teeth within the same subjects.

Methods: Supragingival dental plaque was sampled from healthy and affected teeth from 25 children with molar–incisor hypomineralization (MIH). Total DNA was extracted and the 16S rRNA gene was sequenced by Illumina sequencing in order to describe the bacterial composition.

Results: We detected a higher bacterial diversity in MIH samples, suggesting better bacterial adhesion or higher number of niches in those surfaces. We found the genera Catonella, Fusobacterium, Campylobacter, Tannerella, Centipeda, Streptobacillus, Alloprevotella and Selenomonas associated with hypomineralized teeth, whereas Rothia and Lautropia were associated with healthy sites.

Conclusion: The higher protein content of MIH-affected teeth could favour colonization by proteolytic microorganisms. The over-representation of bacteria associated with endodontic infections and periodontal pathologies suggests that, in addition to promote caries development, MIH could increase the risk of other oral diseases.