Subgingival microbial profiles of smokers with periodontitis

Tobacco-enhanced biofilm formation by Porphyromonas gingivalis and other oral microbes

Microbial biofilms promote pathogenesis by disguising antigens, facilitating immune evasion, providing protection against antibiotics and other antimicrobials and, generally, fostering survival and persistence. Environmental fluxes are known to influence biofilm formation and composition, with recent data suggesting that tobacco and tobacco-derived stimuli are particularly important mediators of biofilm initiation and development in vitro and determinants of polymicrobial communities in vivo. The evidence for tobacco-augmented biofilm formation by oral bacteria, tobacco-induced oral dysbiosis, tobacco-resistance strategies, and bacterial physiology is summarized herein. A general overview is provided alongside specific insights gained through studies of the model and archetypal, anaerobic, Gram-negative oral pathobiont, Porphyromonas gingivalis.

The effect of cigarette smoking on the oral microbiota in a South African population using subgingival plaque samples

Disturbances in the oral microbiota may be due to several mechanisms and factors, such as smoking. An imbalance in oral bacteria may result in changes to the innate immune system and the development of periodontal disease. This study aimed to investigate the distribution of oral microbiota in smokers and non-smokers in a South African population using subgingival plaque samples. From the 128 recruited participants, 57 were identified as smokers (serum cotinine: >15 ng/ml). Analysis of 16S rRNA gene sequencing demonstrated significant differences between the two groups with a reduced abundance of Actinobacteria in smokers. Fusobacterium and Campylobacter were found in higher abundance, while a lower abundance of Leptotrichia, Actinomyces, Corynebacterium, and Lautropia were observed. This study highlighted significant differences in the oral microbiota of smokers, indicating an abundance of anaerobic gram-negative bacteria. These findings suggest that smoking allows certain oral microorganisms to gain dominance, thereby predisposing individuals to periodontal disease development and progression.

Smoking Impacts Alzheimer's Disease Progression Through Oral Microbiota Modulation

Alzheimer's disease (AD) is an important public health challenge with a limited understanding of its pathogenesis. Smoking is a significant modifiable risk factor for AD progression, and its specific mechanism is often interpreted from a toxicological perspective. However, microbial infections also contribute to AD, with oral microbiota playing a crucial role in its progression. Notably, smoking alters the ecological structure and pathogenicity of the oral microbiota. Currently, there is no systematic review or summary of the relationship between these three factors; thus, understanding this association can help in the development of new treatments. This review summarizes the connections between smoking, AD, and oral microbiota from existing research. It also explores how smoking affects the occurrence and development of AD through oral microbiota, and examines treatments for oral microbiota that delay the progression of AD. Furthermore, this review emphasizes the potential of the oral microbiota to act as a biomarker for AD. Finally, it considers the feasibility of probiotics and oral antibacterial therapy to expand treatment methods for AD.

NOD2 contributes to Parvimonas micra-induced bone resorption in diabetic rats with experimental periodontitis

BACKGROUND

Type 2 diabetes mellitus (T2DM) may affect the oral microbial community, exacerbating periodontal inflammation; however, its pathogenic mechanisms remain unclear. As nucleotide-binding oligomerization domain 2 (NOD2) plays a crucial role in the activation during periodontitis (PD), it is hypothesized that changes in the oral microbial community due to diabetes enhance periodontal inflammation through the activation of NOD2.

METHODS

We collected subgingival plaque from 180 subjects who were categorized into two groups based on the presence or absence of T2DM. The composition of oral microbiota was detected by 16S rRNA high-throughput sequencing. In animal models of PD with or without T2DM, we assessed alveolar bone resorption by micro-computerized tomography and used immunohistochemistry to detect NOD2 expression in alveolar bone. Primary osteoblasts were cultured in osteogenic induction medium with high or normal glucose and treated with inactivated bacteria. After 24 h of inactivated bacteria intervention, the osteogenic differentiation ability was detected by alkaline phosphatase (ALP) staining, and the expressions of NOD2 and interleukin-12 (IL-6) were detected by western blot.

RESULTS

The relative abundance of Parvimonas and Filifactor in the T2DM group was increased compared to the group without T2DM. In animal models, alveolar bone mass was decreased in PD, particularly in T2DM with PD (DMPD) group, compared to controls. Immunohistochemistry revealed NOD2 in osteoblasts from the alveolar bone in both the PD group and DMPD group, especially in the DMPD group. In vitro, intervention with inactivated Parvimonas significantly reduced ALP secretion of primary osteoblasts in high glucose medium, accompanied by increased expression of NOD2 and IL-6.

CONCLUSIONS

The results suggest that T2DM leading to PD may be associated with the activation of NOD2 by Parvimonas.

Association Between `Life's Essential 8` and Periodontitis: A Cross-Sectional Study From the NHANES Database

BACKGROUND

Periodontitis is a chronic inflammatory disease, and the persistent inflammatory state it confers may lead to cardiovascular disease. Studies have shown that `Life's Essential 8 (LE8)`, an indicator of cardiovascular health, was associated with the risk of several inflammatory diseases. This study aimed to assess the association between LE8 and its subsets and the risk of periodontitis.

METHODS

Data of participants who consented to periodontitis examinations were extracted from the National Health and Nutrition Examination Surveys (NHANES) database (2009-2014). LE8 contains 4 health behaviours (diet, physical activity, nicotine exposure, sleep health) and 4 health factors (body mass index, blood lipids, blood glucose, and blood pressure) and was categorised into low (0-49), moderate (50-79), and high (80-100) levels. Covariates included demographic information, laboratory values, disease history, and medication history. Weighted univariate and multivariate logistic regression models were performed to assess the association between LE8 and periodontitis, with odds ratios (ORs) and 95% confidence intervals (CIs). Subgroup analyses based on age, gender, and cardiovascular disease (CVD) history were further assessed the association.

RESULTS

A total of 5106 adults were included, of whom 2606 (51.04%) had periodontitis. After adjustment for age, gender, race, poverty-to-income ratio, education level, marital status, drinking, CVD, nonsteroidal anti-inflammatory agents, waist circumference (WC), vitamin D, and dental floss using, a high LE8 score (odds ratio [OR], 0.48; 95% confidence interval [CI], 0.32-0.73), a higher health behaviours score (OR, 0.56; 95% CI, 0.42-0.73), and a higher health factors score (OR, 0.71; 95% CI, 0.51-0.99) were associated with a lower occurrence of periodontitis, especially in adults who were male, younger than 60 years, and without a history of CVD. Moreover, the occurrence of periodontitis decreased when scores of total LE8, health factors, and health behaviours increased every 10 scores.

CONCLUSIONS

LE8 score and its subscale scores were associated with lower odds of periodontitis. Promoting improved cardiovascular health may be beneficial to reduce the burden of periodontitis.

Effects of Sjogren's syndrome and high sugar diet on oral microbiome in patients with rampant caries: a clinical study

OBJECTIVE

The purpose of this study was to assess the composition of the oral microbial flora of adults with rampant caries in China to provide guidance for treatment.

PATIENTS AND METHODS

Sixty human salivary and supragingival plaque samples were collected. They were characterized into four groups: patients with rampant caries with Sjogren's syndrome (RC-SS) or high-sugar diet (RC-HD), common dental caries (DC), and healthy individuals (HP). The 16S rRNA V3-V4 region of the bacterial DNA was detected by Illumina sequencing. PCoA based on OTU with Bray-Curtis algorithm, the abundance of each level, LEfSe analysis, network analysis, and PICRUSt analysis were carried out between the four groups and two sample types. Clinical and demographic data were compared using analysis of variance (ANOVA) or the nonparametric Kruskal-Wallis rank-sum test, depending on the normality of the data, using GraphPad Prism 8 (P < 0.05).

RESULTS

OTU principal component analysis revealed a significant difference between healthy individuals and those with RC-SS. In the saliva of patients with rampant caries, the relative abundance of Firmicutes increased significantly at the phylum level. Further, Streptocpccus, Veillonella, Prevotella, and Dialister increased, while Neisseria and Haemophilus decreased at the genus level. Veillonella increased in the plaque samples of patients with rampant caries.

CONCLUSION

Both salivary and dental plaque composition were significantly different between healthy individuals and patients with rampant caries. This study provides a microbiological basis for exploring the etiology of rampant caries.

CLINICAL RELEVANCE

This study provides basic information on the flora of the oral cavity in adults with rampant caries in China. These findings could serve as a reference for the treatment of this disease.

Effects of e-cigarette smoking on periodontal health: A scoping review

OBJECTIVES

Use of electronic cigarettes (ECs), also known as vaping, has gained remarkable popularity globally during the last decade especially among young people. Current evidence suggests that vaping may be associated with health risks. The aim of this study is to evaluate whether vaping increases the risk for initiation and progression of periodontal disease; and to appraise the clinical changes seen in patients using e-cigarettes, and how these changes impact the management of periodontal disease.

STUDY SELECTION, DATA AND SOURCES

A comprehensive electronic search was conducted on the PubMed, Scopus and Embase databases using the following search terms: Electronic Cigarettes OR vaping OR electronic nicotine delivery systems OR e-cigarettes AND Periodontitis. The search was limited to studies published from 1st January 2012 to 31st December 2022.

RESULTS

A total of 23 clinical studies focusing on the effect of e-cigarette smoking on the periodontal clinical parameters, levels of inflammatory mediators, alteration in periodontal microflora, and response to periodontal treatment were found to be eligible for inclusion in the review. Vaping may be associated with greater clinical attachment loss (CAL) compared to non-smokers. Moreover, ECs are also associated with unfavorable effects on periodontal microbial counts, biomarkers of inflammation and oxidative stress.

CONCLUSIONS

Vaping may play a role in the initiation and progression of periodontal disease by altering the host response resulting in the release of inflammatory cytokines and periodontal microflora. Clinical studies show deleterious effects of vaping on periodontal health as well as less favourable response to periodontal treatment is observed in e-cigarette users compared to non-smokers. However, compared to cigarette smoking, the effects of vaping are less remarkable.

Impact of surface characteristics on the peri-implant microbiome in health and disease

BACKGROUND

Because little is known about the impact of implant surface modifications on the peri-implant microbiome, we aimed to examine peri-implant communities in various surface types in order to better understand the impact of these surfaces on the development of peri-implantitis (PI).

METHODS

One hundred and six systemically healthy individuals with anodized (AN), hydroxyapatite-coated (HA), or sandblasted acid-etched (SLA) implants that were >6 months in function were recruited and categorized into health (H) or PI. Peri-implant biofilm was analyzed using 16S rRNA gene sequencing and compared between health/disease and HA/SLA/AN using community-level and taxa-level metrics.

RESULTS

Healthy implants did not demonstrate significant differences in clustering, alpha- or beta-diversity based on surface modification. AN and HA surfaces displayed significant differences between health and PI (p < 0.05); however, such a clustering was not evident with SLA (p > 0.05). AN and HA surfaces also differed in the magnitude and diversity of differences between health and PI. Six species belonging to the genera Shuttleworthia, Scardovia, and Prevotella demonstrated lower abundances in AN implants with PI, and 18 species belonging to the genera Fretibacterium, Tannerella, Treponema, and Fusobacterium were elevated, while in HA implants with PI, 20 species belonging to the genera Streptococcus, Lactobacillus, Veillonella, Rothia, and family Ruminococcaceae were depleted and Peptostreptococcaceae, Atopobiaceae, Veillonellaceae, Porphyromonadaceae, Desulfobulbaceae, and order Synergistales were enriched.

CONCLUSIONS

Within the limitations of this study, we demonstrate that implant surface can differentially modify the disease-associated microbiome, suggesting that surface topography must be considered in the multi-factorial etiology of peri-implant diseases.

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.

Association of cigarette smoking with oral bacterial microbiota and cardiometabolic health in Chinese adults

The interplay among cigarette smoking status, oral microbiota, and cardiometabolic health is poorly understood. We aimed to examine the association of cigarette smoking status with oral microbiota and to assess the association of the identified microbial features with cardiometabolic risk factors in a Chinese population. This study included 587 participants within the Central China Cohort, including 111 smokers and 476 non-smokers, and their oral microbiota was profiled by 16S rRNA sequencing. Both oral microbial alpha- and beta-diversity were distinct between smokers and non-smokers (p < 0.05). With adjustment for sociodemographics, alcohol and tea drinking, tooth brushing frequency, and body mass index, the relative abundance of nine genera and 26 pathways, including the genus Megasphaera and two pathways involved in inositol degradation which have potentially adverse effects on cardiometabolic health, was significantly different between two groups (FDR q < 0.20). Multiple microbial features related to cigarette smoking were found to partly mediate the associations of cigarette smoking with serum triglycerides and C-reactive protein levels (p-mediation < 0.05). In conclusion, cigarette smoking status may have impacts on the oral microbial features, which may partially mediate the associations of cigarette smoking and cardiometabolic health.

Periodontal Disease and Smoking: Systematic Review

Introduction

Tobacco has been linked multiple times to many health implications. The relationship between periodontitis and tobacco was thoroughly investigated in this systemic review to evaluate if tobacco specifically smoking impacts the progression of periodontal through impairing vascular and immunity mediators processes.

Materials and Methods

The manual and electronic literature searches up to 2020 in the databanks of the EMBASE, MEDLINE, PUBMED, and SCOPUS were conducted. The search terms were "periodontitis," "periodontitis diseases," "smoking," "tobacco use," "tobacco," and "cigarette, pipe, and cigar." The types of studies included were restricted to the original studies and human trials. Analyses of subgroups and meta-regression were used to calculate the heterogeneity.

Results

15 papers total were considered in the review, however only 14 of them provided information that could be used in the meta-analysis. Smoking raises the incidence of periodontitis by 85% according to pooled adjusted risk ratios (risk ratio 1.845, CI (95%) =1.5, 2.2). The results of a meta-regression analysis showed that age, follow-up intervals, periodontal disease, the severity of periodontitis, criteria used to determine periodontal status, and loss to follow-up accounted for 54.2%, 10.7%, 13.5%, and 2.1% of the variation in study results.

Conclusion

Smoking has an undesirable impact on periodontal incidence and development. Therefore, when taking the history of the patients at the initial visits the information about the habit of smoking has to be thoroughly noted.

Influence of Smoking on Periodontal and Implant Therapy: A Narrative Review

BACKGROUND

smoking is considered the most modifiable risk factor for periodontal disease.

OBJECTIVE

the aim of this narrative review is to emphasize the effect of smoking on periodontal and implant therapy.

METHODS

The authors reviewed the literature reporting the clinical outcomes of smoking on periodontal surgical and nonsurgical treatment. The impact of smoking on implant therapy and sinus lifting procedures were also reviewed.

RESULTS

Periodontal and implant therapy outcomes are adversely affected by smoking. Smokers respond less favorably to periodontal therapy and periodontal flap procedures as compared to nonsmokers. Clinical outcomes for smokers are 50-75% worse than for nonsmokers. Studies reveal that smokers experience a significantly lower reduction in pocket depth compared to nonsmokers as well as less bone growth after treating infra-bony defects with guided tissue regeneration. The relative risk of implant failure is significantly higher in patients who smoke 20 cigarettes or more per day compared to nonsmokers. Additionally, smoking has also been shown to increase postoperative wound dehiscence and infection rates following sinus floor elevation. Longitudinal studies on smoke cessation have shown a reduction in bone loss and probing depths for periodontitis patients after cessation compared to those who smoke.

CONCLUSION

Smoking cessation can reduce probing depths and improve clinical attachment after nonsurgical periodontal therapy. There is insufficient evidence regarding the effect of smoking on peri-implantitis, as well as the loss of implants in the long-term.

Adiposity is associated with expansion of the genus Dialister in rheumatoid arthritis patients

OBJECTIVE

To analyze the intestinal microbiota of patients with rheumatoid arthritis (RA) and obesity and a higher percentage of fatty tissue.

METHODS

Nested case-control study of 80 RA patients and 80 age and sex-matched controls. Obesity was defined as a body mass index ≥ 30, and body composition using dual-energy x-ray absorptiometry. The gut microbiota was analyzed using 16 S rRNA gene sequencing; bioinformatics analysis was performed using QIIME2 and PICRUSt. Other variables included averaged 28-joint Disease Activity Score (DAS28-ESR), cytokines and adipokines. Two multivariate were constructed with obesity and fat mass index (FMI).

RESULTS

Obesity was more frequent in RA patients than in controls (36.3 % vs 25.1 %; p = 0.026), as was a higher FMI value (mean [SE]=11.6 [3.9] vs 10.2 [3.9]; p = 0.032). Alpha and beta diversity analysis revealed differences in gut microbiota between RA patients with and without obesity. Dialister and Odoribacter were more abundant in RA patients with obesity than in RA patients without obesity, while the genus Clostridium was more abundant in RA patients without obesity. The factors associated with obesity in RA patients were age (OR [95 % CI], 1.09 [1.02-1.17]), mean DAS28-ESR (OR [95 % CI], 1.46 [1.12-1.67]), leptin levels (OR [95 % CI], 1.06 [1.01-1.10]), the genus Dialister (OR [95 % CI], 1.03 [1.01-1.07]), and the genus Clostridium (OR [95 % CI], 0.013 [0.00-0.36]). The associations observed for FMI were similar.

CONCLUSIONS

In patients with RA, obesity, and a higher percentage of fatty tissue, intestinal microbiota differed from that of controls and of the other patients. The genus Dialister was associated with obesity and FMI.

Differential oral microbiome in nonhuman primates from periodontitis-susceptible and periodontitis-resistant matrilines

Rhesus monkeys (n = 36) exhibiting a healthy periodontium at baseline were used to induce progressing periodontitis through ligature placement around premolar/molar teeth. Bacterial samples were collected at baseline, 0.5, 1, and 3 months of disease and at 5 months for disease resolution. The animals were distributed into two groups (18/group): 3-7 years (young) and 12-23 years (adult) and stratified based upon matriline susceptibility to periodontitis (PDS, susceptible; PDR, resistant). A total of 444 operational taxonomic units (OTUs) with 100 microbes representing a core microbiome present in ≥75% of the samples were identified. Only 48% of the major phylotypes overlapped in the PDS and PDR samples. Different OTU abundance patterns were seen in young animals from the PDS and PDR matrilines, with qualitative similarities during disease and the relative abundance of phylotypes becoming less diverse. In adults, 23 OTUs were increased during disease in PDS samples and 24 in PDR samples; however, only five were common between these groups. Greater diversity of OTU relative abundance at baseline was observed with adult compared to young oral samples from both the PDS and PDR groups. With disease initiation (2 weeks), less diversity of relative abundance and some distinctive increases in specific OTUs were noted. By 1 month, there was considerable qualitative homogeneity in the major OTUs in both groups; however, by 3 months, there was an exacerbation of both qualitative and quantitative differences in the dominant OTUs between the PDS and PDR samples. These results support that some differences in disease expression related to matriline (familial) periodontitis risk may be explained by microbiome features.

Gut microbiota of two invasive fishes respond differently to temperature

Temperature variation structures the composition and diversity of gut microbiomes in ectothermic animals, key regulators of host physiology, with potential benefit to host or lead to converse results (i.e., negative). So, the significance of either effect may largely depend on the length of time exposed to extreme temperatures and how rapidly the gut microbiota can be altered by change in temperature. However, the temporal effects of temperature on gut microbiota have rarely been clarified. To understand this issue, we exposed two juvenile fishes (Cyprinus carpio and Micropterus salmoides), which both ranked among the 100 worst invasive alien species in the world, to increased environmental temperature and sampled of the gut microbiota at multiple time points after exposure so as to determine when differences in these communities become detectable. Further, how temperature affects the composition and function of microbiota was examined by comparing predicted metagenomic profiles of gut microbiota between treatment groups at the final time point of the experiment. The gut microbiota of C. carpio was more plastic than those of M. salmoides. Specifically, communities of C. carpio were greatly altered by increased temperature within 1 week, while communities of M. salmoides exhibit no significant changes. Further, we identified 10 predicted bacterial functional pathways in C. carpio that were temperature-dependent, while none functional pathways in M. salmoides was found to be temperature-dependent. Thus, the gut microbiota of C. carpio was more sensitive to temperature changes and their functional pathways were significantly changed after temperature treatment. These results showed the gut microbiota of the two invasive fishes differ in response to temperature change, which may indicate that they differ in colonization modes. Broadly, we have confirmed that the increased short-term fluctuations in temperatures are always expected to alter the gut microbiota of ectothermic vertebrates when facing global climate change.

The Effects of Smoking on Human Pharynx Microbiota Composition and Stability

The oral microbiota is essential to the health of the host, yet little is known about how it responds to disturbances. We examined the oropharyngeal microbiota of 30 individuals over 40 weeks. As the oropharynx is an important gateway to pathogens, and as smoking is associated with increased incidence and severity of respiratory infections, we compared the microbiota of smokers and nonsmokers to shed light on its potential for facilitating infections. We hypothesized that decreased species diversity, decreased community stability, or increased differences in community structure could facilitate invading pathogens. We found that smoking is associated with reduced alpha diversity, greater differences in community structure, and increased environmental filtering. The effects of short-term perturbations (antibiotic use and participants exhibiting cold symptoms) were also investigated. Antibiotic use had a negative effect on alpha diversity, irrespective of smoking status, and both antibiotic use and cold symptoms were associated with highly unique bacterial communities. A stability analysis of models built from the data indicated that there were no differences in local or global stability in the microbial communities of smokers, compared to nonsmokers, and that their microbiota are equally resistant to species invasions. Results from these models suggest that smoker microbiota are perturbed but characterized by alternative stable states that are as stable and invasion-resistant as are the microbiota of nonsmokers. Smoking is unlikely to increase the risk of infectious disease through the altered composition and ecological function of the microbiota; this is more likely due to the effects of smoking on the local and systemic immune system. IMPORTANCE Smoking is associated with an increased risk of respiratory infections. Hypothetically, the altered community diversity of smokers' pharyngeal microbiota, together with changes in their ecological stability properties, could facilitate their invasion by pathogens. To address this question, we analyzed longitudinal microbiota data of baseline healthy individuals who were either smokers or nonsmokers. While the results indicate reduced biodiversity and increased species turnover in the smokers' pharyngeal microbiota, their ecological stability properties were not different from those of the microbiota of nonsmokers, implying, in ecological terms, that the smokers' microbial communities are not less resistant to invasions. Therefore, the study suggests that the increased propensity of respiratory infections that is seen in smokers is more likely associated with changes in the local and systemic immune system than with ecological changes in the microbial communities.

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.

Modifiable risk factors for the development and progression of periodontal tissue diseases

In this review, an analysis of modifiable risk factors for the development and progression of periodontal tissue diseases was carried out. The review highlights the data on the relationship of periodontal infection, tobacco smoking, diabetes mellitus, cardiovascular disease, drug-induced periodontal tissue damage, stress, and obesity with the risk of developing and progression of periodontal tissue diseases. A rather detailed analysis of the mechanisms of pathogenic influence of the microflora of the oral cavity, including in the subgingival plaque, was carried out. The mechanisms of the pathological effect of smoking on the state of periodontal tissues are described. Data on the effect of periodontal treatment on glycemic control in patients with diabetes mellitus are presented. The article emphasizes the importance of the presence of periodontal diseases as a risk factor for cardiovascular and cerebrovascular diseases, describes the mechanisms of the mutual influence of cardiovascular pathology and the inflammatory process in the periodontium. In addition, the article presents the possibilities of the iatrogenic effect of systemic drugs on the state of periodontal tissues. The data on the influence of stress loads on the development of dental diseases are presented. The review article describes in detail the mechanisms of influence of overweight and obesity on the risks of development and progression of periodontal tissue diseases. Based on the results of the scientific research publications presented in the article, it can be stated that not only the dentist, but also doctors of other specialties need to work to change the modifiable risk factors for the development and progression of periodontal diseases.

Smoking-induced microbial dysbiosis in health and disease

Smoking is associated with an increased risk of cancer, pulmonary and cardiovascular diseases, but the precise mechanisms by which such risk is mediated remain poorly understood. Additionally, smoking can impact the oral, nasal, oropharyngeal, lung and gut microbiome composition, function, and secreted molecule repertoire. Microbiome changes induced by smoking can bear direct consequences on smoking-related illnesses. Moreover, smoking-associated dysbiosis may modulate weight gain development following smoking cessation. Here, we review the implications of cigarette smoking on microbiome community structure and function. In addition, we highlight the potential impacts of microbial dysbiosis on smoking-related diseases. We discuss challenges in studying host–microbiome interactions in the context of smoking, such as the correlations with smoking-related disease severity versus causation and mechanism. In all, understanding the microbiome’s role in the pathophysiology of smoking-related diseases may promote the development of rational therapies for smoking- and smoking cessation-related disorders, as well as assist in smoking abstinence.

The role of cigarette smoking in periodontal disease and treatment outcomes of dental implant therapy

Tobacco smoking has been implicated in periodontal pathology through various mechanisms, including perturbations of the inflammatory and host responses to putative periodontal pathogens, alterations in the subgingival microbial communities, and a compromised healing potential of the tissues leading to imbalance of tissue homeostasis. This review provides the evidence for the relationship between cigarette smoking and periodontal disease in an attempt to explain possible mechanisms of how tobacco smoking may exert its negative effects on the periodontal tissues via systemic and localized pathways. Early and more recent studies explore cigarette smoking-induced changes in periodontal clinical indices; in subgingival microbial flora by employing traditional detection methods for selected microorganisms, in addition to modern techniques such as deep sequencing and bioinformatics analyses that are able to fully characterize the microbial communities; and in inflammatory and immune responses critically appraising study limitations and differences in study protocol designs. Periodontal treatment outcomes and implant therapy outcomes are reviewed in an attempt to shed light on possible mechanisms for the inferior treatment outcome noted in smokers. The potential harmful effects of passive smoking are also reviewed, providing evidence for the advantages of smoking cessation. Quitting cigarette smoking should be recommended by the dentist, and effort should be made to inform smokers about the negative effects of smoking on the periodontal status and implant therapy outcomes.

Impact of smoking on protein levels of beta-defensins in periodontal disease

Antimicrobial peptides (AMPs) are important components of the host response against invading pathogens. In addition to their direct antimicrobial activity, they can also participate in the immune system modulation. However, the role of AMPs in the etiopathogenesis of periodontal disease and the risk factors that may influence their expression in the oral cavity are not fully understood. The aim of this study was to determine the impact of smoking on beta-defensin (hBD) 1 and 2 levels analyzing samples from periodontitis patients. Fifty patients with periodontitis, 25 smokers and 25 non-smokers, and 20 periodontally healthy patients were recruited. After periodontal clinical evaluation, gingival crevicular fluid (GCF) samples were collected from healthy sites of patients without periodontal disease and from healthy and diseased sites of patients with periodontitis. Peptides quantification was performed by sandwich ELISA technique. Smokers showed reduced GCF hBD 1 levels and increased hBD 2 levels compared to non-smokers in diseased sites (p <0.05). Higher levels of hBD 1 were observed in healthy sites of patients without periodontal disease than in healthy sites of patients with periodontitis (p<0.0001). Diseased sites of non-smokers presented higher levels of hBD 2 than healthy sites (p <0.05). These results reveal that protein levels of hBDs 1 and 2 can be impaired by cigarette smoking in the presence of periodontal disease.

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.

Microbial differences between active and remission peri-implantitis

Peri-implantitis has a polymicrobial etiology and is a major cause of dental implant loss. Various clinical protocols for its prevention and treatment have been proposed; however, some cases show a rapid progression with non-resolving clinical symptoms. To clear a means of differentiating between such cases, the implants with peri-implantitis in this study were categorized as the active group and the remission group and that two kinds of samples were obtained from the same subjects (n = 20). The microbiome was analyzed through pyrosequencing of the 16S rRNA gene. From LEfSe results, Porphyomonas, Fusobacterium, Treponema, Tannerella, and other periodontal pathogens were abundant in the active group, while lactic acid bacteria (Lactobacillales and Bifidobacterium) were abundant in the remission group.

A Tale of Two Fimbriae: How Invasion of Dendritic Cells by Porphyromonas gingivalis Disrupts DC Maturation and Depolarizes the T-Cell-Mediated Immune Response

Porphyromonas gingivalis (P. gingivalis) is a unique pathogen implicated in severe forms of periodontitis (PD), a disease that affects around 50% of the US population. P. gingivalis is equipped with a plethora of virulence factors that it uses to exploit its environment and survive. These include distinct fimbrial adhesins that enable it to bind to other microbes, colonize inflamed tissues, acquire nutrients, and invade cells of the stroma and immune system. Most notable for this review is its ability to invade dendritic cells (DCs), which bridge the innate and adaptive immune systems. This invasion process is tightly linked to the bridging functions of resultant DCs, in that it can disable (or stimulate) the maturation function of DCs and cytokines that are secreted. Maturation molecules (e.g., MHCII, CD80/CD86, CD40) and inflammatory cytokines (e.g., IL-1b, TNFa, IL-6) are essential signals for antigen presentation and for proliferation of effector T-cells such as Th17 cells. In this regard, the ability of P. gingivalis to coordinately regulate its expression of major (fimA) and minor (mfa-1) fimbriae under different environmental influences becomes highly relevant. This review will, therefore, focus on the immunoregulatory role of P. gingivalis fimbriae in the invasion of DCs, intracellular signaling, and functional outcomes such as alveolar bone loss and immune senescence.

Electronic Cigarette Use Promotes a Unique Periodontal Microbiome

Electronic cigarettes (e-cigs) have become prevalent as an alternative to conventional cigarette smoking, particularly in youth. E-cig aerosols contain unique chemicals which alter the oral microbiome and promote dysbiosis in ways we are just beginning to investigate. We conducted a 6-month longitudinal study involving 84 subjects who were either e-cig users, conventional smokers, or nonsmokers. Periodontal condition, cytokine levels, and subgingival microbial community composition were assessed, with periodontal, clinical, and cytokine measures reflecting cohort habit and positively correlating with pathogenic taxa (e.g., Treponema, Saccharibacteria, and Porphyromonas). α-Diversity increased similarly across cohorts longitudinally, yet each cohort maintained a unique microbiome. The e-cig microbiome shared many characteristics with the microbiome of conventional smokers and some with nonsmokers, yet it maintained a unique subgingival microbial community enriched in Fusobacterium and Bacteroidales (G-2). Our data suggest that e-cig use promotes a unique periodontal microbiome, existing as a stable heterogeneous state between those of conventional smokers and nonsmokers and presenting unique oral health challenges. IMPORTANCE Electronic cigarette (e-cig) use is gaining in popularity and is often perceived as a healthier alternative to conventional smoking. Yet there is little evidence of the effects of long-term use of e-cigs on oral health. Conventional cigarette smoking is a prominent risk factor for the development of periodontitis, an oral disease affecting nearly half of adults over 30 years of age in the United States. Periodontitis is initiated through a disturbance in the microbial biofilm communities inhabiting the unique space between teeth and gingival tissues. This disturbance instigates host inflammatory and immune responses and, if left untreated, leads to tooth and bone loss and systemic diseases. We found that the e-cig user's periodontal microbiome is unique, eliciting unique host responses. Yet some similarities to the microbiomes of both conventional smokers and nonsmokers exist, with strikingly more in common with that of cigarette smokers, suggesting that there is a unique periodontal risk associated with e-cig use.

Oral Microbiome and Gingival Gene Expression of Inflammatory Biomolecules With Aging and Periodontitis

Although data describe the presence and increase of inflammatory mediators in the local environment in periodontitis vs. health in humans, details regarding how these responses evolve in the transition from health to disease, changes during disease progression, and features of a resolved lesion remain unknown. This study used a nonhuman primate model of ligature-induced periodontitis in young, adolescent, adult, and aged animals to document features of inflammatory response affected by age. Rhesus monkeys had ligatures tied and provided gingival tissue biopsy specimens at baseline, 0.5, 1, and 3 months of disease and at 5 months of the study, which was 2 months post-ligature removal for clinically resolved tissues. The transcriptome was assessed using microarrays for chemokine (n = 41), cytokine (n = 45), chemokine receptor (n = 21), cytokine receptor (n = 37), and lipid mediator (n = 31) genes. Limited differences were noted in healthy tissues for chemokine expression with age; however, chemokine receptor genes were decreased in young but elevated in aged samples. IL1A, IL36A, and IL36G cytokines were decreased in the younger groups, with IL36A elevated in aged animals. IL10RA/IL10RB cytokine receptors were altered with age. Striking variation in the lipid mediator genes in health was observed with nearly 60% of these genes altered with age. A specific repertoire of chemokine and chemokine receptor genes was affected by the disease process, predominated by changes during disease initiation. Cytokine/cytokine receptor genes were also elevated with disease initiation, albeit IL36B, IL36G, and IL36RN were all significantly decreased throughout disease and resolution. Significant changes were observed in similar lipid mediator genes with disease and resolution across the age groups. Examination of the microbiome links to the inflammatory genes demonstrated that specific microbes, including Fusobacterium, P. gingivalis, F. alocis, Pasteurellaceae, and Prevotella are most frequently significantly correlated. These correlations were generally positive in older animals and negative in younger specimens. Gene expression and microbiome patterns from baseline were distinctly different from disease and resolution. These results demonstrate patterns of inflammatory gene expression throughout the phases of the induction of a periodontal disease lesion. The patterns show a very different relationship to specific members of the oral microbiome in younger compared with older animals.

Influence of Oral Intaking Habit on Tongue Coating Microbiota in Patients with Esophageal Precancerous Lesions

Background: Esophageal cancer (EC) is a common digestive tract tumor in China, and oral intaking habit has a great influence on the development of EC. The present study explored the correlation between oral intaking habit and tongue coating (TC) microbiota in patients with esophageal precancerous lesions (EPL) to provide a reasonable interpretation of the influence of oral intaking habit on microbial alterations in the EPL. Methods: A case-control study was designed with 123 EPL patients and 176 volunteers with mild esophagitis, and they were well matched using sex, age, and body mass index. The TC microbiota was profiled using high-throughput sequencing of the V3-V4 region of the 16S rRNA gene, and the serum levels of total bile acid (TBA) and interleukin-17α (IL-17α) were measured using enzyme-linked immunosorbent assay. Alpha diversity, community structure, and linear discriminant analysis were conducted, and Spearman correlation analysis was used to build the symbiotic network. Results: No significant differences were observed in the diversity and richness of the TC microbiota between the cases and controls (P > 0.05). TC Peptostreptococcus and Capnocytophaga were enriched in EPL patients. Stratified analysis showed that TC microbial composition was affected by both EPL and oral intaking habit; for example, Atopobium and Actinomyces were positively related to oral intaking habit scores in both the cases and controls, while Simonsiella was negatively correlated with oral intaking habit status in cases but positively correlated with oral intaking habit status in controls. Although serum TBA and IL-17α were not associated with EPL (P > 0.05), the daily-drinking cases had a higher level of serum TBA than the nondrinking cases (P < 0.05), and Helicobacter pylori (Hp) negative controls had a higher level of serum TBA than the Hp-positive controls (P < 0.05). The symbiotic networks were comprised of 71 significant correlations in the controls and 52 significant correlations in the cases. Conclusions: The development of EPL changed the TC microbiota and decreased the symbiotic complexity of the TC bacteria, which were also influenced by the cancer-related oral intaking habit. Bile acid may be a key factor mediating changes in TC microbiota.

Subgingival Microbiota Profile in Association with Cigarette Smoking in Young Adults: A Cross-Sectional Study

While smoking is recognized as one of the factors for the development and progression of periodontal diseases, a relation between the composition of the subgingival microbiota and smoking is yet to be elucidated. The aim of this study was to investigate the prevalence of subgingival bacteria in young smokers and non-smokers without clinical signs of periodontal disease. In this cross-sectional study, performed at the Department of Pharmacology, School of Dental Medicine, University of Zagreb, we enrolled 32 periodontally healthy smokers and 32 non-smokers, aged 25–35 years old. The number of oral bacteria and the prevalence of particular bacteria were assessed for each subject. Subgingival plaque samples were collected with sterile paper points from two first molars for microbiological analyses with MALDI-TOF mass spectrometry. In smokers, a significantly higher prevalence of Actinomyces odontolyticus was observed compared to non-smokers, and a significantly lower prevalence of Streptococcus sanguinis was observed compared to non-smokers. Smoking affects the composition of subgingival microbiota, either via depletion of beneficial bacteria or the increase in pathogenic bacteria.

Oral Osteomicrobiology: The Role of Oral Microbiota in Alveolar Bone Homeostasis

Osteomicrobiology is a new research field in which the aim is to explore the role of microbiota in bone homeostasis. The alveolar bone is that part of the maxilla and mandible that supports the teeth. It is now evident that naturally occurring alveolar bone loss is considerably stunted in germ-free mice compared with specific-pathogen-free mice. Recently, the roles of oral microbiota in modulating host defense systems and alveolar bone homeostasis have attracted increasing attention. Moreover, the mechanistic understanding of oral microbiota in mediating alveolar bone remodeling processes is undergoing rapid progress due to the advancement in technology. In this review, to provide insight into the role of oral microbiota in alveolar bone homeostasis, we introduced the term “oral osteomicrobiology.” We discussed regulation of alveolar bone development and bone loss by oral microbiota under physiological and pathological conditions. We also focused on the signaling pathways involved in oral osteomicrobiology and discussed the bridging role of osteoimmunity and influencing factors in this process. Finally, the critical techniques for osteomicrobiological investigations were introduced.

Periodontal risk assessment in a teaching hospital population in Saudi Arabia's Eastern Province

OBJECTIVE

With this cross-sectional study, we aimed to evaluate factors associated with moderate and high risk of periodontal disease (PD) progression in the Saudi population.

METHODS

We reviewed 281 patients' clinical charts from predoctoral periodontal clinics at the dental teaching hospital in the College of Dentistry (COD) at Imam Abdulrahman Bin Faisal University (IAU) in Dammam, Saudi Arabia. After obtaining ethical approval, we determined the Periodontal Risk Assessment (PRA) of the included patients based on the modified criteria developed by Lang and Tonetti (2003). We used logistic regression on stratified data and divided the results into two categories (low-moderate and high risk) to assess the effect modifier for potential risk factors. We used SPSS version 22 for data analysis, and considered a P-value ≤ 0.05 to be statistically significant.

RESULTS

Out of the 281 patients, 104 (37.0%) were male and 177 (63.0%) were female, with a mean age of 39.9 ± 14.0 years; 78.1% were Saudi nationals, 77% were married, and 44.6% were in the age group of 30 to 49. The PRA revealed 86 (30.5%) to represent high risk, 108 (38.3%) denoted moderate risk, and 88 (31.2%) signaled low risk for periodontitis. Logistic regression analysis showed that males were three times more likely to have high PRA (OR = 3.24) and to be married (OR = 2.77), as well as to be active smokers (OR = 8.87). The highest predictive factors of high PRA were 8 or more pockets ≥ 5 mm (OR = 29.0), those with active diabetes mellitus (DM; OR = 10.2), and those with 8 or more missing teeth (OR = 9.15).

CONCLUSION

Saudi males who are married and have residual periodontal pockets, are actively diabetic, and with missing teeth are at high risk of PD. Further research is needed with a larger sample size comparing the general population with and without PD.

Tobacco Use and Oral Health

This review outlines the important oral implications of tobacco use. The lining of the mouth (oral mucosa), if exposed to tobacco and its products in a susceptible individual, can develop benign, potentially malignant, and malignant tumours. Treatment and prognosis depend on tumour type, how early it is detected, its size and site in the oral cavity and whether it has spread. Advanced oral squamous cell carcinoma (OSCC) has a 20% 5-year survival rate. Tobacco use also increases the risk of periodontitis, peri-implantitis, caries, alveolar osteitis and halitosis. Although less life threatening than OSCC, these tobacco related conditions create a substantial financial and health burden for individuals and society. Dental practitioners routinely examine the oral cavity for signs of mucosal and tooth changes, are experienced in recognising variations from normal and have established management and referral pathways. They are also ideally positioned to provide brief interventions to assist their patients to quit smoking.

Altered microbiomes in thirdhand smoke-exposed children and their home environments

INTRODUCTION

Tobacco smoke contains numerous toxic chemicals that accumulate in indoor environments creating thirdhand smoke (THS). We investigated if THS-polluted homes differed in children's human and built-environment microbiomes as compared to THS-free homes.

METHODS

Participants were n = 19 THS-exposed children and n = 10 unexposed children (≤5 years) and their caregivers. Environmental and biological samples were analyzed for THS pollutants and exposure. Swab samples were collected from the built-environment (floor, table, armrest, bed frame) and child (finger, nose, mouth, and ear canal), and 16S ribosomal RNA genes were analyzed for bacterial taxa using high-throughput DNA sequencing.

RESULTS

Phylogenetic α-diversity was significantly higher for the built-environment microbiomes in THS-polluted homes compared to THS-free homes (p < 0.014). Log2-fold comparison found differences between THS-polluted and THS-free homes for specific genera in samples from the built-environment (e.g., Acinetobacter, Bradyrhizobium, Corynebacterium, Gemella, Neisseria, Staphylococcus, Streptococcus, and Veillonella) and in samples from children (esp. Corynebacterium, Gemella, Lautropia, Neisseria, Rothia, Staphylococcus, and Veillonella).

CONCLUSION

When exposed to THS, indoor and children microbiomes are altered in an environment-specific manner. Changes are similar to those reported in previous studies for smokers and secondhand smoke-exposed persons. THS-induced changes in child and built-environmental microbiomes may play a role in clinical outcomes in children.

IMPACT

Despite smoking bans, children can be exposed to tobacco smoke residue (i.e., thirdhand smoke) that lingers on surfaces and in settled house dust. Thirdhand smoke exposure is associated with changes in the microbiomes of the home environment and of the children living in these homes. Thirdhand smoke is associated with increased phylogenetic diversity of the home environment and changes in the abundances of several genera of the child microbiome known to be affected by active smoking and secondhand smoke (e.g., Corynebacterium, Staphylococcus, Streptococcus). Thirdhand smoke exposure by itself may induce alterations in the microbiome that play a role in childhood pathologies.

Gut microbiota changes in patients with spondyloarthritis: A systematic review

OBJECTIVE

Gut microbiota has been proposed as a pivotal role in the progression of Spondyloarthritis (SpA), however diverse results remain to be synthesized. We performed a systematic review to collect evidence on the characteristic of the gut microbiota in patients with SpA, as compared to controls.

METHODS

We systematically searched MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials databases, through June 1, 2021 for studies that compared gut microbiota of cases with SpA versus healthy controls.

RESULTS

Of 3756 records identified, 28 studies from 23 articles were included in the analysis. Results of β-diversity showed SpA patients hold a significantly different microbial composition compared with controls. Several taxa-level differences of gut microbiota between SpA (and its subtypes) cases and controls were identified. Fourteen studies including only patients with ankylosing spondylitis (AS) reported increased amounts of Actinobacteria, Dialister, Streptococcus, and Clostridium bolteae, and decreased amounts of Bacteroidales and Parasutterella in AS cases versus controls in ≥ 3 studies. Dialister invisus was increased in axial-SpA cases versus controls in 3 studies. Bacteroides fragilis was increased in enthesitis-related arthritis (ERA) cases versus controls in 2 studies. For all SpA studies, Proteobacteria, Enterobacteriaceae, and Bacteroidaceae were increased, whereas Bacteroidetes, Bacteroidales, and Akkermansia were decreased in cases versus controls in ≥ 3 studies. Over 40% of the studies showed comparable data of both sex and age between cases and controls.

CONCLUSION

The microbial characteristics of SpA summarized in the systematic review laid the groundwork for evidence-based microbial treatment. The microbial variance among subtypes of SpA remains to be explored. Further studies are needed to elucidate how the altered microbiota participate in the pathogenesis of SpA.

Cigarette Smoking and Opium Use in Relation to the Oral Microbiota in Iran

Cigarettes and opium contain chemicals and particulate matter that may modify the oral microbiota. This study aimed to investigate the association between cigarette and opium use with the oral microbiota. A total of 558 participants were recruited from Iran between 2011 and 2015. Individuals were categorized as never cigarette nor opium users, ever cigarette-only smokers, ever opium-only users, and ever both cigarette and opium users. Participants provided saliva samples for 16S rRNA gene sequencing. Logistic regression, microbiome regression-based kernel association test (MiRKAT), and zero-inflated beta regression models were calculated. For every increase in 10 observed amplicon sequence variants (ASVs), the odds for being a cigarette-only smoker, opium-only user, and both user compared to never users decreased by 9% (odds ratio [OR] = 0.91; 95% confidence interval [95% CI] = 0.86 to 0.97), 13% (OR = 0.87; 95% CI = 0.75 to 1.01), and 12% (OR = 0.88; 95% CI = 0.80 to 0.96), respectively. The microbial communities differed by cigarette and opium use as indicated by MiRKAT models testing the three beta-diversity matrices (P < 0.05 for all). Three genera were less likely and one genus was more likely to be detected in cigarette-only smokers or opium-only users than in never users. The relative abundance of the phylum Actinobacteria (never, 14.78%; both, 21.20%) was higher and the phyla Bacteroidetes (never, 17.63%; both, 11.62%) and Proteobacteria (never, 9.06%; both, 3.70%) were lower in users of both cigarettes and opium, while the phylum Firmicutes (never, 54.29%; opium, 65.49%) was higher in opium-only users. Cigarette and opium use was associated with lower alpha-diversity, overall oral microbiota community composition, and both the presence and relative abundance of multiple taxa. IMPORTANCE Cigarette smoking and opium use are associated with periodontal disease caused by specific bacteria such as Porphyromonas gingivalis, which suggests a link between cigarette smoking and opium use and the oral microbiota. Alterations of the oral microbiota in cigarette smokers compared to nonsmokers have been reported, but this has not been studied across diverse populations. Additionally, the association of opium use with the oral microbiota has not been investigated to date. We conducted this study to investigate differences in the oral microbiota between ever users of cigarettes only, opium only, and both cigarettes and opium and never users of cigarettes and opium in Iran. Lower alpha-diversity, distinct overall oral microbial communities, and the presence and relative abundance of multiple taxa have been found for users of cigarettes and/or opium.

The Impact of Smoking on Subgingival Plaque and the Development of Periodontitis: A Literature Review

Smoking seriously affects oral health and causes a variety of oral diseases. Numerous clinical data show that smoking significantly increases the risk of periodontitis, and the duration and amount of smoking are positively correlated with the severity of periodontitis. In fact, smoking creates an environment conducive to the colonization of periodontopathogens, which affects the process of periodontitis. Since subgingival plaque which harbors periodontopathogens is the initiation factor of periodontitis, it is critical to study the impact of smoking on subgingival microbiota for understanding the relationship between smoking and periodontitis. Continuous advances have been made on the understanding of effects of smoking on subgingival plaque and the development of periodontitis. Smoking is observed to enhance the pathogenicity of periodontopathogens, especially the red complex microorganisms, via promoting their colonization and infection, and regulating the expression and function of multiple virulence factors. Furthermore, smoking has a negative impact on periodontal microecological homeostasis, which is reflected in the decrease of commensal bacteria and the increase of periodontopathogens, as well as the changes in the interaction between periodontopathogens and their commensal microbes in subgingival biofilm, thus influencing the pathogenicity of the subgingival plaque. In summary, the mechanism of smoking on subgingival plaque microorganisms represented by the red complex and its effect on the periodontal microecology still need to be further explored. The relevant research results are of great significance for guiding the periodontal clinical treatment of smoking population. This review summarizes the effects and relevant mechanisms of smoking on subgingival plaque and the development of periodontitis.

Context-dependent effects of glucocorticoids on the lizard gut microbiome

The vertebrate gut microbiota (bacterial, archaeal and fungal communities of the gastrointestinal tract) can have profound effects on the physiological processes of their hosts. Although relatively stable, changes in microbiome structure and composition occur due to changes in the environment, including exposure to stressors and associated increases in glucocorticoid hormones. Although a growing number of studies have linked stressor exposure to microbiome changes, few studies have experimentally explored the specific influence of glucocorticoids on the microbiome in wild animals, or across ecologically important processes (e.g., reproductive stages). Here we tested the response of the gut microbiota of adult female Sceloporus undulatus across gestation to ecologically relevant elevations of a stress-relevant glucocorticoid hormone (CORT) in order to determine (i) how experimentally elevated CORT influenced microbiome characteristics, and (ii) whether this relationship was dependent on reproductive context (i.e., whether females were gravid or not, and, in those that were gravid, gestational stage). We show that the effects of CORT on gut microbiota are complex and depend on both gestational state and stage. CORT treatment altered microbial community membership and resulted in an increase in microbiome diversity in late-gestation females, and microbial community membership varied according to treatment. In nongravid females, CORT treatment decreased interindividual variation in microbial communities, but this effect was not observed in late-gestation females. Our results highlight the need for a more holistic understanding of the downstream physiological effects of glucocorticoids, as well as the importance of context (here, gestational state and stage) in interpreting stress effects in ecology.

Oral and periodontal implications of tobacco and nicotine products

Tobacco use contributes to more mortality and morbidity globally than any other behavioral risk factor. Adverse effects do not spare the oral cavity, with many oral diseases more common, and treatments less successful, in the tobacco-using patient. Many of the oral health effects of cigarette smoking are well established, but other forms of tobacco, including cigars and smokeless tobacco, merit dental professionals' attention. Recently, an expanding variety of new or emerging tobacco and/or nicotine products has been brought to market, most prominently electronic cigarettes, but also including heated tobacco and other noncombustible nicotine products. The use of cannabis (marijuana) is increasing and also has risks for oral health and dental treatment. For the practicing periodontist, and all dental professionals, providing sound patient recommendations requires knowledge of the general and oral health implications associated with this wide range of tobacco and nicotine products and cannabis. This review provides an overview of selected tobacco and nicotine products with an emphasis on their implications for periodontal disease risk and clinical management. Also presented are strategies for tobacco use counselling and cessation support that dental professionals can implement in practice.

Compositional profile of mucosal bacteriome of smokers and smokeless tobacco users

INTRODUCTION

Smoked, and especially smokeless, tobacco are major causes of oral cancer globally. Here, we examine the oral bacteriome of smokers and of smokeless tobacco users, in comparison to healthy controls, using 16S rRNA gene sequencing.

METHODS

Oral swab samples were collected from smokers, smokeless tobacco users, and healthy controls (n = 44). Microbial DNA was extracted and the 16S rRNA gene profiled using the Illumina MiSeq platform. Sequencing reads were processed using DADA2, and taxonomical classification was performed using the phylogenetic placement method. Differentially abundant taxa were identified using DESeq2, while functional metagenomes based on KEGG orthology abundance were inferred using LIMMA.

RESULTS

A significantly higher microbial diversity was observed in smokeless tobacco users and smokers relative to controls (P < 0.05). Compositional differences in microbial communities were observed in all comparisons with healthy controls (PERMANOVA P < 0.05) but not between smokers and smokeless tobacco users. Levels of Fusobacterium spp., Saccharibacterium spp., and members of Shuttleworthia were elevated in smokers when compared to controls (BH adj P < 0.01). In addition, the relative abundance of three bacterial taxa belonging to genera Fusobacterium spp., Catonella, and Fretibacterium spp. was significantly increased in smokeless tobacco users relative to controls (BH adj P < 0.01). Major functional pathways significantly increased in smokeless tobacco users relative to both controls, and smokers were similar and involved amino acid metabolism including glutamate and aspartate biosynthesis and degradation (log FC > 1.5; BH adj P < 0.01).

CONCLUSIONS

A distinct taxonomic and functional profile of oral microbiome in smokers and smokeless tobacco users as compared to healthy controls implicates a significant role of microbes and their metabolites in diseases associated with tobacco use including oral cancer.

CLINICAL RELEVANCE

Future efforts in preventive, diagnostic, curative, and prognostic strategies for diseases associated with tobacco use in smokers and smokeless tobacco users could incorporate the oral microbiome.

Association of oral microbiota with lung cancer risk in a low-income population in the Southeastern USA

PURPOSE

Oral microbiome plays an important role in oral health and systemic diseases, including cancer. We aimed to prospectively investigate the association of oral microbiome with lung cancer risk.

METHODS

We analyzed 156 incident lung cancer cases (73 European Americans and 83 African Americans) and 156 individually matched controls nested within the Southern Community Cohort Study. Oral microbiota were assessed using 16S rRNA gene sequencing in pre-diagnostic mouth rinse samples. Paired t test and the permutational multivariate analysis of variance test were used to evaluate lung cancer risk association with alpha diversity or beta diversity, respectively. Conditional logistic regression models were used to evaluate the association of individual bacterial abundance or prevalence with lung cancer risk.

RESULTS

No significant differences were observed for alpha or beta diversity between lung cancer cases and controls. Abundance of families Lachnospiraceae_[XIV], Peptostreptococcaceae_[XI], and Erysipelotrichaceae and species Parvimonas micra was associated with decreased lung cancer risk, with odds ratios (ORs) and 95% confidence intervals (CIs) of 0.76 (0.59-0.98), 0.80 (0.66-0.97), 0.81 (0.67-0.99), and 0.83 (0.71-0.98), respectively (all p < 0.05). Prevalence of five pre-defined oral pathogens were not significantly associated with overall lung cancer risk. Prevalence of genus Bacteroidetes_[G-5] and species Alloprevotella sp._oral_taxon_912, Capnocytophaga sputigena, Lactococcus lactis, Peptoniphilaceae_[G-1] sp._oral_taxon_113, Leptotrichia sp._oral_taxon_225, and Fretibacterium fastidiosum was associated with decreased lung cancer risk, with ORs and 95% CIs of 0.55 (0.30-1.00), 0.36 (0.17-0.73), 0.53 (0.31-0.92), 0.43 (0.21-0.88), 0.43 (0.19-0.94), 0.57 (0.34-0.99), and 0.54 (0.31-0.94), respectively (all p < 0.05). Species L. sp._oral_taxon_225 was significantly associated with decreased lung cancer risk in African Americans (OR [95% CIs] 0.28 [0.12-0.66]; p = 0.00012).

CONCLUSION

Results from this study suggest that oral microbiota may play a role in the development of lung cancer.

The Role of Periodontopathogens and Oral Microbiome in the Progression of Oral Cancer. A Review

Chronic periodontal disease and oral bacteria dysbiosis can lead to the accumulation of genetic mutations that eventually stimulate Oral Squamous Cell Cancer (OSCC). The annual incidence of OSCC is increasing significantly, and almost half of the cases are diagnosed in an advanced stage. Worldwide there are more than 380,000 new cases diagnosed every year, and a topic of extensive research in the last few years is the alteration of oral bacteria, their compositional changes and microbiome. This review aims to establish the relationship between bacterial dysbiosis and OSCC. Several bacteria implicated in periodontal disease, including Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, and some Streptococcus species, promote angiogenesis, cell proliferation, and alteration in the host defense process; these same bacteria have been present in different stages of OSCC. Our review showed that genes involved in bacterial chemotaxis, the lipopolysaccharide (LPS) of the cell wall membrane of gram negatives bacteria, were significantly increased in patients with OSCC. Additionally, some bacterial diversity, particularly with Firmicutes, and Actinobacteria species, has been identified in pre-cancerous stage samples. This review suggests the importance of an early diagnosis and more comprehensive periodontal therapy for patients by the dental care professional.

Dysregulation of metallothionein and zinc aggravates periodontal diseases

BACKGROUND

Periodontitis (PD) is a multifaceted inflammatory disease connected to bacterial infection that results in the destruction of tooth supporting structures and eventually tooth loss. Given their involvement in infection and inflammation, both metallothionein (MT) and zinc (Zn) might play vital roles in the development and progression of PD. More specifically, both MT and Zn are heavily involved in regulating immune functions, controlling bacterial infection, balancing inflammatory responses, and reducing oxidative stress, all of which are associated with the pathogenesis of PD.

OBJECTIVE

This review paper will explore the physiological functions of MT and Zn and hypothesise how dysregulation could negatively affect periodontal health, leading to PD.

FINDINGS

Bacterial lipopolysaccharide (LPS) derived from periodontal pathogens, namely P. gingivalis initiates the acute phase response, thus upregulating the expression of MT which leads to the subsequent deficiency of Zn, a hallmark of periodontal disease. This deficiency leads to ineffective NETosis, increases the permeability of the gingival epithelium, and disrupts the humoral immune response, collectively contributing to PD. In addition, the presence of LPS in Zn deficient conditions favours M1 macrophage polarisation and maturation of dendritic cells, and also inhibits the anti-inflammatory activity of regulatory T cells. Collectively, these observations could theoretically give rise to the chronic inflammation seen in PD.

CONCLUSION

A disrupted MT and Zn homeostasis is expected to exert an adverse impact on periodontal health and contribute to the development and progression of PD.

Sources of SARS-CoV-2 and Other Microorganisms in Dental Aerosols

On March 16, 2020, 198,000 dentists in the United States closed their doors to patients, fueled by concerns that aerosols generated during dental procedures are potential vehicles for transmission of respiratory pathogens through saliva. Our knowledge of these aerosol constituents is sparse and gleaned from case reports and poorly controlled studies. Therefore, we tracked the origins of microbiota in aerosols generated during ultrasonic scaling, implant osteotomy, and restorative procedures by combining reverse transcriptase quantitative polymerase chain reaction (to identify and quantify SARS-CoV-2) and 16S sequencing (to characterize the entire microbiome) with fine-scale enumeration and source tracking. Linear discriminant analysis of Bray-Curtis dissimilarity distances revealed significant class separation between the salivary microbiome and aerosol microbiota deposited on the operator, patient, assistant, or the environment (P < 0.01, analysis of similarities). We also discovered that 78% of the microbiota in condensate could be traced to the dental irrigant, while saliva contributed to a median of 0% of aerosol microbiota. We also identified low copy numbers of SARS-CoV-2 virus in the saliva of several asymptomatic patients but none in aerosols generated from these patients. Together, the bacterial and viral data encourage us to conclude that when infection control measures are used, such as preoperative mouth rinses and intraoral high-volume evacuation, dental treatment is not a factor in increasing the risk for transmission of SARS-CoV-2 in asymptomatic patients and that standard infection control practices are sufficiently capable of protecting personnel and patients from exposure to potential pathogens. This information is of immediate urgency, not only for safe resumption of dental treatment during the ongoing COVID-19 pandemic, but also to inform evidence-based selection of personal protection equipment and infection control practices at a time when resources are stretched and personal protection equipment needs to be prioritized.

Association between toothbrushing and non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic manifestation of metabolic syndrome. Periodontitis, as chronic inflammatory destructive disease, is associated metabolic syndromes bidirectionally. Toothbrushing is an essential and important way to manage periodontitis through mechanical removal of biofilm at periodontal tissue. We aimed to assess the association between toothbrushing frequency and the prevalent NAFLD in nationally representative Korean adults. Among adults aged 19 years and older who participated in the Korea National Health and Nutrition Examination Survey in 2010, a total of 6,352 subjects were analyzed. NAFLD was defined as fatty liver index ≥60. Multiple logistic regression analysis was used to estimate multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs). An inverse association between toothbrushing frequency and NAFLD was found. The adjusted ORs (95% CIs) of NALFD was 0.56 (0.35-0.91) in the group who performed toothbrushing ≥ 3 per day compared to the group that performed toothbrushing ≤ 1 per day. For those with toothbrushing frequency ≤1 per day, the adjusted OR (95% CIs) of NAFLD was 2.26 (1.22-4.19) in smokers and 4.52 (1.97-10.38) in subjects with diabetes mellitus (DM), compared to those without the disease and with toothbrushing frequency ≥2 per day, respectively. Our results indicate that higher frequency of toothbrushing is inversely associated with NAFLD. As a modifiable oral habit, regular toothbrushing may be recommended to lower risk of NAFLD, especially in high risk groups such as smokers and diabetic patients.

Changes in the gut microbial community of the eastern newt (Notophthalmus viridescens) across its three distinct life stages

Understanding the forces that shape vertebrate gut microbial community assembly and composition throughout development is a major focus of the microbiome field. Here, we utilize the complex life cycle of the eastern newt (Notophthalmus viridescens) as a natural wild model to compare the effects of host and environmental factors on gut microbiome development. We compared bacterial inventories of each of the newt's three physiologically distinct developmental stages to determine if each hosted a unique community, or if the two stages which share an aquatic habitat (larvae and adults) harbored more similar communities than those of the third stage, the terrestrial juvenile eft. Additionally, we assessed how the contribution of selective processes to gut microbial assembly changed through development. We found that structurally, each life stage harbored a distinct community, which may be attributable to host factors. Further, across development, we found that community assembly processes shifted from a predominance of neutral to selective forces. However, habitat may also be important in determining community membership and diversity due the uniqueness of eft communities based on these metrics. Our results are similar to those in other vertebrate taxa, suggesting that gut microbiota assembly processes may be conserved across diverse lineages.

Clinical Characteristics of Chronic Lung Abscess Associated with Parvimonas micra Diagnosed Using Metagenomic Next-Generation Sequencing

Purpose

Parvimonas micra (P. micra) is a Gram-positive anaerobic bacterium distributed in the oral cavity, with a potential to become pathogenic causing lung abscess. Due to the lack of specificity of symptoms and the difficulty in culture, the diagnosis of lung abscess associated with P. micra is delayed. It is essential to elucidate the clinical characteristics of lung abscess associated with P. micra.

Methods

From January 2019 to July 2020, five patients with chronic lung abscess associated with P. micra diagnosed by pathological biopsy and metagenomic next-generation sequencing (mNGS) were analyzed in this retrospective study.

Results

Among the five patients, four had a history of smoking, three had periodontitis, and two had a history of drinking. The average course of the disease was 6.5 months. High-density flake-like or mass shadows with irregular boundaries were observed in the chest computed tomography (CT) images of the five patients, and liquefactive necrosis was detected in the middle of the lesions; however, no gas-liquid plane or cavity was noted, making it difficult to distinguish a lung cancer. The pathological biopsy of the five patients showed chronic inflammation of lung tissue, and P. micra was detected by mNGS in the biopsy or bronchoalveolar lavage fluid samples. Two patients were treated with amoxicillin-clavulanate, two had metronidazole, and one had moxifloxacin. Among them, four recovered after receiving antibiotic treatment, and the remaining one underwent surgical resection due to poor antibiotic treatment effect.

Conclusion

Chronic lung abscess associated with P. micra, common in elderly male smokers with poor oral hygiene, is often diagnosed in a delayed manner and misdiagnosed as lung cancer. The mNGS technology is beneficial to the rapid determination of P. micra.

Dysbiosis of the Human Oral Microbiome During the Menstrual Cycle and Vulnerability to the External Exposures of Smoking and Dietary Sugar

Physiological hormonal fluctuations exert endogenous pressures on the structure and function of the human microbiome. As such, the menstrual cycle may selectively disrupt the homeostasis of the resident oral microbiome, thus compromising oral health. Hence, the aim of the present study was to structurally and functionally profile the salivary microbiome of 103 women in reproductive age with regular menstrual cycle, while evaluating the modifying influences of hormonal contraceptives, sex hormones, diet, and smoking. Whole saliva was sampled during the menstrual, follicular, and luteal phases (n = 309) of the cycle, and the participants reported questionnaire-based data concerning their life habits and oral or systemic health. No significant differences in alpha-diversity or phase-specific clustering of the overall microbiome were observed. Nevertheless, the salivary abundances of genera Campylobacter, Haemophilus, Prevotella, and Oribacterium varied throughout the cycle, and a higher species-richness was observed during the luteal phase. While the overall community structure maintained relatively intact, its functional properties were drastically affected. In particular, 11 functional modules were differentially abundant throughout the menstrual cycle, including pentose phosphate metabolism, and biosynthesis of cobalamin and neurotransmitter gamma-aminobutyric acid. The menstrual cycle phase, but not oral contraceptive usage, was accountable for greater variations in the metabolic pathways of the salivary microbiome. Further co-risk factor analysis demonstrated that Prevotella and Veillonella were increased in current smokers, whereas high dietary sugar consumption modified the richness and diversity of the microbiome during the cycle. This is the first large study to systematically address dysbiotic variations of the oral microbiome during the course of menstrual cycle, and document the additive effect of smoking and sugar consumption as environmental risk factors. It reveals the structural resilience and functional adaptability of the oral microbiome to the endogenous hormonal pressures of the menstrual cycle, while revealing its vulnerability to the exogenous exposures of diet and smoking.

Looking beyond the smokescreen: can the oral microbiome be a tool or target in the management of tobacco-associated oral cancer?

A wide range of microbes inhabit the oral cavity, and bacterial and fungal communities most often exist as structured communities or biofilms. The use of tobacco alters the structure of the oral microbiome, including that of potentially malignant lesions, and the altered oral microbiome influences key microenvironmental changes such as chronic inflammation, secretion of carcinogenic toxins, cellular and tissue remodelling and suppression of apoptosis. Given this, it is clear that the bacterial and fungal biofilms in potentially malignant states are likely not passive entities, but could play a critical role in shaping potential malignant and carcinogenic conditions. This holds potential towards leveraging the oral microbiome for the management of tobacco-associated potentially malignant lesions and oral cancer. Here, we explore this line of investigation by reviewing the effects of tobacco in shaping the oral microbiome, and analyse the available evidence in the light of the microbiome of oral potentially malignant and cancerous lesions, and the role of dysbiosis in carcinogenesis. Finally, we discuss possible interventions and approaches using which the oral microbiome could be leveraged towards precision-based oral cancer therapeutics.

The impact of smoking different tobacco types on the subgingival microbiome and periodontal health: a pilot study

Smoking is a risk factor for periodontal disease, and a cause of oral microbiome dysbiosis. While this has been evaluated for traditional cigarette smoking, there is limited research on the effect of other tobacco types on the oral microbiome. This study investigates subgingival microbiome composition in smokers of different tobacco types and their effect on periodontal health. Subgingival plaques were collected from 40 individuals, including smokers of either cigarettes, medwakh, or shisha, and non-smokers seeking dental treatment at the University Dental Hospital in Sharjah, United Arab Emirates. The entire (~ 1500 bp) 16S rRNA bacterial gene was fully amplified and sequenced using Oxford Nanopore technology. Subjects were compared for the relative abundance and diversity of subgingival microbiota, considering smoking and periodontal condition. The relative abundances of several pathogens were significantly higher among smokers, such as Prevotella denticola and Treponema sp. OMZ 838 in medwakh smokers, Streptococcus mutans and Veillonella dispar in cigarette smokers, Streptococcus sanguinis and Tannerella forsythia in shisha smokers. Subgingival microbiome of smokers was altered even in subjects with no or mild periodontitis, probably making them more prone to severe periodontal diseases. Microbiome profiling can be a useful tool for periodontal risk assessment. Further studies are recommended to investigate the impact of tobacco cessation on periodontal disease progression and oral microbiome.