The Role of the Oral Microbiota Related to Periodontal Diseases in Anxiety, Mood and Trauma- and Stress-Related Disorders

Evidence for the association between psychological stress and peri-implant health among middle-aged and elderly adults: A systemic review

BACKGROUND

Chronic psychological stress (CPS) is increasingly recognized for its detrimental effects on systemic and oral health, yet its impact on peri-implantitis remains underexplored.

AIM

To evaluate the evidence linking CPS to peri-implantitis.

METHODS

This systematic review was conducted according to the PRISMA guidelines. Publications searching PubMed, EMBASE, MEDLINE, Cochrane Library, and ClinicalTrials.gov for human studies published in English from 1983 to December 2024. Additionally, quality assessment of selected full-text articles were performed using the modified Newcastle–Ottawa Scale.

RESULTS

From an initial total of 3964 studies, 4 cross-sectional studies comprising 432 participants met the inclusion criteria and consistently demonstrated a positive association between CPS and peri-implantitis. However, the findings are compromised by small sample sizes, study design limitations, methodological heterogeneity, and inadequate adjustment for critical confounders such as smoking and prior periodontitis.

CONCLUSION

Cortisol levels in peri-implant sulcus fluid were linearly correlated with probing depth, with evidence suggesting this relationship may be independent of hyperglycemia. Depression emerged as the most significant CPS subtype associated with peri-implantitis. Additionally, CPS may amplify peri-implantitis inflammation by modulating cytokine expression effects. Long-term studies with larger, more diverse patient populations and careful control of confounding variables are needed to establish causality and understand the underlying mechanisms. Including psychological evaluations and stress management techniques in peri-implant care protocols could improve treatment outcomes and patient health.

The sequential association between school bullying and oral health related quality of life (OHRQoL) in Chinese children and adolescents

BACKGROUND

School bullying has negative impacts on the overall health of children and adolescents, but the association between bullying and oral health-related quality of life (OHRQoL) is still unclear.

METHODS

In this study, a two-wave prospective design was used to collect data in Yunnan Province, southwest China. A total of 5,346 children and adolescents aged 10-17 years were included in the study through two-stage randomized cluster sampling. Univariate and multivariate logistic regression models were employed to assess the sequential associations between baseline bullying and the subsequent OHRQoL. Stratified analyses were further performed to evaluate the effect modification by important demographic variables.

RESULTS

The prevalence of school bullying was 16.40%. After adjustment, bullying involvement at baseline was associated with increased odds of subsequent poor OHRQoL (odds ratio, OR: 1.77, 95% CI: 1.50-2.11). Victims and bully-victims were seen significantly deteriorated OHRQoL, with ORs of 1.81 (95% CI: 1.50-2.19) and 2.10 (95% CI: 1.35-3.33). For different types of bullying victimization, only verbal victimization displayed a significant association with OHRQoL (OR: 2.07; 95% CI: 1.63-2.65). Bullying involvement was significantly associated with all four subdomains of OHRQoL, particularly for social well-being (OR: 1.91, 95% CI: 1.60-2.27). Stratified analyses revealed prominent effect modification by age, sex, ethnicity, and left-behind status in bullying-OHRQoL association.

CONCLUSION

Our findings suggest that children and adolescents who experienced school bullying had a significantly higher risk of subsequently poor OHRQoL, particularly for verbal victims. Targeted interventions should be designed and implemented.

Presumed periodontitis and multimorbidity patterns: a prospective cohort study in the UK Biobank

OBJECTIVES

To examine the pattern of multimorbidity among people with high risk of periodontitis.

MATERIALS AND METHODS

Over 358,000 UK Biobank participants aged 40-69 years at baseline who took part in the baseline assessment and answered mouth/teeth dental problems were included (2006-2010). Cox proportional hazard models and logistic regression models were used to estimate the association of the risk factors of periodontitis with chronic diseases and multimorbidity, stratified by follow-up time.

RESULTS

A total of 154,985 participants developed multimorbidity during follow-up. We observed increased risk of multimorbidity among participants with presumed periodontitis (adjusted HR = 1.06, 95% confidence interval [CI] = 1.05-1.08), especially in those participants with age < 50 years old (adjusted HR = 1.11, 95% CI = 1.08-1.14). Among the different multimorbidity patterns, presumed periodontitis was mainly associated with the mental disorder pattern and metabolic and vascular disease pattern.

CONCLUSIONS

Presumed periodontitis was positively associated with multimorbidity, even more so in younger age. We need to pay more attention to the prevention of periodontitis in the early stage to reduce the burden of multimorbidity in the future.

CLINICAL RELEVANCE

Early life interventions to prevent periodontitis are crucial to reduce the incidence of multimorbidity and enhance the quality of life in older adults. Additionally, greater attention should be given to the mental and cardiovascular metabolic health of patients with periodontitis.

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

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

Emerging therapeutic strategies targeting bone signaling pathways in periodontitis

Periodontitis is a multifactorial immune-mediated disease exacerbated by dysregulated alveolar bone homeostasis. Timely intervention is crucial for disease management to prevent tooth loss. To successfully manage periodontitis, it is imperative to understand the cellular and molecular mechanisms involved in its pathogenesis to develop novel treatment modalities. Non-surgical periodontal therapy (NSPT) such as subgingival instrumentation/debridement has been the underlying treatment strategy over the past decades. However, new NSPT approaches that target key signaling pathways regulating alveolar bone homeostasis have shown positive clinical outcomes. This narrative review aims to discuss endogenous bone homeostasis mechanisms impaired in periodontitis and highlight the clinical outcomes of preventive periodontal therapy to avoid invasive periodontal therapies. Although the anti-resorptive therapeutic adjuncts have demonstrated beneficial outcomes, adverse events have been reported. Diverse immunomodulatory therapies targeting the osteoblast/osteoclast (OB/OC) axis have shown promising outcomes in vivo. Future controlled randomized clinical trials (RCT) would help clinicians and patients in the selection of novel preventing therapies targeting key molecules to effectively treat or prevent periodontitis.

Magnesium Nanocomposite Hydrogel Reverses the Pathologies to Enhance Mandible Regeneration

The healing of bone defects after debridement in medication-related osteonecrosis of the jaw (MRONJ) is a challenging medical condition with impaired angiogenesis, susceptible infection, and pro-inflammatory responses. Magnesium (Mg) nanocomposite hydrogel is developed to specifically tackle multiple factors involved in MRONJ. Mg-oxide nanoparticles tune the gelation kinetics in the reaction between N-hydroxysuccinimide-functionalized hyperbranched poly (ethylene glycol) and proteins. This reaction allows an enhanced mechanical property after instant solidification and, more importantly, also stable gelation in challenging environments such as wet and hemorrhagic conditions. The synthesized hydrogel guides mandible regeneration in MRONJ rats by triggering the formation of type H vessels, activating Osterix+ osteoprogenitor cells, and generating anti-inflammatory microenvironments. Additionally, this approach demonstrates its ability to suppress infection by inhibiting specific pathogens while strengthening stress tolerance in the affected alveolar bone. Furthermore, the enhanced osteogenic properties and feasibility of implantation of the hydrogel are validated in mandible defect and iliac crest defect created in minipigs, respectively. Collectively, this study offers an injectable and innovative bone substitute to enhance mandible defect healing by tackling multiple detrimental pathologies.

The effect of exercise on depression and gut microbiota: Possible mechanisms

Exercise can effectively prevent and treat depression and anxiety, with gut microbiota playing a crucial role in this process. Studies have shown that exercise can influence the diversity and composition of gut microbiota, which in turn affects depression through immune, endocrine, and neural pathways in the gut-brain axis. The effectiveness of exercise varies based on its type, intensity, and duration, largely due to the different changes in gut microbiota. This article summarizes the possible mechanisms by which exercise affects gut microbiota and how gut microbiota influences depression. Additionally, we reviewed literature on the effects of exercise on depression at different intensities, types, and durations to provide a reference for future exercise-based therapies for depression.

Microglial DBP Signaling Mediates Behavioral Abnormality Induced by Chronic Periodontitis in Mice

Several lines of evidence implicate that chronic periodontitis (CP) increases the risk of mental illnesses, such as anxiety and depression, yet, the associated molecular mechanism for this remains poorly defined. Here, it is reported that mice subjected to CP exhibited depression-like behaviors and hippocampal memory deficits, accompanied by synapse loss and neurogenesis impairment in the hippocampus. RNA microarray analysis disclosed that albumin D-site-binding protein (DBP) is identified as the most prominently upregulated target gene following CP, and in vivo and in vitro immunofluorescence methods showed that DBP is preferentially expressed in microglia but not neurons or astrocytes in the hippocampus. Interestingly, it is found that the expression of DBP is significantly increased in microglia after CP, and knockdown of microglial DBP ameliorated the behavioral abnormality, as well as reversed the synapse loss and hippocampal neurogenesis damage induced by CP. Furthermore, DBP knockdown improved the CP-induced hippocampal inflammation and microglial polarization. Collectively, these results indicate a critical role of DBP in orchestrating chronic periodontitis-related behavioral abnormality, hippocampal synapse loss and neurogenesis deficits, in which the microglial activation may be indispensably involved.

Experimental Periodontitis Increases Anxious Behavior and Worsens Cognitive Aspects and Systemic Oxidative Stress in Wistar Rats

OBJECTIVES

Periodontitis (PD) has the potential to induce systemic changes that affect both physical and behavioral aspects. These alterations may be associated with changes in both the inflammatory profile and the oxidative stress status of individuals with PD. Therefore, we aimed to evaluate the effects of PD on oxidative stress, as well as on behavioral parameters and cognitive impairment, in a preclinical model.

MATERIAL AND METHODS

Twenty-four male Wistar rats were randomly assigned to PD and sham groups. PD was induced by the ligature protocol for 14 days. Behavioral tests were initiated on the 9th day of the experiment to evaluate anxious behavior and cognition (learning and memory). After euthanasia, oxidative stress was evaluated in the gums, blood, hippocampus, and amygdala. Alveolar bone loss, bone microstructure, and elemental compositions of the mandibular bone were also assessed.

RESULTS

PD increased alveolar bone loss, reduced the calcium and phosphorus content in the mandibular bone, and increased anxiety-like behavior and cognitive decline (p < 0.05). Furthermore, PD significantly affected the redox balance, as evidenced by increased total antioxidant capacity (TAC) in the gingiva and hippocampus (p < 0.05). It also led to increased lipid peroxidation in the gingiva and erythrocytes (p < 0.05), decreased antioxidant defenses in erythrocytes (superoxide dismutase) and the hippocampus (catalase), and increased antioxidant activity (catalase) in the amygdala (p < 0.05).

CONCLUSION

PD resulted in cognitive alterations, including impairments in spatial learning and memory, as well as increased anxious behavior, likely due to redox imbalance in rats.

The Oral-Gut-Brain Axis: The Influence of Microbes as a Link of Periodontitis With Ischemic Stroke

Periodontitis, a non-communicable chronic inflammation disease resulting from dysbiosis of the oral microbiota, has been demonstrated to have a positive association with the risk of ischemic stroke (IS). The major periodontal pathogens contribute to the progression of stroke-related risk factors such as obesity, diabetes, atherosclerosis, and hypertension. Transcriptional changes in periodontitis pathogens have been detected in oral samples from stroke patients, suggesting a new conceptual framework involving microorganisms. The bidirectional regulation between the gut and the central nervous system (CNS) is mediated by interactions between intestinal microflora and brain cells. The connection between the oral cavity and gut through microbiota indicates that the oral microbial community may play a role in mediating complex communication between the oral cavity and the CNS; however, underlying mechanisms have yet to be fully understood. In this review, we present an overview of key concepts and potential mechanisms of interaction between the oral-gut-brain axis based on previous research, focusing on how the oral microbiome (especially the periodontal pathogens) impacts IS and its risk factors, as well as the mediating role of immune system homeostasis, and providing potential preventive and therapeutic approaches.

Poor perceived oral health is associated with adverse mental health outcomes among Syrian refugees in Canada

While inadequate oral health has been linked to adverse mental health outcomes, there is limited understanding of such implications among refugees who bear a disproportionate burden of oral health disparities. This study aims to examine the effect of self-rated oral health on depression, anxiety, and stress among Syrian refugee parents resettled in Ontario. In this cross-sectional study, a total of 540 Syrian refugee parents who resided in Ontario for an average of 4 years and had at least one child under 18 years old were interviewed between March 2021 and March 2022. Information about self-rated oral health was gathered based on the question "In general, how would you rate the health of your teeth and mouth". Responses ranged from 1 representing "excellent" and 5 representing "very poor". The mean score (SD) of self-rated oral health was 3.2 (1.2). Mental health outcomes of depression, anxiety, and stress were measured using the Depression Anxiety Stress Scales (DASS-21). Multiple linear regression analyses were performed to assess the independent relationship between self-rated oral health and depression, anxiety, and stress, adjusting for other variables including, sociodemographic-, migration-, and health-related factors. Among participants, 6.3% rated their oral health as excellent, 26.9% as good, 23.1% as fair, 24.8% as poor, and 18.7% as very poor. Results of the multiple linear regression analyses indicated that poorer self-rated oral health was significantly associated with higher levels of depression (Adjβ = 0.98; p = 0.002; 95% CI = 0.38-1.59), anxiety (Adjβ = 1.03; p< 0.001; 95% CI = 0.54-1.52), and stress (Adjβ = 1.25; p< 0.001; 95% CI = 0.61-1.88). Further efforts and targeted interventions are needed to address the unmet oral health needs of Syrian refugees to improve mental health outcomes within this vulnerable population.

Comparison of Micro-CT and Morphometric Outcomes in a Modified Experimental Rat Model of Periodontitis

AIM

To assess the correlation between micro-computed tomography (micro-CT) and linear morphometric measurements in terms of mandibular bone levels in a modified experimental periodontitis model in rodents to study the mechanisms of association between periodontal destruction and neuroinflammation.

METHODS

The proposed in vivo experimental periodontitis model involves the administration of oral rinses with Porphyromonas gingivalis and Fusobacterium nucleatum, four times per week during 4, 8 or 12 weeks, in 24 male Wistar Hannover rats (180 g, 5 weeks old). After euthanasia, hemi-mandibles were collected. One hemi-mandible was analysed using morphometry, while the other was assessed with micro-CT. Linear measurements were taken at the buccal aspect and furcation level for both techniques, and volumetric measurements were also obtained with micro-CT. Passing-Bablok regression analysis was used to compare the results of both techniques, with morphometric measurements serving as the reference. Moreover, Lin's Concordance correlation coefficient was calculated to assess the level of agreement. Periodontal clinical variables with neuroinflammatory parameters from the frontal cortex were used to evaluate the association between the resulting condition and neuroinflammation.

RESULTS

Twenty-one out of the initial 24 rats were analysed. The micro-CT linear measurements demonstrated high concordance values with the linear morphometric measurements at the buccal surfaces of the roots in molars (r = 0.714) but not at the furcation area (r = 0.052). At 12 weeks, there was a significant impact on neuroinflammation with significant decreases in iNOS levels and p-mTOR levels at 4 and 8 weeks.

CONCLUSION

The proposed in vivo experimental periodontitis model demonstrated a high degree of correlation between morphometric and micro-CT measurements in buccal areas but not at the furcation level. Concomitantly, there was a significant temporary modulation of the neuroinflammatory response.

Probing the oral-brain connection: oral microbiome patterns in a large community cohort with anxiety, depression, and trauma symptoms, and periodontal outcomes

The role of the oral microbiome in mental health has recently been appreciated within the proposed oral-brain axis. This study examined the structure and composition of the salivary microbiome in a large-scale population-based cohort of individuals reporting mental health symptoms (n = 306) compared to mentally healthy controls (n = 164) using 16S rRNA sequencing. Mental health symptoms were evaluated using validated questionnaires and included depression, anxiety, and posttraumatic stress disorder (PTSD), with accompanying periodontal outcomes. Participants also indicated current or previous diagnoses of anxiety, depression, periodontitis, and gingivitis. Mental and periodontal health variables influenced the overall composition of the oral microbiome. PTSD symptoms correlated with a lower clr-transformed relative abundance of Haemophilus sputorum and a higher clr-transformed relative abundance of Prevotella histicola. The clr-transformed relative abundance of P. histicola was also positively associated with depressive scores and negatively associated with psychological quality of life. Anxiety disorder diagnosis was associated with a lower clr-transformed relative abundance of Neisseria elongate and a higher clr-transformed relative abundance of Oribacterium asaccharolyticum. A higher clr-transformed relative abundance of Shuttleworthia and lower clr-transformed relative abundance of Capnocytophaga were evident in those who reported a clinical periodontitis diagnosis. Higher Eggerthia and lower Haemophilus parainfluenzae clr-transformed relative abundances were associated with reported clinical periodontitis diagnoses and psychotherapeutic efficacy. Functional prediction analysis revealed a potential role for tryptophan metabolism/degradation in the oral-brain axis, which was confirmed by lower plasma serotonin levels across symptomatic groups. This study sheds light on the intricate interplay between oral microbiota, periodontal and mental health outcomes, and a potential role for tryptophan metabolism in the proposed oral-brain axis, emphasizing the need for further exploration to pave the way for novel therapeutic interventions and predicting therapeutic response.

Systemic Factors Affecting Prognosis in Periodontics: Part II

This study gives an insight into certain systemic conditions and factors such as nutrition, age, hematological disorders, hypertension, smoking, obesity, and metabolic syndrome that have a notable effect on the periodontium. The review highlights the importance of taking these factors into consideration in periodontal therapy and their impact on the prognosis of periodontal therapies. The other systemic factors are discussed in detail elsewhere in the special issue.

Balancing the Oral-Gut-Brain Axis with Diet

Background: The oral microbiota is the second largest microbial community in humans. It contributes considerably to microbial diversity and health effects, much like the gut microbiota. Despite physical and chemical barriers separating the oral cavity from the gastrointestinal tract, bidirectional microbial transmission occurs between the two regions, influencing overall host health. Method: This review explores the intricate interplay of the oral-gut-brain axis, highlighting the pivotal role of the oral microbiota in systemic health and ageing, and how it can be influenced by diet. Results: Recent research suggests a relationship between oral diseases, such as periodontitis, and gastrointestinal problems, highlighting the broader significance of the oral-gut axis in systemic diseases, as well as the oral-gut-brain axis in neurological disorders and mental health. Diet influences microbial diversity in the oral cavity and the gut. While certain diets/dietary components improve both gut and oral health, others, such as fermentable carbohydrates, can promote oral pathogens while boosting gut health. Conclusions: Understanding these dynamics is key for promoting a healthy oral-gut-brain axis through dietary interventions that support microbial diversity and mitigate age-related health risks.

Microglial morphological/inflammatory phenotypes and endocannabinoid signaling in a preclinical model of periodontitis and depression

BACKGROUND

Depression is a chronic psychiatric disease of multifactorial etiology, and its pathophysiology is not fully understood. Stress and other chronic inflammatory pathologies are shared risk factors for psychiatric diseases, and comorbidities are features of major depression. Epidemiological evidence suggests that periodontitis, as a source of low-grade chronic systemic inflammation, may be associated with depression, but the underlying mechanisms are not well understood.

METHODS

Periodontitis (P) was induced in Wistar: Han rats through oral gavage with the pathogenic bacteria Porphyromonas gingivalis and Fusobacterium nucleatum for 12 weeks, followed by 3 weeks of chronic mild stress (CMS) to induce depressive-like behavior. The following four groups were established (n = 12 rats/group): periodontitis and CMS (P + CMS+), periodontitis without CMS, CMS without periodontitis, and control. The morphology and inflammatory phenotype of microglia in the frontal cortex (FC) were studied using immunofluorescence and bioinformatics tools. The endocannabinoid (EC) signaling and proteins related to synaptic plasticity were analyzed in FC samples using biochemical and immunohistochemical techniques.

RESULTS

Ultrastructural and fractal analyses of FC revealed a significant increase in the complexity and heterogeneity of Iba1 + parenchymal microglia in the combined experimental model (P + CMS+) and increased expression of the proinflammatory marker inducible nitric oxide synthase (iNOS), while there were no changes in the expression of cannabinoid receptor 2 (CB2). In the FC protein extracts of the P + CMS + animals, there was a decrease in the levels of the EC metabolic enzymes N-acyl phosphatidylethanolamine-specific phospholipase D (NAPE-PLD), diacylglycerol lipase (DAGL), and monoacylglycerol lipase (MAGL) compared to those in the controls, which extended to protein expression in neurons and in FC extracts of cannabinoid receptor 1 (CB1) and to the intracellular signaling molecules phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2). The protein levels of brain-derived neurotrophic factor (BDNF) and synaptophysin were also lower in P + CMS + animals than in controls.

CONCLUSIONS

The combined effects on microglial morphology and inflammatory phenotype, the EC signaling, and proteins related to synaptic plasticity in P + CMS + animals may represent relevant mechanisms explaining the association between periodontitis and depression. These findings highlight potential therapeutic targets that warrant further investigation.

High-intensity interval training mitigates the progression of periodontitis and improves behavioural aspects in rats

AIM

To investigate the effects of high-intensity interval training (HIIT) on periodontitis (PD) progression and behavioural outcomes.

MATERIALS AND METHODS

Forty-eight Wistar rats were divided into four groups: non-trained (NT); non-trained with PD; HIIT with PD; and HIIT. The HIIT protocol, involving daily treadmill sessions, spanned 8 weeks, with PD induced by ligature after the 6th week. Behavioural tests were conducted to assess anxiety and memory. Post euthanasia, we evaluated the systemic inflammatory profile and oxidative stress markers in the hippocampus and amygdala. A morphological evaluation and elemental composition analysis of the mandibular alveolar bone were performed.

RESULTS

PD exacerbated alveolar bone level, bone surface damage and alterations in calcium and phosphorus percentages on the bone surface (p < .05), while HIIT attenuated these changes (p < .05). HIIT improved systemic inflammatory markers altered by PD (tumour necrosis factor [TNF]-α, interleukin [IL]-10, TNF-α/IL-10 and IL-1β/IL-10 ratios, p < .05). PD animals exhibited lower total antioxidant capacity and levels of thiobarbituric acid reactive substances in the amygdala and hippocampus, respectively (p < .05). HIIT maintained these parameters at levels similar to those in NT animals. HIIT improved anxiety and memory outcomes altered by PD (p < .05).

CONCLUSIONS

HIIT attenuates systemic inflammation, anxiety and memory outcomes promoted by PD.

Oral microbiome in human health and diseases

The oral cavity contains the second-largest microbiota in the human body. The cavity's anatomically and physiologically diverse niches facilitate a wide range of symbiotic bacteria living at distinct oral sites. Consequently, the oral microbiota exhibits site specificity, with diverse species, compositions, and structures influenced by specific aspects of their placement. Variations in oral microbiota structure caused by changes in these influencing factors can impact overall health and lead to the development of diseases-not only in the oral cavity but also in organs distal to the mouth-such as cancer, cardiovascular disease, and respiratory disease. Conversely, diseases can exacerbate the imbalance of the oral microbiota, creating a vicious cycle. Understanding the heterogeneity of both the oral microbiome and individual humans is important for investigating the causal links between the oral microbiome and diseases. Additionally, understanding the intricacies of the oral microbiome's composition and regulatory factors will help identify the potential causes of related diseases and develop interventions to prevent and treat illnesses in this domain. Therefore, turning to the extant research in this field, we systematically review the relationship between oral microbiome dynamics and human diseases.

Assessment of dental and periodontal indices and Streptococcus mutans virulence in fragile X syndrome patients

INTRODUCTION

Fragile X syndrome (FXS) is the most common cause of hereditary genetic disorder in a single gene characterised by intellectual disability. Behavioural features such as autism, hyperactivity and anxiety disorder may be present. Biofilm development and pathogenicity of Streptococcus mutans may be altered because FXS renders the dental approach and oral hygiene more complex.

OBJECTIVES

The purpose of this study was to compare the levels of transcripts for VicRK and CovR of S. mutans isolated from FXS patients with the levels of transcripts for VicRK and CovR of standard strain ATCC, using a quantitative polymerase chain reaction (qPCR).

METHODS

The caries experience index was assessed by the International Caries Detection and Assessment System (ICDAS), Periodontal Condition Index (PCI) and Invasive Dental Treatment Need Index (INI).

RESULTS

The clinical index findings revealed a high rate of caries cavities and bleeding on probing of FXS patients. When VicRK and CovR transcript levels were compared with the reference strain, Fragile X patients were found to have significantly higher values.

CONCLUSION

The present study demonstrated that FXS patients have more adverse clinical conditions, with increased biofilm accumulation and virulence. When combined with behavioural abnormalities, these patients become even more vulnerable to dental caries.

The brain-gut axis: communication mechanisms and the role of the microbiome as a neuroprotective factor in the development of neurodegenerative diseases: A literature overview

The study of the brain-gut axis and its impact on cognitive function and in the development of neurodegenerative diseases is a very timely topic of interest to researchers. This review summarizes information on the basic mechanisms of gut-brain communication. We then discuss the roles of the gut microbiome as a neuroprotective factor in neurodegeneration. The gut microbiota is extremely important in maintaining the body's homeostasis, shaping the human immune system and the proper functioning of the brain. The intestinal microflora affects the processes of neuroplasticity, synaptogenesis, and neuronal regeneration. This review aims to explain changes in the composition of the bacterial population of the intestinal microflora among patients with Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Abnormalities in gut microflora composition are also noted in stress, depression, or autism spectrum development. New observations on psychobiotic supplementation in alleviating the symptoms of neurodegenerative diseases are also presented.

Periodontitis and Depressive Disorders: The Effects of Antidepressant Drugs on the Periodontium in Clinical and Preclinical Models: A Narrative Review

Background/Objectives: Several psychological conditions, including stress and depression, can adversely affect oral health; in fact, antidepressants, commonly used to treat depressive disorders, may have conflicting effects on the periodontal status of individuals. The aim of this review was to determine the effects of antidepressants on the periodontium. Methods: A literature search was conducted using electronic databases, Pubmed/MEDLINE, Cochrane Library, focusing on the use of antidepressants and their effects on periodontal health in animals or humans. Results: Seventeen articles have been included with the use of amitriptyline (two studies), desipramine (one study), imipramine (two studies), desvenlafaxine (one study), fluoxetine (six studies), venlafaxine (three studies) and tianeptine (two studies). One study evaluated several categories of antidepressants, such as selective serotonin reuptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), tricyclic, atypical and monoamine oxidase inhibitors (MAO). Most trials showed improvements in periodontal health, especially with fluoxetine, but also with imipramine, desipramine, desvenlafaxine and tianeptine; on the contrary, worsening of clinical periodontal indices and increased loss of alveolar bone were reported with venlafaxine. Conclusions: This review suggests that in the presence of comorbidity between periodontitis and depression, pharmacological treatment with SNRIs, SSRIs and mixed antidepressants is associated with improvement in periodontal parameters, except for venlafaxine. Healthcare professionals (especially oral and mental health professionals) should investigate proper adherence to medication therapy in patients with a history of periodontitis and depression. Further clinical trials are needed to confirm these results.

The hidden psychological cost of lack of access to dental care

This opinion piece highlights the hidden psychological and other costs of the lack of access to dental care.

Antimicrobial management of dental infections: Updated review

Dental infections, which include anything from severe periodontal illnesses and abscess forms to routine tooth caries, are a major public health risk. This review article focuses on the pathophysiology and treatment of dental infections. A narrative review was conducted based on several published articles, relevant journals, and books in Google Scholar PubMed using the keywords dental caries, periodontal disease, gingivitis, and related diseases; we excluded duplicated information. Our review illustrated the types of dental infections and the proper antimicrobial drug that is suitable for this disease. Drawing from recent research findings and clinical evidence, we explore the spectrum of bacteria commonly associated with dental infections and their susceptibility profiles to various antibiotics. Emphasis is placed on understanding the mechanisms of antibiotic action and resistance in the context of dental pathogens, shedding light on optimal treatment regimens and potential challenges in clinical management. Additionally, we go over the clinical consequences of antibiotic therapy in dentistry, taking into account factors like patient selection, dose guidelines, and side effects. The management of dental infections through antimicrobial strategies has undergone significant advancements, as evidenced by this updated review. Besides the normal methods, emerging technologies such as 3D printing for drug delivery of antibiotics and disinfectants hold promise in enhancing treatment efficacy and patient outcomes. By leveraging the precision and customization afforded by 3D printing, dentistry can tailor antimicrobial interventions to individual patient needs, optimizing therapeutic outcomes while minimizing adverse effects.

Exploring the Link Between Oral Health Factors and Hearing Impairments in Children: A Cross-Sectional Study

Background Hearing-impaired children may face challenges in communication, social interaction, academic performance, and emotional well-being, which can have a notable impact on their overall quality of life. Beyond these challenges, oral health can also be significantly impacted. The relationship between hearing impairment and dental diseases is an intriguing and interconnected aspect of overall well-being that merits attention and exploration. This study aimed to assess the relationship between various oral health factors and hearing impairments. Methodology This cross-sectional study involved 90 hearing-impaired children aged 6-12 years. To evaluate the children's hearing abilities, diagnostic tools such as pure-tone audiometry were employed. To measure dental health, the decayed, missing, and filled teeth (DMFT) and decayed, missing, and filled primary teeth (dmft) indices, as well as plaque index (PI) and gingival index (GI) were calculated. The chi‑square test was used to identify significant differences between genders. Spearman's test was used to determine the correlation between variables. Results The severity of hearing impairment varied, with 5.6% having severe hearing loss, 8.9% having profound hearing loss, and 85.6% having complete hearing loss. The mean DMFT score was 2.5 ± 1.86, with no significant difference observed between males and females. The mean dmft score was 4.2 ± 3.12, with no significant difference between genders. However, there was a difference in the PI scores between males and females. Males presented a higher PI score of 2.6 ± 0.09 compared to 1.8 ± 0.08 for females. The overall mean PI was 2.1 ± 0.80. The mean GI was 1.5 ± 0.90, and no significant difference was observed between males and females. Spearman's test identified a significant positive correlation between the severity of hearing impairment and both PI scores (p = 0.000) and GI scores (p = 0.000). Conversely, the severity of hearing impairment showed a weak positive correlation with both DMFT scores (p = 0.487) and dmft scores (p = 0.229), but these correlations were not statistically significant. Conclusions The connection between oral health and severe hearing impairment in children is significant and has potential implications. Pediatric healthcare providers, including dentists and audiologists, need to work collaboratively to monitor the oral and aural health of young patients.

Role of Nonalcoholic Fatty Liver Disease in Periodontitis: A Bidirectional Relationship

Nonalcoholic fatty liver disease (NAFLD) and periodontitis share common risk factors such as obesity, insulin resistance (IR), and dyslipidemia, which contribute to systemic inflammation. It has been suggested that a bidirectional relationship exists between NAFLD and periodontitis, indicating that one condition may exacerbate the other. NAFLD is characterized by excessive fat deposition in the liver and is associated with low-grade chronic inflammation. There are several risk factors for the development of NAFLD, including gender, geriatric community, race, ethnicity, poor sleep quality and sleep deprivation, physical activity, nutritional status, dysbiosis gut microbiota, increased oxidative stress, overweight, obesity, higher body mass index (BMI), IR, type 2 diabetes mellitus (T2DM), metabolic syndrome (MetS), dyslipidemia (hypercholesterolemia), and sarcopenia (decreased skeletal muscle mass). This systemic inflammation can contribute to the progression of periodontitis by impairing immune responses and exacerbating the inflammatory processes in the periodontal tissues. Furthermore, individuals with NAFLD often exhibit altered lipid metabolism, which may affect oral microbiota composition, leading to dysbiosis and increased susceptibility to periodontal disease. Conversely, periodontitis has been linked to the progression of NAFLD through mechanisms involving systemic inflammation and oxidative stress. Chronic periodontal inflammation can release pro-inflammatory cytokines and bacterial toxins into the bloodstream, contributing to liver inflammation and exacerbating hepatic steatosis. Moreover, periodontitis-induced oxidative stress may promote hepatic lipid accumulation and IR, further aggravating NAFLD. The interplay between NAFLD and periodontitis underscores the importance of comprehensive management strategies targeting both conditions. Lifestyle modifications such as regular exercise, a healthy diet, and proper oral hygiene practices are crucial for preventing and managing these interconnected diseases. Additionally, interdisciplinary collaboration between hepatologists and periodontists is essential for optimizing patient care and improving outcomes in individuals with NAFLD and periodontitis.

Adolescent alcohol use is associated with differences in the diversity and composition of the oral microbiome

BACKGROUND

Adolescence is a sensitive stage of oral microbial development that often coincides with the initiation and escalation of alcohol use. Thus, adolescents may be particularly susceptible to alcohol-induced alterations in the oral microbiome, though minimal research has been done in this area. Understanding the connection between the oral microbiome and alcohol use during adolescence is important to understand fully the biological consequences of alcohol use to mitigate potential adverse outcomes.

METHODS

Saliva samples were collected from adolescents aged 17-19 who used alcohol heavily (n = 21, 52.4% female) and those who did not use alcohol or any other substances (n = 18, 44.4% female). We utilized 16S rRNA sequencing to examine differences in microbial diversity and composition between the groups.

RESULTS

For alpha diversity, evenness was significantly lower in the drinking group than the control group as indicated by Pielou's evenness, Shannon, and Simpson indices. There were no statistically significant findings for beta diversity. Differential abundance analyses revealed higher abundances of Rothia and Corynebacterium in the alcohol-using group using both centered-log-ratio and relative abundance normalization. These genera are known for their high capacity to convert alcohol into acetaldehyde, a toxic metabolite reported to play a role in the neurobiological effects of alcohol. An unclassified Clostridia UCG-014, Streptobacillus, Comamonas, unclassified Lachnospiraceae, and Parvimonas were also identified as significantly different between groups when using only one of the normalization techniques.

CONCLUSIONS

This is the first study designed specifically to compare the oral microbiome of adolescents who use alcohol with that of control participants. Our findings reveal distinct alcohol-related differences in microbial composition and taxon abundance, emphasizing the importance of understanding the impact on the oral microbiome of alcohol use during adolescence. Because the oral microbiome is malleable, this study provides foundational work for future prevention and intervention studies.

The role of Toll-like receptors in neuropsychiatric disorders: Immunopathology, treatment, and management

Neuropsychiatric disorders denote a broad range of illnesses involving neurology and psychiatry. These disorders include depressive disorders, anxiety, schizophrenia, bipolar disorder, attention deficit hyperactivity disorder, autism spectrum disorders, headaches, and epilepsy. In addition to their main neuropathology that lies in the central nervous system (CNS), lately, studies have highlighted the role of immunity and neuroinflammation in neuropsychiatric disorders. Toll-like receptors (TLRs) are innate receptors that act as a bridge between the innate and adaptive immune systems via adaptor proteins (e.g., MYD88) and downstream elements; TLRs are classified into 13 families that are involved in normal function and illnesses of the CNS. TLRs expression affects the course of neuropsychiatric disorders, and is influenced during their pharmacotherapy; For example, the expression of multiple TLRs is normalized during the major depressive disorder pharmacotherapy. Here, the role of TLRs in neuroimmunology, treatment, and management of neuropsychiatric disorders is discussed. We recommend longitudinal studies to comparatively assess the cell-type-specific expression of TLRs during treatment, illness progression, and remission. Also, further research should explore molecular insights into TLRs regulation and related pathways.

Bibliometric Analysis and Visualization of Clinical Trials on Psychological Stress and Oral Health (1967-2024)

Stress is ubiquitous in modern life, influencing various facets of human health and well-being. While the impact of stress on mental and physical health is well-documented, its effects on oral health have garnered increasing attention in recent years. This bibliometric analysis explores the literature on the impact of stress on oral health. The study utilizes data from the PubMed database, focusing on publication trends, influential contributors and the temporal analysis of their publications, coauthorship analysis of authors and institutions, key thematic clusters, thematic evolution, and collaboration between various countries. Examining clinical trials investigating the impact of stress on oral health unveils significant trends and insights. Over time, there has been a steady rise in publication frequency, although with occasional fluctuations, indicating an increasing interest in the subject. The University of California has been identified as a leading institution, while Psychoneuroendocrinology emerges as a pivotal journal for disseminating research findings in the field. Keyword analysis reveals diverse thematic clusters, reflecting the multifaceted nature of the impact of stress on oral health. The analysis of topic trends showcases significant shifts over different periods, from basic correlations between mental health conditions and physiological indicators to a broader exploration of psychological interventions and social contexts in recent years. Thematic evolution analysis further elucidates this progression, categorizing themes into motor, basic, niche, and emerging or declining categories. Additionally, the analysis of corresponding authors' countries uncovers patterns of collaborative efforts, with the United States leading in collaboration levels. In summary, these analyses collectively highlight an evolving comprehension of the impact of stress on oral health, providing valuable insights for clinical practice and guiding future research endeavors.

Evolutionary History of Periodontitis and the Oral Microbiota—Lessons for the Future

Purpose of Review

Currently, periodontal disease is the sixth most prevalent disease in the world. Emerging evidence suggests the possibility of pre-historic humans having relatively low occurrences of oral diseases, particularly periodontitis when compared to modern humans. In this review, we look back into the history of Homo sapiens and explore the emerging scientific literature to discuss the evolution of the human oral microbiota and the prevalence of periodontitis from pre-historic to modern times.

Recent Findings

Most of the scientific literature points to a more health-associated, eubiotic oral microbiota and a seemingly lower prevalence of periodontitis in pre-historic humans compared to modern times. The oral microbiome has evolved along with humans. Humans of the contemporary era are exposed to a far greater number of risk factors for periodontal disease. Also, major lifestyle changes induced by the agricultural revolution and the industrial revolution have led to the development of a more dysbiotic oral microbiota and a rise in the prevalence of periodontitis in modern humans.

Summary

An understanding of the prevalence of periodontitis across human history, the evolution of the oral microbiota, and the factors that influenced its nature and complexity helps identify and modify the disease-associated lifestyle factors acquired through modernization to manage the common worldwide problem of periodontitis.

Increased IgA-mediated responses to the gut paracellular pathway and blood-brain barrier proteins predict delirium due to hip fracture in older adults

Introduction

Delirium is accompanied by immune response system activation, which may, in theory, cause a breakdown of the gut barrier and blood-brain barrier (BBB). Some results suggest that the BBB is compromised in delirium, but there is no data regarding the gut barrier. This study investigates whether delirium is associated with impaired BBB and gut barriers in elderly adults undergoing hip fracture surgery.

Methods

We recruited 59 older adults and measured peak Delirium Rating Scale (DRS) scores 2-3 days after surgery, and assessed plasma IgG/IgA levels (using ELISA techniques) for zonulin, occludin, claudin-6, β-catenin, actin (indicating damage to the gut paracellular pathway), claudin-5 and S100B (reflecting BBB damage), bacterial cytolethal distending toxin (CDT), LPS-binding protein (LBP), lipopolysaccharides (LPS), Porphyromonas gingivalis, and Helicobacter pylori.

Results

Results from univariate analyses showed that delirium is linked to increased IgA responses to all the self-epitopes and antigens listed above, except for LPS. Part of the variance (between 45-48.3%) in the peak DRS score measured 2-3 days post-surgery was explained by independent effects of IgA directed to LPS and LBP (or bacterial CDT), baseline DRS scores, and previous mild stroke. Increased IgA reactivity to the paracellular pathway and BBB proteins and bacterial antigens is significantly associated with the activation of M1 macrophage, T helper-1, and 17 cytokine profiles.

Conclusion

Heightened bacterial translocation, disruption of the tight and adherens junctions of the gut and BBB barriers, elevated CDT and LPS load in the bloodstream, and aberrations in cell-cell interactions may be risk factors for delirium.

Analysis of influencing factors of anxiety and depression in patients with periodontitis

BACKGROUND

Periodontitis is a chronic oral disease caused by pathogenic microorganisms that corrode tooth tissue, form periodontal pockets, absorb alveolar bone, and finally lead to tooth loss. During treatment, patients are prone to anxiety, tension, and other negative emotions, which affect their ability to face the disease and may also lead to aggravation of the original condition and affect oral health. Therefore, it is important to improve the negative psychology of patients with periodontitis to clarify the factors that may lead to negative psychological emotions.

AIM

To investigate the risk factors that may lead to anxiety and depression in patients with periodontitis.

METHODS

One hundred patients with periodontitis were selected between March 2022 and March 2023 at our hospital. All patients were assessed with the Zung Self-rating Depression Scale (SDS) (≥ 53 points indicate a depressive state) and Zung Self-rating Anxiety Scale (SAS) (≥ 50 points indicates an anxious state). In this study, patients who experienced anxiety or depression were included in the occurrence group and those without anxiety or depression were included in the non-occurrence group. The baseline data of the two groups were compared to explore the risk factors for anxiety and depression in patients with periodontitis.

RESULTS

A total of 100 patients with periodontitis were included in this study. According to the SDS, 38 patients (38.00%) developed depression, with an average SDS score of (68.52 ± 5.85) points. According to the SAS, 40 patients (40.00%) developed anxiety, and the average SAS score was (72.15 ± 4.15) points. In this study, 56 patients with anxiety or depression were included. Compared with the non-occurrence group, the occurrence group had higher ages (≥ 60 years), lower level of hope (low level), educational level (high school or below), disease perception (poor), and sleep disorder (yes). The negative coping dimension scores of the simplified coping style questionnaire (SCSQ) and Dental Fear Scale (DFS) in the occurrence group were higher, whereas the score of the positive coping dimension of the SCSQ was significantly lower (P < 0.05). There were no significant differences in the other data between the groups (P > 0.05). The results of multiple logistics regression analysis showed that age (≥ 60 years), level of hope (low level), educational level (high school or below), disease perception (poor), sleep disorder (yes), high negative coping dimension scores of SCSQ, high score of DFS, and low positive coping dimension scores of SCSQ were all factors contributing to the anxiety and depression in patients with periodontitis (odds ratio > 1, P < 0.05).

CONCLUSION

Age, hope level, educational level, disease perception, sleep disorders, coping style, and dental fear were all associated with anxiety and depression in patients with periodontitis.

Periodontitis salivary microbiota exacerbates colitis-induced anxiety-like behavior via gut microbiota

The gut-brain axis is a bidirectional communication system between the gut and central nervous system. Many host-related factors can affect gut microbiota, including oral bacteria, making the brain a vulnerable target via the gut-brain axis. Saliva contains a large number of oral bacteria, and periodontitis, a common oral disease, can change the composition of salivary microbiota. However, the role and mechanism of periodontitis salivary microbiota (PSM) on the gut-brain axis remain unclear. Herein, we investigated the nature and mechanisms of this relationship using the mice with dextran sulfate sodium salt (DSS)-induced anxiety-like behavior. Compared with healthy salivary microbiota, PSM worsened anxiety-like behavior; it significantly reduced the number of normal neurons and activated microglia in DSS mice. Antibiotic treatment eliminated the effect of PSM on anxiety-like behavior, and transplantation of fecal microbiota from PSM-gavaged mice exacerbated anxiety-like behavior. These observations indicated that the anxiety-exacerbating effect of PSM was dependent on the gut microbiota. Moreover, the PSM effect on anxiety-like behavior was not present in non-DSS mice, indicating that DSS treatment was a prerequisite for PSM to exacerbate anxiety. Mechanistically, PSM altered the histidine metabolism in both gut and brain metabolomics. Supplementation of histidine-related metabolites had a similar anxiety-exacerbating effect as that of PSM, suggesting that histidine metabolism may be a critical pathway in this process. Our results demonstrate that PSM can exacerbate colitis-induced anxiety-like behavior by directly affecting the host gut microbiota, emphasizing the importance of oral diseases in the gut-brain axis.

Salivary signatures of oral-brain communication in sleep bruxers

Introduction

Microbiota and their interaction with hosts have been of great interest in brain research in recent years. However, the role of oral microbiota in mental illness and the underlying mechanism of oral-brain communication remains elusive. Sleep bruxism (SB) is an oral parafunctional activity related to the nervous system and is considered a risk factor for harmful clinical consequences and severe systemic conditions. Exploring the connection between oral microbiota and sleep bruxism may deepen our understanding of the complex relationship between oral-brain axis and provide insights for treatment.

Methods

In this study, salivary samples were collected from 22 individuals with SB and 21 healthy controls, and metagenomics with metabolomics was performed. Nonparametric Wilcoxon test were applied for the statistical analysis between the two groups. Microbial dysbiosis and altered oral metabolites were found in the SB individuals.

Results

The characteristic metabolite N-acetylglucosamine (GlcNAc) (VIP=8.4823, P<0.05) was correlated to a statistically lower Streptococcus mitis level in SB individuals. Salivary IFN-g level and IFN-g/IL-4 ratio were detected with significant changes in a chip assay. Amino acid metabolism pathways were upregulated, and the pathway with the largest number of differentially expressed genes is related to amino-tRNA charging pathway, while the most significantly enriched pathway is related to arginine biosynthesis. Neurotransmitter-associated pathways with glutamatergic and GABAergic synapses and cardiovascular system-related pathways were enriched in the SB group.

Discussion

These results indicate a possible neuroimmune regulatory network of oral-brain communication in SB, which helps explain the mechanism of the oral microbiome with the host in sleep bruxers and provides a reference for early clinical and therapeutic intervention to improve the diagnosis and treatment of SB and similar diseases.

Alterations of the salivary microbiota in gastroesophageal reflux disease

OBJECTIVES

Gastroesophageal reflux disease (GERD) is among the most prevalent gastrointestinal disorders. The oral microbiota plays an important role in human health and may be altered by the presence of GERD. Here, we aimed to investigate the alterations of salivary microbiota in GERD patients.

METHODS

We collected clinical information and salivary samples from 60 individuals. All participants underwent combined pH/impedance monitoring measurement and submitted samples for salivary microbiota sequencing. According to acid exposure time and DeMeester score, participants were divided into two groups: GERD + (Group G) and GERD - (Group C).

RESULTS

There was no significant difference in alpha diversity between study groups. Regarding beta diversity, principal coordinate analysis plots indicated that the microbiota composition data of the participants were grouped within partial overlapping clusters. The statistical analysis of the distance matrices was performed using the Adonis test (p = 0.017). Based on linear discriminant analysis effect size, the relative abundances of the phylum Bacteroidetes, class Bacteroidia, order Bacteroidales, family Prevotellaceae, and genus unidentified_Prevotellaceae were enriched in Group G. Compared with Group C, the phylum Actinobacteria, classes unidentified_Actinobacteria and Bacilli, orders Micrococcales and Lactobacillales, families Micrococcaceae and Streptococcaceae, and genuses Rothia and Streptococcus were decreased in Group G. At the genus level, the abundances of Streptococcus and Rothia were negatively correlated with DeMeester score and acid exposure time.

CONCLUSIONS

This study revealed alterations of the salivary microbiota in GERD patients, suggesting that acid reflux changes the oral ecosystem.

Mendelian randomization studies of depression: evidence, opportunities, and challenges

BACKGROUND

Major depressive disorder (MDD) poses a significant social and economic burden worldwide. Identifying exposures, risk factors, and biological mechanisms that are causally connected to MDD can help build a scientific basis for disease prevention and development of novel therapeutic approaches.

METHODS

In this systematic review, we assessed the evidence for causal relationships between putative causal risk factors and MDD from Mendelian randomization (MR) studies, following PRISMA. We assessed methodological quality based on key elements of the MR design: use of a full instrumental variable analysis and validation of the three key MR assumptions.

RESULTS

We included methodological details and results from 52 articles. A causal link between lifestyle, metabolic, inflammatory biomarkers, particular pathological states and MDD is supported by MR investigations, although results for each category varied substantially.

CONCLUSIONS

While this review shows how MR can offer useful information for examining prospective treatment targets and better understanding the pathophysiology of MDD, some methodological flaws in the existing literature limit reliability of results and probably underlie their heterogeneity. We highlight perspectives and recommendations for future works on MR in psychiatry.

Genetically predicted causal associations between periodontitis and psychiatric disorders

BACKGROUND

Psychiatric disorders have serious harm to individuals' lives with high disease burden. Observational studies reported inconsistent associations between periodontitis and some psychiatric disorders, and the causal correlations between them remain unknown.

OBJECTIVE

This study aims to explore the causal associations between periodontitis and psychiatric disorders.

METHODS

A series of two-sample Mendelian randomisation (MR) analyses were employed using genome-wide association study summary statistics for periodontitis in adults from Gene-Lifestyle Interactions in Dental Endpoints Consortium and 10 psychiatric disorders from Psychiatric Genomics Consortium. Causal effects were primarily estimated using the inverse-variance weighted (IVW) method. Various sensitivity analyses were also conducted to assess the robustness of our results.

FINDINGS

The MR analysis suggested that genetically determined periodontitis was not causally associated with 10 psychiatric disorders (IVW, all p>0.089). Furthermore, the reverse MR analysis revealed that 10 psychiatric disorders had no causal effect on periodontitis (IVW, all p>0.068). We discovered that all the results were consistent in the four MR analytical methods, including the IVW, MR-Egger, weighted median and weighted mode. Besides, we did not identify any heterogeneity or horizontal pleiotropy in the sensitivity analysis.

CONCLUSIONS

These results do not support bidirectional causal associations between genetically predicted periodontitis and 10 common psychiatric disorders. Potential confounders might contribute to the previously observed associations.

CLINICAL IMPLICATIONS

Our findings might alleviate the concerns of patients with periodontitis or psychiatric disorders. However, further research was warranted to delve into the intricate relationship between dental health and mental illnesses.

Association between oral microbial dysbiosis and poor functional outcomes in stroke-associated pneumonia patients

BACKGROUND

Despite advances in our understanding of the critical role of the microbiota in stroke patients, the oral microbiome has rarely been reported to be associated with stroke-associated pneumonia (SAP). We sought to profile the oral microbial composition of SAP patients and to determine whether microbiome temporal instability and special taxa are associated with pneumonia progression and functional outcomes.

METHODS

This is a prospective, observational, single-center cohort study that examined patients with acute ischemic stroke (AIS) who were admitted within 24 h of experiencing a stroke event. The patients were divided into three groups based on the occurrence of pneumonia and the use of mechanical ventilation: nonpneumonia group, SAP group, and ventilator-associated pneumonia (VAP) group. We collected oral swabs at different time points post-admission and analyzed the microbiota using 16 S rRNA high-throughput sequencing. The microbiota was then compared among the three groups.

RESULTS

In total, 104 nonpneumonia, 50 SAP and 10 VAP patients were included in the analysis. We found that SAP and VAP patients exhibited significant dynamic differences in the diversity and composition of the oral microbiota and that the magnitude of this dysbiosis and instability increased during hospitalization. Then, by controlling the potential effect of all latent confounding variables, we assessed the changes associated with pneumonia after stroke and explored patients with a lower abundance of Streptococcus were more likely to suffer from SAP. The logistic regression analysis revealed that an increase in specific taxa in the phylum Actinobacteriota was linked to a higher risk of poor outcomes. A model for SAP patients based on oral microbiota could accurately predict 30-day clinical outcomes after stroke onset.

CONCLUSIONS

We concluded that specific oral microbiota signatures could be used to predict illness development and clinical outcomes in SAP patients. We proposed the potential of the oral microbiota as a non-invasive diagnostic biomarker in the clinical management of SAP patients.

CLINICAL TRIAL REGISTRATION

NCT04688138. Registered 29/12/2020, https://clinicaltrials.gov/ct2/show/NCT04688138 .

Emerging role of the host microbiome in neuropsychiatric disorders: overview and future directions

The human body harbors a diverse ecosystem of microorganisms, including bacteria, viruses, and fungi, collectively known as the microbiota. Current research is increasingly focusing on the potential association between the microbiota and various neuropsychiatric disorders. The microbiota resides in various parts of the body, such as the oral cavity, nasal passages, lungs, gut, skin, bladder, and vagina. The gut microbiota in the gastrointestinal tract has received particular attention due to its high abundance and its potential role in psychiatric and neurodegenerative disorders. However, the microbiota presents in other body tissues, though less abundant, also plays crucial role in immune system and human homeostasis, thus influencing the development and progression of neuropsychiatric disorders. For example, oral microbiota imbalance and associated periodontitis might increase the risk for neuropsychiatric disorders. Additionally, studies using the postmortem brain samples have detected the widespread presence of oral bacteria in the brains of patients with Alzheimer's disease. This article provides an overview of the emerging role of the host microbiota in neuropsychiatric disorders and discusses future directions, such as underlying biological mechanisms, reliable biomarkers associated with the host microbiota, and microbiota-targeted interventions, for research in this field.

The Role of the Gut Microbiome in Bipolar Disorder and its Common Comorbidities

Bipolar disorder is a decidedly heterogeneous and multifactorial disease, with significant psychosocial and medical disease burden. Much difficulty has been encountered in developing novel therapeutics and objective biomarkers for clinical use in this population. In that regard, gut-microbial homeostasis appears to modulate several key pathways relevant to a variety of psychiatric, metabolic, and inflammatory disorders. Microbial impact on immune, endocrine, endocannabinoid, kynurenine, and other pathways are discussed throughout this review. Emphasis is placed on this system's relevance to current pharmacology, diet, and comorbid illness in bipolar disorder. Despite the high level of optimism promoted in many reviews on this topic, substantial obstacles exist before any microbiome-related findings can provide meaningful clinical utility. Beyond a comprehensive overview of pathophysiology, this review hopes to highlight several key areas where progress is needed. As well, novel microbiome-associated suggestions are presented for future research.

Neuroinflammation related to the blood-brain barrier and sphingosine-1-phosphate in a pre-clinical model of periodontal diseases and depression in rats

AIM

To explore the potential mechanisms of neuroinflammation (microglia, blood-brain barrier [BBB] permeability, and the sphingosine-1-phosphate [S1P] pathways) resulting from the association between periodontitis and depression in rats.

MATERIALS AND METHODS

This pre-clinical in vivo experimental study used Wistar rats, in which experimental periodontitis (P) was induced by using oral gavages with Porphyromonas gingivalis and Fusobacterium nucleatum. Then, a chronic mild stress (CMS) model was implemented to induce a depressive-like behaviour, resulting in four groups: P with CMS (P+CMS+), P without CMS (P+CMS-), CMS without P (P-CMS+), and control (P-CMS-). After harvesting brain samples, protein/mRNA expression analyses and fluorescence immunohistochemistry were performed in the frontal cortex (FC). Results were analysed by ANOVA.

RESULTS

CMS exposure increased the number of microglia (an indicator of neuroinflammation) in the FC. In the combined model (P+CMS+), there was a decrease in the expression of tight junction proteins (zonula occludens-1 [ZO-1], occludin) and an increase in intercellular and vascular cell adhesion molecules (ICAM-1, VCAM-1) and matrix metalloproteinase 9 (MMP9), suggesting a more severe disruption of the BBB. The enzymes and receptors of S1P were also differentially regulated.

CONCLUSIONS

Microglia, BBB permeability, and S1P pathways could be relevant mechanisms explaining the association between periodontitis and depression.

Impact of local predisposing/precipitating factors and systemic drivers on peri‐implant diseases

BACKGROUND

Strong evidence suggests the infectious nature of peri-implant diseases occurring in susceptible hosts. Epidemiological reports, though, indicate that peri-implantitis is a site-specific entity. Hence, the significance of local factors that may predispose/precipitate plaque accumulation and the impact of systemic drivers that alter the immune response are relevant in the prevention and management of peri-implant disorders.

PURPOSE

The purpose of the present review is to shed light on the significance of local and systemic factors on peri-implant diseases, making special emphasis on the associations with peri-implantitis.

METHODS

The biologic plausibility and supporting evidence aiming at providing a concluding remark were explored in the recent scientific literature for local predisposing/precipitating factors and systemic drivers related to peri-implant diseases.

RESULTS

Local predisposing factors such as soft tissue characteristics, implant position and prosthetic design proved being strongly associated with the occurrence of peri-implant diseases. Hard tissue characteristics, however, failed to demonstrate having a direct association with peri-implant diseases. Robust data points toward the strong link between residual sub-mucosal cement and peri-implant diseases, while limited data suggests the impact of residual sub-mucosal floss and peri-implantitis. Systemic drivers/habits such as hyperglycemia and smoking showed a strong negative impact on peri-implantitis. However, there is insufficient evidence to claim for any link between metabolic syndrome, atherosclerotic cardiovascular disease, and obesity and peri-implant diseases.

CONCLUSION

Local predisposing/precipitating factors and systemic drivers may increase the risk of peri-implant diseases. Therefore, comprehensive anamnesis of the patients, educational/motivational programs and exhaustive prosthetically-driven treatment planning must be fostered aiming at reducing the rate of biological complications in implant dentistry.

Healthy microbiome – a mere idea or a sound concept?

Hundreds of studies in last decades have aimed to compare the microbiome of patients suffering from diverse diseases with that of healthy controls. The microbiome-related component was additionally identified in pathophysiology of many diseases formerly considered to depend only on the host physiology. This, however, opens important questions like: “What is the healthy microbiome?” or “Is it possible to define it unequivocally?”. In this review, we describe the main hindrances complicating the definition of “healthy microbiome” in terms of microbiota composition. We discuss the human microbiome from the perspective of classical ecology and we advocate for the shift from the stress on microbiota composition to the functions that microbiome ensures for the host. Finally, we propose to leave the concept of ideal healthy microbiome and replace it by focus on microbiome advantageous for the host, which always depends on the specific context like the age, genetics, dietary habits, body site or physiological state.

Mental health and periodontal and peri-implant diseases

Mental health disorders, particularly depression and anxiety, affect a significant number of the global population. Several pathophysiological pathways for these disorders have been identified, including the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and the immune system. In addition, life events, environmental factors, and lifestyle affect the onset, progression, and recurrence of mental health disorders. These may all overlap with periodontal and/or peri-implant disease. Mental health disorders are associated with more severe periodontal disease and, in some cases, poorer healing outcomes to nonsurgical periodontal therapy. They can result in behavior modification, such as poor oral hygiene practices, tobacco smoking, and alcohol abuse, which are also risk factors for periodontal disease and, therefore, may have a contributory effect. Stress has immunomodulatory effects regulating immune cell numbers and function, as well as proinflammatory cytokine production. Stress markers such as cortisol and catecholamines may modulate periodontal bacterial growth and the expression of virulence factors. Stress and some mental health disorders are accompanied by a low-grade chronic inflammation that may be involved in their relationship with periodontal disease and vice versa. Although the gut microbiome interacting with the central nervous system (gut-brain axis) is thought to play a significant role in mental illness, less is understood about the role of the oral microbiome. The evidence for mental health disorders on implant outcomes is lacking, but may mainly be through behaviourial changes. Through lack of compliance withoral hygiene and maintenance visits, peri-implant health can be affected. Increased smoking and risk of periodontal disease may also affect implant outcomes. Selective serotonin reuptake inhibitors have been linked with higher implant failure. They have an anabolic effect on bone, reducing turnover, which could account for the increased loss.

No bidirectional relationship between depression and periodontitis: A genetic correlation and Mendelian randomization study

Background

Observational and in-vivo research suggested a bidirectional relationship between depression and periodontitis. We estimated the genetic correlation and examined directionality of causation.

Methods

The study used summary statistics from published genome wide association studies, with sample sizes ranging from 45,563 to 797,563 individuals of European ancestry. We performed linkage disequilibrium score regression (LDSC) to estimate global correlation and used Heritability Estimation from Summary Statistics (ρ-HESS) to further examine local genetic correlation. Latent Heritable Confounder Mendelian randomization (LHC-MR), Causal Analysis using Summary Effect estimates (CAUSE), and conventional MR approaches assessed bidirectional causation.

Results

LDSC observed only weak genetic correlation (rg = 0.06, P-Value = 0.619) between depression and periodontitis. Analysis of local genetic correlation using ρ-HESS did not reveal loci of significant local genetic covariance. LHC-MR, CAUSE and conventional MR models provided no support for bidirectional causation between depression and periodontitis, with odds ratios ranging from 1.00 to 1.06 in either direction.

Conclusions

Results do not support shared heritability or a causal connection between depression and periodontitis.

A genetic association study reveals the relationship between the oral microbiome and anxiety and depression symptoms

BACKGROUND

Growing evidence supports that alterations in the gut microbiota play an essential role in the etiology of anxiety, depression, and other psychiatric disorders. However, the potential effect of oral microbiota on mental health has received little attention.

METHODS

Using the latest genome-wide association study (GWAS) summary data of the oral microbiome, polygenic risk scores (PRSs) of 285 salivary microbiomes and 309 tongue dorsum microbiomes were conducted. Logistic and linear regression models were applied to evaluate the relationship between salivary-tongue dorsum microbiome interactions with anxiety and depression. Two-sample Mendelian randomization (MR) was utilized to compute the causal effects between the oral microbiome, anxiety, and depression.

RESULTS

We observed significant salivary-tongue dorsum microbiome interactions related to anxiety and depression traits. Significantly, one common interaction was observed to be associated with both anxiety score and depression score, Centipeda periodontii SGB 224 × Granulicatella uSGB 3289 (P _{depressionscore} = 1.41 × 10^-8, P _anxietyscore = 5.10 × 10^-8). Furthermore, we detected causal effects between the oral microbiome and anxiety and depression. Importantly, we identified one salivary microbiome associated with both anxiety and depression in both the UKB database and the Finngen public database, Eggerthia (P _{IVW - majordepression - UKB} = 2.99 × 10^-6, P _{IVW - Self - reportedanxiety/panicattacks - UKB} = 3.06 × 10^-59, P _{IVW - depression - Finngen} = 3.16 × 10 , - 16 P _{IVW - anxiety - Finngen} = 1.14 × 10^-115).

CONCLUSION

This study systematically explored the relationship between the oral microbiome and anxiety and depression, which could help improve our understanding of disease pathogenesis and propose new diagnostic targets and early intervention strategies.