Evolución del microbioma oral: de eubiosis a disbiosis

The Importance of Oral Health

Commitment to Oral Health

• Denit emphasizes the significance of maintaining a healthy mouth, which impacts overall well-being and quality of life.

• There is a global need for effective solutions and products to enhance oral health, highlighting ongoing efforts in this area.

Research and Innovation

• Denit is committed to researching and innovating new solutions for oral health across different life stages, recognizing individual uniqueness.

• The session introduces the topic of oral microbiome evolution, focusing on dysbiosis and its implications.

Introduction to the Session

Speakers and Format

• Dr. Iago Leira from the University of Santiago de Compostela joins the discussion alongside another speaker from Denit.

• Attendees are encouraged to submit questions during the session for potential answers at the end.

Understanding Microorganisms in Oral Health

Evolutionary Perspective

• Microorganisms were among the first inhabitants on Earth, co-evolving with their hosts over time.

• In humans, various microorganisms inhabit the oral cavity; advancements in microbiological techniques have revealed diverse species beyond just bacteria.

Complexity of Oral Environment

• The oral cavity presents a challenging habitat due to fluctuating nutrient levels, pH changes, saliva flow, and mechanical forces affecting microbial adherence.

Biofilm Formation in Oral Cavity

Structure and Functionality

• Microorganisms form structured units known as biofilms for protection against environmental challenges; primary colonizers initiate this process by synthesizing a protective matrix.

• Mature biofilms can disperse parts of their community to colonize new surfaces while evading immune responses.

Biofilm Characteristics

• Biofilms primarily develop on tooth surfaces (both supragingival and subgingival), ensuring survival through strong adhesion and resistance to adverse conditions.

Dynamics Within Biofilms

Metabolic Interactions

• Regular hygiene practices are crucial for managing biofilm thickness; excessive growth leads to increased resistance against removal methods.

Environmental Stratification

• As biofilms mature, they exhibit gradients in oxygen levels, pH variations, and metabolic requirements that stratify microbial populations within them.

Biofilm Dynamics and Microbial Interactions

Role of Biofilms in Microbial Proliferation

• Biofilms expose low-affinity proteins that facilitate the growth of otherwise non-proliferative microorganisms, enhancing species diversity.

• Horizontal gene transfer occurs through direct cell contact or via bacteriophages, promoting the spread of antimicrobial resistance genes among biofilm species.

Antagonistic Interactions within Biofilms

• Microorganisms in biofilms compete for resources, releasing inhibitory molecules such as bacteriocins and hydrogen enzymes to eliminate competitors.

Clinical Implications of Biofilm Resistance

• The biofilm matrix provides mechanical resistance against removal methods, complicating treatment efforts with antibiotics that may be trapped within the matrix.

• Different body sites harbor unique microbiota; oral microbiota is particularly diverse due to various niches like teeth and mucosal surfaces.

Homeostasis and Symbiosis in Oral Microbiota

• Healthy oral microbiota maintains a state known as eubiosis, where microbial actions are balanced with host responses, preventing aggressive inflammatory reactions.

• Eubiotic microbiota helps prevent pathogenic colonization; antibiotic use can disrupt this balance, leading to opportunistic infections.

Factors Influencing Oral Microbiota Development

• Saliva plays a crucial role in maintaining oral health by providing nutrients and antimicrobial agents essential for microbial balance.

• The initial acquisition of oral microbiota begins at birth, influenced by delivery method (cesarean vs. natural), maternal antibiotic use during pregnancy, and breastfeeding practices.

Evolution of Individual Microbiomes Over Time

• By 18 months, an infant's microbiome shows significant similarity to their mother's while still differing from other adults; complexity increases with age due to diet and environmental factors.

• The introduction of teeth marks a shift in microbial composition as new species colonize the mouth; stabilization occurs only in adulthood.

Impact of Delivery Method on Microbial Composition

• Studies indicate distinct differences in oral microbiota based on delivery method: cesarean births show different microbial profiles compared to natural births.

Dietary Influence on Microbiome Convergence

• As children grow, dietary choices lead to convergence in microbiome composition regardless of initial differences from birth type or feeding method.

This structured overview captures key insights from the transcript regarding biofilms' roles in microbial interactions and their implications for health. Each point is linked directly to its corresponding timestamp for easy reference.

Microbiota and Oral Health: Understanding the Transition from Childhood to Adulthood

The Development of Microbiota Through Dentition Stages

• The microbiota evolves significantly from early childhood through adolescence to adulthood, with a notable portion acquired before the first tooth erupts or during teething.

Hypotheses Explaining Oral Diseases

• Early 20th-century theories suggested that oral diseases stemmed from biofilm enrichment regardless of bacterial species due to limited identification techniques. This is known as the non-specific plaque hypothesis.

• In 1976, the specific plaque hypothesis emerged, proposing that certain pathogens are responsible for initiating diseases like caries, initially linked to Streptococcus species.

• The ecological plaque hypothesis is currently favored; it posits that external pressures (e.g., frequent sugar intake) alter microbial communities, leading to an acidic environment conducive to caries development.

Role of Sugar in Microbial Dynamics

• Increased sugar consumption enhances acidogenic bacteria's activity, lowering pH and inhibiting neutral pH-adapted commensals while promoting acidophilic species' growth, resulting in demineralization and cavity formation.

• Streptococcus mutans is commonly associated with caries but not exclusively necessary for cariogenic communities; other species can also contribute significantly under certain conditions.

Advances in Understanding Microbial Communities

• Recent studies utilizing advanced omics technologies have identified additional species associated with caries beyond traditional methods, including Prevotella, Atopobium, and others. Some cases of caries occur without S. mutans, indicating its non-essential role in all cariogenic scenarios.

Transitioning from Caries to Periodontal Disease

• The key pathogen hypothesis proposed in 2012 suggests that specific low-abundance species can disproportionately influence community dynamics and disease progression despite their scarcity. However, gingivitis has been more closely linked to overall plaque quantity than specific pathogens thus far.

• Authors later updated this model to include polymicrobial synergy and dysbiosis concepts where pathogenic potential arises under certain conditions rather than being inherent traits of specific microbes alone. This leads to inflammation through pro-inflammatory molecules released by these pathogens when conditions permit their proliferation.

Factors Influencing Dysbiosis and Oral Health

• Dysbiosis can arise from various factors such as stress, ethnicity, diet composition, geographical location, etc., disrupting the symbiotic relationship between host and microbiota which may lead to oral diseases if prolonged. Conditions like diabetes or obesity can exacerbate these risks by affecting saliva flow or immune response over time.

Impact of Smoking on Oral Microbiota

Effects of Immunosuppression and Environmental Factors

• Discusses how immunosuppression, hormonal changes (e.g., during pregnancy), and smoking can alter oral microbiota. Antibiotic use may create under-colonized areas in the community, allowing pathogenic entry.

Influence of Smoking on Microbial Diversity

• Highlights studies showing that smoking decreases microbial diversity and increases the proportion of pathogens within the oral microbiota.

Differences in Microbiota Between Smokers and Non-Smokers

• Observations indicate distinct differences in oral microbiota between smokers and non-smokers, with smokers exhibiting dysbiosis regardless of periodontal health status.

Risk Factors for Periodontal Disease

• Summarizes a model illustrating how behavioral, environmental, genetic, or epigenetic risk factors contribute to periodontal disease through interactions with the host's immune response.

Immune Response Dynamics

• Describes how a healthy state maintains symbiosis between microbiota and host immunity. The balance shifts when dysbiosis occurs due to increased microbial pressure leading to an exaggerated immune response.

Progression from Dysbiosis to Chronic Inflammation

Transition from Health to Dysbiosis

• Explains that prolonged exposure to risk factors leads to dysfunctional immune responses where microbiota no longer resolve inflammation but instead extract nutrients from the host.

Chronic Inflammation Consequences

• Details how chronic inflammation results in tissue destruction as dysbiotic conditions persist, indicating a gradual transformation rather than a binary state between healthy and unhealthy microbiota.

Pathogen Emergence Under Favorable Conditions

• Discusses how certain conditions allow opportunistic pathogens to thrive, altering community dynamics and potentially introducing new species into the microbiome.

Microbial Community Characterization Techniques

Clustering of Microbial Species by Health Status

• Introduces clusters representing different stages of health: homeostasis with beneficial species versus inflammatory states enriched with pathogenic species like Fusobacterium.

Importance of Omics Technologies

• Emphasizes advancements in omics technologies since 2012 for studying microbial communities' composition, potential activities, and products beyond traditional methods like PCR or culturing.

Core Taxa Concept in Microbiome Studies

Understanding Core Taxa Across Conditions

• Defines "core taxa" as those maintaining similar prevalence across healthy and diseased states. This indicates that not only harmful species increase but also some taxa adapt without significant change in relative abundance.

Role of Polymicrobial Synergy Hypothesis

• Concludes that dysbiotic microbiomes contribute to diseases like periodontitis through synergistic functions involving signaling pathways rather than just shifts in microbial composition.

Transcript Summary Analysis of Bacterial Expression in Health and Disease

Transcriptomic Analysis of Bacterial Expression

• The transcriptomic analysis shows varying levels of bacterial expression during health and disease phases, indicating that not all pathogens activate simultaneously; rather, it is a gradual process.

• Specific bacteria like Fastidioso increase their transcriptional activity during health stages, while others like Noatum only show increased expression at later stages, highlighting diverse responses among different species.

Factors Influencing Disease Progression

• A multitude of virulence factors are identified, with some species increasing significantly (e.g., over 300 factors for Falis) when transitioning from health to disease states.

• Transcriptional changes correlate with biological processes; for instance, dysbiotic microbiota in periodontitis exhibits enhanced flagellar motility and iron metabolism but reduced potassium ion transport.

Microbiota in Implantation Regions

• The microbiota associated with peri-implant regions differs from periodontal regions due to the unique surface characteristics of titanium implants and epithelial differences.

• Certain genera are frequently linked to diseases; however, each condition has specific species more commonly associated with it.

Comparative Analysis of Healthy vs. Diseased States

• Genera such as Streptococcus appear consistently across healthy and diseased conditions, while others like Neisseria are more prevalent in healthy states.

• Species such as Aggregatibacter actinomycetemcomitans are closely tied to periodontitis, whereas others like Prevotella are linked to peri-implant diseases.

Clinical Perspectives on Oral Microbiome Impact

Overview of Presentation Topics

• The presentation will cover the oral microbiome's role in gingivitis and periodontitis, treatment effects on dysbiosis, and implications for systemic health related to these conditions.

Gingivitis Mechanisms

• A typical case of gingivitis shows inflammation without loss of attachment or bone loss; radiographic evidence supports this observation.

• Historical studies have demonstrated that withholding oral hygiene leads to gingivitis development within 21 days due to plaque accumulation.

Microbial Changes During Gingivitis Development

• As plaque accumulates over time, there is a shift from gram-positive cocci to gram-negative bacilli and other pathogenic bacteria such as Fusobacterium nucleatum, which serves as a bridge between different bacterial groups.

Progression Towards Periodontitis

• Without intervention after 21 days, gingival inflammation can progress into irreversible lesions characterized by bone loss and attachment loss. This progression varies among individuals based on their immune response.

Understanding the Role of Host Response in Periodontal Disease

The Connection Between Inflammation and Periodontitis

• Discusses how an inflammatory lesion can be encapsulated, potentially preventing progression to periodontitis. The host's immune response may influence this outcome.

Study on Gingivitis and Mucositis

• A 2017 study involving subjects with both implants and natural teeth examined the experimental models of gingivitis and peri-implant mucositis.

Findings on Microbial Load and Diversity

• As gingival inflammation increased, a corresponding rise in subgingival microbial load was observed, indicating a relationship between inflammation and microbial diversity.

Correlation Between Microbiome Changes and Clinical Parameters

• Positive linear correlation noted between microbiome changes, pro-inflammatory mediators, and clinical parameters typical of gingivitis.

Specific Bacterial Associations with Inflammation

• Identifies specific bacteria (e.g., Fusobacterium nucleatum, Porphyromonas gingivalis) that correlate strongly with clinical parameters related to inflammation.

Characteristics of Periodontitis

Classic Signs of Periodontitis

• Describes classic signs such as deep probing depths, bleeding on probing, and radiographic evidence of bone loss associated with periodontitis.

Irreversibility of Tissue Loss

• Emphasizes that once insertion is lost due to periodontitis, it is typically irreversible unless regenerative techniques are applied.

Microbiome Analysis in Periodontal Health vs. Disease

Differences in Bacterial Populations

• Analyzes differences in bacterial populations between sites diagnosed with periodontitis versus healthy periodontal sites.

Prevalence of Specific Bacteria

• Highlights that Treponema species are more prevalent in periodontitis while Actinomyces species dominate healthy periodontal conditions.

Impact of Pocket Depth on Oral Microbiome

Relationship Between Pocket Depth and Bacterial Diversity

• Observations indicate deeper pockets harbor more Gram-negative bacteria, leading to greater diversity compared to shallower pockets or healthy sites.

Risk Factors for Periodontitis

Influence of Smoking on Oral Microbiome

• Discusses how smoking negatively impacts oral microbiome diversity, contributing to dysbiosis even without existing periodontal disease.

Diagnostic Potential of Subgingival Microbiome Profiles

• Introduces research exploring the diagnostic potential of subgingival microbiome profiles for predicting periodontitis risk.

Periodontitis Progression and Microbiome Insights

Understanding Periodontitis and Microbiome Profiles

• The study found that 80% of analyzed subgingival microbiome profiles could distinguish between sites with periodontitis and those without, as well as predict disease progression in affected areas.

• A more dysbiotic microbiome profile was associated with a higher likelihood of periodontitis progression compared to a less dysbiotic one.

Effectiveness of Non-Surgical Periodontal Treatment

• Non-surgical periodontal treatment is effective, achieving successful outcomes in approximately 75% of periodontal pockets through proper subgingival instrumentation alone.

• Meta-analysis indicated that deeper pockets (greater than 4 mm) showed better clinical results post-treatment, reducing pocket depth by nearly 3 mm after 6 to 8 months.

Impact on Oral Microbiome Post-Treatment

• A study published in 2021 involving 45 patients demonstrated that non-surgical periodontal treatment led to an increase in bacteria associated with periodontal health while decreasing those linked to disease states.

• Despite changes in the oral microbiome, no statistically significant correlation was found between these alterations and clinical treatment responses; however, reductions in local inflammation markers were observed.

Site-Specific Responses to Treatment

• The response to periodontal treatment appears site-specific rather than uniform across the entire mouth; some teeth exhibited significant microbiota changes while others did not show notable differences post-treatment.

• Clinical improvements were defined by at least a 2 mm gain in insertion or reduction in probing depth without bleeding, indicating localized effectiveness of the treatment approach.

Mucositis Periimplantaria: An Overview

• Mucositis periimplantaria is characterized by inflammation of periimplant tissues without evident bone loss; it mirrors gingivitis but occurs around implants where probing depths can be considered physiological even at greater measurements (4–5 mm).

• Experimental models for mucositis have been developed similarly to gingivitis models, showing local tissue responses akin to those seen in periodontal conditions when induced experimentally.

Microbiome and Peri-implantitis: Insights from Recent Studies

Overview of Microbial Changes in Peri-implantitis

• A study published in 2017 analyzed implants with induced peri-implant mucositis, revealing results similar to those seen in experimental gingivitis. The subgingival microbial load increases as inflammation is induced.

• Pro-inflammatory mediators are overexpressed as inflammation progresses, indicating a direct correlation between microbial changes and inflammatory responses.

Structural Changes in the Microbiome

• Initial changes in microbiome structure at 7 and 14 days are subtle; however, significant interactions among bacterial groups emerge towards the end of the experiment.

• Specific bacteria such as Porphyromonas, Fusobacterium, and Selenomonas show positive correlations with clinical parameters of inflammation and plaque levels.

Understanding Peri-implantitis

• Peri-implantitis is increasingly recognized as a significant issue for dentists, potentially becoming a new pandemic due to the rising number of implants placed.

• Clinical signs include deep probing depths and significant bleeding upon probing, which can be more pronounced than in natural teeth. Radiographic evidence often shows aggressive bone loss compared to periodontitis.

Biological Differences Between Periodontitis and Peri-implantitis

• The biological differences between periodontitis and peri-implantitis stem from the absence of connective tissue fibers that protect bone around implants. This lack leads to increased susceptibility to infection.

Impact of Oral Microbiome on Lesions

• A multicenter study published in the Journal of Clinical Periodontology found a linear correlation between probing depth and microbial diversity index; deeper pockets had higher dysbiotic microbiota diversity.

Bacterial Interactions in Deep Pockets

• Certain bacteria like Frenetobacterium interact significantly within deep periodontal pockets. These bacteria differ from those typically found in periodontitis lesions, suggesting distinct pathogenic mechanisms.

Challenges in Treating Peri-implantitis

• Treatment challenges arise due to implant surface characteristics that differ from natural teeth. The involved bacteria may also vary, necessitating different treatment approaches.

Effects of Tobacco on Microbiome Health

• Tobacco use negatively impacts peri-implant tissues' microbiome health, leading to increased dysbiosis compared to non-smokers. This complicates clinical management of peri-implant lesions.

Non-surgical Management Approaches

• A study indicated minimal changes post-non-surgical treatment (subgingival debridement), highlighting persistent bacterial interactions that maintain biofilm structure resistant to mechanical treatment.

Research Directions at Santiago University

• Ongoing research focuses on non-surgical methods for managing advanced peri-implant lesions, emphasizing the need for adjunctive therapies alongside standard treatments.

Antibiotic Use in Implant Dentistry

Importance of Systemic Antibiotics

• The discussion emphasizes the necessity of systemic antibiotics to disinfect not only dental implants but also surrounding tissues.

• It is noted that despite performing curettage, a systemic antibiotic remains essential. Common choices include metronidazole for strict anaerobic gram-negative bacteria or azithromycin due to its antibacterial and anti-inflammatory properties.

Treatment Approaches for Peri-implantitis

• The speaker argues that mechanical treatment alone is insufficient for managing peri-implant infections, contrasting it with periodontitis treatment which may not require systemic antibiotics.

Link Between Periodontal Disease and Systemic Health

• There is a long-standing association between periodontal diseases like periodontitis and various systemic diseases, including cardiovascular issues, diabetes, and certain cancers.

• Chronic low-grade inflammation from periodontal disease can relate to non-communicable chronic inflammatory diseases, highlighting the need for further research into these connections.

Microbiome's Role in Periodontal Disease

Evidence Linking Microbiome to Neurodegenerative Diseases

• Recent studies have shown a solid epidemiological link between periodontitis and neurodegenerative conditions such as Alzheimer's disease.

Research Findings on Microbiome Alterations

• A study published in the Journal of Clinical Periodontology analyzed patients with both periodontitis and Alzheimer’s disease versus cognitively healthy individuals. Significant alterations were found in the microbiome at subgingival sites among those with Alzheimer’s.

Specific Bacterial Associations

• Certain bacteria typical of periodontitis were identified as significantly altered in patients with Alzheimer’s. Notably, Fusobacterium nucleatum was highlighted among others.

Holistic Approach to Microbiome Research

Limitations of Focusing on Single Bacterial Types

• The findings suggest that focusing solely on specific bacterial types may be limiting; other less-studied bacteria could play significant roles in the relationship between periodontitis and Alzheimer's disease.

Need for Comprehensive Research Strategies

• A holistic approach is recommended for future research into the microbiome, encouraging exploration beyond traditional bacterial associations to uncover potentially relevant factors.

Conclusions on Oral Microbiome Impact

Key Takeaways from Discussion

• An altered oral microbiome correlates with clinical signs of peri-implant disease.

• Risk factors such as smoking negatively impact oral microbiomes, leading to dysbiosis.

• Treatments aimed at periodontal health can influence oral microbiota composition. Further investigation is needed regarding the role of oral microbiomes in systemic health relationships.