Microbiology

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Questions and Answers

What is the primary causative factor associated with dental caries and periodontal disease?

Oral microorganisms (correct)

Hormonal changes

Dietary habits

Tooth structure

What aspect of biofilm makes it resistant to destruction?

The chemical messengers

Fluid channels

Oxygen supply

Extra-cellular slime layer (correct)

How quickly can biofilm reform after being disrupted?

48 hours (correct)

24 hours

One week

72 hours

Which type of bacteria is associated with forming biofilms in the oral cavity?

Both Gram-positive and Gram-negative bacteria Signup and view all the answers

Which characteristic of biofilm allows for nutrient and waste movement?

Fluid channels Signup and view all the answers

What is the total estimated number of species of oral microorganisms?

700-1000 species Signup and view all the answers

In a biofilm, what type of community structure is formed by the microorganisms?

Inter-dependent organisms Signup and view all the answers

What type of bacteria is primarily found in subgingival plaque?

Gram-negative anaerobic bacteria Signup and view all the answers

What role do chemical messengers play within a biofilm?

Facilitate communication among microbes Signup and view all the answers

What occurs when there is a dynamic equilibrium between dental plaque and host defenses?

Oral health is maintained Signup and view all the answers

What can disturb the balance between bacteria virulence and host response?

Increased amount of plaque Signup and view all the answers

What is a potential consequence of increased pathogenicity of microorganisms in the biofilm?

Increased periodontal tissue damage Signup and view all the answers

How does a compromised host defense contribute to periodontal disease?

It can tilt the balance towards tissue damage Signup and view all the answers

Approximately how many types of bacteria are recognized as significant periodontal pathogens?

12-15 types Signup and view all the answers

When is periodontal damage unlikely to occur?

When host response is strong Signup and view all the answers

Which of the following statements is true regarding the balance in periodontal health?

Microbial virulence must exceed host response for damage. Signup and view all the answers

What role does the host's immune system play in periodontal health?

It helps maintain a balance against bacterial virulence. Signup and view all the answers

Which condition does NOT contribute to tissue destruction in periodontitis?

Strong host defense mechanisms Signup and view all the answers

What is the relationship between periodontal pathogens and virulence factors?

Virulence factors enhance the pathogenicity of the bacteria. Signup and view all the answers

Which bacterium is associated with aggressive periodontitis and has the ability to produce leukotoxin?

Aggregatibacter actinomycetemcomitans Signup and view all the answers

What is a key characteristic of the virulence factor produced by T.denticola?

It degrades cytokines. Signup and view all the answers

Which hypothesis suggests that periodontal disease is caused by specific bacterial species?

Specific Plaque Hypothesis Signup and view all the answers

How does Aggregatibacter actinomycetemcomitans primarily disrupt host defenses?

Producing leukotoxin Signup and view all the answers

What role do chemical mediators play in the immune system's response to infection?

They assist in the activation of the immune response. Signup and view all the answers

What is the effect of T.denticola on PMNs during the immune response?

It inhibits their migration. Signup and view all the answers

Which of the following is NOT true about Aggregatibacter actinomycetemcomitans?

It is an anaerobic bacterium. Signup and view all the answers

Which hypothesis emphasizes the ecological balance between bacteria and host responses in periodontal disease?

Ecological Plaque Hypothesis Signup and view all the answers

What is a consequence of the virulence factors produced by T.denticola?

Delayed immune responses Signup and view all the answers

What is a common outcome when fibronectin-binding components are disrupted?

Reduced host defense effectiveness Signup and view all the answers

What does the Non Specific Plaque Hypothesis primarily suggest about plaque?

Only high amounts of plaque are implicated in periodontal disease. Signup and view all the answers

Which of the following accurately critiques the Non Specific Plaque Hypothesis?

Patients with high plaque levels always experience tissue destruction. Signup and view all the answers

What is the key shift described in the Specific Plaque/Microbial Shift Hypothesis?

From beneficial microbes to harmful pathogens. Signup and view all the answers

What is suggested by Socransky's Microbial Complexes regarding periodontal diseases?

Different diseases are linked to varying groups of bacteria. Signup and view all the answers

What common misconception is highlighted about patients with high amounts of plaque?

They might not progress to periodontal disease. Signup and view all the answers

Which key aspect differentiates the Specific Plaque Hypothesis from the Non Specific Plaque Hypothesis?

Focus on the quantity of plaque rather than the quality of bacteria. Signup and view all the answers

Which statement about gingivitis and periodontitis progression is true?

Most cases of gingivitis do not lead to periodontitis. Signup and view all the answers

What is a characteristic of anaerobic bacteria in the progression of periodontal disease?

They can lead to significant tissue destruction. Signup and view all the answers

What outcome is associated with the presence of specific pathogenic bacteria?

Reduction in gingival inflammation. Signup and view all the answers

What primarily triggers the changes in microbial types leading to periodontal destruction?

Shift in local environment Signup and view all the answers

Which of the following changes in the subgingival environment favors pathogenic bacteria?

Increased GCF flow and decreased oxygen concentration Signup and view all the answers

What is the role of gingival crevicular fluid (GCF) in microbial ecology?

It changes microbial ecology and enables growth of pathogenic bacteria. Signup and view all the answers

According to the Microbial Homeostasis - Host Response Hypothesis, what is primarily triggered by a pathogenic biofilm community?

Uncontrolled host response Signup and view all the answers

What factors are recognized as influencing the start and progression of periodontal disease?

Genetic variations, inflammatory immune response, and environmental factors Signup and view all the answers

What effect does subgingival debridement have on the microbial environment?

Reduces the number of pathogens in the ecosystem Signup and view all the answers

Study Notes

Oral Microbiology

There are between 700-1000 species of oral microorganisms
Some oral microorganisms are beneficial while others are pathogenic
Oral microorganisms can be categorized by:
- Gram staining (Gram positive and Gram negative)
- Oxygen requirements (facultative and anaerobic)

Biofilm

Biofilm is a primary causative factor of caries and periodontal disease
Dental plaque is a type of biofilm
Biofilm is a community of interdependent organisms growing together on a surface
Biofilm has an extra-cellular slime layer that provides protection for the microbes within
Biofilm can reform within 48 hours

Periodontal Disease

Periodontal disease is caused by an imbalance between host defenses and bacterial virulence
When there is an increase in pathogenicity or a decrease in host defenses, the balance can be tipped toward tissue damage
Periodontal pathogens can cause tissue damage via several mechanisms:
- Producing enzymes that can breakdown the periodontal tissues
- Producing toxins that can kill or damage host cells
- Disrupting the host defenses
- Preventing wound healing
There are around 12 - 15 types of bacteria commonly associated with periodontal disease

Theories on the Role of Bacteria in Periodontal Disease

There are several hypotheses about how bacteria contribute to periodontal disease, including:
- Non-specific plaque
- Specific plaque
- Ecological plaque
- Microbial homeostasis-host response
- Keystone pathogen - host response

Non-Specific Plaque Hypothesis

This hypothesis states that accumulation of dental plaque on tooth surfaces leads to inflammation and periodontal disease
This hypothesis is considered outdated

Issues with Non-Specific Plaque Hypothesis

This hypothesis doesn't explain why some patients with heavy plaque don't develop periodontal disease
This hypothesis doesn't explain why some patients with light plaque experience significant periodontal destruction.

Specific Plaque/Microbial Shift Hypothesis

This hypothesis proposes the microbial composition of plaque is more important than the amount
This hypothesis suggests that as periodontal disease develops, there is a shift in the oral microbiota, from beneficial bacteria (Gram-positive) to pathogenic bacteria (Gram-negative)
This hypothesis supports the theory that different periodontal conditions are caused by specific bacteria

Ecological Plaque Hypothesis

This hypothesis proposes that changes in the subgingival environment can trigger the growth of pathogenic bacteria
An inflammatory response caused by non-specific bacteria can alter the local environment, favoring growth of pathogenic bacteria
This hypothesis highlights the importance of the subgingival environment in influencing the types of bacteria present

Support for the Ecological Plaque Hypothesis

Sites with deeper pockets and bleeding on probing have increased gingival crevicular fluid (GCF)
GCF changes the subgingival microbial ecology by providing nutrients and altering the local environment
Subgingival debridement can alter the ecosystem, reducing the number of pathogens and decreasing the flow of gingival crevicular fluid

Microbial Homeostasis-Host Response Hypothesis

This hypothesis proposes that pathogenic bacterial biofilm communities trigger an uncontrolled host response, leading to damage to the periodontal tissues
Both genetic variations and inflammatory immune responses contribute to the development and progression of periodontal disease
This is a more contemporary view that considers the interplay between host and microbial factors

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Description

This quiz explores the vast world of oral microorganisms, their classification, and their roles in oral health and disease. Topics include biofilm formation and its implications for caries and periodontal disease. Test your knowledge on how microbial communities impact oral health.

Microbiology - periodontal disease hard

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