Periodontal Disease Microbiology Quiz

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Questions and Answers

What role do systemic diseases play in oral health?

They are only relevant during childhood.

They have no impact on oral health.

They can exacerbate oral conditions like periodontal disease. (correct)

They eliminate the risk of oral infections completely.

Which of the following describes the primary cause of periodontal disease?

Genetic predisposition alone

Plaque biofilm formation and immune response (correct)

Fluoride treatments

Poor oral hygiene and diet

How do virulence factors of oral microorganisms contribute to periodontal disease?

They promote inflammation and tissue damage. (correct)

They enhance the immune response.

They solely function in dental plaque removal.

They prevent bacterial colonization.

What is a key transition observed in the microbial community from gingival health to periodontal disease?

Decrease in bacterial diversity Signup and view all the answers

Which of the following is a potential route of transmission for infectious agents in dental practice?

Direct contact with saliva of infected patients Signup and view all the answers

Which of the following factors is NOT associated with the initiation and progression of periodontal disease?

Regular dental check-ups Signup and view all the answers

What is identified as the primary cause of tissue destruction in periodontal disease according to current understanding?

Uncontrolled host inflammatory response Signup and view all the answers

In the context of periodontal disease, what does the term 'keystone species' refer to?

Microbes that trigger a dysbiotic biofilm shift Signup and view all the answers

Which aspect is NOT considered a part of the multifactorial aetiology of periodontal disease?

Genetic mutations unrelated to occlusion Signup and view all the answers

What role do environmental factors play in the development of periodontal disease?

They interact with microbial and host factors to influence disease. Signup and view all the answers

What is the proposed relationship between biofilm stability and periodontal health?

Stable biofilm microbiota is associated with health. Signup and view all the answers

According to Page and Schroeder's hypothesis, what is necessary for gingivitis to progress to periodontitis?

An unknown factor altering the biofilm-host balance. Signup and view all the answers

Which of the following is considered an important host defence factor in periodontal disease?

Presence of PMN cells Signup and view all the answers

Which types of bacteria are primarily recognized pathogens causing periodontal breakdown?

Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans Signup and view all the answers

What characterizes the biofilm associated with dental plaque?

It consists of inter-dependent organisms that grow on a surface. Signup and view all the answers

Which factor is least likely to disturb the equilibrium between dental plaque and host defenses?

Decreased amount of plaque Signup and view all the answers

Which virulence factor is produced by Porphyromonas gingivalis that plays a role in periodontal disease?

Proteinases such as gingipains that digest tissue proteins Signup and view all the answers

What distinguishes Gram-positive bacteria from Gram-negative bacteria in the context of oral microorganisms?

Gram-positive bacteria have a thicker peptidoglycan layer. Signup and view all the answers

In what condition do subgingival microbes typically exist?

They exist only loosely adherent rather than tightly attached. Signup and view all the answers

What is a common consequence of a disturbed equilibrium in oral health?

Progression to periodontitis Signup and view all the answers

Which of the following is NOT a characteristic of biofilms in dental plaque?

They are formed exclusively by pathogenic bacteria. Signup and view all the answers

Study Notes

Periodontal Disease Microbiology

Periodontal disease is a multifactorial disease with different components influencing its development.
Microbial factors include the presence of specific bacteria and their virulence factors.
Environmental factors include smoking, poor oral hygiene, plaque-retentive factors, pre-existing pockets and other factors.
Host defence factors can include compromised immune responses, neutrophil defects, and genetic factors.

Dental Plaque and Biofilm

Dental plaque is a biofilm, a community of inter-dependant organisms that grow on a surface, often containing more than 700 bacterial species.
Dental plaque contains both gram-positive and gram-negative bacteria, as well as facultative and anaerobic bacteria.
The composition of dental plaque shifts as the disease progresses.
In health, there's a dynamic equilibrium between dental plaque and the host defenses, however, this equilibrium is disturbed in periodontitis.
due to: ØAn increased amount of plaque

ØIncrease in pathogenicity of the micro-organisms in the biofilm

ØCompromised host defence

Key Bacteria in Periodontal Disease

About 12-15 types of bacteria have been identified as particularly associated with periodontal destruction, known as periodontal pathogens.
Four key pathogens include Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), and Aggregatibacter actinomycetemcomitans (Aa).
Porphyromonas gingivalis (Pg) produces proteinases called gingipains, which can digest tissue proteins for nutrients and help the bacterium evade host defenses.

Virulence Factors

Proteinases such as gingipains, produced by Pg . Can digest tissue proteins for nutrient and to destroy host defences such as antibodies.
Endotoxins (also called lipopolysaccharide) produced by Gram-negative organisms
Haemagglutination of RBC by e.g. Pg can release haem for nutrient and also help the bacteria to adhere

Fimbraie and Tissue invasion

•These virulence factors can aid bacterial binding to epithelium, thus aiding tissue invasion. e.g. Pg.

•Once the bacterium has invaded a host cell it can be safe from host defences and may be more able to replicate.

Porphyromonas gingivalis

•Gram-negative bacillus, anaerobe, non-saccharolytic, non-motile

•Carbohydrate capsule to resist some host defences

•Produces gingipains: these enable the bacterium to use GCF (gingival crevicular fluid) as a source of nutrients

•LPS (Lipopolysaccharide)

•Haemaglutins & platelet aggregators (? Contributory to heart disease)

•Fimbrae and tissue invasion.

•Can suppress the early PMN (polymorphonuclear leukocytes) response

Tannerella forsythia

•Gram-negative, anaerobic, fusiform. Very difficult to culture

•A particular phenotype (prtH) seems to be found much more often in periodontitis than in health

•Produce proteases and apoptotic-inducing factor (i.e. causes cell death)

Treponema denticola

•Use GCF components for energy, to aid multiplication

•Adherence factors can bind to fibroblasts

•Motile and can invade tissue

•Disruption of host defences by inducing and degrading cytokines

•May delay wound healing by inhibiting migration of PMNs

Keystone Pathogen-Host Response Hypothesis

The Keystone Pathogen-Host Response Hypothesis proposes that a "keystone" species within the biofilm community triggers a dysbiotic shift in the microbial community.
This dysbiotic shift leads to a dysregulated host response, primarily an uncontrolled inflammatory response.
The uncontrolled host response is directly responsible for periodontal tissue damage, rather than the specific bacteria themselves.

Microbial Transition

The oral microbiome undergoes a transition from a mostly beneficial composition in health to a pathogenic composition in periodontitis.
The bacterial composition and abundance change leading to a shift in the microbial community.
This shift from a mostly beneficial to a pathogenic microbiome is associated with the onset and progression of periodontitis.

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Description

Test your knowledge on the microbiology of periodontal disease. This quiz covers the role of microbial, environmental, and host defense factors in the development of periodontal conditions. Understand the intricacies of dental plaque and biofilm composition as well.