Periodontal Immunology - Aetiology Flashcards Preview

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Flashcards in Periodontal Immunology - Aetiology Deck (23)
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Describe gingivitis

Acute inflammation localised to gingival tissues
Normal physiological response to infection or injury


Describe periodontitis

Chronic inflammation of the gingival tissues and supporting periodontal structures
Pathological inflammatory response associated with tissue destruction


What role does saliva play in immune defence of the oral cavity

It bathes the oral surfaces, containing antimicrobial proteins, peptides, and antibodies which are designed to target and inhibit microbial growth


Why is tooth brushing necessary

To remove the accumulated oral biofilm


What are the functions of the gingival epithelium

Physical barrier preventing microbes from gaining access to underlying tissues
Functional barrier so can detect and respond to microbial challenge through the activation of TLRs, this will lead to activation of inflammatory pathways and the release of antimicrobial peptides, cytokines and chemokines


What is the function of gingival crevicular fluid

Predominant immune defence in the subgingival portion of the tooth - contains an array of antimicrobial factors designed to limit microbial growth in the tooth surface


Where is gingival crevicular fluid released

From the gingival margin


What is the primary aetiological factor in periodontal disease

Poor oral hygiene


Describe the oral biofilm ecology

First species to colonise the teeth are gram positive strep species eg - strep gordonii, strep oralis
They modify the environment by creating new attachment sites for different types of species which can either bind directly to the microbes or produce metabolites that help support the growth of these later species


What is the rule of thumb for bacteria colonising in the oral cavity

Early colonisers are aerobic, gram positive while later colonisers are typically gram negative anaerobic species


What are the main microbial complexes found in subgingival plaque

Red complex - bacterial species most commonly isolated from diseased sites
Periodontal pathogens - implying that they cause the disease, but can be found in healthy sites in lower numbers
Orange complex - significantly associated with disease parameters but less than red


What bacteria are found in the red complex

P. gingivalis
T. forsythia
T. denticola


Describe periodontal pathogens

Present at low numbers in healthy sites, increased numbers in diseased sites but can be absent in diseased sites


What is polymicrobial dysbiosis

A community of microorganisms that work together to actively disrupt the normal homeostatic balance in the oral cavity for their own benefit


What can disrupt homeostasis in the mouth

Changes in the biofilm through either accumulation of bacterial plaque or acquisition or transmission of periodontal pathogens


What is the outcome of changes in the oral biofilm

These changes lead to inflammation that manifests as gingivitis


How does chronic inflammation affect the oral biofilm

It will give some of the species a competitive advantage allowing them to persist while others will succumb to the inflammation


Describe commensal bacteria

Predominant in health but incompatible with inflammation


What shift occurs in the oral biofilm during periodontitis

A shift towards a dysbiotic biofilm that actively disrupts homeostasis and stimulated inflammation for its own benefit to gain access to nutrients


What is a virulence factor

Molecules produced by bacteria enabling them to evade and subvert the immune responses


What are common virulence factors of P. gingivalis

Asaccharolytic - breaks down proteins and peptides for nutrients
Gingipains - expresses protease which actively degrade host proteins for nutrients
Atypical LPS


Describe an atypical LPS

TRL4 antagonist - blocks signalling of TLR4 which would normally respond to LPS, so you don’t get activation of information through that pathway


Why can P. gingivalis be detected in the biofilm during health

It only expresses its full range of virulence factors under inflammatory conditions