Periodontal Immunology - Aetiology Flashcards
(23 cards)
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
Inflammophilic
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
