Aetiology Of Periodontal Disease Flashcards
Define gingivitis and periodontitis
- Gingivitis
- inflammation localised to the gingival tissues
- acute inflammation
- normal physiological response to infection or injury - Periodontitis
- inflammation of the gingival tissues and supporting periodontal structures
- chronic inflammation
- pathological inflammatory response associated with tissue destruction
What is the function of gingival crevicular fluid?
Primary immune defence for sub gingival tooth surface
• contains
- AMPs
- cytokines
- chemokines
- lactoferrim
- IgG
All designed to inhibit microbial growth on tooth surfaces
How does saliva help with protection against microbes in the mouth?
Saliva contains many components which are designed to inhibit microbial growth
• examples are:
- S-IgA
- lysozyme
- peroxidase
- lactoferrin
- Mucins
- agglutinins
- cyststatins
- histatins
How does the oral mucosa help defend the mouth and teeth from microorganisms?
- Forms a physical barrier that prevents microbes in oral cavity gaining access to underlying tissues
- Is also a functional barrier that can detect and respond to microbial challenge through activation of tool like receptors (TLRs)
- leads to activation of inflammatory pathways
- resulting in release of AMPs, cytokines and chemokines
What is typically the first bacterial species present in a biofilm on the tooth surfaces?
Aerobic Gram positive streptococcal species
- s.gordonii
- s.sanguis or oralis
- s.mitis
What species are typically found later in bio films on tooth surfaces?
Anaerobic gram negative bacteria
- p.gingivalis
- prevotella intermedia
What is the “red complex” of periodontal pathogens?
- P. gingivalis (porphyromas)
- T. forsythia (Tannerella)
- T. denticola (Treponema)
Do specific bacteria species cause periodontal diseases?
• periodontitis does not occur in the absence of bacteria
• difficult to establish role of specific microbes
• periodontal pathogens:
- present at low numbers in healthy sites
- increased numbers in diseased sites
- can be absent from diseased sites
Specific bacteria ARE and aetiological factor but it is not the full picture
What does the term polymicrobial dysbiosis mean in relation to periodontitis?
Periodontitis is associated with a community of microorganisms that work together to actively disrupt the normal homeostatic balance of the oral cavity for their own benefit
What are some virulence factors of P. gingivalis?
- Asaccharolytic - nutrients from breakdown of proteins and peptides
- Gingipains - proteases with broad-specificity (actively degrade host proteins for nutrients)
- Atypical LPS - TLR4 antagonist (blocks signalling)
- Inflammophilic - inflammatory environment favours expression of virulence
- Drives dysbiosis (in susceptible hosts)
Why may P. gingivalis only sometimes express virulence factors?
If the host response (both innate and adaptive) is capable of creating enough selective pressure, then expression of virulence factors will be inhibited
How can environmental and genetic risk factors effect the relationship between microbial challenge and host response?
They can reduce the host response which will result in a more pro inflammatory (altered) environment which allows expression of virulence factors and drives dysbiosis and altered competitiveness between bacterial species
What does an altered environment lead to in the oral cavity?
Altered environment is pro inflammatory drives dysbiosis and altered competitiveness which leads to unresolved chronic inflammation as only species that thrive in pro inflammatory conditions will survive
What are factors that may cause dysbiosis of the oral microbiome?
- Disease e.g. diabetes
- Genetic differences
- Activity of salivary proteins
- Salivary flow rates
- Innate/adaptive immune factors
- Oral hygiene
- Diet
- Smoking
- Antibiotics/antimicrobiano agents
Summarise the aetiology of periodontitis
Associated with:
- Accumulated plaque bacteria
- Presence of periodontal pathogens
- Polymicrobial dysbiosis
(In susceptible hosts)
- host-pathogen interactions determine susceptibility
