Aetiology of Periodontitis Flashcards
What are the signs of healthy periodontium?
Lack of inflammation symptoms such as oedema swelling, and bleeding.
Lack of plaque bacteria
What are the 3 stages of the inflammatory response?
Acute
Immune
Chronic
What are the signs and symptoms of established gingivitis?
Infiltration of connective tissue by large numbers of defence cells
Destruction of normal anatomy
No apical migration of the junctional epithelium
Does gingivitis progress to periodontitis?
Healthy gingiva
Early gingiva
Established chronic gingivitis. This can be stable and unstable.
What happens to periodontal tissue during periodontitis?
Apical migration of the junctional epithelium
Inflammatory lesion extends apically and laterally
Resorption of alveolar bone
What immune cells are found in periodontitis?
Neutrophils
B lymphocytes
Macrophages
Cytokines
What do neutrophils do in periodontitis?
They kill bacteria in 2 ways:
Intracellular killing via phagocytosis
Extracellular killing via release of destructive enzymes and oxygen radicals but also cause significant damage to periodontal tissues.
What do B lymphocytes do in periodontitis?
Transform into plasma cells and produce specific antibodies. Antibodies released in the presence of complement facilitate enhanced PMN bacterial killing.
What do macrophages do in periodontitis?
They are recruited to an area and activated by binding to LPS to release inflammatory mediators.
How do cytokines affect periodontitis?
IL1 and TNF-alpha bind to fibroblasts which are also stimulated to produce additional quantities of inflammatory mediators.
How does periodontitis progress?
It is rapid and takes place in random bursts that are asynchronous
How does chronic periodontitis progress?
Overall there is an attachment loss of 0.1 - 0.2 mm per tooth per year.
Aggressive periodontitis grade C could be as much as 3mm in a year.
What is the host reponse to inflammation of the gums that leads to periodontal destruction?
Bacterial products and toxins cross the JE.
This stimulates epithelium and connective tissue to produce inflammatory mediators.
Blood vessels dilate and become more permeable and as a result defense cells migrate from the capillaries towards chemotactic stimulus.
What are the mechanisms of action of bacterial virulence factors in periodontitis?
Direct destruction: H2S, NH3, fatty acids, indole, Bacterial derived enzymes
Indirect destruction: Via host response
What is different about the bacteria involved in gingivitis compared to periodontitis?
The quantitiy of bacteria increasing in gingivitis causes progression.
The quality of bacteria is important in the pathogenesis of periodontitis due to production of enzymes, toxins, and metabolic products.
What type of enzymes are poduced by pathogenic bacteria causing periodontitis?
Collagenase
Elastase
Other proteases
Hyaluronidase
What type of toxins are produced by pathogenic bacteria causing periodontitis?
Exo-toxins
Endo-toxins
What metabolic products are potentially causative of periodontal tissue damage?
Hydrogen sulphide
Ammonia
Volatile fatty acids
What are the most commonly studied bacterial virulence factors?
LPS: Constituent of the other cell wall of gram negative bacteria
Fimbriae: Numberous thin straight appendages on outer cell wall
Proteases: Hydrolysis of peptide bonds of proteins, acquisition of nutrients, and modification of host response.
What inflammatory mediators have an important role in inflammation?
Research has focused on mediators of inflammatory response:
Prostanoids such as prostaglandins E2 which stimulates alveolar bone resorption
Cytokines such as IL1 and TNF a
MMP which has a key role in breakdown of connective tissue
What is periodontitis due to infection associated with?
Dental plaque constitutes the primary etiological factor in chronic inflammatory periodontal disease. A non-resolving inflammation that is ineffective at eliminating pathogens is considered periodontitis.
What kind of structure is a biofilm?
It is highly structured with channels traversing to a depth.
They have a primitive circulatory system
Organisms are not randomly distributed but spatially and functionally organised
Outer organisms may have a protective role
How do bacteria within a biofilm communicate?
VIa a sophisticated cell to cell gene expression called quorum sensing.
Cells within the biofilmcan alter gene expression so that they have a different phenotype (strength in numbers)
How do biofilms affect susceptibility to antibiotics?
Bacteria in bioilms can be up to 1000 times more resistant to antibiotics than they are in the planktonic state.
There is evidence of gene transfer of antimicrobial resistance.
