Aetio-Pathogenesis of Periodontal Disease Flashcards
(20 cards)
Define pathogenesis
Origination and development of disease
Define Periodontal disease
A complex interplay between subgingival biofilm and host immune – inflammatory response.
Develops in gingival and periodontal tissues in response to challenges by bacteria.
Define Gingivitis
Inflammatory response confined to the gingivae.
Precedes periodontitis but not all cases progress to periodontitis.
Define Periodontitis
Inflammatory process extends additionally to affect the PDL.
and alveolar bone.
Breakdown of PDL Clinical attachment loss (CAL) with resorption of alveolar bone.
Explain the Loe study
Conducted on Sri Lankan tea workers.
No access to dental care, abundant plaque and calculus deposits.
Findings divided into 3 categories:
Individuals who had rapid progression of periodontal disease (8%).
Those who had moderate progression of disease (81%).
Those who had no progression of disease beyond gingivitis (11%).
What did the Loe study show?
Causative role of plaque clear in initiating and perpetuating inflammatory response in gingival tissues.
However, a major determinant of susceptibility to disease – nature of immuno-inflammatory response.
Explain clinically healthy periodontal tissues in terms of inflammation and cells.
Clinically healthy non inflamed gingival tissues have evidence of inflammatory responses when examined microscopically.
Normal as there is chronic low grade challenge presented by sub gingival plaque bacteria.
The dentogingival junction attaches gingiva to tooth. The junctional epithelial cells are specialised for this attachment.
Explain saliva as a host defence.
Washing effect
Vehicle for swallowing bacteria
Antimicrobial effects:
- Salivary peroxidase system
- lysozymes/lactoferrin
- Antibodies (IgA)
Explain the gingival epithelium as a host defence.
Physical barrier
Seals against bacteria
Keratinocytes
Langerhans cells
However, initiation of tissue destruction results in increased permeability of the junctional epithelium meanings bacterial products enter giving increased risk of disease.
Define inflammation.
Inflammation is the response of living tissue to injury and provides a rapid first line defence.
It is non-specific and has fluid and cellular components.
Describe the fluid response of inflammation.
Vasodilation
Increased permeability of endothelial cells
Fluid and plasma proteins (antibodies, complement) released into tissues and through gingival crevicular fluid.
Oedema and swelling of gingiva.
Describe the cellular response of inflammation.
Polymorphonuclear leucocytes (eg; PMNs, neutrophils).
- Recognise and bind to bacteria, phagocytosis, expel remnants. Bystander damage may occur.
Macrophages.
- emigrate to inflamed gingival tissue
- important in both inflammation and immunity
Highlight the key features of the immune response.
Stimulus specific.
Memory.
Initiated by antigens.
Antigens recognised by lymphocytes.
Humoral - B Lymphocytes
- Plasma cells
- Immunoglobulins
Cell mediated - T Lymphocytes
- T helper cells
- T cytotoxic cells
Activation of the humoral response
- Plaque
- Bacteria
- Toxins
List the mediators that have a role in the immune response.
- Histamine / Bradykinin.
- Cytokines.
- Prostaglandins.
- Metalloproteinases.
Explain bystander damage.
Bacteria initiates disease by activating host mechanism that destroys supporting structure.
Describe the pathology/result of plaque related periodontal diseases.
- In periodontitis attachment is lost.
- Leaves cementum ‘bare’.
- Epithelium proliferates apically to cover connective tissue, deepening the pocket.
- ‘Pocket’ wall is scene of inflammatory response; defence cells continually emerge to keep bacteria form invading tissues.
Explain the features of an initial lesion (wk 1)
- Vasodilation
- Neutrophils
- Increased crevicular fluid
- Small inflammatory infiltrate
Explain the features of an early lesion (wk 2/3)
- Increased infiltrate
- lymphocytes and macrophages appear
- Rete peg formation in JE
- loss of gingical collagen
Explain the features of an established lesion (wk 3+)
- chronic inflammatory cell in gingival tissue
- JE ulceration
- pocket contains neutrophils, complement, antibodies
Explain the features of an advanced lesion
- JE migrates apically
- PDL fibres breakdown
- Alveolar bone lost
