12. Pathogenesis of periodontitis

Question 1

Difference between periodontitis inflammation and general inflammation in body

Answer 1

• Anatomy of periodontium- Permeable junctional epithelium
• Occurs in response to large varied microbes

Question 2

Clinically healthy gingiva characteristics

Answer 2

• Keratinised oral epithelium continous w/ junctional epithelium
• Dentinogingival plexus w/in junctional epithelium-large no. of vessels
• Small infiltrate of inflammatory cells(lymphocytes and macrophages) in response to biofilm(in JE and CT)
• Gingival crevicular fluid containing plasma proteins in sulcus
• Neutrophils in sulcus-migrate between JE

Question 3

Mechanisms that enable clinically healthy ginigiva to prevent progression to gingivitis

Answer 3

• Junctional epithelium barrier
• Regular shedding of epithelial cells into oral cavity
• Flushing action of fluid into gingival crevice
• Antibodies in GCF
• Phagocytic action of neutrophils and macrophages
• Compliment action on mo

Question 4

Phases of Gingivitis/Periodontitis

Answer 4

1. Initial lesion (clinically healthy gingiva)
2. Early lesion (early stages of gingivitis)
3. Established lesion chronic gingivitis)
4. Advanced lesion (gingivitis progesses to periodontitis)

Question 5

Initial lesion

Answer 5

• Plaque on gingival third of tooth for 24h
• Dentinogingival plexus changes
• PMN cell migration(neutrophils, eosinohils and basophils)
• after 2-4 days process well established

DGP changes-
* Increased vascularisation-dilation of capillaries, arterioles and venules
* Increased permeability of microvascular bed
* Proteins and fluids leak into tissues
* Increase flow of GCF-antibodies, compliment

Question 6

Early lesion

Answer 6

• Several days of plaque accumulation
• Vessels of dentinogingival plexus dilated
• Increased marginal redness
• Lymphocytes and PMNS predominate w/ small amounts of plasma cells
• Breakdown of collagen fibres in infiltrated area
• Proliferation of JE and SE cells to strengthen barrier
• Loss of coronal portion of JE

Question 7

Established lesion

Answer 7

• Progression of inflammation
• Increased GCF
• CT and JE w/ increased PMNs and plasma cells
• Collagen loss->infiltration and accumulation of lymphocytes
• JE replaced by pocket epithelium not attached to tooth surface
• Established lesion does not progress further for months/years or can progress to more destructive advanced lesion

Pocket epithelium more permeable to passage of substances into and out of underlying CT

Question 8

Advanced lesion

Answer 8

• Deepening of pocket
• Inflammatory infiltrate deeper into CT
• Extensive damage to collagen fibres=>apical migration of pocket epithelium to CEJ=>
• CT and bone loss
• Plasma cells dominant cell type