Periodontal Pathogenesis

Study Notes

Biofilm formation is a crucial step in periodontal pathogenesis
A biofilm is a complex community of microorganisms adhering to a surface
In periodontal disease, biofilm forms on the tooth surface and beneath the gingiva
Biofilm formation involves:
- Initial attachment of bacteria to the tooth surface
- Adhesion and accumulation of bacteria
- Production of extracellular polymeric substances (EPS)
- Maturation of the biofilm
Key bacteria involved in biofilm formation:
- Streptococcus spp.
- Actinomyces spp.
- Fusobacterium spp.
- Porphyromonas gingivalis

The immune response plays a crucial role in periodontal pathogenesis
The immune response is initially triggered by the presence of bacteria in the biofilm
Key components of the immune response:
- Innate immune response:
  - Recognition of bacteria by pattern recognition receptors (PRRs)
  - Activation of immune cells (e.g., neutrophils, macrophages)
- Adaptive immune response:
  - Activation of T cells and B cells
  - Production of cytokines and antibodies
The immune response can contribute to periodontal tissue destruction:
- Overproduction of pro-inflammatory cytokines
- Activation of matrix metalloproteinases (MMPs)

Bacterial virulence factors contribute to periodontal pathogenesis
Key virulence factors:
- Adhesins: facilitate bacterial attachment to the tooth surface and to host cells
- Toxins: damage host cells and tissues
- Enzymes: break down host tissues and facilitate bacterial invasion
- Modulins: modulate the host immune response
Key bacteria with virulence factors:
- Porphyromonas gingivalis
- Aggregatibacter actinomycetemcomitans
- Tannerella forsythia

Host-microbe interactions play a crucial role in periodontal pathogenesis
Key interactions:
- Bacterial recognition by host cells (e.g., Toll-like receptors)
- Activation of host cells (e.g., immune cells, epithelial cells)
- Production of cytokines and chemokines
- Modulation of the host immune response
Host-microbe interactions can contribute to periodontal tissue destruction:
- Overproduction of pro-inflammatory cytokines
- Activation of MMPs

Periodontal tissue destruction is the ultimate outcome of periodontal pathogenesis
Key mechanisms of tissue destruction:
- Inflammation:
  - Activation of immune cells
  - Production of pro-inflammatory cytokines
- Tissue breakdown:
  - Activation of MMPs
  - Degradation of extracellular matrix
- Bone resorption:
  - Activation of osteoclasts
  - Resorption of alveolar bone
The outcome of periodontal tissue destruction:
- Periodontal pocket formation
- Attachment loss
- Tooth loss