Periodontal Pathogenesis

Biofilm Formation

• 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

Immune Response

• 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

• 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

• 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

• 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