Microbes in oral health and disease

• Disease processes


  Infection, inflammation, disorders of the immune system and degeneration
• Dental diseases may be examples of ecological catastrophes
• Microbiome


  The sum of microbes, their genetic information & the environment in which they interact
• Streptococcus mutans


  • Gram positive cocci in chains
• Streptococcus mutans: virulence factors

  • Acid production
  • Acid tolerance
  • Extracellular polysaccharide synthesis
  • Biofilm formation
• Stephan curve: Single sugar exposure
• Relative abundance of bacteria found in the oral microbiome of Temiar at the phylum level
• Ecological plaque hypothesis in caries aetiology

  Dysbiosis leads to ecological catastrophe
• SES= Socioeconomic status impacts dental caries
• Porphyromonas gingivalis


  • Gram negative bacilli
  • Susceptible to Metronidazole & Penicillin antibiotics
  • Black pigmenting anaerobe
  • 7 days growth on blood agar without oxygen
• Porphyromonas gingivalis: Virulence factors

  • Capsule
  • Outer membrane vesicles (OMVs)
  • Lipopolysaccharides (LPS) endotoxin
• Porphyromonas gingivalis


  • Increased resistance to phagocytosis
  • Ability to cause an inflammatory reaction
• Ecological plaque hypothesis for periodontal disease

  Red complex leads to catastrophe
• In the most deprived areas, individuals had a mean of 4.6 fewer sound teeth than those in the least deprived areas