Oral Ecology 2 Flashcards
What 2 external factors have a role on whether host population of microorganisms can colonize on tooth surface?
- Saliva
2. Environment
Describe dental plaque interactions between bacteria
- Acquired pellicle on tooth surface made up of components of saliva and bacterial fragments
- Layer of bacteria on top of pellicle made up of streptococcus species
- F. nucleatum bridges early and late colonizers
What are the 2 ways dental plaque can form with regards to species interaction?
- Interaction between bacteria and bacteria
2. Interaction between bacteria and fungi
What is the bacterial composition of the climax community of dental plaque at the fissure site?
Gram positive facultative anaerobes e.g. streptococcus, acitnomyces
What is the bacterial composition of the climax community of dental plaque at the approximal site?
Gram positive and gram negative facultative and obligate anaerobes e.g. neisseria, prevotella, veillonella
What is the bacterial composition of the climax community of dental plaque at the gingival crevice?
Gram positive and gram negative facultative and obligate anaerobes e.g. eubacterium, prevotella, treponema
What 4 things affect oral flora?
- Saliva
- Chewing
- Oral hygiene
- Diet
Describe the ecological stages in establishment of a microbial community
- Transmission
- Acquisition and colonization
- Pioneer species
- Microbial succession
- Increasing species diversity
- Climax community / Environment modification (return to pioneer species)
Give an example of gram positive cocci found in dental plaque
Streptococcus salvaris
Give an example of gram positive rod found in dental plaque
Lactobacillus acidophilus
Where are streptococci spp. found in the oral cavity?
Isolated from all sites in the oral cavity
Give 3 examples of streptococci spp. which are early colonisers of tooth surface
- S. sanguinis
- S. oralis
- S. gordonii
What is the primary pathogen in the aetiology of enamel caries in children and young adults?
S. mutans
Name another gram positive cocci found in dental plaque
Peptostreptococcus spp.
Name 3 types of gram positive rods and filaments found in dental plaque
- Actinomyces spp.
- Lactobacillus spp.
- Propionibacterium spp.
What is most commonly associated with lactobacillus spp.?
Advanced caries
Name 2 gram negative cocci found in dental plaque
- Neisseria spp.
2. Veillonella spp.
Describe neisseria spp. and how they contribute to the formation of dental plaque
- Facultatively anaerobic or aerobic bacteria isolated in fairly low numbers from most sites in oral cavity
- Contribute to plaque by consuming oxygen and creating conditions necessary for obligate anaerobes
Describe veillonella spp. and how they contribute to the formation of dental plaque
- Strictly anaerobic isolated from most sites in oral cavity but in high numbers in dental plaque
- Cannot metabolise carbohydrates so utilise intermediate metabolites e.g. lactic acid
- Reduce potentially harmful effects of lactic acid on dissolution of enamel
Name 4 gram negative rods found in dental plaque
- Aggregatibacter spp.
- Prevotella spp.
- Porphyromonas spp.
- Fusobacterium spp.
Describe aggregatibacter spp.
- Facultative anaerobes
- Implicated in particular aggressive form of periodontal disease in adolescents
Describe prevotella spp.
- Strictly anaerobes
- P. intermedia associated with periodontal disease
- P. nigrescens isolated more often from healthy sites
Describe porphyromonas spp.
- P. gingivalis strictly anaerobic
- Isolated mainly from subgingival sites especially in advanced periodontitis
Describe fusobacterium spp.
- F. nucleatum is obligate anaerobe
- Able to aggregate with most oral bacteria so believed to be important bridging organism between early and late colonisers during plaque formation
