Microbiology Of Periodontal Disease Flashcards
Define pathogen
A disease causing microorganism
Define opportunistic pathogen
A member of the normal microbiota that causes infection under certain circumstances
Define symbiont
A member of the resident microbiota conferring benefit to the host
Define pathobiont
The capacity of a molecule to cause damage to the host dysbiosis occurs
Define dysbiosis
Lack of balance between host responses and resident microbiota
Define virulence
The degree of pathogenicity- capacity to cause damage to host
Define pathogenicity
The relative capacity of an organism to cause damage
Define virulence determination/ factor
Component of pathogen that causes host damage/ allows pathogen to cause damage
Why is there a balance between in health?
There’s a balance between microbes and our responses to them
Host-microbe homeostasis
What do neutrophils do in disease?
They migrate to the tooth surface guided by chemokines| Neutrophils enter and protect the gingival tissues
Give some examples of evidence that microbes are asscocaited with perio diseases
- Healthy animals bred in germ free environment exhibit perio disease when given perio (gnotobiotic animal studies)
- Cross sectional & longitudinal studies in humans
- Microbiological studies carried out -correlation between appearance & prevalence
- Immunological studies show the responses to the pathogen from the body
- Treatment is plaque removal
Which type of plaque forms first in the mouth?
Supragingival plaque forms first
Describe Supragingival plaque
It moves down tooth to root eventually forming subgingival plaque
Name the microbes found in the mouth in health
Gram positive aerobes like cocci & rods that are facultative anaerobes
What happens to the microbiota as gingivitis forms?
The population of obligatory anaerobes increases
Name the microbes found in the mouth in periodontitis
Predominantly Gram negative anaerobes & spirochetes
Why does the microbiology composition change with gingivitis and periodontitis formation?
Organisms thrive and outcompete each other and succession occurs The change has a lot to do with the nutritional availabilities for microbes
What changes occur when pocketing occurs?
- There is an increase in inflammation
- Increased GCF flow
- Haem provides nutrients for subgingival organisms
- As pocket gets deeper, O2 levels drop Obligatory anaerobes thrive
- Slight increase in temp leads to increase in metabolic activity of microbes6. Slight increase in pH More favourable for obligate anaerobes
Go through the ecological plaque hypothesis steps (marsh,PD 2003)
- Plaque levels increase due to poor oral hygiene 2. This leads to the formation of gingivitis 3. Inflammation increases 4. Environmental changes occur due to an increase in inflammation 5. Environmental change instigates ecological shift (Periodontitis) like the increase in gram negative anaerobes 6. Periodontal diseases occur due to responses of these anaerobes
When are pathogens present in high numbers?
In disease compared to health
List some of the reasons why is it is difficult to identify the pathogen responsible for causing periodontal disease
- Episodic cyclic nature of the disease
- Definitions of disease change
- Sampling & detection techniques - taking samples at right time from right place
4.complexity of microbiota - Taxonomy
- Approx 40% of microbiota is non culturable
How do you carry out a DNA-DNA checkerboard? Hybridisation
- Place DNA from species & DNA from clinical sample & see if hybridisation occurs
- This method has been succeeded by Next generation sequencing
Then socransky 1998 found ‘colour complexes’
What can be used to determine how many organism are in a sample that hasn’t yet cultured ?
HOMIM
Name some unculturable organism associated with chronic periodontal disease
- Spirochete’s 2. T7 phylum3. Methanogens 4. Novel phonotypes
