properties and formation of dental plaque :) Flashcards
what is plaque
biofilm mixture of different species of bacteria embedded in a matrix of polymers
what is a microbiome
all the bacteria in the body
what is an oral microbiome
all the bacteria in the oral cavity
where can micro biome be found in babies not born
in amniotic fluid
rupture to membrane can mean that bacteria can enter the placenta
post natal acquisition of oral flora
normal delivery
c section
what does the micro biome reflect from normal delivery
vaginal tract microbiota
e.g. lactobacillus
what does the micro biome reflect through c section
skin microbiiota
e.g. staphylococcus
what does breast feeding affect
more lactobacillus may reduce candida levels
most common colonisation from mother to child
streptococcus saliarius
colonisation sites in the mouth
teeth tongue cheeks, lips, saliva orthodontic saliva implants dentures
what is dental disease caused by
mix of species of bacteria working together
formation of plaque biofilm steps
host surface adhesion
host surface adhesion (specific)
inter bacterial adhesion
growth and multiplication
describe the first host surface adhesion
reversible
physio-chemicla interactions
describe the second host surface adhersion
irreversible
specific molecular interctions
interbacterial adhesion
co aggregation
how do bacteria adhere to the tooth
through the acquirred pellicle
what is the pellicle on the tooth
layer of selectively absorbed salivary protiens
forms on the surface enamel
what is found in the pellicle
proline rich protien
mucins
statherian
what are the adhesion mechanisms
electrostatis
protein carbohydrate/protien-protein
polymer bridging
what are glycoprotiens
sugar chains linked by N/O glycosylation to mucins
how can bacteria be attached to glycoprotiens
by lectins (lectins target is a sugar on another molecule)
what are cryptitiopes
hidden receptors for bacteial adhesion
how can species of bacteria help each other
one uses proteins to remove the sugar exposing the cryptitiope so the other can attach to the exposed region
what is it called when bacteria adhere to each other
co aggregation
what does coaggregation of bacteria involve
surface appendages (fimbria or fibrils) fibrils can grab sugar or protien so the bactiera can stick down
how can a microbiome build up
bacteria can aggreagate between them
bind to acid of mucins
bind to polysaccharides or surface protiens
sources of nutrition for plaque
salivery glycoprotiens
salivery protiens
urea
how does ph vary in plaque
pH lower in lower bifilm
how does salivery nutriens vary in biofilm
higher closer to top
where do aerobic species prefer in the biofilm
top
what do gradients in the plaque lead to
different niches
what do autoinducers do
signal to increase the density of bacteria where bacteria are most beneficial
what can bacteria sense
population numbers influencing behavior
what happens at high cell density
high autoinducer
leads to transcription of target gene
what happens at low cell density
low autoinducer
no transcription of target gene
what is calculus
calcified plaque matrix and bacteria
how does calculus form
increase in pH, Ca and phosphate
mineral growth around bacteria
limitations to plaque deveolping
salivary flow
gingival crevicular fluid
antibacterial substances
antibacterial substances
lysosome (breaks down cell walls)
lactoferrin (limits and binds iron)
sialoperoxidase (attack bacteria)
aggreagating factor (stop bacteria attatching to surface)
progression of plaque formation steps
primary adherer metabolism changes environment bacterial succession climax community
colonisation sites in the mouth
teeth tongue cheeks/lips/palate orthdontic appliances implants dentures
teeth niche
calciumhydroxyapitite mineral
stagnation sites have less saliva flow
food source from ofood
tongue niche
lots of niches due to irregular surface
cheeks/lips/saliva niche
more saliva present
micro biome more stable, less diverse
dominated by streptococcus
denture niche
favours fungal growth
how to cryotitopes become exposed
adsorption to the tooth enzymic alteration (protease/glucosidase action)
building up of a micro biome coloniser
actinomyces selectively bind tostatherin and PRPs
strep. sanguimis binds to silica acid of mucisn
strep. mutans binds to PRPs and mucin like glycoprotein
inter bacterial substaces
salivary material
bacterial exopolysaccharides
bacterial surface structres
what can components of interbacteral substances do
adsorb to bacterial surfaces
precipitate from solution
chemical change pH
what does quorum sensing and autoinducers do
allow coordination of behaviour
- biofilm formation
- virulence factor producion
- bioluminesense
