6. Dental Biofilm (plaque) Formation Flashcards
LOs
What is biofilm
- a community of organisms attached to a surface
- defined as a complex aggregation of microorganisms growing on a solid surface
-most important microorganism for the formation of biofilm = bacteria
3 different forms of bacteria found in the oral cavity
- planktonic = float in saliva
- sessile = attached onto the hard, non shedding,
surfaces of the mouth that grow in a biofilm - intracellular colonisation (will look at next year)
Normal micro-flora types
In the oral cavity all the microorganisms can be grouped into 3 groups
What is dental plaque?
What is calculus? What’s another name for it?
Main stages in plaque formation
What happens during the first stage of dental plaque formation?
ACQUIRED PELLICLE FORMATION
- bacteria cannot attach onto clean enamel surface
- when brushing most dental plaque is removed BUT saliva = rich in glycoproteins, phosphoproteins, lipids that can attach onto clean enamel surface
- enamel = negatively charged
- glycoproteins, phosphoproteins, lipids = positively charged
- hence they are attracted to each other and attach to enamel
- This begins minutes after brushing
- first proteins that attach = low molecular weight proteins BUT later higher molecular weight proteins also attach (mucins)
-mucins = bigger proteins important for adhesion - bacteria DO NOT take part in this first stage
CARD 2 What happens during the first stage of dental plaque formation?
What happens during stage 2 of plaque formation?
- bacteria can only attach onto the acquired dental pellicle NOT to a clean tooth surface
- during stage two, bacteria adhere to the acquired pellicle
-bacteria have different receptors
- these receptors can attach onto the surface of the acquired pelicle by recognising the complimentary proteins that have attached to the enamel (lock and key type model)
- through the acquired dental pellicle, these pioneering microbial colonisers can start to form dental biofilm
- Once bacteria is firmly attached onto the surface of the acquired dental pellicle, these pioneering microbial colonisers start to divide and they start to produce extracellular polysaccharides
Why do these bacteria produce extracellular polysaccharides? How are they produced?
WHY
- as oral bacteria are constantly subjected to cycles to feast and famine
- most oral bacteria take their nutrients from our diet
- because we don’t eat constantly, they have to store these nutrients
- hence EPS (extracellular polysaccharides) = strategy for carbohydrate storage
- those bacteria that can ferment carbohydrates are able to produce these extracellular polysaccharides
-EPS = v important cementing structure that are taking part in formation of dental biofilm (provide scaffold for formation of dental biofilm)
HOW
-these bacteria can produce 2 diff enzymes = glucosyltrasferase + fructosyltransferase
- reactions below
- glucan + fructan = important EPS
- both broken down from sucrose hence important to limit sucrose intake if you want inhibit the formation of dental plaque
- they start to build communities which are embedded in the matrix if the salivary components that produces the acquired dental pellicle and the EPS = established dental biofilm
Late Stage 2 - what happens in the establish dental biofilm?
- there is now microbial succession and syntrophism
-pioneering microbial bacteria ferment glucose + other metabolites, produce new things that other species can use as nutrients (eg below) - this helps dental biofilms become more rich
-not all microbial interactions help each other (eg’s below)
What happens during stage 3 of plaque formation
CO-AGGREGATION
-
What happens during the last stage of plaque formation
Dental biofilm formation summary?
- establishment of acquires pellicle = minutes after brushing
- early colonisers = after a few days have established themselves
- late colonisers = after 7-10 days = maturations of dental biofilm
What is materia Alba?
