tys shen ti perio Flashcards
what is biofilm
how will understanding of concept of biofilm affect periodontal therapy?
biofilm = structured community of bacterial cells enclosed in a self produced polymeric matrix, adherent to each other or surfaces of tooth
- hosts ecological communities of bacteria which maintain their envt through homeostatic mechanisms
- as suprag plaque accumulates, it becomes organised into biofilms
- EPS has proteins, glycoproteins, lipids, extracellular DNA
role of biofilm
- slow down rate of gorwth
- limit diffusion of substances into biofilm
- alter genotype/phenotype
rate of plaque formation varies among individuals and is influenced by OH, diet and salivary flow rate
- gram + change to gram -ve
can talk about the formation of biofilm:
1) acquired pellicle formation
- salivary glycoproteins adsorb onto tooth surface
2) early colonisation (0-7 days after cleaning)
- initial colonisers are gram +ve cocci (strep)
- as bulk of plaque increases, o2 deprived envt develops within deeper layers of biofilm and favour growth of anaerobes
3) late colonisation (>7 days after cleaning)
4) plaque maturation
HOW WILL UNDERSANDING affect perio therapy
- because aim of periodontal therapy is to disrupt biofilm and prevent recolonisation of bacteria to form the biofilm
- see that physical disruption is the most effective way to disrupt biofilm (because of the physical adhesion of bacteria to tooth?) hence chemical not first line
- understanding biofilm will allow us to understand why therpay might be ineffective (slow penetration, resistant phenotype)
- eg MIC (minimum inhibitory conc of a biofilm is 2-1000x greater than planktonic cells)
- virulence factors must be removed from root surface for perio healing and regen to occur
plaque is the initiator of perio disease but whether or not it affects an individual, and how the disease progresses is VARIABLE
what factors could modify outcome of plaque induced perio
SYSTEMIC
- genetic conditions like IL1 polymorphism
- DM
- CVS
- obesity
LOCAL (tooth factors)
- virulence of plaque
- type of bacteria,must be able to colonise the subg surface (adhesin molecule)
ENVT factors
- smoking
role of dental plaque in perio
non specific plaque hypothesis
- all bacteria can be pathogen
specific plaque hypothesis
- healthy: gram +ve facultative (streptoccoci, actinomyces)
- mild to mod gingivitis: gram -ve rods (Fusobacterium Bacteroides, Campylobacter, Spirochetes)
- chronic perio: P gingi, P intermedius, Fusobacterium, Aa
