Plaque maturation Sample Clauses

Plaque maturation. Plaque structures are extremely complex and have multiple receptor binding sites on multiple co- adhered species of bacteria. The secondary colonizing bacterial species that adhere to the oral biofilm also produce EPS, it is estimated that once plaque has reached a mature state only 5-25% of plaque consists of bacterial cells whist 75-95% consists of the glycocalyx (tangled polysaccharide fibres), which often encases the bacterial cells; the oral biofilm does however contain many porous layers and water channels to provide the bacteria with essential nutrients (Xxxxx et al., 2011). As biofilms mature there is a proportionality change from streptococci species to more gram-negative species, which has been attributed as a risk factor for gum disease. The risk factor is increased in mature plaque due to bacteria detaching from oral biofilms as single cells or clusters; this dispersion has been explained by two hypotheses. Firstly as the biofilm matures, there is less nutrition available to bacteria or there is another undesirable change in the biofilm conditions (pH, oxygen tension and temperature) which result in some bacteria actively detaching in an attempt to find more favourable conditions. The second is that saliva flow which attempts to control plaque growth has an effect on passively dispersing surfaces of mature plaque through shear rate (Xxxxxx et al., 2010). The active dispersal of bacteria from oral biofilm to a planktonic state has been hypothesised as being a therapeutic target to reduce the proliferation of biofilm development (Filoche et al., 2010).