Development of dental biofilm Flashcards
What are the 3 basic stages of dental plaque development
- the formation of the pellicle on the tooth surface
- initial adhesion and attachment of bacteria
- colonisation and plaque maturation
What are examples of substances which make the dental pellicle?
Consists of more than 180 peptides, proteins, Glyco proteins, including mucins, proline – rich proteins, and Phosphoproteins (Statherin), Histidine rich proteins function as adhesion sites( receptors) for bacteria.
e.g. saliva agglutinin glycoprotein (SAG)
When does the dental pellicle form?
- Forms within nanoseconds of prophylaxis.
- Forms by selective adsorption of environmental macromolecules.
What are mechanisms involved in the formation of the pellicle?
¤ Electrostatic forces
¤ Van der waals
¤ Hydrophobic forces
What is phase I and II of bacterial adhesion and attachment to a surface?
transport to the surface
initial adhesion
What occurs in the phase 1 of “Initial Adhesion and attachment of bacteria”
Stage I : Transport to the surface
- Initial contact of bacterium to tooth surface
- Random contacts through Brownian movement
(40μm/hr) - Through Active bacterial movement (Chemotatctic activity)
What bacterial movement allows random contacts to surfaces?
Brownian movement
What occurs in phase II of “Initial Adhesion and attachment of bacteria”?
Stage II : Initial Adhesion
- Reversible adhesion
- Including van der waals attractive and electrostatic repulsive forces
What happens in stage 3. “Colonization and Plaque Maturation”?
- After initial adhesion, a firm adhesion is established by specific interactions (covalent, ionic or hydrogen).
- Rough surfaces are more conducive for attachment as bacteria are better protected against sheer force leading change from reversible to irreversible bonding.
- The bonding between bacteria and pellicle is mediated by specific extracellular protein components.
What protein do S. sangius bind to?
Streptococci (S sangius) early colonizer binds to acidic proline-rich proteins, also α-amylase and sialic acid
What is the role of primary colonisers?
- They provide new binding sites for adhesion by other oral bacteria.
- The metabolic activity of the primary colonizers modifies the local microenvironment which influences the ability of other bacteria to survive in the dental plaque biofilm.
What are examples of genus which are primary colonisers?
Streptococci and Actinomycetes
What are secondary colonisers?
They do not initially colonize the clean tooth surface but adhere to bacteria already in the plaque mass.
What are examples of bacteria which are secondary colonisers?
P. intermedia, P. loescheii, Capnocytophaga,
F. nucleatum, P. gingivalis
What allows co-aggregation of bacterial cells?
Highly specific stereo chemical interaction of proteins and carbohydrate molecules located on bacterial cell surfaces
