16. Dental Plaque Flashcards
Cycle of plaque build up
- 0-18 hr is initial colonization phase on tooth surface with pellicle
- 18 hr-4d is pre-organization phase
- 4-7 d is microflora alteration phase
- cleaning occurs taking it back to the initial colonization phase
What part of the plaque build up cycle goes wrong for caries?
- no cleaning
- goes to dental caries and gingivitis/periodontitis
- rather than to the intial colonization phase
Why do we need to floss?
- brushing doesn’t remove plaque from gumline
- flossing is used
Attachment and biofilm formation in plaque
- aggregates in saliva drive initial attachment
- biofilms reform from cells that haven’t been removed at gingival margins etc
- uses proteins, glycoproteins that are complex and hard to break down
What’s the one saving grace of oral biofilms?
- most bacteria after sticking to teeth
- are not well adapted to grow in saliva
3 stages of biofilm formation
- attachment
- biofilm initiation
- biofilm development
Environmental factors affecting dental plaque accumulation
- diet
- smokingH
Host factors affecting dental plaque accumulation
- saliva (amount and composition)
Bacterial factors affecting dental plaque accumulation
- adhesins that recongise pellicle
- coaggregation
Dental plaque starts to accumulate … after cleaning
It occurs faster during the day/night?
- minutes
- day
… attach to the saliva pellicle to initiate biofilm
pioneer colonisers
How do bacteria initially attach to teeth?
- primary colinising bacteria in dental plaue attaches to conditioning layer
- is acquired enamel pellicle in teeth
Features of the acquired enamel pellicle
- thickness
- toughness
- presence where?
- composition
-1-3 micrometers thick
- may permeate outer layer of enamel/sub-surface cuticle
- not easily removed
- present on most enamel surfaces
- originally thought to be Nasmyth’s membrane
- now is known as a deposit of saliva proteins
The acquired enamel pellicle is a deposit of what?
saliva proteins
How does the pellicle form?
- precipitation of denatured salivary proteins
- selective absorption of salivary proteins
- tooth surface charged due to calcium and phosphate and molecules bind in proportion to affinity for substrate
- enrichment of high binding rather than medium or low
Additional components of pellicle include …
- gingival crevicular fluid
- oral mucosa
- microbial cells
How do MG2 and MG1 interact with pellicle?
- MG1 is viscous and gets into the pellicle
- MG2 is non-mucin and not involved as much
Role of pellicle in oral environment
- acts as a lubricant to reduce tooth wear
- reduces mobility of calcium and phosphate ions (diffusion barrier and binding of PRP, reduces enamel demineralisation/erosion and caries)
- prevents inappropriate crystal growth (statherin and PRP)
- contains active enzymes
- can inhibit bacterial adhesion
- substrate for bacterial adhesion
What enzymes does the pellicle contain?
- amylase
- lysozyme
- peroxidase
- carbonic anhydrase isotope VI
- glucosyltransferase
Explain how the pellicle is a substrate for bacterial adhesion
- salivary proteins in pellicle act as receptors for bacteria
- has MG1 (sticks within plaque and allows some bacteria to stick/stop some that don’t recognise it to protect tooth surface)
- amylase to bind some strep
- proline-rich proteins
- statherin (changes shape in binding and bacteria attach)
- GP340 (salivary agglutinin) - in lungs for aggregating bacteria and sticking bacteria in pellicle
Role of MG1 in pellicle
- sticks within plaque
- allows bacteria to stick and stops those that don’t recognise it
- protects tooth surface
