MFD 20 Flashcards
• To provide an overview of supragingival and subgingival dental plaque, including how they form and why it is important to control plaque. Content • Overview of dental plaque. • The acquired enamel pellicle. • Some key plaque bacteria. • Subgingival plaque and calculus.
What tooth surfaces are available for colonisation?
- fissures
- smooth surfaces
- approximal
- gingival crevice
How do we measure dental plaque on the clinic?
disclosing tables, plaque score
IN supragingival plaque:
1) anaerobic or aerobic organisms
2) present in health or disease?
3) Ease of removal?
4) possible consequences of presence?
5) nutrient source:
1) aerobic (mainly)
2) present in health
3) easily removed from smooth surfaces
4) can causes caries in cracks and fissures
5) saliva
IN subgingival plaque
1) aneorobic or aerobic?
2) what diseases is significant plaque associated with?
3) ease of removal?
4) Nutrient source:
1) perio pockets become anaeobic
2) gingivitis/periodontitis
3) difficult to remove
4) GCF
Is plaque accumulation faster at night or during the day?
at night
How long after tooth cleaning does dental plaque start to accumulate again?
within minutes
What do pioneer colonisers of dental plaque attach to?
saliva pellicle
match location of plaque growth with disease.
Location: gum line, tooth surface
Disease: caries, periodontitis
- gum line= periodontitis
- tooth surface= caries
What are the stages of the cyclic nature of plaque build up?
START: being after cleaning
- tooth surface with pellicle
- initial colonisation phase
- pre-organisation phase
- microflora alternation phase
- EITHER;
a) dental caries
b) ginigivits/periodontitis
c) cleaning
As with other biofilms, the primary colonising bacteria in dental plaque attach to a _____a____. In dental plaque this is _____b____
a) conditioning layer
b) acquired enamel pellicle
What is the thickness of the acquired enamel pellicle?
1-3mm thick
What was the enamel pellicle originally thought to be ?
2)What is that?
Nasmyth’s Membrane
2) reduced enamel epithelium (REE) produced by the ameloblast, that covers the tooth once it has erupted
What can the enamel pellicle permeate?
2) WHat is it made up of??
1) the outer layer of enamel (sub-surface cuticle)
2) is a deposit of saliva proteins
What is the difference between the pellicle and non-pellicle surface in a histology slide?
pellicle surface has scalloped edge for the bacteria to attach to so can attach easier
How does the pellicle form?
Precipitation of denatured salivary proteins on enamel.
Why is the formation of the pellicle described as selectively absorptive?
as different salivary proteins have different binding properties as molecules bind in proportion to their affinity for a substrate
What are the salivary proteins attracted to on the enamel which causes them to bind?
charges due to Ca and phosphate
Why is the pellicle important?
- Acts as a lubricant to reduce tooth wear
- Reduces mobility of calcium & phosphate ions (preventing it from dissolving i.e. the hydroxyapitate)
- Diffusion barrier and binding to PRP
- Reduces enamel demineralisation (erosion & caries)
- Prevents inappropriate crystal growth (Statherin and PRP)
- Contains active enzymes
7) Sometimes inhibits bacterial adhesion
8) Substrate for bacterial adhesion
What enzymes does the pellicle contain?
2) which is the most important enzyme and why? in terms of tooth protection
1.) Amylase
Lysozyme
Peroxidase
Carbonic anhydrase isotype VI (acts as a buffer)
Glucosyltransferase
2) Carbonic anhydrase isotype VI (acts as a buffer)
Give an example of molecule in the pellicle that:
1) inhibits bacterial adhesion
2) is for bacterial adhesion
1) mucin MG1
2) • Salivary proteins in pellicle act as receptors for bacteria
• MG1
• Amylase
• Proline-rich proteins
• Statherin
• Gp340 (salivary agglutinin)
What does mucin MG1 specifically inhibit?
S. mutans biofilm formation.
What species of bacteria makes up over half of the bacteria in the initial plaque?
streptococci
Which group of streptococci are the most numerous ( most abundant and most number of genuses) in the mouth?
mitis
Describe the following group in streptococci:
anginosus
generally commensal but are associated with abscesses. (including those in the brain)
Describe the following group in streptococci:
salivarius
• Salivarius group are generally considered commensal, some involved with caries, (some being investigated as probiotics, ).
Describe the following group in streptococci:
Mutans
Mutans group associated with dental caries.
What is Antigen 1/2 in streptococcal ?
2) What is its role?
it is an important adhesion, for as being a long protein (around 170 kDa) on the surface of the bacterium present as a subunit part of a chain it can reach out and attach to other molecules
2) a) it can attach to other molecules including G3 protein and other bacteria (Actinomyces spp. and P.gingivalis),
b) mediates adhesion to gp340 (salivary agglutinin) in fluid phase or in pellicle
Describe the reason for differences in binding protein properties of adhesion 1/2 in streptococci:
It is a multi-domian region and Binding properties mostly in variable region and varies between strep bacteria.
What are the domains of the protein, adhesion 1/2 in streptococci?
- N-terminal domain
- Alanine-rich repeats
- Variable region
- Proline-rich repeats
- Carboxy-terminal domain, containing motif for wall anchoring
What protein is required in the interaction between streps and cadida hyphe (straight bits)?
antigen 1 and 2
what property of actinomyces allows it to survive in anaerobic and aerobic conditions?
they are facultative anaerobe, which is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent.
Actinomyces spp. a :
Gram-positive or Gram-negative
2) What shape is it?
1) positive
2) pleimorphic rods
Veillonella spp.
Gram-positive or Gram-negative
2) What shape is it?
gram-negative
2) cocci
Veillonella spp.
1) What does it feed on?
2) How may it contribute to caries?
1) feed on lactate, produced by other oral bacteria
2) • So elevated in caries but doesn’t make acid, and is instead is feeding on the acid therefore benefiting the strapes. So may contribute disease as a secondary factor.
Is acitonmyces spp. pathogenic?
mostly harmless, though can cause disease
Name 2 bacteria species that are pioneer “colinisers” of the mouth other than human oral streptococci:
Veillonella spp.
Actinomyces spp.
Describe how the food web of dental biofilm are salivary glycoproteins digested??
2) what is the nutrients of initial growth from?
3) What are the different relationships occurring between bacteria in the food web of dental biofilm?
1) Digestion of salivary glycoproteins requires enzymes contributed by multiple species
2) saliva
3) a) are synergistic relationships between bacteria e.g. Porphyomonas produces butyrate which provides nutrients to Treponema
b) Some bacteria utilise waste products from other species
c) Other relationships are used and involved in the metabolises glycoprotein
List the stages of dental plaque formation:
1) Attatchment (via adhesion)
2) growth (via coaggregation)
3) Coadhesion
4) Mature biofilm formed
5) dispersal
True or False , plus Mature Supragingival Dental Plaque has a stratified appearance
true,
Gram-positive cocci and short rods at tooth surface; filaments towards outer layers
What problems can mature supraginigival dental plaque cause:
1) caries, as shift towards acidogenic/aciduric bacteria
2) Gingivitis occurs when plaque grows below the gumline
What is the difference between acidoduric and acidogeneic bacterai?
acidogenic: produces acid
acidoduric: can survive in acidic environments
What causes ginigivitis?
2) What hypothesis is there not evidence to support?
1) accumulation of plaque at the gum margins directly irritates the gum tissue
2) that the ammount of plaque correlates with dental caries
How long does it take for a mature biofilm to occur?
24 hrs
What is the difference between coadhesion and coaggregation?
coaggregation: happens first, its when bacteria stick to one another
coadhesion: happens later, When a bacteria attaches when to another bacteria once it is already present in the biofilm
In health is there subgingival plaque?
2) what quantity of bacteria will be present in health under the gum line?
1) no
2) • Relatively few bacteria (103 to 106 CFU/crevice).
What does CFU stand for?
olony-forming unit (CFU, cfu, Cfu) is a unit used to estimate the number of viable bacteria or fungal cells in a sample. Viable is defined as the ability to multiply via binary fission under the controlled conditions.
What sort of bacteria will be found as we go from health to ginigivitis to periodontitis?
1) HEALTH: aerobic, saccharolytic (break down polysaccharides)
Periodontitis: some asaccharolytic, proteolytic bacteria, and anaerobic bacteria
Where will you find anaerobic bacteria in health?
dorsal surface of the tongue
1) What bacteria sits between the pioneers of plaque and later colonisers, as a bridging organism
2) give an example of a pioneer bacteria:
3) give 2 e.g of later colonisers it adheres to:
1) Fusobacterium nucleatum
2) Streptococcus sp.
3) Treponema denticola , Porphyromonas gingivalis
Fusobacterium nucleatum
1) is it gram + or -
2) is it proteolytic or aproteolytic
3) is it cocci or rod shaped?
4) Where CAN it be present in high numbers (over 20%)?
1) -
2) proteolytic
3) cocci
4) subgingival plaque
If Fusobacterium nucleatum adheres to later colonisers, what does it do with early colonisers?
coaggregates
What is bacteria embedded in in mature subgingival dental plaque?
polymeric matrix
What is the lay term for dental calculus?
tartar
Why does calculus occur?
too much mineralization occurs in the wrong place (triggered by an epitactic agent, probably bacteria) forming mineralised plaque which can trigger inflammation.
What is another term for subgingival calculus?
serumnal calculus
Supragingival calculus is a deposit from ___A___
Subgingival calculus is a deposit from ___B____
a= saliva b= serum
What about calculus triggers inflammation?
its rough surface
Where is calculus more likely to form?
near salivary duct openings
What are sialoliths?
supersaturated calcium phosphate, kind of like a stone, thats forms in salivary ducts
2) its because over mineralisation occurs
