Acquisition of Oral Microflora (Oral microbiology)

Question 1

List stages of microbial colonization

Answer 1

1) Vertical transmission -> Mother to baby
2) acquisition and colonization
3) Pioneer species -> First set of species
4) Microbial succession
5) Increasing species diversity
6) environmental modification -> go back to microbial succession
7) Climax community -> Once flora community has reached a relatively constant community

Question 2

Describe streptococci in Oral Cavity:

Answer 2

• First group to appear (pioneer species)
• Found in all mouth sites
• Produce extracellular polysaccharides (plaque)

Question 3

List the four groups of streptococci:

Answer 3

• Mitis group
• Salivarius group
• Mutans group
• Anginosus group

Question 4

Describe mitis group

Answer 4

Most common group; opportunistic; first bacteria to attach to pellicle

Question 5

Describe salivarious group

Answer 5

Prefers mucosal sites

Question 6

Describe mutans group

Answer 6

Found on hard surfaces; linked with caries

Question 7

Describe anginosus group

Answer 7

Found in plaque and mucosal sites; associated with distant infections (e.g. endocarditis)

Question 8

Describe microbial succession

Answer 8

Pioneer species modify local environment -> allows colonization by other species.

Question 9

Describe autogenic succession (environmental modification)

Answer 9

Changes by microflora community

• pH
• Lower Oxygen
• Cryptitopes -> proteases partially destroy receptors
• Nutrient generation
• Inhibition of other organisms

Question 10

Describe allogenic succession (environmental modification)

Answer 10

External changes

• Tooth eruption
• Antimicrobial agents
• Dentures

Question 11

Describe fastidious organisms in microbial succession and give an example

Answer 11

“Fussier” organisms that need specific nutrients and environment.
e.g. Fusobacterium nucleatum

Question 12

Microbial succession in tooth eruption and periodontal disease

Answer 12

Tooth eruption and periodontal disease allow new bacteria to enter.
Red-complex -> Three bacteria common in periodontal disease
1) Porphyromonas gingivalis
2) Tannerella forsythia
3) T. Denticola

Question 13

pH tolerance of cariogenic bacteria and give examples

Answer 13

Cariogenic bacteria are acid tolerant (e.g. S. mutans and lactobacilli)
- supragingival bacteria metabolize sugars into acid

Question 14

pH tolerance of periodontal disease bacteria

Answer 14

Periodontal disease bacteria are basic tolerant.

- Subgingival bacteria metabolize proteins (blood and gingiva) into nitrogen products which are basic

Question 15

List stages of plaque/biofilm formation

Answer 15

1. Acquire pellicle
2. Reversible attachment
3. Adhesin-receptor attachment
4. Coadhesion
5. Biofilm formation
6. Detachment

Question 16

Describe ‘acquire pellicle’

Answer 16

Salivary protein coating covers surface.

• Acquired seconds after brushing
• Proteins and fragments from saliva attach to tooth surface
• Thinner on lingual side due to tongue

Question 17

Describe ‘reversible attachment’

Answer 17

Bacteria reversibly bind to wrong receptors

Question 18

Describe ‘adhesin-receptor attachment’

Answer 18

Bacteria strongly bind with receptors on pellicle. Glycans are produced.

Question 19

Describe ‘coadhesion’

Answer 19

New bacteria bind to first bacteria and glycans

Question 20

Describe ‘Biofilm formation’

Answer 20

Bacteria produce more glycans to form biofilm; more bacteria bind and replicate

Question 21

Describe ‘detachment’

Answer 21

Parts of biofilm detach

Question 22

Describe ‘plaque formation’

Answer 22

1. Pioneer species colonize pellicle (Streptococci bacteria - Mitis group esp.)
2. Plaque matrix produced of carbohydrate polymers (Glucans and fructans)
3. Coaggregation of other of bacteria bind to pioneer species (Actinomyces, Haemophilus, and Neisseria species)
4. Fusobacterium nucleatum aggregate wide range of bacteria: Form bridge between early and late colonizers
5. Obligate anaerobes bind as oxygen levels fall

Question 23

Describe ‘life in biofilm advantages’

Answer 23

• Plaque is food storage
• Lower oxygen
• Coadhesions
• Quorum sensing -> Environment sensing
• Enzyme sharing
• Gene transfer
• Resistance to antimicrobial substances
• Resistance to host immune

Question 24

what is calculus?

Answer 24

Mineral deposition within the dental plaque due to mineral precipitation from saliva.