Dental Plaque Biofilm & Calculus

Question 1

Biofilm

Answer 1

Biofilm consists of one or more communities of microorganisms embedded in glycocalyx (glycoprotein matrix), usually attached to a solid surface.

Question 2

Classification of dental plaque biofilm

Answer 2

1. Supra gingival
   - coronal
   - marginal
   - fissural
2. Sub gingival
   - tooth attached
   - tissue attached
   - unattached

Question 3

4 phases of dental plaque biofilm formation

Answer 3

1. Initial attachment of bacteria to pellicle.
2. Initial colonisation of the tooth surface: new bacteria join.
3. Secondary colonisation: extracellular slime layer formation.
4. Mature biofilm: mushroom shaped colonies.

Question 4

Free floating bacteria

Answer 4

Found in saliva.

Can become attached within minutes.

Question 5

Initial attachment of bacteria to pellicle

Answer 5

1st stage of dental plaque biofilm formation.

Thin coating of salivary proteins that attach to tooth surface.

Pellicle is laid down a few hours after cleaning.

Question 6

Primary colonisers

Answer 6

Streptococcus sanguis
Streptococcus mutans
Streptococcus salivarius

(gram +, Aerobic)

Question 7

Initial colonisation of the tooth surface

Answer 7

2nd stage of dental plaque biofilm formation.

New bacteria attach to surfaces and each other.

Attachment activates quorum sensing.

Question 8

Quorum sensing

Answer 8

Cell to cell communication.

Used by bacteria to form biofilms.

Allows bacteria to detect and respond to cell population density.

Question 9

Secondary colonisation

Answer 9

3rd stage of dental plaque biofilm formation.

Formation of extracellular slime layer - protective barrier that surrounds the colony.

Primary facultative colonisers start to lose oxygen – making room for anaerobes.

Bacteria grow away from the tooth.

Question 10

Coaggregation

Answer 10

Secondary colonisers attaching to primary colonisers.

Question 11

Bacterial bloom

Answer 11

Periods of accelerated bacterial growth.

Question 12

Fluid channels

Answer 12

Penetrate extracellular slime layer.

Provides; nutrients, o2, movement of waste products, metabolites and enzymes through colony.

Question 13

Mature biofilm

Answer 13

4th stage of dental plaque biofilm formation.

Formation of mushroom shaped colonies.

Own fluid channels (nutrient and waste system).

Allows for self survival.

Question 14

Bacteria associated with periodontal disease

Answer 14

Porphyromonas gingivalis

Aggregatibacter actinomycemcomitans

Treponema denticola

Tanneralla forsythia

Question 15

Bacteria associated with caries

Answer 15

Streptococcus mutans

Lactobacilli

Question 16

Porphyromonas gingivalis key features

Answer 16

Bacillus (Rod shaped)
Gram negative
Anaerobic
Inflammation, tissue destruction and invades immune system

Question 17

Aggregatibacter actinomycemcomitans key features

Answer 17

Coccoid bacillus (Rod shaped)
Gram negative
Facultative anaerobe
Localised aggressive periodontitis

Question 18

Treponema denticola key features

Answer 18

Spirochete
Gram negative
Anaerobic
Produces enzymes that damage tissues

Question 19

Virulence factors

Answer 19

Mechanisms that determine the degree to which the pathogen causes damage, invasion and infectivity.

Question 20

Removal of plaque biofilm

Answer 20

Contact with biofilm
Friction
Physical removal

Question 21

Dental calculus

Answer 21

Mineralised bacterial biofilm.

Question 22

How long does it take for calculus to form?

Answer 22

48 hours - 2 weeks after plaque biofilm formation.

Question 23

Dental calculus composition

Answer 23

Inorganic 70-90%

Organic 10-30%

Question 24

Dental calculus organic components

Answer 24

10-30%
- plaque bacteria
- dead epithelial cells/white blood cells

Question 25

Dental calculus inorganic components

Answer 25

70-90% - magnesium phosphate - calcium carbonate - calcium phosphate

Question 26

Factors that can effect calculus crystalline

Answer 26

Location - posterior/anterior Supra or sub Age of calculus The individual

Question 27

Common sites of dental calculus:

Answer 27

Salivary duct opening Gingival crevice Root surface with periodontal pockets Prosthesis Restoration ledges Crowded teeth

Question 28

Where does supra gingival calculus get minerals from?

Answer 28

Saliva

Question 29

Where does sub gingival calculus get minerals from?

Answer 29

Gingival crevicular fluid (GCF)

Question 30

What causes sub gingival calculus to go black?

Answer 30

Red blood cells and break down products.

Question 31

Ways calculus can attach to a surface:

Answer 31

Acquired pellicle. Penetration into enamel, cementum or dentine. Tooth irregularities.

Question 32

How to detect calculus

Answer 32

Visually Probing Radiographs

Question 33

Patient calculus classifications

Answer 33

Heavy Moderate Slight None

Question 34

Dental calculus formation

Answer 34

Element of organic matrix (plaque bacteria) acts as seeding agent for crystal formation. Bacterial enzymes (proteases and phosphatases) enhance process by degrading calcification inhibitors in saliva. Insoluble calcium phosphate crystals begin to form. These combine into calcified mass, called CALCULUS

Question 35

Tanneralla forsythia key features

Answer 35

Fusiform Gram negative Anaerobe Contributes to tissue destruction