Dental Plaque

Question 1

What are some general properties of biofilm? (4)

Answer 1

• Protection (ie moisture, predators)
• Slow growth rate
• Get their physical characteristics from surface
• The variation of biofilm leads to their metabolic interactions

Question 2

Define dental plaque

Answer 2

A complex microbial community on a tooth surface, embedded in a matrix of polymers of bacterial and salivary origin (BIOFILM)

Question 3

Define biofilm

Answer 3

Biofilms are a collective of one or more types of microorganisms that can grow on many different surfaces

Question 4

How are the properties of micro-organisms growing in microfilm different to ones growing from planktonic growth? (2)

Answer 4

• Microfilm grows slower
• Microfilm much more resistant to antimicrobial agents

Question 5

Give some examples of synergistic interactions between organisms in a biofilm (5)

Answer 5

• Enzyme sharing
• Food chains
• Co-adhesion
• Cell-to-cell signalling
• Gene transfer

Question 6

Give some examples of antagonistic interactions between organisms in a biofilm (6)

Answer 6

• Bacteriocin production
• H2O2 production
• Organic acid production
• Bacteriophage release
• Competition for nutrients
• Predation

Question 7

Name some different types of dental plaque (5)

(Think location)

Answer 7

• Fissure plaque
• Approximal plaque
• Gingival crevice plaque
• Denture plaque
• Calculus

Question 8

What are the 5 steps of the development of dental plaque

Answer 8

1. Acquired enamel pellicle is deposited on clean tooth surface about 1μm thick
2. Pioneer species of bacteria will adhere to the acquired pellicle
3. Pioneering species multiply and form a confluent layer
4. Accumulated bacterial growth leads to a decrease in oxygen tension which cultures additional anaerobic bacteria
5. Plaque maturity

Question 9

After brushing your teeth how long does it take for the acquired enamel pellicle to form?

Answer 9

2 Hours

Question 10

What is the acquired enamel pellicle composed of? (5)

{3 Molecules + 2 fluids}

Answer 10

• Proteins
• Lipids
• Glycoproteins
• Saliva
• Gingival crevicular fluid

Question 11

What components of the enamel pellicle are bacteria derived? (4)

Answer 11

• Glycosyl transferase
• Glucans
• Fructans
• Bacterial cell fragments

Question 12

What components of the enamel pellicle are host derived? (5)

Answer 12

• Acidic, proline-rich proteins
• Amylase
• Lysozyme
• Albumin
• Immunoglobulins

Question 13

What are the interactions that attract pioneer bacteria to the pellicle?

Answer 13

Van der Waals

Question 14

What are the interactions that repel pioneer bacteria to the pellicle?

Answer 14

Electrostatic repulsion between negatively charged bacterial cell and pellicle surface.

Question 15

Explain the molecular interactions between bacteria and pellicle

Answer 15

Bacteriums have adhesive molecules that are complementary to the pellicle surface receptors

Question 16

During the multiplication stage of the pioneer species, co-aggregation occurs, what is this?

Answer 16

Cell-to-cell interactions leading to distinctly different bacterial species becoming predetermined ‘partners’ in forming plaque.

Question 17

Mature plaque is a _____ community

Answer 17

Mature plaque is a climax community

Question 18

Are there any benefits of dental plaque for the host?

Answer 18

Small amount of dental plaque can help exclude exogenous organisms

Question 19

How can dental plaque help in the exclusion of exogenous organism from entering the mouth? (3)

Answer 19

• Competition for adhesion receptor sites
• Competition for nutrients and co-factors
• Production of inhibitory substances, eg acids, H2O2

Question 20

What is calculus?

Answer 20

Calcified dental plaque

Question 21

What is calculus composed of? (3)

Answer 21

• Mineral deposits
• Proteins
• Carbohydrates

Question 22

Where is the most predominant supra gingival location for calculus?

Answer 22

Near salivary ducts