Plaque in Caries

Question 1

What are the 4 factors that directly contribute to plaque formation?

Answer 1

• Tooth
• Time
• Diet
• Bacteria

Question 2

What oral environmental factors that can affect plaque formation?

Answer 2

•	Saliva
-buffering capacity
-composition
-flow rate
•	Protein
•	Sugars 
-frequency
-clearance rate
•	Plaque pH
•	Microbial species
•	Fluoride
•	Sealants
•	Chewing gum
•	Antibacterial agents

Question 3

What personal factors that can affect plaque formation?

Answer 3

• Income/socio-economic status
• Knowledge/education
• Attitude/ dental aspirations
• Behaviours: oral health, smoking, alcohol

Question 4

What is the critical pH of enamel?

Answer 4

pH of 5.5

Question 5

What are the 4 stages of plaque formation?

Answer 5

1. Pellicle formation (acquired) builds up in seconds
2. Initial colonisation predominantly strep and gram +ve bacteria. They adhere within minutes.
3. Secondary colonisation (some bacteria attach via pellicle, others use other bacteria and appendages)
4. Maturation where gram –ve bacteria eventually dominate the colony i.e. bacilli

Question 6

What does plaque consist of?

Answer 6

• Bacteria
• An amorphous matrix, derived from salivary mucoids and extracellular bacterial polysaccharides (glucans).
• Leucocytes and desquamated epithelial cells that may become entrapped in the matrix.

Question 7

What is the pellicle?

Answer 7

-It is a tenacious protein film that forms on hard surfaces within seconds. It forms ion enamel within seconds of after a tooth is cleaned or after chewing. -It can anchor specific types of bacteria to the tooth surface.

Question 8

What is the pellicle layer made from?

What holds the bacteria to the pellicle?

Answer 8

• Pellicle is made from glycoproteins from the saliva

- subatomic Van der Waals forces anchor the bacteria to the pellicle

Question 9

Which acids are produced by plaque bacteria?

Answer 9

-The main acid produced by bacteria is lactic acid

but also: acetic acid, formic acid, and propionic acid are produced.

Question 10

Which bacteria are most involved in causing caries?

What is the relationship between them?

Answer 10

-The bacteria that are most involved in caries are:
• Streptococcus mutans (S. Mutans)
• Lactobacilli eg. L. Acidophilus
• Actinomyces eg. A. Viscosus/Naeslundi

-It is believed that S Mutans is important for initiating caries, and Lactobacilli keep it going
after it has started.

Question 11

What are the types of plaque?

Answer 11

• supragingival: found on the smooth surfaces/crowns of teeth
• supragingival: develops by extension from subgingival plaque into the crevice/pocket

Question 12

• Where are the most common places for plaque to accumulate?

- Which site has the heaviest deposition of plaque?

Answer 12

• Fissures of molar teeth
• Between adjacent teeth (interproximally)
• Gingival margin

-The site of heaviest plaque deposition is the gingival crevice.