ICP L3: Dental Plaque

Question 1

What is dental plaque

Answer 1

A complex microbial community embedded in a matrix of salivary and bacterial origin (biofilm) found on the tooth surface

Question 2

What are the general properties of a biofilm

Answer 2

• protect from dessication (drying) and host defences or predators
• slow rate of growth
• spatial and environmental hetrogeneity

Question 3

List the different areas dental plaque can arise§

Answer 3

1. Fissure plaque = supragingival
2. Approximal plaque = supragingival
3. Gingival crevice plaque = subgingival
4. Denture plaque
5. Calculus = calcified plaque either supra or subgingival

Question 4

Outline the stages involved in plaque development

Answer 4

1. Acquired enamel pellicle
2. Pioneering species
3. Multiplication of pioneering species to give confluent layer
4. Accumulated bacterial growth leads to decreased oxygen tension and so anaerobic bacterial growth which increases the diversity in dental plaque
5. Plaque maturity is attained at the stagnant sites as the climax community has been reached

Question 5

What are the components of the acquired pellicle

Answer 5

Bacteria derived

• glycosyl transferases
• glucans, fructans
• bacterial cell fragments

Host derived

• acidic, proline rich proteins
• amylase, lysozyme
• albumin
• immunoglobulins

Question 6

What is the pioneering species in dental plaque

Answer 6

These bacteria will adhere to the acquired pellicle after 2 hours and is composed of strep. species and actinomyces species; this occurs via specific receptors

Question 7

What is the confluent layer in dental plaque

Answer 7

This is where coaggregation and coadherence occurs

Question 8

What is fusobacterium nucleatum

Answer 8

This bridges between early and later colonisers

Question 9

What does the establishment of bacterial homeostasis in plaque result in

Answer 9

• enhanced catabolism of nutrients
• protection from stressful environments
• synergy in the recycling of nutrients
• metabolic efficiency in the community

Question 10

Why can plaque be beneficial

Answer 10

Because some of the organisms within it uses up lactic acid in the mouth and so this can protect against caries

Question 11

What is calculus

Answer 11

Calcified dental plaque known as tartar which consists of mineral deposits, protein and carbohydrates supra or subgingivally

It is porous so there is retention of bacterial antigens causing bone resorption