Bacteria

Question 1

During plaque formation what are they initial colonisers? What makes them good at this?

Answer 1

Streptococci

GTFs and adhesion molecules makes them sticky

Question 2

What were the findings of the Takeuchi et al 2004 study?

Answer 2

The development of subgingival biofilm occurred in five sequential phases: pellicle formation, microbial adherence, initial colonization, microbial organization, and establishment. There were initial, secondary and tertiary colonizers.

Question 3

What is the ecological plaque theory Marsh 1994?

Answer 3

Increased plaque causes increased inflammation,
which caused an environmental change (high GCF flow, bleeding, raised pH and temperature)
This causes an ecological shift from gram positive bacteria to gram negative
This causes a shift in disease from gingival health to gingivitis and periodontal disease

Question 4

What were the findings of the Socransky et al 1998 study?

Answer 4

Sub gingival bacteria lives in complexes. Yellow and blue are early colonisers. Red and orange are predominantly anaerobes

Question 5

Describe the association of p.gingivalis with perio disease

Answer 5

P.gingivalis is associated with an increased risk for alveolar bone loss and attachment loss
It’s numbers are decreased in health and increased in periodontal lesions

Question 6

What disease is A.a associated with?

Answer 6

Aggressive periodontitis

Question 7

Name the clone of A.a. What individuals is this mostly associated with?

Answer 7

JP2 clone

Northern African

Question 8

What is the keystone pathogen hypothesis? What study proposed this hypothesis?

Answer 8

The keystone-pathogen hypothesis holds that certain low-abundance microbial pathogens can orchestrate inflammatory disease by remodelling a normally benign microbiota into a dysbiotic one

Hajishengallis et al 2011

Question 9

Give an example of a keystone pathogen and explain why

Answer 9

P.gingivalis

It maintains and governs entire microbiome
It causes a shift from symbiotic to dysbiotic

Question 10

What is the link between viruses and periodontal disease?

Answer 10

A study found an association between cytomegalovirus and Epstein Barr virus with periopathogenic bacteria and severity of periodontal disease

Question 11

What is a dental pellicle?

Answer 11

Dental pellicle is a protein film that forms on the surface enamel

Question 12

Describe the formation of the dental pellicle

Answer 12

• Starts within seconds
• It develops over 30-90 minutes
• Protein absorption by protein-protein interaction
• Electrostatic attraction to hydroxyapatite

Question 13

Name some subgingival pellicle proteins

Answer 13

Albumin, IgA, IgG, IgM

Question 14

What is a biofilm?

Answer 14

Bacterial species organised in complex communities

Question 15

How do biofilms create bacterial resistance?

Answer 15

• Protection from host defence
• Protection from dessication
• Protection from antimicrobial agents (slow growth rate, poor penetration)
• Quorum sensing (communication between bacteria through channels)

Question 16

Describe the association of Tanerella Forsythensis with perio disease

Answer 16

Increase in lesions of periodontitis
Decrease in health or gingivitis
Increase in progressive lesions
Increase in periodontal abscesses
Its presence indicates increased risk of alveolar bone loss and attachment loss

Question 17

What were the main findings of the following study: “ Ximenez-Fyvie et al, 2000 - Comparison of the microbiota of supra‐ and subgingival plaque in health and periodontitis”

Answer 17

• Actinomyces species were the dominant taxa in both supra and subgingival plaque from healthy and periodontitis subjects
• P.gingivalis, B.forsythus and T.denticola could be detected in subgingival plaque sample of both healthy and periodontitis subjects
• The main differences between supra and subgingival plaque as well as between health and disease were in the proportions and to some extent levels of Actinomyces, “orange” and “red” complex species.

Question 18

State some major bacterial activities that define periodontal disease

Answer 18

• Iron acquisition
• Lipopolysaccharide synthesis
• Flagellar synthesis
• Potassium uptake