Periodontal Immunology

Question 1

Describe the differences between gingivitis and periodontitis.

Answer 1

Gingivitis:
Localised inflammation
Acute inflammation
Normal physiological response occurs = resolution = reversible disease

Periodontitis:
Inflammation of the gingival tissues and the supporting structures.
Chronic inflammation
Pathological response which leads to tissue destruction and no resolution = irreversible disease

Question 2

What factors contribute to periodontitis?

Answer 2

Plaque accumulation
Bacteria (virulence factors of the bacteria)
Host immune response

Question 3

Describe the composition of the plaque biofilm; what species colonise at the early and late stages?

Answer 3

Early colonisers = commensal species

Later colonisers = gram negative anaerobes

Question 4

What bacteria are heavily associated with periodontitis?

Answer 4

p. gingivalis
T. Forsythia
T. Denticola

Question 5

Describe the virulence factors of P.gingivalis.

Answer 5

Inflammophilic - inflammatory environment favours it virulence

Secretes gingipans;
Activate MMP’s
Degrade host proteins.

Asaccharolytic: receive nutrients from the host proteins and peptides

Question 6

What are the immune defences in the oral cavity?

Answer 6

Gingival crevicular fluid
Oral mucosa
Saliva

Question 7

What are the roles of neutrophils in periodontal disease?

Answer 7

Maintains healthy periodontium

Increase in numbers and act as reactive oxygen species to trap and destroy bacteria - fight and contain.

However these reactive oxygen species can also cause harm to the host when there is excessive infiltration in periodontitis = predispose to disease

Question 8

What is leukocyte adhesion deficiency?

Answer 8

Immune under reaction associated with aggressive periodontitis.

Neutrophils cannot migrate from the blood to the tissues = bacteria exist uncontrolled = periodontitis

Question 9

What is there excessive infiltration of in chronic periodontitis?

Answer 9

Degradative enzymes - MMPs

Inflammatory cytokines and oxygen radical = hypoxic environment (favours the gram negative anaerobes?)

Question 10

Describe the adaptive immune response in periodontitis.

Answer 10

T and B cells are present initially

CD4 T cells, B cells and dendritic cells are present as the lesion progresses

Biofilm becomes unregulated and dysbiotic

In the advances lesion mostly B cells and plasma cells are present

IgG fails to regulate

Protective response prevents the infection from becoming systemic

Inflammatory response causes tissue destruction and bone loss

Question 11

Describe bone turn over in health compared to disease.

Answer 11

In health:
Balance between OPG and RANKL

T and B cells secrete RANKL
RANKL binds to RANK to start osteoclast differentiation
(Osteoclasts resorb bone)
OPG binds to RANK to inhibit bone resorption.

In periodontitis:
High levels of RANKL
Low levels of OPG