Aetiology of Periodontitis

Question 1

What are the signs of healthy periodontium?

Answer 1

Lack of inflammation symptoms such as oedema swelling, and bleeding.

Lack of plaque bacteria

Question 2

What are the 3 stages of the inflammatory response?

Answer 2

Acute

Immune

Chronic

Question 3

What are the signs and symptoms of established gingivitis?

Answer 3

Infiltration of connective tissue by large numbers of defence cells

Destruction of normal anatomy

No apical migration of the junctional epithelium

Question 4

Does gingivitis progress to periodontitis?

Answer 4

Healthy gingiva

Early gingiva

Established chronic gingivitis. This can be stable and unstable.

Question 5

What happens to periodontal tissue during periodontitis?

Answer 5

Apical migration of the junctional epithelium

Inflammatory lesion extends apically and laterally

Resorption of alveolar bone

Question 6

What immune cells are found in periodontitis?

Answer 6

Neutrophils

B lymphocytes

Macrophages

Cytokines

Question 7

What do neutrophils do in periodontitis?

Answer 7

They kill bacteria in 2 ways:

Intracellular killing via phagocytosis

Extracellular killing via release of destructive enzymes and oxygen radicals but also cause significant damage to periodontal tissues.

Question 8

What do B lymphocytes do in periodontitis?

Answer 8

Transform into plasma cells and produce specific antibodies. Antibodies released in the presence of complement facilitate enhanced PMN bacterial killing.

Question 9

What do macrophages do in periodontitis?

Answer 9

They are recruited to an area and activated by binding to LPS to release inflammatory mediators.

Question 10

How do cytokines affect periodontitis?

Answer 10

IL1 and TNF-alpha bind to fibroblasts which are also stimulated to produce additional quantities of inflammatory mediators.

Question 11

How does periodontitis progress?

Answer 11

It is rapid and takes place in random bursts that are asynchronous

Question 12

How does chronic periodontitis progress?

Answer 12

Overall there is an attachment loss of 0.1 - 0.2 mm per tooth per year.

Aggressive periodontitis grade C could be as much as 3mm in a year.

Question 13

What is the host reponse to inflammation of the gums that leads to periodontal destruction?

Answer 13

Bacterial products and toxins cross the JE.

This stimulates epithelium and connective tissue to produce inflammatory mediators.

Blood vessels dilate and become more permeable and as a result defense cells migrate from the capillaries towards chemotactic stimulus.

Question 14

What are the mechanisms of action of bacterial virulence factors in periodontitis?

Answer 14

Direct destruction: H2S, NH3, fatty acids, indole, Bacterial derived enzymes

Indirect destruction: Via host response

Question 15

What is different about the bacteria involved in gingivitis compared to periodontitis?

Answer 15

The quantitiy of bacteria increasing in gingivitis causes progression.

The quality of bacteria is important in the pathogenesis of periodontitis due to production of enzymes, toxins, and metabolic products.

Question 16

What type of enzymes are poduced by pathogenic bacteria causing periodontitis?

Answer 16

Collagenase

Elastase

Other proteases

Hyaluronidase

Question 17

What type of toxins are produced by pathogenic bacteria causing periodontitis?

Answer 17

Exo-toxins

Endo-toxins

Question 18

What metabolic products are potentially causative of periodontal tissue damage?

Answer 18

Hydrogen sulphide

Ammonia

Volatile fatty acids

Question 19

What are the most commonly studied bacterial virulence factors?

Answer 19

LPS: Constituent of the other cell wall of gram negative bacteria

Fimbriae: Numberous thin straight appendages on outer cell wall

Proteases: Hydrolysis of peptide bonds of proteins, acquisition of nutrients, and modification of host response.

Question 20

What inflammatory mediators have an important role in inflammation?

Answer 20

Research has focused on mediators of inflammatory response:

Prostanoids such as prostaglandins E2 which stimulates alveolar bone resorption

Cytokines such as IL1 and TNF a

MMP which has a key role in breakdown of connective tissue

Question 21

What is periodontitis due to infection associated with?

Answer 21

Dental plaque constitutes the primary etiological factor in chronic inflammatory periodontal disease. A non-resolving inflammation that is ineffective at eliminating pathogens is considered periodontitis.

Question 22

What kind of structure is a biofilm?

Answer 22

It is highly structured with channels traversing to a depth.

They have a primitive circulatory system

Organisms are not randomly distributed but spatially and functionally organised

Outer organisms may have a protective role

Question 23

How do bacteria within a biofilm communicate?

Answer 23

VIa a sophisticated cell to cell gene expression called quorum sensing.

Cells within the biofilmcan alter gene expression so that they have a different phenotype (strength in numbers)

Question 24

How do biofilms affect susceptibility to antibiotics?

Answer 24

Bacteria in bioilms can be up to 1000 times more resistant to antibiotics than they are in the planktonic state.

There is evidence of gene transfer of antimicrobial resistance.