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BDS2 CLINICAL Periodontology > Aetiology and Pathogenesis > Flashcards

Aetiology and Pathogenesis Flashcards

1
Q

What does clinical periodontal health require

A

A health promoting biofilm within which symbiotic relationships exist between microorganisms and with the host response

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2
Q

What does the host response provide to the biofilm in clinical health

A

Key nutrients via GCF

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3
Q

What happens if the biofilm is not disrupted frequently and is allowed to accumulate

A

The conditions within it start to favour bacterial species that are capable of sensing and influencing their environment by employing chemical cues.

These organisms triggers stronger host response, which, can lead to the development of gingival inflammation and increase the supply of nutrients that encourage the proliferation of traditional pathogens (e.g p. gingivalis)

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4
Q

What can developing dysbiosis trigger in susceptible patients

A

An inappropriate and frequently excessive host response in which excess cytokines, ROS and MMPs are generated resulting in periodontal tissue damage.

DAMPs are released which further propagate the inflammatory response and failure of innate inflammation resolving mechanisms results in chronic inflammation

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5
Q

What do local plaque retention factors do

A

make you more likely to get gingivitis as an accumulation of plaque causes gingivitis

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6
Q

What are examples of plaque retention factors

A
  • Calculus
  • Restoration margins
  • Crowding
  • Mouth breathing
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7
Q

What does mouth breathing do that results in plaque retention

A

interferes with saliva

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8
Q

What are examples of systemic modifying factors that can also impact the route to clinical disease

A
  • Sex hormones

* Medication

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9
Q

What are signs of gingival health

A
  • Knife edge, scalloped gingival margin
  • Stippling (in about 30%)
  • Pink
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10
Q

In gingival health what is the intact barrier provided by

A

junctional epithelium

it is non ulcerated

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11
Q

What is the turnover of the intact barrier

A

very quick

4-5 day turnover

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12
Q

What is the turnover of the intact barrier referred to as

A

epithelial cell shedding

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13
Q

What is the advantage of epithelial cell shedding

A

makes invading difficult due to this continuous shedding

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14
Q

What is the cellular response present in health

A

There are neutrophils that are finding their way to the gingiva, keeping the environment under control with the help of lymphocytes.

There is a flow of gingival crevicular fluid that contains antibodies.

There is phagocyte function and lymphocyte infiltrate as well as complement activity.

The key to the immune response in health is it is regulated.

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15
Q

What occurs in gingivitis

A

altered microbial colonization

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16
Q

What is the appearance of the gingiva in gingivitis

A

now red and inflamed with a shiny appearance clinically

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17
Q

What happens as a result of gingivitis

A

Increased flow of GCF with an influx of neutrophils, increased lymphocytes and monocytes.

There is plasma cell infiltrate as well as proliferation and ulceration of epithelium – the ulceration is what causes the bleeding.

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18
Q

In disease what kind of bacteria is it shifted to

A

gram positive aerobes

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19
Q

What happens in periodontitis

A

In periodontitis there is apical migration of the junctional epithelium
There is bone loss
Plasma cells constitute more than 50%

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20
Q

what happens in a false pocket

A

In a false pocket, bone is still intact. The junctional epithelium has not changed position, it has just become ulcerated and the rest of the epithelium has started to proliferate creating a pocket

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21
Q

What is the progression of attachment loss once periodontitis has been initiated

A

may be episodic rather than continuous

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22
Q

What is the progression of attachment loss usually

A

0.05-0.1mm a year

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23
Q

What is a biofilm

A

A biofilm is one or more communities of microorganisms embedded in a glycocalyx attached to a solid surface

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24
Q

what are the properties of a biofilm

A

Biofilms provide protection for colonizing species from competing organisms and environment (host defenses, antibiotics etc)
They facilitate the uptake of nutrients and removal of metabolic products
Development of appropriate physiochemical environment e.g pH, O2 concentration
It allows for communication between bacteria

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25
Q

Describe bacteria virulence

A

The bacteria have the ability to colonise and compete in an ecological niche

26
Q

What are the different ways bacteria can evade host defenses

A
  • Degrading host immunoglobulin and complement
  • Leucotoxin production
  • Tissue invasion
  • Inhibition of antibody synthesis
27
Q

What is the evidence for specific bacterial causation

A
  • Presence in elevated numbers at diseased sites
  • Reduced numbers following periodontal therapy
  • Presence of an elevated specific immune response
  • Production of virulence factors (which is what allows them to cause disease)
  • Evidence from animal models
28
Q

What are the bacteria in the strongest associated complex

A

p. gingival
b. forsythus
t. denticola

29
Q

What are some of the bacteria in the second strongest associated complex

A

f. nuc. polymorphum
p. intermedia
p. micros

30
Q

what is the model of oral biofilm formation

A

Those at the bottom are the early colonisers – as the biofilm accumulates it allows for other bacteria to come in and attach

31
Q

what is the keystone pathogen in periodontitis

A

p. gingivalis

32
Q

what does the presence of the keystone pathogen do

A

Their presence in the biofilm will change it and they will use bacteria that were previously friendly and use them as allies to create a dysbiotic biofilm resulting in an inflammatory response. The bacteria like the inflammation because the environment suits them.

33
Q

what are the host response mechanisms

A

saliva
epithelium
GCF
inflammatory response and immune responses

34
Q

how does epithelium act as a immune response

A

o Physical barrier
o Shedding of cells
o Production of inflammatory mediators

35
Q

how do neutrophils help in the immune response

A

 Generate reactive oxygen species that kill bacteria but also cause bistandard damage to the host
 Extracellular traps – neutrophil explodes into a web of sticky DNA and other molecules allowing it to trap bacteria. In doing so it releases mediators that kill bacteria but also damage the host
 They are found in health also but the numbers are lower

36
Q

describe how we go from health to periodontitis

A

The normal flora turn into a dysbiotic biofilm and this results in an inflammatory response including neutrophils. For some patients this can contain the disease meaning they will have gingivitis without progression. For the vast majority it results in the evolution of the pathogenic biofilm and will progress to periodontitis

37
Q

what is the initial periodontal lesion composed of

A

mainly T lymphocytes (CD4) which generate cytokines and summon other cells to come in

38
Q

what cells predominate in the later stage

A

b cells and plasma cells

39
Q

what is produced locally in periodontitis

A

antibodies

40
Q

what are the functions of antibodies

A
  • Complement activation
  • Neutralization of toxins
  • Opsonization and phagocytosis
  • Prevents progression infection and therefore potentially serious systemic consequences
  • Inadvertent local tissue damage (bystander damage) combined with attempts at repair
41
Q

what are MMPs

A

MMPs are a family of zinc and calcium dependent proteolytic enzymes, which include collagenases

42
Q

what is matrix degradation in periodontitis due to

A

matrix degradation is largely a result of MMPs secreted by host inflammatory cells.

43
Q

what do MMPs do

A

break down connective tissue which is key to the progression

44
Q

what is bone loss caused by

A

The other part of the periodontitis is bone loss which is caused by osteoclast activation

45
Q

describe how osteoclast activation occurs

A

When the host immune response is excessive for long periods it will promote production of osteoclasts and promote bone loss. Cytokines e.g tnf will cause osteoclasts to activate and resorb bone

46
Q

how much bone loss is there usually

A

1-2mm

47
Q

what is horizontal bone loss

A

bone resorbs at the same level

48
Q

what is vertical bone loss

A

one side of the bone level is higher than the other. In angular bone loss there may be possibility to regenerate the bone because of the wall of bone on one side of it so sometimes we can use that bone to help it regenerate. There is no chance of regeneration in horizontal bone loss.

49
Q

why do we get different patterns of bone loss

A

The reason why we get different patterns is presumed to be down to the shape of the bone to begin with. If the bone is quite narrow you will get horizontal bone loss as the zone of destruction form the most apical point of plaque. If it is wider than it will be vertical bone loss

50
Q

what are general risk factors for periodontitis

A
  • Smoking
  • Diabetes
  • Stress
  • Drugs
  • Systemic disease
  • Nutrition
51
Q

what are general risk determinants for periodontitis

A
  • Genetics
  • Socioeconomic status
  • Gender
52
Q

what are the local risk factors

A

anatomical
tooth position
iatrogenic

53
Q

what are anatomical risk factors

A

o Enamel pearls/projections
o Grooves
o Furcation
o Gingival recession

54
Q

what are tooth position risk factors

A 
o	Malalignment 
o	Crowding
o	Tipping
o	Migration
o	Occlusal forces
55
Q

what are iatrogenic risk factors

A

o Restoration overhangs
o Defective crown marginas
o Poorly designed partial dentures
o Orthodontic appliances

56
Q

what is the key risk factor

A

smoking

57
Q

what are the effects of smoking

A
  • Effect on subgingival plaque is uncertain
  • Vasoconstriction of gingival vessels and increased gingival keratinization
  • Impaired antibody production
  • Depressed numbers of Th lymphocytes
  • Impaired PMN function
  • Increased production of proinflammatory cytokines
58
Q

what is the primary etiological agent in inflammatory periodontal disease

A

plaque

59
Q

what is the extent and severity of disease dependent on

A

interaction between microbe and host

60
Q

what conveys supectibility

A

risk factors which interfere with host defenses

61
Q

In clinical periodontal health, what does the biofilm release and what is its effect on the host response?

A

The various proteins and peptides released by the biofilm organisms trigger a host response that is both proportionate and resolving

62
Q

What does dysbiosis refer to

A

The concept that some diseases are due to a decrease in the number of beneficial symbionts and an increase in the number of pathogens
Simultaneously, a succession of microbial complexes develops.

BDS2 CLINICAL Periodontology (17 decks)

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