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Oral Disease > Oral mucosa: Allergies > Flashcards

Oral mucosa: Allergies Flashcards

1
Q

Define allergy

A

When immune system responds in an exaggerated or inappropriate way to an extrinsic (non-self) antigen

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2
Q

Define autoimmunity

A

When immune system responds in an exaggerated or inappropriate way to an intrinsic (self) antigen

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3
Q

Define hypersensitivity

A

When immune system responds in an exaggerated or inappropriate way resulting in harm
e.g. allergy and autoimmunity are forms of hypersensitivity

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4
Q

When does hypersensitivity occur?

A

Occurs on 2nd exposure to antigen

Is a characteristic of the individ (genetics involved)

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5
Q

Types of hypersensitivity?

A

Type I - immediate/anaphylaxis
II - cytotoxic
III - immune complex
IV - delayed

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6
Q

How is type IV hypersensitivity mediated?

A

Cell mediated

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7
Q

What hypersensitivities are antibody mediated?

A

I, II, III

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8
Q

Type I hypersensitivity features?

A 
Anaphylaxis
Rapid onset
IgE mediated
Antigen gives rise to type I hypersensitivity rxns 
Most allergens are small proteins
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9
Q

What does histamine release in type I hypersensitivity cause?

A

Vascular dilation (vasodilation)
Increased vascular permeability e.g. oedema
Bronchospasm
Urticarial rash
Increased nasal and lacrimal secretions = runny nose

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10
Q

What do type I hypersensitivity reactions most commonly present as?

A

Hayfever
Asthma
Acute allergic rxns
Angio-oedema/anaphylaxis e.g. penicillin, latex allergies

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11
Q

How to diagnose type I hypersensitivities?

A

Wheel and flare skin test
Apply small amount of allergen under skin using prick test
Wheel caused by extravasation of serum into skin due to histamine e.g. angio-oedema
Flare caused by axon reflex
Late phase 6hrs plus due to leukocyte infiltrate and more oedema

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12
Q

How to manage type I hypersensitivities?

A

Adrenaline
Antihistamines
Corticosteroids
Avoidance of allergen

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13
Q

Type II hypersensitivity features?

A

Antibodies target self antigens (auto-antibodies)
Usually IgG or IgM
Antibodies induce cell damage and inflammation
Auto-antibodies activate either Antibody dependent cell cytotoxicity (ADCC) OR complement

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14
Q

What does complement activation in type II hypersensitivity result in?

A 
Inflammation
Cell death (membrane attack complex)
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15
Q

What are type II hypersensitivity responses important in?

A

Acute transplant rejection
Autoimmune diseases
- Pemphigus
- Pemphigoid

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16
Q

Type III hypersensitivity features?

A

Immune complex forms between antibodies and antigens

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17
Q

What can immune complexes in type III hypersensitivity deposit in?

A

The lining of BVs
Glomeruli
Lung

18
Q

What can immune complexes in type III hypersensitivity induce?

A

Complement activation
Neutrophil binding
= Inflammation and vascular permeability

19
Q

What are type III hypersensitivity reactions important in?

A

Immune complex mediated vasculitis e.g. erythema multiforme, systemic lupus erythematosus (SLE)

20
Q

Type IV hypersensitivity features?

A

Cell mediated - generally localised
Mediated by T cells
Slow to develop, resolve
Localised

21
Q

Type IV hypersensitivity - what are they important in?

A

Delayed hypersensitivity responses
Contact dermatitis
Lichenoid reactions to amalgam fillings
Oral lichen planus

22
Q

How does type IV hypersensitivity occur?

A

Langerhan’s cells form a network within the epithelium
They intercept and process antigen entering the mucosa
The antigen stimulates keratinocytes to release TNF
= Stimulates langerhan’s cells to migrate to the draining lymph nodes
Langerhan’s cells process than antigen
And present parts of it to T cells circulating though the lymph node
Antigen specific T cells become activated
Proliferate of antigen specific T cells (clonal expansion)
Cytotoxic T cells (CD8) kill basal karatinocytes (apoptosis)

23
Q

How do T cells kill keratinocytes?

A

They induce apoptosis by:
Fas/fas-ligand mediated apoptosis
Perforin/granzyme B

24
Q

What is increasing in the population?

A

Large increase in children with asthma
and allergic responses in adults
= allergies increasing in dental surgery - latex and dental materials

25
Q

What are the main concerns regarding allergies in dental surgeries?

A

Drug allergies
Dental material and latex allergies
Type I reactions - penicillin and other antibiotics, LA, NSAIDs

26
Q

What can penicillin hypersensitivity reactions cause?

A

Skin rash

Angioedema

27
Q

LA allergy?

A

Rare since preservatives removed from cartridges
Most reactions are vasovagal and due to IV injection
Some rxns due to latex allergies

28
Q

Allergies in ortho?

A

Nickel containing wires
Bracket adhesives - bisGMA
Acrylic materials

29
Q

Allergies in restorative dentistry?

A

Amalgam
Composite filling materials - bisGMA
Denture bases - acrylics
Rarely metals in crowns and denture bases

30
Q

How are dental materials grouped?

A

Into plastics (denture bases and composites) and metals
Usually present as type IV responses
- Usually chronic and localised
- Skin patch testing can be helpful

31
Q

How to test for type IV hypersensitivity?

A

Skin patch testing

Samples applied to skin or back of arm for 72-96 hrs

32
Q

Denture acrylic hypersensitivity - common allergens?

A 
Polymethyl methacrylate
Methyl methacrylate monomer
Stabiliser (hydroquinone)
Initiator (benzoyl peroxide)
Chemicals released during polymerisation (formaldehyde)
33
Q

Cold cure acrylics - why are they a problem?

A

More hypersensitivity
Less polymerisation
More free monomer, stabiliser, initiator
Activator

34
Q

What do composite filling materials contain that may cause hypersensitivity?

A 
Quartz or borosilicate fillers
BisGMA
Low MW monomers
e.g. TEG-DMA or EG-DMA
Coupling agents
Stabilisers, activators, initiators
35
Q

What do bonding agents contain?

A

More resin and less filler than composite filling materials

More likely to cause problems

36
Q

Metal hypersensitivity in dentistry?

A

Generally type IV
Nickel - ortho wires
Mercury - lichenoid rxns to amalgam fillings

37
Q

Causes of rubber related reactions?

A

Latex protein allergy
Chemical allergy
Powder irritancy

38
Q

Latex protein allergy (type I reactions) occur with?

A

Skin contact -

  • Urticaria
  • Angioedema
  • Rarely anaphylaxis

Air dispersal on glove powder particles
- Asthma, cough, weeze, rhinitis, rarely anaphylaxis

39
Q

Chemical allergy - type IV reactions due to?

A

Accelerators and antioxidants used during manufacture
Chemicals produced during manufacture
Allergic contact dermatitis
75% of work related glove allergies

40
Q

How to avoid occupational glove allergy problems?

A

Use powder free and hypoallergenic latex gloves

Latex free gloves

Oral Disease (42 decks)

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