Allergy to Dental Materials & Drugs Flashcards
What are the 4 routes of entry for an allergen?
Percutaneous/mucosa- plants/pet scratch
Injection- bee stings
Inhalational- hay fever (pollen), asthma (dust)
Ingestion- food (nuts), medicines
What is an allergy?
An immunologically based sensitivity:
Specific immune response to the allergen
Not dose dependent
Reaction will change on subsequent exposure
What is toxicity?
A non-immunologically based reaction:
Non-specific, not immune
Dose dependent
May be accumulative
Reaction will be similar on subsequent exposure
What is hypersensitivity?
A state of altered reactivity in which the body reacts with an exaggerated immune response to a foreign substance
Hypersensitivity reactions are classified as immediate or delayed types I and IV, respectively, in the Gell and Coombs classification of immune responses
What are the 4 types of hypersensitivity?
Type 1– immediate IgE mediated: anaphylaxis
Type 2– auto antibody mediated
Type 3– immune complexes
Type 4– T cell mediated: delayed hypersensitivity
Describe a type I hypersensitivity reaction:
-Mediated by IgE bound to high affinity Fc receptors on mast cells.
-Cross linking of IgE/Fc receptor complex by antigen = degranulation + release of histamine, serotonin, proteases, cytokines etc
-This activates and attracts eosinophils, neutrophils and macrophages
-Leukotrienes + histamines = vascular permeability/smooth muscle contraction.
extreme reaction - anaphylactic shock
Describe a type II hypersensitivity reaction:
-Auto-antibodies bind to antigens coating a target cell, mediated by IgG once bound to antigen it binds to Fcy receptors on macrophages, NK cell
-This combination insights a chemical cascade which invokes the complement cascade.
-Causes cytotoxic reaction (degranulation or phagocytosis) which leads to cell damage
Describe a type III hypersensitivity reaction:
-Souble antigens (from infection/persistent exposure to antigens) bind to antibodies (IgG/IgM) in excess or in the wrong proportions = immune complexes
-Immune complexes circulate in blood and can be deposited in various tissues.
-These can then activate complement cascade = production of chemotactic factors and recruitment of inflammatory cells.
Describe a type IV hypersensitivity reaction:
-Mediated by T cells
-Activated T cells secrete chemokines, cytokines to recruit and activate macrophages
-Activated macrophages secrete further pro-inflammatory cytokines, tissue damage from degranulation.
-Formation of granuloma: including macrophages/multi-nucleated giant cells, eosinophils, T cells etc.
What types of materials in dentistry could possibly induce an allergic reaction?
Drugs: Local anaesthetics, cortico-steroids, antibiotics, analgesics (pain reliever)
Restorative materials: Amalgams, ionomers, composites, metals & porcelains
Clinical materials: Latex, impression materials
Tooth paste/mouth washes
Which drugs can cause reactions on your mucosa and what are their respective reactions?
Corticosteroids- candidosis
Methotrexate- ulceration
Gold- lichenoid reactions
Penicillamine (Wilsons disease and rheumatoid arthritis) - loss of taste
Antimalarials- lichenoid reactions
NSAIDs- lichenoid reactions (rarely) oral ulceration
What reactions can you get to toothpastes & mouthwashes?
toothpastes and mouthwashes:
-Gingival desquamation (loss of surface)
-Gingival swelling & granulomatous reactions
-Benign migratory glossitis
-Epithelial desquamation, inflammation
-Ulceration
What reactions can you get to creams, ointments & impression materials?
Creams, Ointments, Impression materials:
-Contact stomatitis - inflammation or pain of the oral mucosa due to both irritant and allergic substances
-Gingival desquamation, swelling & granulomatous reactions
-Mucosal Swelling
-Epithelial desquamation, inflammation
-Ulceration
Are there lots of allergic reactions to LA?
True allergy is rare and accounts for <1% of adverse reactions to LA
True allergy may be delayed as well as immediate type
Are there lots of adverse reactions to LA?
LA account for 5-10% of adverse reactions to anaesthetics drugs, so it’s not a lot, it’s mainly GA to which there are more adverse reactions.
What are adverse effects to LA associated with?
Blocking of ion channels in cell membranes (CVS and CNS toxicity).
What are the main reasons of referral after using LA?
Collapse after LA (immediate or 2 hours later) (25%)
Swelling of lips, eyes, cheeks, face (immediate and up to 2 hours later) (25%)
Rash on chest, limbs, or contact area (1-7 hours later) (15%)
Breathlessness, sweating, nausea, disorientation (10%)
Headaches, irregular pulse and low BP(8%)
Swelling of throat, difficulty in breathing (8%)
Behavioural changes (minutes to hours later) (5%)
Sleepiness, dizzy (5%)
Describe the experiment that was taken out to see reactions to scratch & intradermal challenge LAs
Scratch testing = skin prick test
Intradermal = 25 macro-metres of LA is introduced beneath the skin
Asthma, eczema and hay fever = atopic conditions
What were the conclusions from the experiment?
Scratch skin tests alone are not good discriminators of allergy,
intradermal tests are better discriminators.
- Prilocaine produced more positive skin reactions than any
other local anaesthetic agent tested. - In 95 of the 100 patients referred with suspected
anaphylactoid reactions to local anaesthetic agents, negative
skin reactions to at least one of the agents allowed intrabuccal
challenge and subsequent recommendation of an agent for
future use. - Skin testing, though not providing formal proof of allergy,
provides a useful test to indicate local anaesthetics which
may be used for future procedure
What can the Type IV hypersensitivity (contact hypersensitivity) reaction be seen in?
Mantoux skin test
Homograft rejection (when immune system rejects transplantation form another individual)
It’s thought that it could also be involved in orofacial granulomatosis
What were the skin sensitisation figures (reaction to latex) for different health care professionals?
Dentists: about 10%
General hospital staff: 5-8%
Nurses: 9%
Anaesthetists: 16%
Therefore, latex has mostly stopped being used in the dental clinics for gloves- it’s normally latex-free
Amalgam can also cause lichenoid reactions in Buccal
How do you manage a latex allergy?
- Wear non latex gloves- plastic/polyvinyl:
-Sensitisation by contact, inhalation of protein dust, so reduce dust by use of powderless gloves - Specific RAST test
-Skin scratch test
-70% have atopic history - Avoid contact with latex at home & work
-Patients are advised to carry non latex gloves with them to hairdressers etc:)
-Polyurethane condoms
-Non rubber erasers etc. - Dental Practices should have a latex allergy policy in place
-Antihistamines
-Some patients may need to carry Epipen
What are some other causes of lip swelling?
- Urticaria (hives) & Angioedema (swelling)
- Reactions to foods (as part of type I reaction)
- Granulomatous conditions affecting the lips & oral cavity (may possibly be type IV)
What is urticaria?
Commonly referred to as ‘hives’, characterised by wheals: spots or patches of raised red or white skin
These usually clear away in a few hours, and are then replaced by other fresh wheels.
Are wheals painful?
Yes, they’re usually itchy, painful or cause a burning sensation
What can urticaria sometimes occur together with?
Angioedema
What is angioedema?
Name given to the deeper swelling affecting the skin over the arms, legs, torso or face.
May also affect the tongue, mouth, throat and sometimes the upper airway.
How long does the swelling usually last in angioedema and what is it usually associated with?
Swellings commonly last for more than 24hrs, and usually there is no itching
Often associated with autoimmune disease
What are some causes of chronic angioedema?
- Food allergy
- Oral allergy syndrome
- Medicine (ACE inhibitors, aspirin, beta blockers)
- Antibiotics
- Latex
It is often not possible to identify the case of chronic angioedema
Describe oral cavity reactions to foods.
Not common but when they do happen, can be devastating.
Usually type I reaction, although sometimes is type IV.
The oral cavity is less sensitive than the skin/nose
Peanuts is the most common food
What other agents have been identified as causing problems in the oral cavity?
Octyl gallate antioxidant preservative- sore tongue & erythema
Pumpkin seed- swelling and asthma
What happens in an immediate food allergy?
It’s a type I reaction so can result in anaphylaxis and only a small quantity of food is needed to trigger the reaction which develops in minutes to hours.
What are the symptoms of an immediate food allergy?
-Perioral erythema
-Lip swelling
-Oral itching
-Tongue & pharyngeal swelling
-Nausea & vomiting
How does a delayed food allergy contrast with an immediate food allergy?
Debate as to whether a delayed food allergy actually exists
You need a large quantity of food for a delayed
food allergy
Develops in hours & weeks
No diagnostic test for it except withdrawal & re-challenge
Is food intolerance (non-allergic hypersensitivity) much more common than a delayed food allergy?
yes
What are the guidelines for managing these reactions?
Establish provisional diagnosis - determine previous history, onset, symptoms and previous management
How does food intolerance differ from a delayed food allergy?
-Onset of symptoms usually slower and delayed by many hours after eating the offending food
-Symptoms may last for many hours, even into the next day
-Intolerance to several foods or a group of foods is not uncommon, & it can be much more difficult to decide whether food intolerance is the cause of chronic illness, and which foods or substances may be responsible
What are the symptoms of a delayed food allergy?
- Eczema
- Arthralgia (joint pain)
- Poor concentration /headaches/ depression
- Irritable bowel syndrome/Crohn’s disease
- Urinary frequency
- Arthritis & rhinitis
What do the features of oral allergy syndrome include?
Swelling of mouth, periorbital tissues, pharynx
How are the antigens inactivated in oral allergy syndrome?
by cooking
What is oral allergy syndrome (pollen food syndrome)?
Oral allergy syndrome (OAS) is a common food-related allergic condition that develops in adults.
OAS is connected to environmental allergies, such as hay fever
Distinctive type I reaction following direct contact of food and oral mucosa
What has the strongest association with oral allergy syndrome?
Birch allergy:
Specific allergen Bet vI identified in birch and apple, most common foods associated with this are apples, peaches, kiwi, hazelnuts & almonds
What might 20% of patients with oral allergy syndrome also be scratch positive to?
Apples, peaches, kiwifruit, and rarely, chestnut, salami
People with latex allergy may also react to avocado, banana and mango
What investigations should you undertake for a patient with a Type IV reaction (delayed hypersensitivity) ?
Allergy testing- patch tests
What investigations should you undertake for a patient with a Type I reaction?
Allergy testing- scratch tests/intradermal/intrabuccal challenges
Serology- mast cell tryptase levels ; complement/C1 esterase inhibitor; total IgE & specific IgE (RAST tests)
Other Routine blood tests- FBP/B12/folate/ferritin
What are some complementary and alternative testing you can do?
None of these have been validated
-Leukocytotoxic test
-IgG Elisa test
-Applied kinesiology
-VEGA testing (Electrodermal testing)
-Hair analysis
-Auriculo-cardiac reflex
-Stools analysis for yeast & parasites
How do you manage a patient who you have done testing on for allergies?
Send letter to referrer of findings and diagnosis
Always Copy to GP
If allergy proven, give info to patient and provide letter to GP
Give advice such as avoidance of precipitating allergen
Prophylactic antihistamines/corticosteroids
Prednisolone 10mg for severe acute attacks
Summary of established examples of hypersensitivity reactions in the oral cavity
Type 1 - peanut
Type 2 - pemphigus
Type 3 - herpes and erythema multiforme
Type 4 - lichenoid
