Allergy Flashcards
Type 1 vs type 4 hypersensitivity
1: mast cell mediated
4: cell mediated
Type 1
Histamine (mast cell) mediated
Atopic e.g. eczema, rhinitis, asthma, anaphylaxis*?
Urticarial: localised e.g. latex contact or generalised e.g. LA
Ask re swelling of lips or other systemic symptoms
High molecular weight vs low molecular weight
High molecular weight: immunoglobulin E mediated type 1 hypersensitivity reaction
Low: Absorbed directly - type 4 hypersensitivity reaction
Symptoms and signs due to dental allergies and irritants - patients
Mouth – sore: localised, generalised
Lips / perioral
White striae oral mucosa
Collapse, faint, short of breath
Symptoms and signs due to dental allergies and irritants - - dental personnel
Hands: acute, chronic itching, cracking,
Facial/ neck dermatitis
Respiratory: wheeze, rhinitis
Contact dermatitis
Irritant (80%?)
-barrier creams, dry hands properly, rinse off soap residue
Allergic
-type IV hypersensitivity reaction
Allergy to local anaesthetic
Adrenaline (or preservative) 236 cases studied: no LA allergy found Mostly psychogenic or vaso-vagal French study: 1 case of allergy in 1993 Systemic toxicity: cardiac dysrhythmia
Lichenoid reactions
Removing amalgams may remove white patch (limited evidence)
Cheilitis
Dry, itchy, cracked lips Usually irritant but sometimes allergy -36% lip lick (ICD) -25% ACD -19% eczema -9% unknown Allergens: medicaments, toothpaste ingredients (including Na lauryl sulphate) Rarely: potassium persulfate (dental cleaner), colophonium (floss), nail varnish, cosmetics, nickel (musical instrument)
Anaphylaxis
1) Oxygen, airway, breathing
2) Adrenaline from pre-filled autoinjectors
- flick off one end
- give 0.5mg (may be 2 pens)
Presentations in dental patients
Oral lichenoid lesions: presents with discomfort, or may be asymtomatic Cheilitis: +/- swelling Collapse: faint, short of breath Stomatitis: and ulceration, redness Burning mouth: burning sensation Facial swelling: may not be dental cause
Presentations in dental personnel: complaints include
Hand dermatitis or swelling, especially after use of gloves
Facial, exposed skin rash and itching +/- swelling
Respiratory: e.g. wheezing, rhinitis
Generalised: e.g. collapse
Anaphylaxis definition
A severe, life-threatening, generalised or systemic hypersensitivity reaction
Type 4 hypersensitivity reaction - contact dermatitis
Allergic contact dermatitis is due to cell-mediated immune response
Prior sensitization through antigen presentation by Langerhans cells
Secondary contact brings out the allergic reaction
Potential allergens often used in dental practice
Hygiene products: cleaning: disinfectant, mouthwash (e.g. chlorhexidine), toothpaste limonene, other flavourings,
Lip salve: flavourings
Cements: Glass ionomer, Zirconium, resin-modified glass ionomer, self-etching, resin
Rubber and rubber chemicals: latex gloves, rubber dam,
Impression materials: silicone, polyether, eugenol, colophony
Other: LAs, curing light, etching gel(benzalkonium Cl, dye), astringent, acid
Plastics used in dental surgery
Resins used in dentures: an oligomer matrix, eg Bisphenol-A glycidyl methacrylate (BISGMA) or triethylene glycol dimethacrylate (TGDMA)
Initiators: benzoyl peroxide, camphorquinone.
Inhibitors: hydroquinone
Adhesives: acrylates eg polymethyl methacrylate (PMMA)
Plasticiser - dibutyl phthalate
Potential metal allergens used in dental surgery
Metals: used in dentistry for amalgam, crowns, inlays, bridges, posts and cores
Amalgam: Hg, Ag, Sn, Cu
Gold alloys: Au, lower amounts Ag & Cu, small amounts of Pt, Pd & Zn- for Silver-palladium alloys: Ag, Pd also Zn, Cu
Non-noble metal alloys: Co, Cr, Mo, C, Be,
Other metals in alloys: gallium, rhodium, iridium
Patch testing: the basic principles
Allergens : prepared chemicals in petrolatum placed in aluminium chambers on tape on back
Probability trawl: up to 100 substances may be tested
Application: patches applied on Monday, removed & read on Wednesday & read again on Friday
Patch testing: allergic and irritant reactions
Induces localised eczema patch: inexact science but the best available method to detect cell-mediated allergy
Reaction types: allergic vs irritant
Relevance: must show contact likely
Prick test: for type I allergy as needed, e.g. for latex, foods
Prick testing: for immediate hypersensitivity to latex
Mechanism: relies on antigen-triggered mast cell histamine release
Wheal develops: at test site (>4mm) after 15 minutes
Blood test: allergen-specific IgE often + (not invariably)
Patch test: usually neg, v occasional +
Oral lichenoid lesions: amalgam removal
May help even when no allergy
13/15 cases healed or much improved on removal of amalgam adjacent to OLL
13/16 cases healed on replacement of adjacent amalgam
8/9 improved at 1 y evaluable in Sheffield
The gold conundrum: patch test positive of relevance?
Au+ not uncommon on PT for oral problem
If asymptomatic, 24+/71 with oral Au, 7+/65 no Au, on P/T
Correlate Au+ with presence Au in mouth
Problems stomatitis, lichenoid, dermatitis
Removal- some clear
Acrylates
Quite common allergens in dentistry
-fingertip eczema typical appearance
-respiratory signs: occupational asthma
-cross reactivity between monomers
Generally: commonest acrylate problem is false nails
> dental use of acrylics as adhesives
Figure: red gum, acrylate allergy, capped teeth
Pt complaints: of swelling, pain, redness or gingivostomatitis
Commonest allergens: are EGDMA, HEMA, HPMA, MMA, PGDMA
Burning mouth
Most cases are not due to allergy
Symptom syndrome: usually no signs
Most patients: are denture wearers
Causes: iron/ folate deficiency, C albicans, psychological factors
Acrylate allergy: in one report 6/22 cases had acrylate allergy on P/T
Most series: conclude no relevant allergy
