LA Symposium Flashcards
How do local anaesthetics work?
LAs stop nerve conduction by blocking Na+ channels
- prevention of Na+ influx
- action potential generation and propagation blocked
Describe the structure of A nerve fibres:
Myelinated
Describe the structure of C nerve fibres:
Unmyelinated
What nerve fibres are found in the dental pulp?
Mostly unmyelinated C fibres
What are examples of Amide local anaesthetics?
- lidocaine
- prilocaine
- articaine
Give an example of an ester local anaesthetic:
Benzocaine (topical LA)
Why do most LA preparations include a vasoconstrictor agent?
LA itself is a vasodilator
- without vasoconstrictor the LA washes out of tissues quicker, leading to shorter usage time
What vasoconstrictor agents are typically found in LAs?
- adrenaline
- felypressin
Give examples of preservatives commonly used in LA solutions:
- Bisulphite
- Propylparaben
- people with “LA allergy” tend to actually be allergic to these preservatives opposed to the LA itself
Describe the difference between infiltration and block LA techniques:
Infiltrations:
- LA deposited around terminal branches of nerves
- can produce pulpal anaesthesia where bone is thin
- useful for maxilla & lower anteriors
Blocks:
- LA deposited beside the nerve trunk
- abolishes sensation distal to site
- used where bone too thick to allow infiltration eg mandible
What length of needle is used for IDB?
35mm
What are the important landmarks to note when performing an IDB?
- pterygomandibular raphe
- lower contralateral premolars
- 0.5 - 1cm above occlusal plane
Describe the “chasing anaesthesia” technique:
- give buccal infil & allow to work
- inject into interdental papillae
- slowly advance needle through interdental papillae until palatal tissues blanch
- inject into blanched palatal area
Give some alternative IAN block techniques:
- Gow Gates
- Akinosi technique
What are some systemic complications associated with LA use?
- fainting
- palpitations
- trembling
- allergy
- interaction with other drugs
- collapse
- toxicity
