LA all Flashcards
what all needs to be in place/checked before local anesthetic can be carried out?
- must be enrolled on GDC register
- signed treatment plan from dentist
- PMH checked
- dentist must be on site if doing an IDB
what position should pts be in for LA and why?
semi recumbant
reduce chance of vaso vagal attack
apply topical for how long?
2 mins
why are infiltrations possible in maxillary teeth and mandibular incisors?
bone is thinner
maxillary incisors and canines/buccal gingivae supplied by?
palatla gingivae?
anterior superior alveolar nerve
nasopalatine nerve
maxillary premolars and buccal gingivae supplied by?
palatal gingivae?
superior plexus
nasopalatine and greater palatine nerve
maxillary molars and buccal gingivae supplied by?
palatal gingivae?
posterior superior alveolar nerve
greater palatine nerve
what problems might there be with LIA at the maxillary molars?
zygomatic arch
mesial and distal infiltrations overcome
where do you give a palatal injection?
equidistant between median raphe and gingival margin above tooth requiring anaesthetic
how do you know a palatal injection achieved?
blanching
where to avoid when giving a palatal injection?
rugae and foramen
why do the lower molars and premolars require an IDB?
thick lamina dura - LIA doesnt work
when giving LIA at the lower incisor/canine region where should you ensure the needle is?
in contact with bone to prevent escape of agent into the tissues
how to anaesthatise the lingual nerve?
LIA below attached gingivae lingually
interpapillary
how to give an interpapillary injection?
insert needle at centre of papilla near crest of bone/perio pocket level
small and slow injection
blanching indicates anaesthesia
how quick should LIA anesthesia be established?
2 mins
lidocaine and ep gives pulpal anaesthesia of how long?
approx 1 hour
do the soft tissues or the hard tissues stay anesthatised for longer?
soft tissues
what are some reasons for LA failure?
pts are different - some la might not last as long IV - syncope IM too little LA infection and injection site
why can an injection stop LA working?
infection sites tend to be acidic and LA works best in alkaline conditions
what is LA?
the loss of sensation in a specific area by depressing excitation of nerve endings or inhibititng conduction processes
what is the main aim of LA in dentistry?
loss of pain
what channels does LA block?
ion channels
where does inferior alveolar nerve pass through?
passes through the foramen ovale into the infratemporal fossa, between the lateral and medial pterygoids
where is the needle entered into?
the pterygomandibular space
what are some contra indications to an IDB?
haemophilliacs
co agulation tx
co operation
what anatomy is identified prior to IDB?
external oblique ridge at anterior aspect of ascending ramus
and V shape of pterygomandibular raphe
where does the thumb palpate when doing an IDB?
and where is the needle advanced from?
palpate the ramus,
needle advanced from opposite premolars in line with lower occlusal plane
enters soft tissues at mid point of thum above last standing molar
why might an IDB fail?
too little LA not enough time inaccurate placement different anatomy inflammed tissues
what complications can an IDB cause?
facial palsy nerve damage ST damage haematoma IV
what systemic effects might an IDB cause?
fainting
allergy
drug interactions
toxic reaction
6 contents of LA?
local anaesthetic agent vasoconstrictor reducing agent preservative fungicide carrier solution
details of lidocaine?
commonly in 2% solution dissolved in sol as hydrochloride salt
with ep gives longer anaesthesia
details of prilocaine?
citanest
3% with octapressin
4% plain
less effective at haemostasis and vasoconstriction
mepivicaine comes as?
2% with epinephring 1:100000
3% plain
articiane details?
4% 1:100/200000
metabolised faster so is useful for repeat injections
advantages of epinephrine?
more profound anaesthesia
longer lasting
hameostasis
details of felypressin?
less effective at haemorrhage control
not as good a vasoconstrictor
what trauma can LA cause?
IV
IM
needle
trauma to mouth while numb
why is an IV injection dangerous?
enough LA agent to be of a toxic dose to the CNS of children and young adults
heart and brain susceptible to effects
why may you think twice about LA and a pt with liver disease on PMH?
liver disease = impaired metabolism, could cause toxic effects
what heart problems can contraindicate use of LA?
arrhythmia, unstable angina
alternate LA for cardiac pts?
use felypressin max 3 cartridges and avoid epinephrine
max lidocaine?
prilocaine?
lido plain - 11 max, ep - 6.8
prilo plain - 9, fely - 4
be careful with use of LA agent and what drugs?
beta blockers - max of two with ep
calcium channel blockers
be careful of what drugs and vasoconstrictors?
diuretics
antiparkinsons
calcium channel blockers
beta blockers
what are some systemic diseases that are contra indicated in LA?
leukaemia anticoag tx steroid tx liver dysfunction renal disease rheumatic fever uncontrolled diabetes haemophilia pregnancy
what is gate control theory?
melzack and wall 1965
pain is modulated at the spinal cord and influenced by socio cultural factors/physiological and psychological factors
what is the adult pain rating scale?
children?
mcGill
wong and baker
what are some ways of distracting the pt?
shift attention
mental task
audio analgesia
visual distraction
what component of LA gives haemostasis?
the vasoconstrictor
what is the aim of analgesia?
haemostasis and elimination of pain
what part of a nerve cell contributes to nerve conduction?
nodes of ranvier
end feet synapses
how does analgesia work r.e nerve anatomy?
gains access to nerve at nodes of ranvier and blocks conduction
what conditions can give rise to pain?
inflammation
trauma
necrosis
ischaemia
what substances give rise to pain?
potassium
chlorine
sodium
calcium
what is polarisation?
no pain
potassium in cytoplasm and sodium outwith
what is depolarisation?
destruction of polarity
ionic exchange
sodium in cytoplasm and potassium outwith
what is action potential?
change in membrane potential permeability
transfer or ions
potassium exchanges with sodium
what is repolarisation?
sodium potassium pumo
reverts to polarised state
