LA Overview Flashcards
why do dentists need to use Local Anaesthetic?
in order to be able to undertake a range of dental procedures pain free
what are common adverse effects of local anaesthetics?
- systemic toxicity
- allergy
- trismus
- ocular complications
- non-surgical paraesthesia
- interactions
- methemoglobinemia
what is trismus?
uncontrolled inability to open mouth or jaw
what is the simple definition of pain?
an unpleasant sensory and emotional experience associated with, or resembling that associated with actual or potential tissue damage
what are the six additional definitions of pain?
- pain is a personal experience
- pain and nociception are different phenomena
- individuals learn the concept of pain throughout life
- a persons report of pain should be respected
- pain may have adverse effects on function and social and psychological well-being
- there are several behaviours used to express pain
what are the divisions of the TYPES of local anaesthetic solutions?
- ester
- amides
what is the more commonly used TYPE of local anaesthetic used?
- amides
- safer in relation to allergy
what is interesting about articaines structure?
it has an ester ring on its surface (however not a true ester)
what is an example of an amide local anaesthetic?
lignocaine
in addition to the local anaesthetic itself, what else is usually found in the solution and why?
- a vasoconstrictor!
- local anaesthetics are vasodilators, without a vasoconstrictor the LA is washed away very quickly and working time is short
what are common vasoconstrictors typically used in local anaesthetics?
- adrenaline
- felypressin
who can you NOT give Felypressin to?
- pregnant people!
- induces labour
what three things make up a local anaesthetic solution?
- local anaesthetic
- vasoconstrictor
- preservatives
when LA allergic reactions are seen, what is usually the primary cause of this?
the PRESERVATIVES! true LA allergy is very rare
what are examples of preservatives used in LA solutions?
- bisulphite
- propylparaben
what are the 2 types of local anaesthetic techniques used?
- infiltration techniques
- block techniques
explain where, in relation to the nerve, the local anaesthetic is deposited when using the infiltration technique?
- LA deposited around terminal branches of nerves
explain where, in relation to nerves, the LA is deposited when using the block technique?
- LA deposited beside the nerve trunk
what is the LA infiltration technique used for?
- used to anaesthetise soft tissues
- used to produce pulpal anaesthesia where alveolar bone is thin
where is the infiltration technique commonly used?
- maxilla
- lower anteriors
when is the block technique used?
- used where bone is too thick to allow infiltration
what is the block technique used for?
- used to produce soft tissue anaesthesia
- abolished sensation distal to site administered
where is the block technique commonly used in the mouth?
- the mandible
if you were restoring a tooth, what tissues would you want to anaesthetise?
- dental pulp
- soft tissues (matrix band/rubber dam placement)
if you were extracting or performing a surgical procedure on a tooth/teeth, what tissues would you want to anaesthetise?
- dental pulp
- gingiva
- surrounding soft tissues
if you were scaling teeth, what tissues might you want to anaesthetise?
- gingivae
- perhaps pulp
if you want to achieve anaesthesia of the dental pulp on the maxillary arch, where do you inject LA?
- buccal infiltration (adjacent to tooth you want anaesthetised)
if you were wishing to achieve anaesthesia of the buccal gingivae of the maxillary arch, where would you inject LA?
- buccal infiltration
if you were wishing to achieve anaesthesia of the palatal gingivae of the maxillary arch, where would you inject LA?
- palatal injection
anaesthesia of the DENTAL PULP of the mandibular molars and second premolar?
inferior alveolar nerve block
anaesthesia of the DENTAL PULP of the mandibular premolars and canine?
- mental nerve block
anaesthesia of the DENTAL PULP of the mandibular canine and incisors?
- buccal/labial infiltration
anaesthesia of the BUCCAL GINGIVAE of the mandibular molars and second premolar?
(long) buccal infiltration
anaesthesia of the BUCCAL GINGIVAE of the mandibular first premolar and canine?
- buccal infiltration
- mental nerve block
- long buccal infiltration
anaesthesia of the BUCCAL GINGIVAE of the mandibular incisors and canine?
buccal/labial infiltration
anaesthesia of the LINGUAL GINGIVAE of the mandibular arch?
- lingual nerve block
- lingual infiltration
what are some examples of different types of LA syringes?
- SAFETY SYRINGE
- metallic (self-aspirating) syringe
- metallic (aspirating) syringe
- pressure syringe
- jet injector
- disposable syringe
what are the different areas of the safety syringe needle called?
- bevel
- shaft
- hub
- cartridge and penetration end
what is interesting about the hub?
- most fragile part of the needle
- never insert the needle this far
- IT CAN SNAP
what is the bevel of the needle?
- the point or tip of the needle
what occurs with an increased bevel angle to the long axis of the needle?
increased deflection ( = less accurate)
what is the gauge of a needle?
- diameter of the lumen of the needle
what does a lower gauge number result in?
a larger diameter of needle lumen
- > gauge needles = increased accuracy
- > gauge reduces risk of breakage
- > gauge = easier aspiration
what are the types of syringe barrels?
- short
- long
what length is the short syringe barrel?
25mm
what length is the long syringe barrel?
35mm
why is it important to stretch the mucosa before giving LA?
- easier to penetrate & see
- prevents ‘tearing’
why is it important to aspirate before injecting the LA?
to ensure you are not injecting a blood vessel
what would you do if blood entered the cartridge upon aspiration?
- remove the needle from the mucosa
- change to a new cartridge
with infiltration anaesthesia, what area is affected?
- pulpal anaesthesia (limited to one or two teeth)
- soft tissue anaesthesia
why is infiltration anaesthesia done supra-periosteal?
very sore if you go below
what are some limitations of infiltration anaesthesia?
- infection may limit effect (pH cause)
- dense bone may limit effect
when doing a palatal infiltration, what needle is used?
short needle
when performing palatal infiltration, where is the area of needle penetration>
5-10mm palatal to the centre of the crown
when performing an inferior alveolar nerve block, what needle is used?
35mm needle (long needle)
what are the important landmarks to identify when performing an inferior alveolar nerve block?
- coronoid notch of the mandibular ramus
- posterior border of mandible
- pterygomandibular raphe
- lower premolar teeth of the opposite site
what are the limitations of IDB?
- increased onset time
- increased lingual nerve palsy
- no change in intravascular injection
go through the steps of performing an inferior alveolar nerve block:
- thumb placed at coronoid notch
- needle entry junction of buccal pad of fat/pterygomandibular raphe
- syringe lies over contra lateral 5-6
- advance to bony contact (1cm of needle visible)
- withdraw 1mm
what would you do if you contact bone too soon when performing an inferior alveolar nerve block?
reposition syringe barrel mesially
when confirming anaesthesia, how might the patients describe how LA feels?
- rubbery
- numb
- tingly
- swollen/fat
