W12: Local Anaesthesia Flashcards
Define Anaesthesia
Loss of all sensations in a circumscribed area of the body caused by depression of excitation in the nerve endings or inhibition of the conduction process in peripheral nerves.
what are the nerves of the maxilla and what do the innervate briefly.
Each take 1
PSA: 2nd 3rd Molars, buccal gingiva, distobucall and palatal roots of mx 1st molar
MSA: MB root of MX first molar and premolars and associated buccal gingiva.
ASA: Canines and incisors and labial gingiva
Greater palatine: Palatal gingiva of post teeth. Post 2/3 of hard palate
Lesser palatine: mucosa of the soft palate and uvula on the given side
Nasopalatine: Palatal gingiva of incisors and canine and the ANT 1/3 of hard palate.
What structures are important to consider when giving LA in the maxilla
Greater palatine A
Posterior superior alveolar A
PTerygoid plexus of veins
Label this diagram.
label
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What are properties of the maxilla that is applicable for Local anasthesia administration
- Bone is thicker and denser near the apices of teeth.
- Zygomatic buttress may prevent diffusion of LA to Buccal roots of 1st MX molar
-Pterygoid venous plexus near the MX tuberosity
Thin bone with canals that allows for diffusion of LA
what are the 4 main methods for LA administration
Buccal/Labial infiltration
Palatal Infiltration
Nasopalatine Block
Greater palatine Block
Describe the steps to performing a LA buccal infiltration
- Position Patient for optimal Visibility
- Retract lip and cheek and apply topical Gel at the Height of the mucolabial fold at the level of the tooth.
- Retract lip using mirror and insert needle with the bevel towards the bone.
- insert needle 5mm till contact bone
- Aspirate
- Inject LA (1ml for Restoration) (2mm for Extraction)
What are the advantages and disadvantages of the Buccal infiltration
Advantages:
- Simple technique
- Anaesthetizes all nerve ending irrespective of the nerve
Disadvantages
- Depends of the diffusion of the solution
- Bone thickness
- Localized infection may spread and LA doesn’t work
- Limited zone of anaesthesia
Why is a palatal infiltration injection challenging
Its challenging in the ANT 1/3 due to the palate having little submucosal tissue and mucosa is tightly bound to the bone.
How deep and how much LA is given for palatal infiltration
insert just enough to get the bevel inside the mucosa. Aprox - 0.5ml a few drops
Describe briefly key points for successful administration of the Nasopalatine block infiltration
This will anaesthetize both left and right Nasoplatine nerves. SO all 1/3 of hard palate will be numb.
Apply topical as this is a very painful injection
Insert needle horizontally just lateral to the incisive papilla until the whole bevel is in and deposit 0.3-0.5ml (few drops)
REMEMBER TO ASPIRATE
DO NOT ENTER THE NASOPALTINE FORAMEN
Describe the process and key tips for the greater palatine block injection
Locate the greater palatine foramen
- At the junction of the alveolar bone and horizontal process of palatine bone. @ last Molar. (7)
- apply topical and insert bevel just anterior to the location of the foramen.
- aspirate
- administer 0.3-0.5 ml
Do not attempt to enter the Greater Palatine Foramen
What are the nerves we anesthetize in the mandible and what do they innervate
IAN: all the teeth and supporting structures on the given side (Buccal)
Incisive: Anterior teeth and supporting structures, and buccal gingiva of the teeth anterior to mental Foramen
Mental: mucosa of the vestibulum and lower lip ant to mental foramen
Buccal : buccal gingiva of the molars and premolars
Lingual: mucosa of the floor of the mouth, Ant 2/3 of tongue. and lingual gingiva of all teeth.
what are important structures to consider in the pterygomandibular space
Maxillary artery
- Middle menigeal, pterygoid, IAN, Buccal
Pterygoid venous plexus which help form the maxillary vein
Spenomandibular ligament
what can occur if LA is injected into the maxillary vein/ Artery
Intravascular injection and hematoma. which can all lead to the spread of infection.
what are key properties of the mandible
Very thick cortical bone (poster especially)
Very few nutrient canals
Large number of muscle attachemnts
close proximity to a number of blood vessels to the nerves we need to numb
foramina and present with location variations
Can have accessory nerve supply to structures
what are the techniques of LA administration in the mandible
Ian block (lingual block)
buccal nerve block
mental nerve block
labial and lingual infiltration
what are the hard tissue landmarks for Ian blocks
Coronoid Notch
Hamulus
Pterygomandibular rapie
Lingula
what are the soft tissue landmarks for an Ian block
Coronoid notch
pterygotemporal depression
pterygomandibular fold
describe the Ian block injection technique process
1) position patient sitting @ 45 degrees
- palpate the coronoid notch/ ext oblique ridge with thumb
3) visualize the pteyrgomandibular fold
4) determine the level of the occlusal plane of MD teeth
5) apply topical
6) position barrel over the opposite side premolars, parallel to the lower occlusal plane
7) Needle enters is 1/2 way between the coronoid notch and pterygomandiular fold @ 1cm able the occlusal plane of teeth.
8) needle is pushed 2/3 of long need until contact with bone is felt (Medial Ramus lateral to the lingula.
9) Aspirate
10) administer 1.4-1.8 ml of LA solution (3/4) of cartridge
11) Withdraw needle towards opposite side premolars
12) after 5mm aspirate again
13) This is the site of the Lingual (administer 0.5 ml)
14) withdraw needle from the pterygomandibular space.
why is a buccal infiltration needed along with an Ian block, particularly in extractions
This is because the buccal nerve is not close enough in the pterygomandibular space to be effected by the LA.
