local anaesthesia- mandible Flashcards
What is the anatomy of the inferior alveolar nerve?
IAN-
~Branch of trigeminal
~Initially deep to lateral pterygoid
~Then enters pterygo-mandibular space where it gives off the mylohyoid and enters mandibular foramen
~then splits in mandibular canal into mental and incisive branches
MYLOHYOID-
~splits from IAN central to mandibular foramen (not relevant for LA)
What is the anatomy of the lingual nerve?
LINGUAL-
~splits from IAN centrally to mandibular foramen and a bit deeper than IAN
~it’s joined by chorda tympani and passes by medial side of roots of third molar
~gives branches to submandibular salivary gland
~runs close to submandibular duct and branches into tongue
What is the anatomy of the long buccal nerve?
LONG BUCCAL-
Passes between 2 heads of lateral pterygoid, along medial side of ramus, anterior to IAN, crosses into cheek
What is required for a lower first molar extraction?
IAN block- pulp, PDL
Lingual block- lingual gingivae
Buccal block- buccal gingivae
Why can’t infiltration be done posteriorly?
There’s a thick cortical plate with few vascular channels
Need regional bock in pterygo-mandibular space central to mandibular foramen
Why might articaine be useful posteriorly?
It has good bone penetration
Can be used for infiltration posteriorly instead of regional block
Good for patients w bleeding problems
Shouldn’t use for mandibular block
Reports of unexplained praesthesia (burning, tingling, shooting pain)
How is an IAN block (and lingual) administered directly for posterior teeth?
Deposit LA at mandibular foramen in pterygo-mandibular space
Palpate external oblique ridge w thumb and posterior border of mandible, sim halfway
Landmark- pterygo-mandibular raphe (fibrous structure- junction of sup. constrictor and buccinator), should pierce lateral to it
Needle from direction of opposite premolars parallel to occlusal plane
Advance to bone, then withdraw slightly and inject 1.5 mil of LA, then halfway deposit the rest for lingual nerve
What might affect the position of the needle for IAN block?
Wide ramus- direct needle from further back oppositely
Smaller mandibles- foramen is lower- should take into account
How is an IAN block administered indirectly for posterior teeth?
Creep needle close to bone, further lateral, to get around concavity of mandible
Often for flared mandibles
Why are LA blocks not administered on both sides?
Likely- bilateral lingual LA
Patient discomfort due to loss of sensation to soft tissues
What are other methods for IAN blocks?
Clarke and Holmes- indirect but higher
Sargenti- direct but higher
Vazirani, Akinosi- mouth closed, along buccal sulcus and higher
Cow-gates- medial to condyle- whole mandibular division
External- if severe ankylosis
How is a mental and incisive nerve block administered?
1-1.5mil deposited at mental foramen (between apices of premolars) to diffuse into mandibular canal
Mouth partly closed to retract
How can you anaesthetise the lingual nerve anteriorly?
Infiltrate adjacent to tooth
How is a long buccal nerve block administered?
For molar/premolar extractions and buccal surgery
Deposit 0.5ml over the external oblique ridge disto-buccal to third molar
+ infiltration
What do the nerves innervate?
IAN- tooth pulp, PDL, gingivae of post. teeth
INCISIVE- tooth pulp, PDL, gingivae of first premolar to midline
MENTAL- buccal gingivae, second premolar to midline and lower lip/chin
LINGUAL- mucous membrane of tongue (anterior to circumvallate papillae), FOM, lingual gingivae
CHORDA TYMPANI- taste, secretomotor and vasomotor
LONG BUCCAL- mucosa of cheek, gingivae buccal to premolars and molars
MYLOHYOID- mylohyoid muscle, anterior belly of digastric and skin over chin (not relevant for LA)
