Still confused about inferior alveolar nerve block?

There is all what you need to know.

Aim:

To deposit solution around the inferior alveolar nerve as it enters the mandibular foramen.

 

Steps:

  • Ask patient to open mouth widely.
  • Palpate the coronoid notch with your index finger.
  • Move medially to palpate the internal oblique ridge.
  • Identify the pterygomandibular raphe.

NOW YOR ARE ALMOST THERE 

  • Insertion point: pterygotemporal depression that is lateral to raphe.
  • To identify insertion point you must first identify :
  • Coronoid notch (greatest concavity on the anterior border of the ramus).
  • Pterygomandibular raphe.
  • Occlusal plane of the mandibular posterior teeth.


PTD: pterygotemporal depression,   PMF: pterygomandibular fold,  CN: coronoid notch,

                                   

GOT IT?!                                                                         

  • Dry the tissues and apply topical anesthesia for 1-2 minutes.
  • Retract the cheek by a mirror.
  • With a long needle, Insert form the contra-lateral premolar area 2/3 of the needle until gently touch bone.
  • ASPIRATION IS MANDATORY.
  • Deposit 1.5 ml of solution slowly (within 60-90 seconds).
  • If you want to anesthetize the lingual nerve, withdraw the needle until have only 5 mm inside the tissue and deposit 0.3 ml.
  • Withdraw the needle carefully.

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Errors:

  • Too High injection lead to:
  • Trismus due to injection into lateral pterygoid muscle.
  • Numbness of the ear due to injection near to auriculotemporal nerve.
  • Toxicity due to injection into the pterygoid plexus of veins.
  1. Too low injection leads to:
  • Trismus due to injection into medial pterygoid muscle.
  • Toxicity due to injection into the facial vein.

3   .Too low and deep injection leads to facial paralysis due to injection into the

substance of the parotid gland.

Clinical tips & tricks:

Don’t:

  • Don’t deposit local anesthetic if bone is not contacted. The needle tip may be resting within the parotid gland near the facial nerve (cranial nerve VII).
  • Don’t contact bone forcefully otherwise, pain is generated.
  • Don’t ever never insert the needle up to the hub.

Ifs :

  • If bone is contacted too soon (less than half the length of a long dental needle):

REASON:  the needle tip is usually located too far anteriorly (laterally) on                            the ramus ,

To correct:

  • Withdraw the needle slightly but do not remove it from the tissue.
  • Bring the syringe barrel around toward the front of the mouth, over the canine or lateral incisor on the contralateral side.
  • Redirect the needle until a more appropriate depth of insertion is obtained.

The needle tip is now located posteriorly in the mandibular sulcus.

  • If bone is not contacted,

REASON:  the needle tip is usually located too far posterior (medial).

To correct:

  • Withdraw it slightly in tissue (leaving approximately one fourth its length in tissue) and reposition the syringe barrel more posteriorly (over the mandibular molars).
  • Continue the insertion until contact with bone is made at an appropriate depth (20 to 25 mm).

 

  • If Over insertion with no contact of bone.

REASON: The needle is usually posterior (medial) to the ramus.

To correct:

  • Withdraw it slightly from the tissues
  • reposition the syringe barrel over the premolars

 

Accessory innervation:

  • Cross the midline:

Nerves from the left side may cross the midline to enervate the right side and vice versa               Counteracted by : Buccal & Lingual infiltration of the tooth in the other side.

  • Cutaneous coli (C.C):

it is derived from the cervical plexus around C2 & C3 to supply the pulp of lower premolars               Counteracted by : Buccal infiltration.

  • Nerve to mylohyoid:

although it is a motor branch , it may carry some sensory fibers to the pulp of lower   molar             Counteracted by : Lingual infiltration.

 

Contraindications:

  • Infection/inflammation at injection site.
  • In patients at risk for self-injury (e.g. children – mentally handicapped), because they might keep biting either the lip or the tongue; causing hematoma.

Long buccal nerve block:

  • Identify landmarks :
    1. Hard tissue landmark : anterior border of the ramus.
    2. Soft tissue landmark : mucus membrane distal and buccal to the last molar in the arch.
  • Dry then apply topical
  • Needle inserted 2-3 mm, parallel and at the level of the occlusal plane.
  • When touch bone, deposit 0.3 mm of solution.
  • withdraw the needle carefully.

Credits: Dr. Abdalla Jallal

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