Nerve Block: Inferior Alveolar

Background

• Inferior alveolar nerve provides sensation to all of the teeth on the ipsilateral side of the mandible as well as the lower lip and chin via the mental nerve.
• Buccal gingiva adjacent to the lower molars will retain normal sensation unless that nerve is anesthetized separately, via a (long) buccal nerve block

Dental Anesthesia

Indications

• Dental pain
• Dentoalveolar trauma
• Dry socket
• Periapical abscess.
• Need to perform painful procedure on mandible or lower lip/chin

Contraindications

• Infection overlying injection site
• Allergy to local anesthetic being used

Equipment Needed

• Topical anesthetic
  

  Block performed from contralateral side.
  • Consider soaking Gauze/Cotton in lidocaine to be placed at injection site
• Local anesthetic
• 5-10 mL syringe
• Blunt fill needle
• 25-27ga needle

Procedure

Preparation

1. Place patient in seated position or in dental chair so that when his mouth is open, the mandible is parallel to the floor
2. Place yourself on the opposite side of the the site being injected
3. Consider Topical Anesthetic with lidocaine soaked gauze

Injection

1. Palpate the retromolar fossa with your thumb
   

   The origin of the inferior alveolar nerve: note the retromolar fossa just anterior/superior/lateral.
2. Place the index finger of the same hand externally over the ramus of the mandible retracting the tissues toward the buccal aspect
3. Visualize the pterygomandibular triangle
4. Hold the syringe parallel to the occlusal surfaces of the teeth and angle so that the barrel lies between the 1st/2nd premolars of the opposite side
   • If a large syringe is being used, consider bending the needle 30 degrees for this approach
5. Puncture with the needle 1cm above the occlusal surface of the molars
6. Advance the needle until bone is felt
7. Inject 1-2cc
   • Injecting as your withdraw has the added benefit of including the lingual (ant 2/3 of the tongue)

Complications

• Inadvertent injection of the parotid gland (may → iatrogenic Bell's Palsy). Occurs when bone is not felt during the initial approach. Redirect needle anteriorly until bone is felt
• Carotid sheath injection (Horner's from stellate ganglion blockade)
• Carotid artery puncture
• If the needle enters too low (at the level of the teeth), the anesthetic will be deposited over the bony canal that house the mandibular nerve and not over the nerve itself
• Bleeding
• Pain
• Infection

See Also

• Nerve blocks (main)
• Local anesthetic systemic toxicity

Video

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References

• Amsterdam J and Kilgore K. Regional Anesthesia of the Head and Neck. In: Roberts and Hedges' Clinical Procedures in Emergency Medicine. 6th ed. Philadelphia, PA: Elsevier; 2014