mandible-showing-nerve-anatomy

Inferior Dental Nerve

Oral & Maxillofacial Surgery

The inferior dental nerve, a sensory nerve, is also known as inferior alveolar nerve. It is a branch of mandibular nerve that gives off a motor branch that supplies to mylohyoid muscle and anterior belly of digastric, before entering the mandibular foramen. Then it travels through mandibular canal and enters the inferior dental canal. From inferior dental canal, it supplies sensory fibers to mandibular third molar, second molar, first molar, and second premolar via inferior dental plexus.

From the level of second premolar, it moves forward as mental nerve and exits through mental foramen. The mental nerve supplies sensory nerve fibers to the chin and lower lip of that side. Within the mandible, after mental foramen, it moves forward as incisive nerve and gives sensory supply to mandibular incisors and mandibular canine of that side.

Anatomical landmarks of Inferior Dental Nerve Block

  1. Mucobucal fold
  2. External oblique Ridge
  3. Anterior border of mandibular ramus
  4. Internal oblique Ridge
  5. Retromolar Triangle
  6. Pterygomandibular ligament
  7. Buccal pad
  8. Pterygomandibular space
Anatomical landmarks for inferior dental nerve block

Nerves Anesthetized by Inferior Dental Nerve Block

  1. Inferior dental nerve and its subdivisions
  2. Mental nerve
  3. Incisive nerve
  4. Lingual nerve
  5. Buccinator nerve

Area Anesthetized by Inferior Dental Nerve Block

  1. Lower portion of the ramus and body of the mandible
  2. Mandibular teeth incisors, canines, premolars, and molars
  3. Mucous membrane and underlying tissues anterior to the mandibular first molar (supplied by lingual nerve)

Remarks

To numb the soft tissues posterior to the buccal aspect of first molar the long buccal nerve should be anaesthetized.

Indications of Inferior Dental Nerve Block

  1. Root canal treatment, implant surgery, flap surgery, extraction of teeth or any other surgical procedure on mandibular teeth.
  2. Surgical procedure on soft and hard tissues anterior to the first mandibular molar.  In this case both inferior alveolar nerve and lingual nerve should be blocked.
  3. Surgical procedure performed on soft tissues and hard tissues posterior to the first mandibular molar.  In this case both inferior dental nerve and long buccal nerve, both should be anaesthetized.
  4. In diagnosing pulp vitality, trigeminal neuralgia et cetera.

Way of the Needle During Insertion for Inferior Dental Nerve Block

The needle passes through mucosa, thin sheet of buccinator muscle, loose connective tissue and fat.

Structures in Neighborhood of the Needle When It is in Final Position

  1. Inferior alveolar arteries and veins
  2. Inferior alveolar nerve
  3. Inferior portion of the internal pterygoid muscle
  4. Myelohyoid artery and veins
  5. Mylohyoid nerve

The needle is present anterior to the deep part of parotid gland.

The needle is present medial to the ramus of the mandible.

The needle is present lateral to 1. Lingual nerve 2. Internal pterygoid muscle 3. Sphenomandibular ligament

muscles-pierced-in-inferior-nerve-block
Relationship of injection needle in final position with neighbouring structures

Symptoms of Anesthesia in Inferior Dental Nerve Block

Subjective Symptoms

Tingling sensation and numbness of the lower lip & tip of the tongue when lingual nerve is also anaesthetized.

Objective symptoms

Instrumentation should be done. Use either the tip of a blunt probe or elevator to check for objective symptoms. The anesthetic tissue and teeth should be pressed and tapped as compared to the normal side without anesthesia.

Complications of Inferior Dental Nerve Block

One or several of the given below complications may develop during inferior alveolar nerve block.

  1. Muscle trismus
  2. Hematoma
  3. Needle breakage
  4. Mucosal irritation
  5. Transient hemifacial paralysis

Failure Rate

The failure rate for inferior dental nerve block injection is 15% to 20% in the most experienced hands, and the rate of positive blood aspiration is 10% to 15%. 

Take the mock test on inferior dental nerve block HERE

Additional reading

  1. A basic review on the inferior alveolar nerve block techniques
  2. Textbook of Head & Neck Anatomy, 4th Ed James L. Hiatt, Ph.D., Leslie P. Gartner, Ph.D. Pg. 288, 325

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