All About Inferior Alveolar Nerve Block

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

From the level of the second premolar, it moves forward as mental nerve and exits through mental foramen.  The mental nerve supplies sensory nerve fibres 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 canines of that side. 

Anatomical landmarks of inferior alveolar nerve block: 

  • mucobuccal fold 
  • external oblique ridge 
  • anterior border of mandibular ramus 
  • internal oblique Ridge 
  • retromolar Triangle 
  • pterygomandibular ligament 
  • buccal pad 
  • pterygomandibular space 

Nerves anesthetized by inferior alveolar nerve block: 

  • inferior dental nerve and its subdivisions 
  • mental nerve 
  • incisive nerve 
  • lingual nerve 
  • buccinator nerve 

Area anaesthetised by inferior alveolar nerve block 

  • lower portion of the ramus and body of the mandible 
  • mandibular teeth incisors, canines, premolars, and molars 
  • mucous membrane and underlying tissues anterior to the mandibular first molar (supplied by lingual nerve) 


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

Indications of inferior alveolar nerve block: 

  • root canal treatment, implant surgery, flap surgery, extraction of teeth or any other surgical procedure on mandibular teeth. 
  • 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. 
  • surgical procedure performed on soft tissues and hard issues posterior to the first mandibular mean second & third molar.  in this case both inferior dental nerve and long buccal nerve, both should be anaesthetised. 
  • in diagnosing pulp vitality, trigeminal neuralgia et cetera. 

Way of the needle during insertion for inferior alveolar 

nerve block: 

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

Structures in neighbourhood of the needle when it is in final position: 

  • inferior alveolar arteries and veins 
  • inferior alveolar nerve 
  • inferior portion of the internal pterygoid muscle 
  • mylohyoid artery and veins 
  • 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 

Symptoms of anaesthesia in inferior dental nerve block: 

Subjective symptoms:

Subjective symptoms of IAN block are tingling sensation and numbness of the lower lip, and tip of the tongue when lingual nerve is also anaesthetised. 

Objective symptoms: 

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

Complications of inferior dental nerve block: 

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

  • muscle trismus 
  • haematoma 
  • needle breakage 
  • mucosal irritation 
  • transient hemifacial paralysis 


This article has already been published on September 15, 2018. 


Read more:

Inferior alveolar nerve block: Alternative technique