Background

The Inferior Alveolar Nerve Block is used in dental anesthesia to numb the lower jaw. 

It is used in the treatment of mandibular teeth, which supplies sensation to the lower teeth along with parts of the lower lip and chin. 

Mandibular nerve exits skull base via foramen ovale. Nervous spinosus branches off to supply meninges through foramen spinosum. 

Second branch of mandibular nerve supplies medial pterygoid muscle. Mandibular nerve splits into anterior and posterior trunks below. 

Inferior alveolar nerve is larger branch of mandibular nerve division. 

The mandibular nerve furnishes sensation to the areas as follows: 

Mandible 

Buccal gingiva anterior to the first molar 

Lower lip and the pulps 

Inferior alveolar nerve goes through mandibular foramen in ramus to reach inferior alveolar canal in body. 

Nerve enters mandible through mandibular foramen to provide sensory function to lower teeth. 

Indications

Dental Extractions: 

Removal of mandibular teeth (molars, premolars, and incisors) 

Restorative Dental Procedures: 

Fillings or crowns on the lower teeth 

Endodontic Procedures: 

Periodontal Surgery: 

Procedures involving the gums and supporting structures of the teeth 

Implant Placement: 

Surgical placement of dental implants in the lower jaw. 

Orthodontic Extractions: 

Extraction of teeth as part of orthodontic treatment plans 

Oral Surgery 

Contraindications

Absolute Contraindications are: 

Local Infection or Inflammation 

Allergy to Local Anesthetic Agents 

Relative Contraindications are: 

Bleeding Disorders 

Trismus or Limited Mouth Opening 

Severe Anxiety or Phobia 

Pregnancy 

Outcomes

It achieves complete numbness in the areas innervated with the inferior alveolar nerve including the mandibular teeth on the side of the block. 

Successful block shows comfortable experience for the patient during the dental procedure with minimal pain or discomfort. 

With effective anesthesia, the dentist can perform the procedure without interruptions due to patient discomfort. 

Dexamethasone before nerve block increase success in irreversible pulpitis patients with molar teeth. 

Equipment required

• Dental Syringe 
• Needles 
• Local Anesthetic Cartridges 
• Topical Anesthetic 
• Antiseptic Solution 
• Gauze Pads 
• Hemostats or Needle Holder 
• Sharps Container 
• Sterile Gloves 
• Suction Tip and Saliva Ejector 

Patient Preparation

Review previous history with alveolar block, including any adverse effects or difficulties. 

All necessary equipment is available in good condition including local anesthetics, syringes, and needles. 

Assess the anatomical landmarks to check for any infections at the injection site. 

Patients should follow as instructed by the physician. All aseptic protocols strictly followed including the use of gloves. 

The injection site should be cleaned with an antiseptic solution before the block is administered. 

Informed Consent:  

Patients should understand procedure, benefits, risks, and alternatives for consent. 

Patient Positioning

The patient should comfortably sit on the chair with the head slightly tilted to provide the best access to the injection site. 

Ensure their mouth is adequately opened during the procedure. 

 Fig. Inferior nerve block in mouth 

Technique

Step 1: Identification of Anatomical Landmarks: 

Coronoid Notch: The deepest point of the anterior border of the ramus. 

Pterygomandibular Raphe: A tendinous band of tissue running from the mandible to the maxilla. 

Occlusal Plane: The plane formed by the biting surfaces of the mandibular teeth. 

Step 2: Apply topical Anesthesia: 

Apply a topical anesthetic to the mucosa at the injection site, on the medial side of the mandible. 

Step 3: Needle Insertion: 

Use a long gauge needle. Insert the needle into the mucosa at the height of the coronoid notch, just lateral to the pterygomandibular raphe, and parallel to the occlusal plane of the mandibular teeth. 

Advance the needle to maintain a parallel orientation with the occlusal plane. The needle should penetrate approximately 20-25 mm until bone is gently contacted. The needle tip should be near the mandibular foramen. 

Step 4: Aspiration 

Before injecting the anesthetic, aspirate by pulling back the plunger slightly. If blood is present in the syringe, then reposition the needle slightly and aspirate again. 

Step 5: Injection 

Slowly inject 1.5 to 1.8 ml of local anesthetic solution near the mandibular foramen. 

Step 6: Withdrawal of needle 

Withdraw the needle slowly and safely after the injection is complete. 

Complications

Inadequate Anesthesia: 

This can occur due to improper needle placement or insufficient anesthetic volume. 

Paresthesia: 

A prolonged or abnormal sensation can occur if the needle or anesthetic solution irritates or damages the nerve. 

Hematoma Formation: 

If a blood vessel is punctured during the injection, it causes hematoma 

Trismus: 

Trismus or restricted opening of mouth can result from trauma or irritation to the medial pterygoid muscle during injection. 

Facial Nerve Paralysis: 

If the anesthetic is inadvertently deposited into the parotid gland can affect the facial nerve occurs in temporary paralysis of the facial muscles 

Systemic Toxicity 

Infection 

Soft Tissue Trauma 

References

Inferior Alveolar Nerve Block – StatPearls – NCBI Bookshelf (nih.gov) 

References

Inferior Alveolar Nerve Block – StatPearls – NCBI Bookshelf (nih.gov)