Inferior Alveolar Nerve Block is one of the most used Nerve Block technique as it supplies to Incisors, Canines, Pre-Molars and Molars of the injected side, modifications of Inferior alveolar nerve block are used on failure to achieve anesthesia using the regular technique. IANB has the most failure rate of all Nerve blocks in both Maxilla and Mandible. In case of failure to achieve Anesthesia inspite of giving a proper Inferior Alveolar Nerve Block, many researchers have developed modifications to IANB which have slight variations to help achieve IANB and anesthetize the structures properly.
Modifications of Inferior Alveolar Nerve Block (IANB):
There are three modifications of IANB which are preferred in case of failure to achieve Anesthesia after administering IANB.
- Modified IANB by Thangavelu et al.
- Arched Needle techique
- Modified IANB by Palti et al.
Modified IANB by Thangavelu et al technique:
Ask the patient to open the mouth completely and Palpate the Anterior border of the ramus of mandible with the left hand thumb. Now insert the needle above the Mandibular teeth in the midpoint between the upper and lower occlusal planes inserting 6-8mm.
The needles whould be positioned 8-10mm posterior to the anterior border of the ramus.
The needle should be inserted until it comes in contact with the medial or inner side of the mandibular ramus.
The body of the syringe is placed at the canine and premolar of the opposite side.
The needles should be maintaining continuous bone contact and extending it inside till the mandibular foramen. The needle is inserted to a depth of 21-24mm.
Inject 1-1.5ml of LA solution in the site
Advantages of Modified IANB by Thangavelu et al technique:
- High success rate of 95%
- No Complications such as Trismus, hematoma, positive aspiration, nerve damage or needle breakage
Disadvantages Modified IANB by Thangavelu et al technique:
- Periosteum on the medial side of mandibular ramus can be damaged with this technique
Arched needle technique – Modification of IANB
The needle is bent into an Arch shaped before being inserted to avoid the bone and damage to the Nerve. This method helps in avoiding complications such as Transient Hemifacial Paralysis.
The Arched needle is directed towards the medial surface of the ramus almost perpendicularly to prevent nerve damage.
The success rate of this technique is 98% and anesthesia onset is within 3-5 mins.
Modified IANB by Palti et al:
The Mandibular Foramen is located using two orthodontic wires.
Position the first wire passing from the Mesio-buccal groove and the midpoint of the slope of the distolingual cusp of the opposite side first molar (Adults) or Second Primary Molar (children).
The second wire is placed on the occlusal plane of the same side, the wire coincided with the center of the mandibular foramen or a 3.5mm radius from this point.
success rate in children was found to be 93% when compared to 82% in children.