There are three main techniques used to administer local anaesthesia in the mandible, Inferior alveolar nerve block, Gow-gates technique and Vazirani Akinosi.
Inferior alveolar nerve block (IANB) is the most routinely employed technique for achieving local anaesthesia in mandible. In 1973 Gow-Gates used extra-oral landmarks for achieving mandibular anaesthesia.
To administer Gow-Gates Mandibular Block (GGMB), firstly the tissue targeted for needle insertion is dried with sterile gauze and topical anaesthetic gel is applied.
The extra-oral and intraoral landmarks are carefully identified in the following manner:
(1) extra-oral landmarks include lower border of the tragus or the intertragic notch and the corner of the mouth; and
(2) intraoral landmarks include the mesio-palatal cusp of the maxillary second molar just below which the needle tip is placed and is moved further to a point just distal to the molar.
After completion of the localization of landmarks, the syringe is advanced, and gentle needle insertion is done, and then slowly progressive forward until the bone of the anterior condyle is contacted.
The needle is withdrawn 1mm so that direct nerve impingement is avoided. If bone contact is not achieved, the needle is slightly withdrawn and redirected.
No local anaesthesia must be deposited if the bone is not contacted. Once you have encountered the target area aspiration is performed to avoid intravenous injection.
The patient is asked to keep his/her mouth open for 1-2 minutes after injection6. In this technique single intraoral injection is given at the lateral
aspect of mandibular condyle, just below the insertion of lateral pterygoid muscle, targeting the main mandibular nerve division as it comes out of the foramen ovale, thus anesthetizing the whole of the mandibular nerve, a branch of trigeminal nerve.
Considerable advantages of the Gow-Gates technique over IANB, include its higher success rate, its lower incidence of positive aspiration (approximately 2% vs. 10% to 15% with the IANB) and the absence of problems with accessory sensory innervation to the mandibular teeth.
