May 4, 20204 min read

GOW-GATES INJECTION

Updated: Dec 7

Open Wide for this Block written by Tina Clarke RDH M.Ed

WHAT IS IT?

The Gow-Gates (GG) is a mandibular nerve block, which covers all teeth in the quadrant injected. Including the periodontium and gingival tissue molar to midline as well as all the lingual tissue and half of the tongue. One item about this injection that can be confusing is whether the buccal tissue of the molar region gets anesthetized. The answer is most likely it will (about 75% of the time). However, since the buccal nerve has a wide range of variance, a clinician should double check to make sure this area really is numb. As a bonus, the mylohyoid nerve (which can sometimes cross innervate the mandibular 1st molar) gets anesthetized as well.

Some consider this injection similar to the Inferior Alveolar (IA) but much higher. I think this a good visual to keep in mind regarding retraction of the tissue and barrel angulation, but there are differences between these two injections.

HOW DO YOU ADMINISTER?

First, make sure the patient can open wide, as this technique does require the patient to stay open and maintain an open mouth position for a while. Since the nerve travels down the posterior portion of the mandible the patient needs to stay open so the IA nerve moves forward, in an anterior manner. Having a mouth prop available for the patient after administration is a good idea.

Palpate the ramus of the mandible confirming its width and locating the coronoid notch. The notch acts as a nice place holder for your thumb or finger of the retraction hand. Another great landmark is the intertragic notch of the ear (just below the tragus). This notch serves as a good extra-oral landmark since it is closely related to the location of the neck of the condyle, which is the ultimate target for the solution.

After identifying those landmarks, place topical on the buccal mucosa just distal to the maxillary 2nd molar and at the height of the ML cusp of the same molar. This is also the site of needle insertion.

While topical is taking effect, assemble your syringe with a 25 or 27 gage long needle. Then uncap your needle and begin your process.

Align the barrel of the syringe over the opposite side of the mouth, just over the premolars. For example, if you are getting the lower left quadrant numb the barrel should be at the corner of the right side of the mouth. The needle will insert just distal to tooth number fifteen at the height of the ML cusp.

The angle of the needle should follow the same path as a line going from the corner of the mouth to the intertragic notch. Basically, the needle is going in a slightly superior fashion…like an airplane taking off.

Prior to inserting, make sure the patient has his/her mouth open wide. This puts the neck of the condyle and the nerve in a proper position. The patient must stay open like this the entire time.

Insert the needle along the pathway just described until bone has been contacted. This is about 25 mm (which is why a long needle must be used). This is one injection in which contact with bone is important. Doing so confirms you are near the neck of the condyle and not in the other soft tissue structures like the parotid gland.

If you haven’t contacted bone, make sure the patient’s mouth is still open wide. You may also need to move the barrel closer towards the molars. Doing this makes the needle move in an anterior fashion which could aid in creating the boney contact needed.

Now that you have reached the proper depth, aspirate, and deposit solution. Again, make sure the patients mouth stays open during this entire process. After depositing solution and safely capping your needle, sit the patient up and have them keep their mouth open for about 2 minutes (this is why a mouth prop is recommended). Generally, after 5 minutes the patient should feel adequately numb. While you are waiting for anesthetic to set up you can prepare the rest of the equipment or instruments you need for your procedure and update any chart notes you have.

PROS AND CONS?

One of the biggest pros of this injection is the high success rate because the anesthetic is deposited higher on the mandibular nerve closer to the nerve trunk. This means the anesthetic will bathe several branches at one time. While there is a steep learning curve, it really is a great injection. Many people give up quickly because the injection wasn’t the success they hoped it would be. Patience must when learning this technique.

Another pro is the low rate of positive aspiration in compared to the IA. Also, there is a decreased risk of other complications such a trismus and hematoma.

Some cons are the need to stay open wide during and after the injection. This requires the clinician’s attention to remind the patient to stay open during and after the injection. Also, since the injection targets the mandibular nerve closer to the trunk the nerve bundles tend to be thicker, requiring more time and sometimes more anesthetic to achieve the profoundness required for certain procedures.

PATIENCE WHILE LEARNING...

When you first begin to use this injection, you may not have the success with it right away. Be patient as you progress. Don’t give up. Remember to give yourself grace. Like the old saying goes. If at first you don’t succeed, try, try again.

I can’t wait for you to give this a try in your practice. I know you’ll give your best shot!

CHEERS!

Tina

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