Gow Gates Technique
Understanding the Basics
The Gow-Gates Nerve Block is a mandibular nerve block technique designed to anesthetize a significant portion of the mandible effectively. Unlike some other techniques, this approach requires the patient to fully open their mouth, providing the dentist with a clear path to the target area: the condylar neck. It is at this point that the mandibular nerve passes through, making it the ideal spot for anesthesia.
Landmarks for Precision
A crucial aspect of performing a successful Gow-Gates Nerve Block is identifying the key landmarks. For example, when administering the block on the left side, there are three essential landmarks to consider:
Mesiopalatal Cusp: This is the first landmark. It's located on the upper last-standing molar on the left side.
Opposite Corner of the Mouth: The second landmark is the opposite corner of the mouth, which is a natural reference point.
Imaginary Line from Tragus to Corner of the Mouth: The third landmark involves drawing an imaginary line from the left tragus (the small, pointed cartilage in front of the ear canal) to the left corner of the mouth.
Preparing the Patient
1. Maintain a Wide Mouth Opening
Before diving into the GGNB, ensure your patient can maintain a wide mouth opening. This technique demands a sustained open-mouth position. It's a good practice to have a mouth prop ready for the patient after administration to aid in this.
Identifying Landmarks
2. Palpating the Ramus of the Mandible
Begin by palpating the ramus of the mandible to confirm its width and locate the coronoid notch. This notch serves as a useful point to place your thumb or finger for retraction.
3. Utilizing the Intertragic Notch of the Ear
Another valuable landmark is the intertragic notch of the ear, located just below the tragus. This notch closely correlates with the neck of the condyle, your ultimate target for the solution.
Applying Topical Anesthesia
4. Precise Application
With the landmarks identified, apply topical anesthetic to the buccal mucosa, slightly distal to the second maxillary molar and at the height of the mesiopalatal cusp of the same molar. This is also the site for needle insertion.
Needle Assembly and Positioning
5. Assembling the Syringe
Assemble your syringe with a 25 or 27 gauge long needle. Uncap the needle, and you're ready to proceed.
6. Proper Barrel Alignment
Position the syringe barrel over the opposite side of the mouth, just above the premolars. For example, if you're numbing the upper left quadrant, align the barrel with the upper right corner of the mouth. The needle will insert just behind tooth number fifteen at the height of the mesiopalatal cusp.
7. Needle Angle
Ensure that the angle of the needle follows a path from the corner of the mouth to the intertragic notch. The needle should be directed slightly upward, resembling an airplane taking off.
The Injection Process
8. Maintaining the Open Mouth
Before inserting the needle, confirm that the patient maintains a wide mouth opening. This keeps the neck of the condyle and the nerve in the correct position. The patient must maintain this open position throughout the entire procedure.
9. Contacting Bone
Insert the needle along the specified path until you encounter bone. This usually happens at a depth of about 25 mm, necessitating the use of a long needle. Contacting bone is crucial as it confirms proximity to the condyle's neck rather than other soft tissues like the parotid gland.
10. Adjusting Needle Position (if necessary)
If bone contact is not achieved, make sure the patient's mouth remains open wide, and consider moving the barrel closer to the molars. This adjustment can help the needle move in an anterior direction, aiding in achieving the necessary bone contact.
11. Aspiration and Injection
Once you've reached the proper depth, perform aspiration and deposit the anesthetic solution. Ensure that the patient's mouth stays open throughout this process.
Post-Injection Care
12. Patient Positioning
After depositing the solution and safely capping your needle, have the patient sit up while keeping their mouth open for approximately 2 minutes. This is why a mouth prop is recommended.
13. Patience is Key
After the injection, it's important to wait at least 10 minutes for the local anesthetic to take full effect. The larger the nerve trunk, the more time it can take for anesthesia to be effective.
