Updated: Apr 27, 2021
The Nasopalatine injection (NP) is the one palatal injection that makes my eyes water and my nose twitch. And it is not because it hurts, but because it’s so close to the nose. While this injection can be painful to receive and challenging to give it, does not have to be. You may find yourself needing to give this injection. It is great for patients with moderate to severe periodontal disease when palatal anesthesia in the anterior region is required. Especially if they are having a hard time achieving profound numbness. I know it can’t just be me that cringes when a patient has 6+ mm pockets on the lingual surface of the maxillary anterior teeth.
WHAT IS IT?
As a refresher the NP injection anesthetizes the nasopalatine nerve as it exits the incisive foramen. This nerve provides sensation to the palatal soft and hard tissue. Generally, canine to canine. I often find it provides bonus numbing to the maxillary incisors as well. Which is a great option for times when your patient is struggling with achieving profound anesthesia.
The maxillary bone is relatively thin and porous. Which allows the anesthetic to penetrate the cortical plate and bathe additional nerves. This is a good thing to remember for any of our maxillary injections and the reason why achieving profound anesthesia is so much easier for maxillary teeth than mandibular ones.
HOW DO YOU ADMINISTER?
Before I dive into syringe set-up let’s review topical options for our palatal injections.
Most of us have plenty of 20% benzocaine topical in our office so it's the first one we grab. It’s not a bad choice, however, it can take longer for the benzocaine to penetrate the thick keratinized palatal tissue.
Another option to consider is using a lidocaine topical for this area. Lidocaine has a deeper and longer lasting anesthesia than benzocaine. While it does take a little longer to take effect, the result in my experience, tends to be worth it. Depending on the manufacturer you can get a 2% - 5% gel or ointment solution. There are several options available, just make sure it is for intra-oral use.
Whether you decide to use lidocaine or benzocaine apply your topical to the incisive papilla. I like to use a 2x2 gauze with a smear layer of topical on it and place it right on the papilla. This allows me to set up my syringe and not require the patient to hold a swab in place.
Set your syringe up with a 27- or 30- gauge short needle. This is one of the injections in which bevel orientation is key for your success. Most needles have a small dot near the hub indicating where the opening of the bevel is located. As you place your needle on your syringe tighten it the best you can, so you have the dot on the needle hub and the large window of the syringe in alignment. This will make it easier for you to insert the needle and still see your anesthetic cartridge to confirm your aspiration.
After your topical has been on the papilla for 2-5 minutes (remember it takes longer for it to penetrate the thick keratinized tissue) remove the 2x2 (or swab) and dry the papilla off. Now grab a cotton swab, you can have a little topical on this as well and place it on the opposite side of the incisive papilla. For example, a left-handed clinician will have the swab on the right side of the papilla.
Sitting in the zone beside to behind your patient (9-12 o’clock) apply pressure to the side of the papilla and push it towards you. Do this for about 30-60 seconds before inserting the needle. The pressure will provide more anesthesia to the papilla. For most people this is the most uncomfortable part of the injection.
Now that the pre-injection process is complete you can finally begin your injection. While these steps can take time, they are immensely helpful with reducing the pain which can accompany this injection.
Still sitting behind your patient, align your syringe so it travels from the papilla towards the canine. Almost a 45-degree angle from the midline of the palate. Insert your needle with the bevel opening towards the palate at the base of the papilla. The incisive papilla resembles a tear drop shape. The needle should slide under the large rounded bottom portion of that shape. If your patient does not have the tear drop shape papilla and it’s more like a raised line, insert your needle under the posterior third of the papilla.
As you insert your needle continue to push the tissue of the papilla towards the needle. A great analogy of how this looks is when popping a zit. Both fingers work together to squeeze the center. So, as you are pushing the tissue towards the needle, the needle is sliding under the papilla.
Notice I keep saying slide the needle under the papilla. When you insert it this way it makes it so much easier for you, the clinician, to deposit the solution in the correct location in a painless way.
Insert your needle about 4-7 millimeters and aspirate. The goal is to be over the foramen. You may even find yourself inside the canal. Huge bonus! Deposit your solution (my favorite is 4% articaine with 1:100,000 epi). About a quarter to half cartridge is plenty. You will see the tissue blanch as the solution spreads across the palate. This will take time. The rule of thumb is to give one cartridge of solution over a one-minute period. With this injection going slow is not a problem. However, clinician hand fatigue can become an issue. If your bevel is aligned so the solution flows up into the foramen instead of towards the tongue it will make it easier for it to flow, and reduce how much pressure you need to apply on the syringe thumb ring.
When you are completed, I highly suggest you aspirate during withdraw. This will assure you don’t accidentally squirt anesthetic down your patient’s throat. Also, don’t be surprised if you notice bleeding after you remove your needle. Use a piece of gauze and apply a little pressure post injection. (After you cap your needle). This will stop the bleeding.
During the injection you may notice the papilla sweat a little. This could be the pressure from the solution causing the small palatal salivary glands to express fluid. Another cause could be the bevel is oriented incorrectly and solution is starting to express out of the tissues.
The approach described above can take some time. This can be a challenge when we are pressed for time in our schedule. The great thing is it really does help reduce patient discomfort. Which in turn makes them think you are the best clinician in the world.
You can modify the pre-injection process as well. Some clinician will use a frozen cotton swab for the pre-numbing procedure. Overall, the use of pressure is a key component to the success of this injection. The use of topical, pressure or ice all have the same impact of disrupting the nerve impulse.
Hand fatigue can be an issue as well. If you remember to orient your bevel towards the opening of the foramen, it will reduce the fatigue aspect.
Next time you find yourself staring at deep pockets and/or tenacious deposit on the lingual of those maxillary incisors do not fear. Now you have all the information you need to give your best shot!
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