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CDA Oasis October 19, 2020

Diagnosing Failed Impressions

CDA Oasis October 16, 2020
  • Apply topical local anaesthetic to the palatal target area (GPF, incisive foramen, etc).
  • Wait 1 or 2 min.
  • Use vapo-coolant spray on a Q-tip (Endo Ice or product like it; used for pulp-testing..).
  • Apply cold Q-tip to target area for 2 sec. and apply pressure.
  • Quickly apply 30 gauge anaesthetic tip to white area produced by cold Q-tip being careful not to contact bone.
  • Inject ONE drop slowly to area over 20 seconds and slowly advance 1-2 mm depending on tissue depth with bone contact.
  • Retract, busy yourself with shade match  or other activities.
  • Return to area with fresh anaesthetic tip (27 or 25 gauge) after 1-2min and complete volume needed.

Important side notes:

  • Explain each step to the patient before doing it and why you are doing it.
  • There is sometimes a small pinch at first (mostly not) and the second injection is NEVER felt.
  • In the posterior palate, do not exceed 2 sec. as there can be cold-burn ulcerations when overdone.
  • A few patients are prone to this anyway, but this always heals.  It is generally not a problem if the
  • 2 sec rule is followed.  Multiple palatal injections can be given sensation-free in most cases.
  • Patients are most appreciative of this lack of sensation when palatal injections are needed.


Contrary to what I was told by an instructor in dental school: “These hurt, so inject forcefully to get it over with quickly”

  1. The slower, the better. This is most easily achieved using a mechanical syringe but can be done with a manual one too.
  2. Applying pressure with a mirror handle helps distract the sensation.
  3. Use a sharp needle.
  4. Avoid making contact with the periosteum.


I can’t pretend that all palatal injections can be painless, regardless of the technique used. I have, however, had good success with the following technique:

  1. Tell the patient that they will feel a lot of pressure during the injection and that you will be injecting slowly, so it will take some time. Often patients interpret feeling anything as pain, so letting them know that they will feel something helps them to relax.
  2. Apply firm pressure to the soft tissue immediately adjacent to the injection site with a cotton swab or the end of the mirror handle.
  3. Orient the bevel of the needle towards the bone.
  4. Insert the needle slowly, injecting while advancing the needle until you contact bone or enter the foramen
  5. Inject the anaesthetic solution very slowly (0.5ml/min). The more slowly the solution is injected, the less pain the patient will feel.

I also find it helps for the patients to be coached in deep, abdominal breathing so that they are more relaxed during the administration of palatal injections.


I am a 64-year old McGill grad who was lucky enough to work in the Montreal general hospital Dental emergency department. We had 50 patients every morning for extactions-2 dental students. I found that to give a painless palatal freeze: take a long wooden cue tip (I show the patient the wood end ) and hold the end that is only wood with pressure (you can press hard because the patient knows it’s only a cue tip) on the site to be injected for 1 MINUTE then place the tip of the needle almost under the wood and the patient was surprised how well  that worked especially, if they had already experienced the regular method. 


  1. Anesthetic gel on buccal and palatal
  2. Freezing  buccal and and wait for five minutes
  3. Rubbing palatal and inject just one drop, wait for few seconds. Inject more, if needed.


  1. Topical on buccal. Then, insert needle slowly between teeth from buccal side injecting as you go.
  2. When needle reaches palatal press forward , inject then you can inject on frozen area of palate with no or little pain


My professor taught me to do it in 3 steps: buccal/labial infiltration wait until it takes affect, then infiltrate into papilla and then to the palatal aspect of the tooth.


  1. Freeze the labial.
  2. Use a 30-gauge needle and go through the papilla from the labial and watch for blanching lingually. Inject into ‎the blanched area. No pain.
  3. If you are good, place the 30-gauge into the sulcus. Press slowly with the bevel towards the root. Inject with pressure and this works as well. 


My technique for a painless palatal injection is the following:

  1. Have fine gauge needle and anaesthetic ready. Apply topical with cotton tip applicator. Place needle tip against injection site without penetration,
  2. Apply pressure to needle tip/injection site with cotton tip.
  3. While keeping pressure firm and steady, SLOWLY and simultaneously penetrate and inject anaesthetic. Talk to patient before and during the injection, letting them know they will feel pressure and that it may feel strange to swallow afterwards. Advise patient to keep mouth open in order to rinse/avoid bad taste once operator’s hand is removed. The pressure applied by the cotton tip overpowers the “pinch”, and the SLOW injection/penetration minimizes noticeable sensory input.    
  4. I developed this technique years ago following a very uncomfortable palatal injections by a colleague. There had to be a better way! With a steady hand, I have never had even a whimper.


I encounter many people who are afraid of the needle, and on many occasions, you just can’t get away from giving a palatal injection. The most painless way I find is to numb the buccal and then begin to numb the palatal via the interdental papilla. You can watch the tissue blanch as you go, and by ensuring that you numb ahead in only the blanched tissue, you can guarantee the most painless injection possible. I have had very few people complain after this procedure due to this technique.


  1. I will start with an infiltration at two adjacent teeth at the buccal. Then I will place the local solution into the interdental papilla and give it time to work.  
  2. The next step is to push the needle tip slowly into the palatal tissue past the interdental papilla from the buccal aspect.  
  3. The solution should be expressed slowly till there is a blanching of the palatal tissue.  Once that happens, the needle can be inserted in the blanched area to begin the process.  
  4. As the area of blanching expands, the needle insertion has to follow the blanching perimeter till the area that you want to work on is numb. This takes time to do, but it will help.


For palatal injections, I use 2 coats of topical anaesthetic – let each take for 2 minutes. Then, when I give the injection, I insert the needle only 1 mm into the palatal tissue, inject a few drops slowly and then guide the needle slowly, while injecting until I hit bone and inject a few more drops.


After years of trying various techniques I have adapted the following from several different educators:

  1. Apply topical anaesthetic with a 6″ cotton tip applicator, with pressure on the tissue for at least 30 seconds.
  2. Wipe off the topical (so that it doesn’t get inadvertently injected), re-apply the pressure for a moment.
  3. Advise the patient that they are going to feel “a lot more pressure for about 3 seconds, please bear with me, focus on the (contralateral side) where I am tickling the roof of your mouth, and continue to breathe in and out.”
  4. Quickly remove the cotton tip applicator, insert needle (27 gauge) and start stroking the contralateral side with the cotton tip applicator.
  5. Inject while counting “3 seconds, 2 seconds, 1 second, done!”
  6. When I remove the needle, my assistant will immediately rinse and suction, as the taste of a drop of extravasated anaesthetic is often the most upsetting part for a patient, especially a child.

1 Comment

  1. Melvin hanzel December 9, 2018

    Use topical made by “the best topical” ever. It is tetracaine and benzocaine mix I believe. Apply topical 60 seconds freeze palate with ethyl chloride in inject slowly. 30 g needle. Pt don’t usually feel much of anything. Someone previously commented inject fast to get it over with. “Great management technique”. Make the patient hate you before you have done anything. Not to mention how the patient will feel driving to you office for additional appointments. If you practice in my community and hurt patients during injection—that is great for my referrals. Thanks!


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