struggling with IA blocks

[StarCraft]

Hey guys, I don't know why but I miss half of my IA blocks. I do what the book says and mark the notch on the ramus with my thumb and go from the level of the contralateral premolar and enter at the level of my thumb. They say to look for the raphe but I never find it because it just looks like a big blob of tissue in the mouth. It's hard for me to hit the bone too. I was wondering if you guys can share your technique and help me out. I want to try a new approach. Thanks

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[peg lateral]

Hey guys, I don't know why but I miss half of my IA blocks. I do what the book says and mark the notch on the ramus with my thumb and go from the level of the contralateral premolar and enter at the level of my thumb. They say to look for the raphe but I never find it because it just looks like a big blob of tissue in the mouth. It's hard for me to hit the bone too. I was wondering if you guys can share your technique and help me out. I want to try a new approach. Thanks

Try watching some youtube videos. I was having trouble too when I was first starting out in clinic. I tend to aim a bit higher than what the textbooks show, and that is what a lot of the oral surgery faculty taught us to do on our rotation. And keep in mind that there is some deviation from "normal" anatomy, and if the patient is edentulous or partially edentulous on the side you are anesthetizing, it can much more difficult to locate your anatomic landmarks. You could also try the closed-mouth technique.

 

[Mackchops]

Hey guys, I don't know why but I miss half of my IA blocks. I do what the book says and mark the notch on the ramus with my thumb and go from the level of the contralateral premolar and enter at the level of my thumb. They say to look for the raphe but I never find it because it just looks like a big blob of tissue in the mouth. It's hard for me to hit the bone too. I was wondering if you guys can share your technique and help me out. I want to try a new approach. Thanks

Mandibular blocks aren't as super easy as they sound - even seasoned dentists will miss one here or there.

First, look at your anatomy. You know that your mandible is V-shaped so to hit the mandibular foramen at a 90-degree angle you'd have to come from somewhere around the contralateral ear. Can't do that, so aim from as far over as you can. You'll still be coming at the foramen at an oblique angle, but this will help you pop over that pesky lingula.

Speaking of lingula, if you find that you hit it then deposit a little drop of anesthetic, wait a second for it to take effect, then slowly "walk" your needle posterior until you feel it drop off. As long as you're at the correct occlusal height (better to be a little high than low -- think of your anatomy!!) you just passed the lingula into exactly where you want to be! Deposit your solution now!

Lastly, if you're not seeing your landmarks then pull the cheek a little tighter. I aim for just anterior to the "V" that's formed by the hamular notch and the pterygomandibular raphe rather than use palpable landmarks.

Keep practicing! Ask an instructor for help -- all docs have their own little tricks that work for them. Maybe you'll pick one or two up! Also, check out dentaltown's online CE section -- good videos that helped me when I was running a solid streak of misses.

 

[tinman831]

Ah. The good ol IANB. The bane of the existence of many dentists. If done correctly, an IANB can make your appointment a breeze, but if done incorrectly can lead to frustration for both you and the patient.

First of all, how do you know that you're missing the block? Studies have shown that the number one cause for ineffective anesthesia is not waiting long enough for onset. The longest I've had to wait for a patient was 15 minutes. One carpule of Xylocaine and it took 15 minutes for profound anesthesia to set in. If it's your first time with the patient, have some patience first before reaching for the syringe for a second carpule.

As far as finding the landmarks, it can be difficult, especially in patients who have flabby cheeks. What I've found to help is to grab a hold of the check with your thumb and fingers and retract it laterally first and then push posteriorly to see if you can define the raphe a little better. You don't want to insert the needle through the raphe as it'll hurt a lot more and cause trauma to the area (don't ask me how I know 😳). Sometimes you just have to do the best you can and hope for the best.

 

[SeattleRDH]

Like tinman said, waiting a few extra minutes might be the trick. I don't know if this will make sense (it's always easier to show than to explain) but aim for the "squishy spot" just lateral to the Pterygomandibular raphe. Or you could take the mandible off your skull, line up a pencil with the mandibular foramen as you would your needle, and just stare at that for a week. You'll memorize the position eventually.

 

[Althingsdentist]

What's coincidental is that on Thurs I cut some video regarding one of 4 million block techniques. Endodontics is a specialty that has a litany of articles on local anesthetics. The folks above mention a really good point - time after anesthesia. Fast regional anesthesia (IAN block)= 15 mins, regular/slow - upwards of 30 mins. I would also block with marcaine (depending on your procedure) - and also - one factor is how long it takes to anesthetize....the slower, the better for effectiveness.

I know what it's like to be a dental student - however - your procedure time actually increases logarithmically (well, maybe not), if you don't wait until you have adequate anesthesia. How can you tell? Well - it has been shown that the "numb lip test" is not an indicator of pulpal anesthesia. Try taking out some endo ice and zapping the tooth with cold before starting. This, according to Cohen et al, is a pretty reliable indicator of pulpal anesthesia.

Here is the video that I cut last Thursday - you guys let me know if I should try a different angle for shooting. This patient was already numb - the initial shot started well - but - someone came and started nattering.....my blocks typically take 2-4 mins - depending on the pain experienced by the patient. The more painful, the slower I go - depositing small amounts of anesthetic along the way to:
1. Anesthetize the tissue along the way
2. To make a path that I can follow when I reanesthetize with another block.....this is my insurance block.

Again, let me know what you think....especially you old guys (like me!)

Cheers

Ashley

http://youtu.be/saeUzRhCS_s



Cohen HP, Cha BY, Spangberg LSW. Endodontic anesthesia in mandibular molars: a clinical study. J Endod 1993;19:370-3.
Purpose: to compare anesthetic efficacy of 3% mepivicaine and 2% lidocaine with 1:100,000 epinepherine by using the DDM cold test. The study also investigated the use of DDM to confirm pulpal anesthesia as well as the use of the supplemental PDL injection with 2% lidocaine with 1:100,000 epinepherine.
Bottom Line: This study demonstrated that 3% mepivacaine (no vasoconstrictor) is as effective as 2% lidocaine with epinephrine in achieving pulpal anesthesia in mandibular molars with the inferior alveolar nerve block. The PDL is an effective supplemental injection when the IANB fails. Lip anesthesia is not a reliable indicator of pulpal anesthesia. The DDM cold test was 92% effective in confirming true pulpal anesthesia.


Hargreaves KM, Keiser K. Local anesthetic failure in endodontics: mechanisms and management. Endodontic Topics 2002;1;26-39.
Purpose: to review the pharmacological mechanisms of local anesthesia and pain from the perspective of identifying potential mechanisms for local anesthetic failure.
Bottom Line: Causes of anesthetic failure include: accessory innervation, tachyphylaxis (desensitization), anesthetic pKa properties and presence of vasoconstrictor, inflammatory mediators, central sensitization, and psychological factors. Consider using fast acting anti-inflammatory drugs as an adjunct to anesthetic with a lower pKa, such as 3% mepivacaine, for teeth with inflamed pulps and/ or periradicular tissues. In order to reduce anxiety and evaluate the depth of pulpal anesthesia repeat cold test prior to the operation.
LCE: 5

 

[KinKs]

One trick to achieving this block most of the time is to simply look at the pan. If you look carefully at the ramus you can see where the nerve enters the inferior alveolar canal. In some people this entrance can be high or low, more posterior etc. What you want to do is to approximate the position of the nerve's entrance to the coronoid notch and aim you needle to that area following all other landmarks as usual.

Basically, the pan will serve as an additional aid particularly for those patients whose anatomy does not read text books.

 

[youngmc27]

I find that if you am slightly higher than the traditional location for an IA I have more success. That being said it is commonly missed by many experienced dentists. I got a review packet with the JADA magazine this month that covers this exactly get a hold of a copy and give it a good read it was well done and had some useful info.

 

[DrJeff]

FYI - any practicing dentist that says that they NEVER miss an IAB is lying 😉😱

It happens. No big deal. Just reposition (I usually go higher and slightly posterior for my second attempt), and then I sit the patient semi upright after depositing the 2nd (or sometimes 3rd and occasionally even a 4th 😳 ) carpule. Whether its the added volume of anesthetic, the vertical repositioning to let gravity spread the ansethetic in a different direction or just that I finally "hit the bullseye" I don't really care what it takes to get my patient numb so that I can step on the reostat and get the bur a spinning or the elevator an elevating!

 

[HupHolland]

I personally aim a little anterior to where we were taught anticipating I will hit bone immediately (close to anterior border of ramus)... Then I back off a mm, reposition the syringe over the occlusal surfaces on the same side I'm anesthetizing, insert ~10mm, then bring the syringe back over the contralateral premolars, insert until I hit bone, back off a mm and inject. Seems to work pretty well for me.

I find that hitting bone early and repositioning gets my bearings right and I know exactly where I am, instead of blindly injecting into soft tissue.

I also follow up every IAN with local infiltration septocaine, saving about 1/4 carpule just in case I need to do some supplemental PDL injection 🙂

Hup

 

[StarCraft]

Thanks for all the help. This definitely helps and I look forward to trying new things and improving. Thanks!

 

[Althingsdentist]

Jeff: Agreed - occasionally miss blocks - do you ever use intraosseous/PDL?

Hup: That's exactly the technique that I was taught by several folks - be it endodontists, oral surgeons and comprehensive dentists - hit bone anteriorly, slowly walk posteriorly, find the depression, hit bone, back off....

A

 

[beannaithe]

I follow a technique close to Hup's. Please note I use a 31 SHORT for this, as I was taught in residency. I palpate the anterior mandible and insert my needle about 1cm posterior to that. I go at a 90 degree angle to the other side's premolars. I hit bone almost immediately (like 1/4 way down the needle). Then I rotate the needle forward so that I'm following the bone and bury it. Inject the entire carpule SLOWLY. This injection doesn't get the long buccal, I save my local infiltration for that.

It takes a while to get the hang of profound anesthesia. It takes about 7 minutes (on average) for the injection to take hold. So talk to patient, go to the bathroom, etc and just wait to see if it sets up. Then have at it! Longest I ever waited was 2.5 hours (in dental school) with a patient who had 4 IAs, 3 of which were from out anesthesia department!!

I missed my IAs a TON in school and a lot less in residency. Getting better since I'm now in practice, but I still miss from time to time. Though any lingering sensitivity usually gets taken care of with an infiltration of septo. Also, remember that most man anteriors/premolars are okay with infiltration since the bone is thin.

 

[DrJeff]

Jeff: Agreed - occasionally miss blocks - do you ever use intraosseous/PDL?

Hup: That's exactly the technique that I was taught by several folks - be it endodontists, oral surgeons and comprehensive dentists - hit bone anteriorly, slowly walk posteriorly, find the depression, hit bone, back off....

A

Intraosseous - occasionally - usually in those "everything else has failed, now what do I do type situations". Pdl, mainly just for extractions and/or endo - I 've noticed that I tend to get a higher rate of patient complaints of "soreness" in the area in the following 24-48hrs with PDL injections vs regular blocks or infiltrations.

And Hup's technique is what I use too - find the bone, "walk the needle" distally off the back edge of the ramus, come back onto the ramus, aspirate and deposit the anesthetic

 

[HupHolland]

I follow a technique close to Hup's. Please note I use a 31 SHORT for this, as I was taught in residency. I palpate the anterior mandible and insert my needle about 1cm posterior to that. I go at a 90 degree angle to the other side's premolars. I hit bone almost immediately (like 1/4 way down the needle). Then I rotate the needle forward so that I'm following the bone and bury it. Inject the entire carpule SLOWLY. This injection doesn't get the long buccal, I save my local infiltration for that.

It takes a while to get the hang of profound anesthesia. It takes about 7 minutes (on average) for the injection to take hold. So talk to patient, go to the bathroom, etc and just wait to see if it sets up. Then have at it! Longest I ever waited was 2.5 hours (in dental school) with a patient who had 4 IAs, 3 of which were from out anesthesia department!!

I missed my IAs a TON in school and a lot less in residency. Getting better since I'm now in practice, but I still miss from time to time. Though any lingering sensitivity usually gets taken care of with an infiltration of septo. Also, remember that most man anteriors/premolars are okay with infiltration since the bone is thin.

In cases like this I just give a mental block with septocaine. PROFOUND anesthesia. Infiltrating with septocaine in the mandibular anterior, in my hands at least, is not always effective.

Hup

 

[Streetwolf]

Lateral border of the raphe, JUST above the deepest portion of the concavity (anesthetic will drip down due to gravity and there's a slightly lesser chance of hitting bone as you enter), direct the syringe in from the SAME SIDE approximately canine/lateral area. Bury the long needle 2/3 or the short needle all the way in and swing the barrel to the contralateral canine/premolar area. Aspirate and inject. I don't look to hit bone... it can be uncomfortable for the patient.

As you bury the needle you should aspirate and inject very small amounts for comfort.

I wouldn't use anything higher than a 27 because I don't feel confident that I'll always get a good aspiration.

Since the end of 2nd year of dental school (summer of 2009) I think I've missed maybe 2 blocks. Is this technique what they taught me? No. But it works for me.

And like someone wrote above, some patients just take like 15 minutes to get numb. It'll be 14 minutes in and they aren't feeling numb at all and a minute later it hits them strongly. Be patient.

 

[DrJeff]

In cases like this I just give a mental block with septocaine. PROFOUND anesthesia. Infiltrating with septocaine in the mandibular anterior, in my hands at least, is not always effective.

Hup

Agree! The mental Nerve block (with or without septocaine) is my 1st choice goto anesthesia technique for the vast majority of my mandibular restorative work from 2nd premolar to 2nd premolar. Works very well in the vast majority of teeth I'm working on, and patients seem to appreciate NOT having a numb tongue! I will always use bilateral mental nerve blocks when working on the mandibular central incisors too, I just have found that the percentage of people with cross innervation of the mand centrals is significant enough that I just put the opposite side mental NB in before I even start working on the tooth.