Getting that "Hot" Tooth Numb

You're listening to The Dr. Phil Klein Dental Podcast from Viva Learning.com. Welcome to the show. This is Dr. Phil Klein. Today we'll be discussing the effectiveness of local anesthetics and how articane can improve the outcome. Our guest is Dr. Stuart Lieblich, a world-respected oral and maxillofacial surgeon. He has contributed to over 19 textbooks and published over 45 peer-reviewed papers and abstracts related to oral surgery and oral medicine. He is a noted speaker nationwide and regularly presents webinars for VivaLearning.com. He is currently in private practice in Avon, Connecticut, and is on the medical staff at a variety of hospitals in Connecticut. Dr. Lieblich, it's a pleasure to have you on Dental Talk. Well, Phil, pleasure to be here. Thanks so much for the kind invitation. Yeah, and you've done so well with your webinars with us. You have quite a following on our program, and the stuff that you've been putting up there is just so valuable. I really encourage all of our listeners, do a search on vivalearning.com for Lieblich, L-I-E-B-L-I-C-H, and you'll find all of Dr. Lieblich's webinars and other podcasts, and it's just phenomenal stuff, really good stuff. To begin, and as the title states, getting that hot tooth numb, so my first question is, What are some of the reasons that a tooth may not achieve profound anesthesia when given a local anesthetic? Critical thing that we face in dentistry, and interestingly as well, it's that often our first meeting of a patient. So it's our chance to shine, our chance to really help that patient who comes in with acute pain. But we know we can't always be successful. And I think educating our patient, letting them know what are some of the reasons that their tooth may not get totally numb allows us to provide expert care for our patients. So I think we all think about infection as the primary cause. And when we have infection, the simplistic way to think about it is that the area, the milieu around the tooth becomes more acidic. What that does, it drives the dissociation constant of the local anesthetic to more charged particles, which. does allow it to dissolve in the water and tissues a little bit better, but it does not let it cross the nerve membrane. So there's this natural blockade now where up to a factor of a thousand or more molecules may be needed to achieve the same effect. There's also... you know for the neuroscience it actually shows that the receptors for the local anesthetics do get altered by the local products of inflammation the cytokines and tissue necrosis factor and all these other things that are there that prevents actually the local anesthetic molecule from binding profoundly and therefore we don't get a good blockade of local anesthetic effects so frustrating for us as a dentist extremely frustrating for the patient of course as well too and i think our conversation of what we can do to try and improve outcomes is certainly critical to our profession. Yeah. So you talk about the infection environment, and obviously the acidity is up. What happens in those vital cases where there's no infection, the pulp is alive, it's what we normally call, and we talked offline about this, irreversible pulpitis, which pulpitis by definition implies a vital pulp tissue. So there shouldn't be any type of acidity in the surrounding tissue. Talk about that, if you would. Is that something you find we also have trouble getting numb, but not for the reason that you just stated? Right. And as I say, infection is somewhat simplified because, you know, you think about giving a mandibular block, you're well away from the site of the infection, and yet the patient may still have sensation when we're opening for access of the tooth endodontically or going to extract a tooth or what have you. So again, the receptors themselves get altered. uh by the inflammatory mediators and there's you know it's interesting thing about those of us that enjoy sushi there's a certain type that's made from puffer fish that's very temperamental if it's not prepared correctly you will die from it because those molecules bind irreversibly to the nurse it's called tetrodotoxin so it's a great way to study it it's an irreversible binding as opposed to our local anesthetics, which reversibly bind and they go away and the nerve sensation returns. Well, some of these receptors in inflamed and in mediated tissues become tetrodotoxin resistant. And that's how profound the effect is of local inflammation and mediator. So it's more than just infection. It's more than just acidity, but it is something that we can try and overcome and get, you know, anesthetic effects for our patient. So interesting enough, you know, and everybody's probably experienced this in the dental profession, You give the patient the local injection and the lip and the chin become numb. And then when you start working on the tooth, the patient responds. So what's going on in that situation? And that is so frustrating. The lip is numb, the chin's numb, and yet you touch the tooth and they're coming up out of the chair and they're very uncomfortable. So, you know, the nerve is like a cable. And there are the various distribution of this cable to the different structures, such as the alveolar process, the bone, the gingivate, the tooth itself, the pulp, and then, of course, extending anteriorly all the way out to the lip and the chin. And as those cables get wrapped around the main nerve and contained within the epineurium, some of those are more superficially located, some are more deeply located. And you would... intuitively that perhaps the ones that are the furthest forward like the lip the tip of the lip would be the deepest nerve fiber inside there but sometimes it's actually more superficially located so we can get numbness we can get profound effects of lip and chin anesthesia but yet the tooth is still hypersensitive to touch and it's again this regulation of these binding sites of the local anesthetics are probably the thing that we need to overcome How can articaine improve outcomes? And if you can, for those of our listeners that are not familiar with articaine, if you could compare that to the standard lidocaine that we generally use as well, and then tell us why articaine can actually improve outcomes. So lidocaine is certainly our workforce, local anesthetic. It diffuses well through tissues. It crosses the nerve membranes. block you know for a reasonable period of time we know of course with lidocaine we need to use a vasoconstrictor with it if we want to get profound local anesthetic effects but when we have a patient in pain when we have a difficult tooth to anesthetize and we perhaps have area of infection inflammation there are a couple of factors why arcticane works to our advantage first off it's a four percent solution as opposed to the two percent with lidocaine so you're getting twice as many molecules so you're doubling your amount in the same concentration of fluid so therefore you have the ability to have more of these nerve uh these molecules that can cross the nerve membrane to now provide nerve conduction blockade. The other important chemical factor of arcticane is that it's much higher protein bound than is lidocaine. So as we inject a local anesthetic solution, it's going to diffuse through the tissue, get to the nerve, cross the nerve membrane, and start to block the nerve conduction. But simultaneously now those molecules are coming out of the nerve, getting picked up by the circulation, and taking away from the site so that the patient has the effect of the nerve block wearing off. With an agent that's more highly protein-bound like arcticane, we're going to get more sticking to the proteins in that area. It's not going to move away as quickly. And so therefore, time is our ally here. It's allowing more molecules to come on the scene to now block our nerve conduction. And so there have been numerous studies that have shown now by comparing lidocaine with arcticane that you will get more profound and effective local anesthetic effect using arcticane in combination perhaps with lidocaine too. Is it a feasible scenario for a dentist just to say, I'm going to just move to arcticane solely and not use lidocaine? Or what's the benefit of the combination of using both? So when you talk about arcticane, it's always important to bring up the controversial issue is that there have been some... reports of persistent numbness or paresthesias after arcticane has been given as a nerve block. And that's basically the studies from Dan Haas and his colleagues up in Canada from 1995. But arcticane has been used routinely in Europe for many, many years before it was released here in the U.S. with very good effects. In tracking these adverse events in Denmark and other countries, they've not really seen an increase in the nerve issues, but it is something that is in our literature and something that we are aware of. So many of us, and what I typically recommend using is lidocaine for the actual inferior alveolar nerve block, and then infiltrating articaine along the buccal and consider a lingual aspect as well, because articaine will also diffuse through the tissues better than will lidocaine too. So using it locally, therefore, we will not have the potential for this long-term paresthesia. But I do want to mention that if you read the package insert of arcticane, that it is FDA approved for the use of a nerve block. And in cases of recalcitrant cases, having difficulty getting someone numb, I will then go ahead and use arcticane as an inferior alveolar nerve block. But it may not always be my first choice in that area. Yeah, very well explained. Now, I did talk to you offline before we started about the process in which the arcticane is manufactured. And as far as sterilization, can you talk about that briefly compared to the standard method and what the advantages with the arcticane method? Most local anesthetics are processed by combining the various agents. Of course, the epinephrine, as I mentioned, is an important component to provide us some hemostasis, but also primarily to keep. the local anesthetic molecules on site. So they continuously block nerve conduction for a reasonable period of time. And for example, we know if we use lidocaine without epinephrine, you will not get enough time to really get true pulpal anesthesia. So there are different ways articating can be formulated. The one that we use in our practice is manufactured by Perel Pharmaceuticals, which is called OraBlock is their trade name. And what they do is that instead of sterilizing the components at the end which then leads to some breakdown of the epinephrine and other particles they sterilize all the agents initially before they're then sterilely combined and provided to you in the cartridges now what's nice also about their packaging is that each cartridge it's in its own separate little column excuse me so therefore when you're opening up onto your surgical field you have a better control of sterility you're not reaching into a standard slip of local anesthetic cartridges and risk contaminating those each one. So, you know, we prefer to use AuroBlock for our brand of Articane. It's been very effective. I think the shelf life, one important factor is because it's sterilized initially, its shelf life is 24 months as opposed to the typical 18 months that you get from conventionally processed Articane. Yeah, and OroBlock seems to be really trending upward as far as prevalence among dental practitioners. I haven't heard any cases, maybe you have, about what you talked about earlier about long-term anesthesia that you don't want with Articane or with OroBlock. Have you heard about that recently? Because OroBlock is certainly being used quite a bit. Quite a bit, and I've not seen any direct reports. I mean, any local anesthetic can contribute or cause a long-term paresthesia, and we're not really sure is it due to specific needle trauma. uh we know that sometimes we when we inject it's a blind injection we can't see the nerve and we want to be as close to the nerve as possible so it's not the fault of the dental practitioner to touch the nerve with the needle and in fact i've had it in my own personal case of getting a nerve block and the needle brushed up against my lingual nerve and it felt just like putting my tongue inside a light socket i mean it's very noticeable so i didn't say my dentist had a poor technique it was perfect technique they were putting the local anesthetic where it needed to be but i did sustain that sensation which then went away after the local anesthetic wore off so if a patient were to report and jump up out of the chair and feel that electrical sensation whether it's along the lip and chin or along the tongue then we should stop remove the needle and then reinsert it in a different position in the one in a million chance that the tip of the needle happens to be within the nerve membrane itself. So it's, again, we can't see the nerves. We know roughly where they are, but it is a consequence. And it's actually a positive thing that the dentist gave a very accurate block and so accurate they may actually have been injecting. Long-term paresthesias have been associated with all the local anesthetic solutions that are out there. Again, there's one report that felt that perhaps the 4% solution, such as prilocaine or arcticane, may have a higher incidence. Whether that is exactly able to be proven is difficult because, fortunately, there are such rare events. When I was in practice many years ago as an endodontist, and I had those cases where the patient would come in and, you know, we'd have a great conversation. We're going to do this root canal. I've done them before on that patient. And all of a sudden this particular tooth, I just, I'm really challenged to get them numb. So I would either try another block. Let's say it's a number 30, but then I would also go in and do in the ligament. So I'd go under the sulcus, run my 30 gauge needle very carefully under the sulcus and inject carefully. Was I really accomplishing some penetration through the cortical plate, especially on a lower molar? It's pretty thick. Maybe lower anteriors would be more effective. But I did that routinely. And then, of course, as an endodontist, I had access to the pulp through the access prep. And I would then proceed to give what we call an intrapulpal, right? And I'd go right into the canal. And it might sting for a second or two, but that was it. Once I got into the intrapulpal part. That patient was comfortable, guaranteed throughout the procedure. And I preferred not to do the intrapulpal, but if I had to, I did. But I was more curious about the PDL injection and locations in the mouth where those are given. And we're talking about getting that hot tooth numb. So if you can give us any feedback on tips and tricks regarding that. Sure. Well, I think your technique is ideal. So first off, if there's swelling and infection, then I think we're probably thinking about. draining the infection or giving the patient antibiotics and getting them back next week. I think what you were talking about, opening the tooth and injecting intrapulply, I mean, occasionally when I'm taking out a third molar and I can't get someone numb, I'll have already drilled a little bit into the bone and I'll inject into the bone itself. So intraosseous injections are certainly very, very effective. And whether it's alleviating some of the pressure that's in there, maybe when you inject intrapulply or I stick the needle in the bone, we may be then allowing some of the uh build up of pressure to then allow the local anesthetic to now diffuse through but again using a higher concentration local anesthetic like arcticane the other techniques you can there are systems out there to drill little holes in the bone and then inject directly into the bone itself and intraosseous and i do want to mention to the group here that we do have to be cautious because when we inject an intraosseous injection it's a great way to get a drug into the central circulation So you can get toxic reactions. So for example, if we have a medical crisis and we cannot start an IV someone, we have a little device that drills a hole in the femur and we can inject into the femur and get the emergency drugs into the central circulation. So similarly, injecting into the bone or the mandible in small amounts is certainly appropriate. A half a cartridge at a time is useful. I think those are great techniques and the tips that... you know experience brings to us and having those things in our armamentarium is very valuable so i think setting the good expectations for the patient that we care of course about the patient we want to alleviate pain we'll check to make sure the lip and chin is numb before we start on the tooth but as you've noted in your past and myself that you go to luxate the tooth or drill into the tooth they're still having discomfort and pdl injections are perfect having a device to inject in the pdl again whether it goes intraosseously as well and again arcticane a four percent a highly diffusible or protein bound it's going to stay around a little bit longer i think it's going to improve your outcomes as well Is there any data on different results with different local anesthetics? Now, you talked about the category of arcticane. Any particular data on different local anesthetics? Again, in comparing head-to-head lidocaine versus arcticane, the original studies that Dr. Malamed did, who we all love and respect, showed they were equally as effective, but newer crossover studies have actually shown a higher efficacy with the use of arcticane. And again, I would say it's the 4% solution, the more highly protein-bound solution. and the fact that it diffuses through the tissues a little bit better. And I also want to comment as well that we always learned, and Dr. Klein went to Penn as well as I did, that we were always telling you how to give a block when you're working in the mandible. But if you look at a skull of a mandible around the alveolus, you know, the bone is relatively porous. There's muscle attachments that allows a flow from the tissue into the bone itself. So again, infiltration type injections are... are very very valuable and they can certainly be a great adjunct and an asset for us and in some of these more challenging cases Yeah, very well said. And for our listeners, if you're interested in learning more about Articane, obviously you can Google Articane, but specifically Orabloc. That's O-R-A-B-L-O-C. It's proven. It's been very successful. Just the fact that Dr. Lieblich loves to use it says something right there. Thank you very much, Dr. Lieblich. And we hope to have you on another podcast soon. We really enjoyed your insight. Great to visit with you all and best of luck in these challenging times.