Path to the Apex: Minimally Invasive or Straight Line Access?

You're listening to the Phil Klein Dental Podcast. We all know that every non-surgical root canal case begins with endodontic access, and that's what we will be covering in today's podcast. We'll also be addressing the two trains of thought when it comes to opening up the tooth. On one side, the belief is that the priority is to be minimally invasive, meaning minimal removal of tooth structure at all costs when preparing your endodontic access prep. The opposing argument prioritizes straight line access to at least the midpoint of all the roots in the tooth, which means if we have to remove additional tooth structure to achieve this, so be it. So let's begin our discussion with our guest, Dr. Ali Nasseh, and see what he has to say. Dr. Nasseh is a world-respected endodontist who currently lives and practices endo in Boston, Massachusetts. He is a senior faculty member at the Harvard School of Dental Medicine, and he has an excellent YouTube channel, by the way, on endo. at youtube.com slash at AANASE, N-A-S-S-E-H. So check that out. Dr. Nasseh will be joining us in a second. But first, if you're doing endo, then you need to know about Jay Morita's new RootZX3, the latest generation of their world-renowned Apex Locator product line. In addition to its sleek design, smaller footprint, and larger high contrast display, the Root ZX3 accommodates the revolutionary HF module which utilizes high frequency conduction. Once you snap on the module, which is quick and easy to do, the RootCX3 becomes an invaluable tool in helping you prepare the canal system. Using its high-frequency conduction, the HF module effectively ablates pulp tissue, residual dental filling materials such as gutta percha, and tissue in and around root canals. It can also tackle procedures such as gingivoplasty, gingivectomy, hemostasis, and excision of intraoral lesions. For more information about this revolutionary advancement in endodontic treatment, Dr. Nasseh, thanks for joining us today. Thanks for having me again. Yes, we really enjoyed your previous podcast. Thank you so much for being a really high-end contributor to Viva Learning with your knowledge of endodontics. So access, that's the first part of endodontics. So we all have to make access to the tooth in order to do this procedure. So what are some of the objectives when making endodontic access in terms of the shape, in terms of the configuration of the so-called... modern endodontic access preparation? Well, I mean, let's think first in terms of what is the objective of an access preparation before we talk about its shape and so on. The main objective of all access preparation is to facilitate finding all of the canals and all of the spaces inside the root canal, and then to also facilitate instrumentation and obturation of those spaces that you've found. So access is not just merely drawing an outline on top of the tooth to find the pulp horns and unroof the pulp chamber, but it is actually a bigger process, it's far more entailed, and in my opinion, it doesn't actually end the process of access preparation until you've... straight line access to the mid-root portion of each tooth. It's a process that's intricate in the sense that it should three-dimensionally align you with that midpoint of each root so that each instrument that you put in the canal can go straight down without any restrictions coronally and reach that space. So what's your response, Dr. Nasseh, to those that say, well, yes, you may be getting straight line access to the midpoint of the root, but you're removing tooth structure that's valuable to the tooth. And long term, the tooth's going to fail because you're weakening it too much. Of course, you know, it is also a balance between how much tissue or how much, you know, unnecessary and sound dentin and enamel you have to remove in order to achieve that. But ultimately, since the main goal of endodontic therapy is to provide a sound foundation for the restoration of the tooth following with canal therapy. The goal of access is try to find that right balance in which you can improve your odds of reaching the apex in all routes, find all routes, get access to all routes, reduce your odds of procedural accidents that can happen with too restricted of an access preparation, such as ledging and breakage of instruments. And yet at the same time, not remove unnecessary dentin. Because you could make the argument that, look, I could have a really easy access if I could just completely hollow out the tooth from top and find every canal and get in there. But then what do you have left to restore the tooth? So talk to us about the different phases of access. What does endodontic access entail from start to finish? It's not just opening up the tooth and you're done with access and you move forward with instrumentation. It obviously all works together. So tell us what that means clinically. The initial part of instrumentation is even part of your access preparation, you know, the very early part of it. So access preparation entails, you know, different phases, getting access to the pulp horns and then unroofing the pulp channel and then finding all of the orifices. Then you're going to need to kind of make sure that you are providing the kind of access that removes some of that strangulation of the dentin around the CEJ that creates this triangle of dentin inside. tooth that could be restrictive in terms of putting your instruments in there and go straight line to the mid root of the tooth so that portion has to be removed that should be removed that involves the use of some diamond bars and some ultrasonics and then some orifice opener files and that So all of that will involve part of the access preparation until you are now able to put a file straight that could go into the midroot of the tooth. And now you'll have a chance to be able to get around any of these apical. curvatures that are oftentimes present in teeth. Furthermore, the other thing that has to happen during access preparation is you have to remove all of the potential free calcifications that are upcoronally into the pulp. And if you don't do that, any of those calcifications fall into the tooth and that can block you. Axis preparation is an intricate procedure. It requires you understanding the anatomy of the tooth, the anatomy of the pulp, some of the areas where you have to be careful in terms of any concavities on the tooth itself, what is the rotation of the tooth, angulation, tilting, all of this stuff. As you look at the radiograph and you create this three-dimensional image in your mind that you then implement clinically. And you can, at that point, you can maximize your odds of finding these canals without any procedural accidents, such as perforations, leging, and other kinds of issues that could happen. So putting it in simple terms, when you have a case like a molar with a very curved mesial root, for instance, it may very well require to remove more tooth structure than you would otherwise remove in a case where you had that same molar with fairly straight roots. And it's a trade-off. You lose some of that sound to structure, but you can't expect to have a successful root canal outcome without navigating that route thoroughly. And to do so, you need satisfactory access. Exactly. I mean, like anything else in life, this is a trade-off too. You don't want to have to remove any extra dentin that you don't have to. But there are times where you need to do that because the risk of you breaking a file and ledging are greater if you try to be too restrictive and too conservative by trying to save a tiny half a millimeter of dentin. And now you've broken a file around the curve and you haven't served anyone by saving a little bit of dentin. So you can't be penny wise and pound foolish. You've got to look at the big picture of things. Your ultimate goal is to make sure that the apex is clean, you've reached the apex, and you've had a safe way of doing it. But again, it goes back to balancing these needs. And today, with, again, three-dimensional imaging and so on, we're capable of knowing in advance where these restrictive areas are. So instead of just... to use stock ideas that we've had in the past about how access preparation should be made and how much dentin you should remove here and there and so on and so forth, you can have a picture of what you're dealing with ahead of time by using your radiography and nowadays with the three -dimensional imaging, have a better sense of where the bottlenecks are, where the hazards are, where you should be careful and where you should actually sacrifice a little bit more dentin, where you don't have to. And these decisions can all be done in advance by... doing pre-planning and then just executing clinically. We'll be getting back to Dr. Nasseh in a second, but first, as a dental professional, you spend a large part of your day in the operatory. That's why partnering with the right dental company for the best dental equipment is so important to you and your practice. The folks at DentalEase understand that every practice is different, so they've created a customizable suite of treatment room packages to fit every need. Whether you have lots of room or need to be super efficient with your space, DentalEase has a configuration that will work for you. known for its revolutionary J-chair and designer-friendly forest equipment, such as lighting and sturdy ergonomic chairs, Dentalese combines comfort, beauty, and efficiency into its state-of-the -art operatory equipment. And when it comes to utility room equipment, nothing beats RAMVAC. It's quiet, reliable, and backed by industry-leading warranties. To learn more about how Dentalese can customize and transform your operatory into one that you'll be proud of. Visit DentalEase.com. So my next question, Dr. Nasseh, is probably one that you've heard many times. How do we know as clinicians with a high level of confidence that we've located all the canals and there are no mystery canals hidden out there? All of us have a sense of how many canals are in each tooth based on probability charts, based on studies, histological studies that have been done by a number of different authors in different populations. So you know what are the odds of a certain number of canals in each specific tooth that actually can vary based on different populations and so on and ethnicities. But you have a sense of what you should be looking for. Each tooth should be started by a bite wing radiograph, a straight shot, and an angled shot. And that will give you a sense of the width of the tooth you're talking about. The wider the tooth, the higher the chance that there might be an additional root in there or something like that. So you can sound with your explorer the tooth also clinically. But ultimately, I think at the present time, a gold standard of something like that would be having a preoperative CBCT that will give you a much better axial section, which is just... across the tooth three-dimensionally and we'll be able to then know in advance how many canals actually are in the tooth and that's the best way because this way there's no guessing and going back to probability charts to see what are the possible places, you will know with a much greater level of probability what's happening. Of course, that's another thing with the CBCT. It has to be a quality CBCT that's been acquired at a very high level of accuracy without patient moving and things like that. So you can have a much... more, we can have a sharper image that could be better diagnostic. So just the CBCT in itself is not enough. It has to be a good quality CBCT. And Jay Marita makes a very good one. Exactly. Yeah, a number of companies make great CBCTs nowadays. More important is the image interpretation software, and those softwares are very important in terms of extracting more from the raw information that the device will give them. But more importantly, there's image acquisition, there is the image interpretation, and then... The image processing that's done by the software and then the image interpretation that's done by you that require, you know, you need to have a good sense of your dental anatomy and your basic jaw anatomy and radiology at the same time. Do you think, in your opinion, if someone's an endodontist, should they have CBCT at this point in the game? Yeah. Absolutely. I mean, I think if you're an endodontist, it's just a no-brainer. You'll have to have a CBCT. The question is, if you're a general dentist, should you have one? Then the answer is, like, if you're going to do enough implants and if you do enough endo, then for sure it would really be helpful. But if you're just doing anterior teeth, basic cases, and you're not doing any implants, I think, you know, it's not necessary, but it would certainly be great because you'll be able to catch the exceptions. If you're doing a lower anterior tooth, you know, where about 20%, 30% of those may have two canals. then you'll know ahead of time if that lower anterior tooth is going to have two canals or not. So here's a common question that if I get a CBCT, will I be able to see vertical root fractures? Is that truth or is that more of a myth? It's not a myth, but it is exaggerated. It is a sales pitch for the most part. No, you are not able to see vertical root fractures predictably enough. Based on some studies that I've seen, you may be able to see vertical root fractures at about 15% higher incidence than conventional radiography, but still not 100%. Sometimes you could infer potential root fractures based on a specific pattern of bone loss on the axial section. but still seeing it is still a function of the resolution. And again, the quality of the image, it all goes back into acquisition. If you're having your, the person who's taking it is not able to communicate with the patient, the importance of staying still during the time that this scan is going around their head and there's movement, you're going to have blurriness and then you lose resolution and then you end up, you know, this finer detail such as a crack or a fracture will require maximum resolution. So there are some, that believe that the main concern when it comes to endodontic access is to be super conservative with tooth structure. In other words, focus on being minimally invasive when preparing our access preparation. What are your thoughts on that? And you did cover it. You know, there's a happy medium. There's a happy medium here. But what are your thoughts about those that literally have you change the way you do instrumentation in order to focus on the main priority of conserving tooth structure in that access prep? Well, I mean, in today's world, everybody's selling something. Sometimes people are selling themselves and their ideas. And I find that, you know, the minimally invasive movement has really been one of those pendulum swings that have really gone way overboard. And in fact, they take exception to the term minimally invasive because it assumes that the rest of us mortals out here are maximally invasive. Right. We're all hacks. Yeah, we're all hacks. Yeah, exactly. Like holistic dentists. Like everybody else is a carpenter and we're just holistic dentists. You know, so it's... That's the same thing. Everybody's trying to be minimally invasive. The question here is what is minimal enough? What are the risks we're taking by removing more or removing less? Because there are risks on both sides. And if you don't understand the risks of removing less, then you are basically not understanding the problem you're trying to solve. And so it comes down to a question of, in my opinion, obviously you want to try as little as possible. where the risk of procedural errors and the risks of unfavorable events are not going to supersede your instrumentation. Now, the other problem I see nowadays is this under-instrumentation that has been shown with these minimally invasive preparations are always leaving bacteria behind. And what I'm hearing from people is that, well, the problem is the model that we're using, endo models have to change and so on. And I'm like, well, I mean, I think the model of removing the infection. should still remain as our main preponderant thing. As every study has shown that you need to have a large enough preparation, in fact, to get adequate irrigation down to the end of the road. And these people then, it seems like, is a coalition of these ideas with industry. And people are saying, well, of course, you don't have to worry about it. All you have to do is to buy this $100,000 machine and irrigate with it, and then you don't have to have a lot. And I'm like, well, wait a minute. The burden of proof is on you first to say that what you're telling me is actually going to really help improve the outcome of this tooth. By trying to save a half a millimeter of dentin, you have to show me that it's actually going to help because otherwise I'm now getting all this additional expensive stuff without any evidence that it's in fact going to help improve the outcome of the case in the long run. And without that, we're just basically being fools, listening to people that are just promoting more difficult cases. It's like, you know what it is, the modern equivalent of that in pharmaceuticals is? It's like, I give you a pill. that creates a side effect, and I'll sell you another pill for the side effect. Right. Yeah, exactly. Give me a break. Yeah. No, no, that's a very good point because, like you said, there are reasons that we don't know when these new ideas come out. And like you said, it could be a particular doctor who's trying to self-promote and start a new movement and get some following and whatever, however he wants to use that. Maybe he wants to start his own podcast program. Who knows? But... Phil, Phil, a lot of this stuff, Phil, is just the... effect of the age of instagram where you can post pictures and you know and get likes and everyone's like oh my god how's this right how's that possible right how did you do that yeah yeah you know you you get a biased sample you get the cases that work they're not going to show you the cases in which the guy alleged broke instruments caused all kinds of problems Right. You're only going to see those cases in which everything worked out perfectly. And so you start by buy a sample and that creates a certain expectation. People go out, they try and they hurt people. They make mistakes on these people. To me, you always have to aim for that type of procedure that will provide the simplest and probably the least expensive and the most efficient and the most predictable outcome. in the long run, for any given patient. And that's what we should be aiming for. Yeah. And the operator has to understand the principles of endodontics, and they have to be able to abide by them and understand what it means to irrigate and remove everything in the canal that needs to be removed. And you could have all the gadgets in the world, but if you don't know the principles and you don't have the diagnostic skills, your clinical outcomes aren't going to be good anyway. That's not going to help you get through it. So the question is, how much better Or what is the benefit? What is the return on investment on something where you have to spend $100,000 and therefore you could obviate the need for opening up the tooth two more millimeters? I don't know. We'll find out as the research comes out. Exactly. Thank you very much, Dr. Nasseh. I appreciate it. That was a good overview on endodontic access. And we'll look forward to having you on future podcasts. Thank you so much. Thank you. If you're enjoying this podcast please leave a review or follow us on your favorite podcast platform. It's a great way to support our program and spread the word to others. Thanks so much for listening. See you in the next episode.