Mastering Working Length: Technology That Elevates Endodontics

I like to say that to my students, that radiographs are the Instagram of endodontics. There are things that appear to be that are not. And we have limitations because the radiograph is just a shadow. It shows you the superimposition of the structures. And when we move to the electronic method, we are considering the three dimensions of our tooth, of our canal. Welcome to Austin, Texas, and welcome to the Phil Klein Dental Podcast. Thank you for joining us. For those of us who perform endodontic therapy, we know that accurate working length determination sits at the core of predictable high-quality outcomes. In this episode, we'll explore why precise working length is so critical. and how the quote-unquote working length 4D concept is shifting the way clinicians think about endodontics and what emerging endodontic technologies are bringing to everyday practice. Our guest today is Dr. Lucila Piasecki. She's an endodontist, researcher, and clinical associate professor of endodontics at the University at Buffalo, New York since 2016. So if you're performing or assisting in endodontic procedures, I'm hoping that this episode will offer you valuable insight into the tools, innovations, and future directions shaping modern endodontic care. Before we bring in our guest, I do want to say that if you're enjoying these episodes and want to support the show, please follow us on Apple Podcasts or Spotify. You'll be the first to know about our new releases, and our entire production team will really appreciate it. Dr. Piasecki, it's a pleasure to have you on the show. I am happy to be here. Thank you for having me. Let's begin with a very fundamental question, and that is, why is establishing an accurate working length so critical in endodontic therapy? First of all, this is a topic that I'm passionate about, but also it's... proving scientifically that is one of the most critical steps in our endodontic therapy. So we think of the working length as the boundary line that tells us exactly how far our procedures of cleaning, infecting, and filling should be. uh should go as far inside the canal so this ideal point is not arbitrary it should be as close as possible of the apical constriction because this narrow diameter that's usually very close to the apical forami is the optimal Point for wound healing. So we can have our periapical tissues promoting the healing in the periapical area. A good point that you made is that clinically, that target is at or very near the apical constriction, but not necessarily the radiographic apex, right? So that's really important for our audience to... I'm sure they all know this. Most of them are doing endodontics, but... You know, you hold up a radiograph, and at least in my day, we used to hold up a radiograph. Now it's on a screen. But a lot of dentists thought the radiographic apex was where you wanted to go to, but it's really not. It's the apical constriction, which is not necessarily determined by a radiograph, correct? Yes, precisely. And actually, even before radiographs, when the dentists were using only the tactile sense to try to... to find this end of the canal so the importance is if we go beyond the constriction we are pushing debris irrigants or filling materials and we can damage the peripheral tissues or maybe if you're close to an atomic important anatomical structures so we are trying to prevent this irritation and even like post-op pain and improve healing. Because when you have overextension, you might delay healing. And of course, we don't want to be short to the apical constriction because this will compromise our disinfection of the broken out treatment. So what's particularly interesting is the way they teach endodontics today versus the past. I think more and more it's encouraged that the dentist confirms his or her working length throughout the procedure. So it's more than just determining your working length in the beginning, but it's confirming it as you move along. And you refer to that as working length 4D. Tell us what that means and how it affects clinical outcome. Okay, so this is a concept that I... I try to reframe how we think about working length and thinking about what you said, how we used to do before. So if you're thinking only about the vertical component, if you're using a paper point or your tactile sense, you're only going for the vertical, just one dimension. When we added the radiographic films for working lengths, we are... working with those two dimensions, right, of our film. And we have limitations because the radiograph is just a shadow. It's just a superimposition. It shows you the superimposition of the structures. And when we move to the electronic method, we are considering the three dimensions of our tooth, of our canal. Because we have that method considering all the anatomy of that canal to find the apical constriction. But then the fourth dimension is time. Because our working length shouldn't be measured just in the beginning of our treatment. Because we have sufficient data to show that we have changes in the working length as we proceed with our preparation of the root canals. Why does it change? Because I know when I did root canal in the old days, we located a cusp that was fairly stable. That cusp tip was not going anywhere. And the rubber stop would land on that cusp as a reference. And if it was 23 millimeters, after we determined what our working length was, that's where it stayed, 23 millimeters. And I didn't really go do another working length again. But you're saying that this is kind of a moving target over time, and that's where the term working limb 4D comes in. It's that fourth dimension of time that's changing. So why is that? Well, actually, the target's the same, is the apical constriction. What changes is our trajectory. get there. So I notice a lot of clinicians, they like to access the tooth and place a file, feel that they have patency and take their working length either with apex locators or radiographs. But after you complete your access, you remove coronal interferences, mainly if you're using an orifice shaper, creating your glide path, you will slightly change the trajectory. and your working length has a tendency to reduce. Sometimes it's 0.2 millimeters, 0.4. Sometimes we cannot even detect clinically if you're just using a regular clinical ruler. But that degree of shift depends on many factors. For example, the more curved the canal is, the more you enlarge, the more taper you give to that canal. The more you enlarge that canal, the more the length can change. Also the instrument type, if you're using more rigid instruments, you will... end up straightening more that canal and as we know the shorter distance between two points is a straight line so if your canal to begin with was curved or double curved as you prepare your root canal you might have these slight changes in the working length and it's interesting because in the same tooth, so we've done a couple of studies, so for example, mandibular molar, in the distal canal, you will not see much of change in the length from when you start to your completion of your preparation. But in a mesial buccal canal or a mesolingual canal with double curve, you might have slight changes over your orifice shaper. coronal preparation, apical preparation that might add up to 0.8, 0.9 millimeters. So it's almost a full millimeter reduction in your working length. And the fact that this is happening and you cannot predict leads us to the 4D concept that is monitoring. Those changes, monitoring your working length, you just use your pixel locator. You can keep the leaf clip there. And as you go after a couple of files, you double check because if anything happened and you have your instrumentation went beyond the framing, you can always adjust and prevent overextension of your obturation. So given that we talked about the working length 4D concept, which means that Over the period or over the course of the instrumentation process, the dentist should be recalibrating their working length using an electronic apex locator. And we'll talk about one that's really, really good in a few moments. But considering that most dentists are still using 2D radiographs, digital radiographs, but it's not CBCT, a lot of them just say, hey, you know, I go a half a millimeter off the radiographic apex and I should be pretty close. to what is the actual apical constriction what do you say to that so that's a very interesting point because when you are using just a radiographic image i like to say that to my students that radiographs are the instagram of endodontics there are things that appear to be that are not. So when you look at a 2D image of the tooth, you have the superimpositions, you don't know, you cannot assess the volume, the depth. Most of cases, you cannot see where is the apical foramen, unless it's in the mesial or distal aspect, and still... And if you could see the apical foramen, you still don't know where is the apical constriction. So what we know from the anatomy studies using micro CT, using microscopic techniques, is that in most of the cases, mainly for posterior teeth, the apical foramen does not coincide with the root apex. So you have this variation. And when you look at some studies from... Cutler and some other studies that didn't use micro CT, the 0.5 millimeters, it's from the foraming, not from the apex and not from the radiographic apex. It could be anywhere from zero to more than two millimeters. So it's between zero and two millimeters, the working length could vary from the actual radiographic apex. Yes. In some cases, even more. There's some studies that for molars, MB2 canal in molars, the distance from the apical constriction to the radiographic apex, it could be even more than two millimeters. Wow. So that's a big deal. So that means that if you're working off the radiographic apex, you're overfilling. Yes. In most cases, you're overfilling the canal, which we talked about in the beginning. That's dangerous because you're pushing debris into the osseous area, the attachment apparatus, and that's going to be certainly minimally an inflammatory response. And it could lead to worse than that, which could spread the infection if you have a necrotic pulp with lots of bacteria in it. So there's no question that using an apex locator... is very very important and not only in the beginning of the procedure but as you mentioned over time with that concept of working with 4d so i want to ask you dr piasecki you've been a big fan of the j marita root cx and now they have a newer version it's been out for a couple of years maybe not that long but uh the root cx3 which has the ability to have this high-frequency module attached to it, and we'll talk about that shortly. And I think in the endodontic community, if not the entire dental profession, the J. Morita Roots EX3 has become the gold standard in apex locators. Tell us why you rely on it so much, and what is it about the Roots EX3 that is really bringing such attention to it in the field of endodontics? Yeah, so you're completely right. RootsX really is the gold standard, not only in the industry, but also for research. And the reputation is because of the functioning method. So it uses two frequencies and calculates the ratio of the impedance inside the canal. So all these complicated words are to explain that this device will use an electrical circuit. to evaluate the anatomy of the canal. And when it reaches the apical constriction, it gives you the sign that this is the nearest part of the canal. And it can also tell you when your file is in the exit of the canal. That probably and hopefully is the apical foramen and not a perforation, for example. When I was in dental school, we used apex locators. And when I was in practice, we used apex locators. Now, there were some false positives when it came to fluid in the canal and that kind of thing. How has that improved now over the years? So the method that RouteZX is using, because it has these two frequencies of alternate current, it's stable in most of the environments, regardless of the type of irrigants, file systems, operators. pulpal diagnosis and many studies confirm the accuracy between 85 percent or almost almost 100 percent within a half millimeter tolerance so it's clinically proven to be efficient and you can use to locate the apical framing the exit of the canal uh if you're trying to find your patency. And you can also use to establish your APCO limit of preparation when you are locating the APCO constriction. So the RootZX has become this benchmark gold standard to which we evaluate any other devices in the market or any other situations. If you want to compare a different irrigant solution, you will always rely on RootZX as your standard. So if you would, Dr. Piasecki, walk us through the workflow of how you would integrate the root ZX3 into the endodontic procedure. So begin with the pre-op film and move through it. Also talk about how you want to continually confirm the working length. Okay. So when you have your first image of the patient, you have a periapical radiograph. So that's when you have your pre-op length, or we can use that estimated working length. And since you mentioned before, if you do have a CBCT that was taken for diagnostic purpose, you can also measure the canal using the CBCT. Actually, there's studies showing that measuring... the pre-op working link from the CBCT is more accurate than only in the 2D radiograph because you're considering the volume, right? Then you proceed for root canal access and... If the dentist wants to check patency or to double check if the file is inside the canal, so they can use the apex locator at this point to go to the apex mark, the first pink mark, and then you know that that's your patency. And then as you start to prepare your canal orifice shaper, you are removing denting and you are straightening a little bit that. that canal. So you could use your apex locator again to find your apical constriction and establish your working length. And as you progress, I always tell my students that after I reach a size 25, it doesn't matter which type of file or which type of rotary you're using. It's always good to double check because at that point, you probably removed most of the pulpitia. And 0.25 millimeters is the average size of apical constriction, even for molars, according to some micro CT studies. So you still have the chance to fix or adapt your working length at that point, if anything is not according to plan. But the interesting part about the root CX3, is that it has a separate module that you can attach to your apex locator and it helps to remove that pulp tissue so you can use they call a high frequency conduction and you can use this electromagnetic pulse to disrupt the pulp tissue So this will help you achieve a better or more stable electronic reading of the apex locator function. So it actually causes electromagnetic disruption in some fashion of the lateral canals and deeper down into the more constricted area of the root canal system and helps us flush out the debris. Is that the way it's supposed to work? Yeah, it's... It's perfect. Yeah, I just read it. You explain. Well, I talked to the company, the research and developers, and I talked to some of the endodontists that use it. And that's how I remember them explaining to me. I've never used it because I don't do root canals anymore. I do podcasts. But I'm not sure which ones I like more, doing the root canals or doing the podcast. Eventually, I'll decide. I prefer the root canals for sure. Yeah. All right. Well, that's good. So is that something that you recommend? With the ZX3 or is that just kind of a luxury item? I mean, is that something that you find hugely clinically beneficial to you as far as removing debris from difficult areas and kind of cauterizing the tissue so that it could be flushed out, not only to get a better length or more accurate length recording, but also just in the process of instrumentation and disinfection? Yeah, that's a very good point. So this HF model is... As we discussed before, it's an add-on to the Roots X3. And what it does, it transforms pure apex locator into a combined measurement and therapeutic unit because it will use high-frequency energy that works similar to an electrosurgical unit. So you will use those pulses to... cuts of tissue and coagulation of soft tissue. And in fact, it comes with tips that you can use for a small gingivectomy, for example, if you need that. But what's interesting for endodontics is that it was designed to work. within the dentinal walls uh so it comes with tips that are partially coated and you can use those files or tips to create a target vaporization or ablation those words i like to use culturization it's easier to understand so you can cut or organic tissues pulp for example you can disrupt small debris, biofilm, even remaining gutter percha after the removal of the bulk gutter percha and retreatments. So this tool is very interesting because it will help you to clear the path for your apex locator to work. And because they are integrated, you can do both at the same time. The only add-on is... It's a pedal, pedal switch to activate the HF module. The way you explain it is very clear because I know that when I practiced endodontics, often I'd be instrumenting the tooth. And even further into it, maybe 50% into my instrumentation, there was still some spongy, resistant, soft tissue that just clung to the side of the dental wall deep down. most likely attached to a lateral canal and had some foundational attachment in there, which was very hard to get out and frustrating. And this particular addition to the RootZX3 seems to have handled that. Like you mentioned, there's a cauterization process that actually cauterizes the tissue, and then it flushes out much more seamlessly, which is really the goal here. So it seems to me what the RootZX3 is doing with the HF module, For the cost of it, and I think it's maybe, I don't know, $3,000, that's almost similar to what the purpose of a laser that would cost $80,000. An erbium-yag laser is also used to disrupt biofilm and disrupt tissue through the bubbling effect that it produces when you put the tip in there. Are we getting similar results with the HF module as you would with possibly a laser? I believe so. And I believe there's a potential to improve, not only for the working length, but to just disrupt pulp tissue, biofilm, and control bleeding. So because it's, it culturizes. So if you have... a case that you have inflamed tissue or bleeding inside the canal. So using the HF module, it will coagulate to stabilize the bleeding, which is a plus for working length determination because excessive bleeding, excessive exudate might interfere with the performance of your apex locator. So the HF module will help by removing debris, helping to cauterize and remove pulp tissue, and also in the process, helping with disinfection. We do have some studies in animals showing that HF has the ability to remove tissue from accessory canals, from lateral canals. And even there's a clinical study showing that it can act even in non-instrumented areas. Yeah, see, that's a big thing because... You know, there's dentists that I know that work in remote areas where the closest endodontist is 35, 40 miles away. That's the closest. In some areas, I have friends where they say that it's a four-hour drive, four hours just to get to an endodontist. So rather than have a dentist, a general dentist, extract a molar. because the patient doesn't want to go four hours each way to the endodontist, and they go, listen, doctor, just take it out. The dentist will have a laser there, and they'll spend $100,000 for a laser because they feel like they could be more successful with molar root canal because they have now a tool that could help with the disinfection of tiny calcified small canals that molars usually present to the operator. But with this HF module, like I mentioned, it's $3,000. I think it's $3,000. Maybe less. I don't know what the cost is now. Everything goes down over time, I guess, as more and more people adopt to that new technology. But to me, it's a no-brainer. for someone who's in a remote area. And again, or if you're a general dentist who's doing molar root canal or an endodontist who's doing molar root canal and doesn't have a laser or just wants to augment their standard operating protocol, which is instrumentation, irrigation, instrumentation, irrigation, and so forth. So it sounds like it's a really good adjunct. And that's probably why they developed it, right? I mean, they knew what was missing in the armamentarium of the dentists that are doing these more difficult cases. Yeah, so as we were discussing, the RootsDX was already the gold standard for Apex Locator, but some of clinical situations would cause interference in the Apex Locator itself, regardless of the brand. So when we had canals with excessive bleeding, with blockage by debris or gutta percha, This was interfering with the electric flow of the apex locator. As a researcher about apex locators, when I saw RootsDX3, I was very happy to know that there was this strategy, HF, that could improve the accuracy of the working length measurements. However, this high-frequency module has so many other... Benefits. Advantages. Yeah. So it's interesting. So they kind of developed it. It sounds like what you're describing to help ascertain the working length in environments where it was more challenging. Right. Because the things that the things that interfered with an accurate working length determination was eliminated with this high frequency electromagnetic impulse that would get down there and help the doctor take out the debris. Therefore, they can get a more accurate working length. But in essence. It's not only doing that, you're saying, it's also helping with the whole disinfection irrigation process. Exactly. And the good thing about using the Roots X3 is that you don't have an extra device. So you don't have a new learning curve. You don't need another setting. in your chair, you still have the same familiar RootZX style interface. So it's very easy to implement and start using. And it doesn't affect the workflow because you're already using the Apex Locator. Another interesting benefit, Dr. Piasecki, that we talked about offline was pain control. Tell us about that. Well, since the HF module will disrupt the pulp tissue, you can go down about like four millimeters, maybe inside the pulp tissue, and you deliver a pulse in a specific setting, which is not very strong, but enough to cause a numbness of the pulp tissue. And you will also coagulate, remove, and it's... way less painful for the patient. Yeah, well, it's certainly less invasive than an intrapulpal. Yeah, so for the cases when you have that inflamed pulp that patient's feeling and you consider using the intrapulpal anesthesia, so let's think that for the intrapulpal anesthesia, you need the back pressure. And sometimes if you're early on, you don't have all your access done, or even if you are already inside canals, it might be very hard to achieve that back pressure or have enough space for you to use your needle. So with this unit, you will use the probes or the tips that come with the HF, which is very small size of a file. So it's easy to place them inside the pulp tissue. You will use one pulse. It's one second. It will coagulate the tissue and instantly, instantaneously causing the anesthesia. So because you're technically removing, culturizing the tissue. So it's convenient and easier on the patient in case of pain, even after a block, if you have inflamed a hot tooth. And there's also one study showing that reduces the post-op pain. By what mechanism would that work? Just by the fact that the tissue is being cauterized at the time the treatment is being done? Yes, not only for decalterization, but also you will be removing, getting rid of tissue, and you will have less debris inside the canal. And... Don't forget that we will also have a better working length determination. So everything comes together. Yeah, see, that's really what I think it comes down to. The fact that you've got a much more accurate working length determination probably precludes over-instrumenting in more cases. So therefore, the postoperative pain or postoperative sensitivity is less just for the fact that you're not manipulating the tissue. outside of the root canal system. The idea is to minimize over-instrumentation by getting a really accurate working length. So as we wrap up this podcast, Dr. Piasecki, and it was very interesting talking with you, what would you recommend to our dentists that are listening to this program about endodontic success? What would you tell them if they were in your endodontic bay right now in the clinic where you teach as like a encouraging pregame pep talk about what they should be doing in order to... maximize our clinical outcomes with our endodontic cases. My closing remarks are always back to basics. We need to remember anatomy. I teach entire anatomy to the students in their first years. And then when they're in clinic, they're like, oh, I don't remember that. I said, yeah, let's go back to the basics. So always. Be mindful of anatomy. Try to understand the principles of functioning, not only of your apex locator, but any device that you're using. Because if any challenges appear, if you encounter any challenges, as long as you understand why you're doing that procedure and how to use your tool, you will be able to overcome or most likely understand or find a solution or an alternative. So anatomy. Understand your tools and trust your apex locator because they work. Yeah, that's excellent advice. And we're hearing that, ladies and gentlemen, from a researcher and an endodontist. But I think that's what you said, Dr. Piasecki, applies to many, many things. If you understand the foundational basis for what you're doing. then you could become a problem solver when the problem arises, rather than following a cookbook and saying, first we do this, then we do that, then we do that. Because most of your cases could go pretty well, but when you run into a problem, if you don't understand the basics, like you said. Anatomy is key for root canal therapy for sure. Thank you very much. Have a great evening and enjoy your trip to Brazil. Thank you for having me.