Endodontic Irrigation: Power-flushing Your Way to Success

When you look at the fluid flow and the acoustic streaming and the other forms of eddy formation in these fluid movements, you see that there is movement many, many millimeters around the curve past the tip of these instruments. Welcome to the Phil Klein Dental Podcast. Like anything else, before you can become really good at something, you have to understand the principles. the fundamentals of what is actually happening behind the scenes. This also applies to endodontics, and today we're going to be specifically talking about irrigation. So what are the principles of endodontic irrigation, and how does it affect the way we clinically practice, and how is that related to the clinical outcomes of our success? To tell us all about it is our guest, Dr. Ali Nasseh. Dr. Nasseh received his dental degree from Northwestern and his specialty certificate in endodontics from Harvard. He is also on the senior faculty at Harvard for the past 28 years. He lives and practices endodontics in downtown Boston. Dr. Nasseh will be joining us in a moment, but first, if you're a dentist who understands the importance of diagnostic accuracy and treatment planning, then you're probably thinking about CBCT for your practice. With the advent of CBCT, the limitations of 2D imaging and the clinical guesswork that goes with it are now things of the past. So the question is, which unit should you buy? Of course, you do your research, ask your colleagues, and talk to different companies. But before you make your final decision, check out the models by Merida. As one of the first companies to market in CBCT, Merida has refined its features for simple, accurate positioning and provides multiple acquisition modes and fields of view. Well known for remarkable image clarity, their technology will help you diagnose apical lesions, root fractures, cysts. TMJ, and so much more. So when you're ready to embrace the transformative power of CBCT, check out the state-of-the-art equipment by Merida. To learn more, visit merida.com slash USA. Dr. Nasseh, we're very happy to have you on our show. Thanks for having me, Phil. Yeah, it's really good to have someone like you on board on our podcast program, and we really appreciate your input over the years. You've been a great contributor to vivalearning.com. Let's talk about irrigation today. What are our main objectives when it comes to the irrigation phase of root canal therapy? Well, first, we have to understand that the endodontic irrigation is a pivotal and very important part of the entire chemo-mechanical instrumentation and obturation, essentially having successful outcomes. That's the part that doesn't get emphasized enough when it comes to people talking about the file systems that they use and the obturation technique they use, all this stuff. Irrigation is really the crux of the issue. That's the stuff that we really should focus on and how to disinfect you. The good news is that it doesn't have to be complicated. It could be very simple. The main three principles that we have to follow is that any irrigation system use or a combination of your against that we use should really do three main things for us it should remove the organic components of the root canal which includes all the tissue cells and you know some of the collagen inside the tooth as well as the inorganic components and that is our dental chips a part of the smear layer all that stuff and then last but not least is to disinfect those spaces that are we left with in order to get rid of the biofilm which is the main component of the problem here and it's a complex structure of microbial interactions and number of different species that work together as kind of resistant to regular disinfection. So we need to kind of have this disinfection component really as the main important part of successful outcomes for our cases. So when we talk about irrigation, even though it's considered one process, it really does involve cleaning as one component. And then... disinfection is the other component. So talk to us about that clinically. How do we approach that so that we make sure we handle both of these components carefully during the clinical procedure? Yeah, you know, historically, when you look at what we learned in Endo 101, which is that triangle of cleaning, shaping, and obturation, the cleaning, in my opinion, should really be divided into disinfection and the cleaning. And the cleaning really involves removal of the macro debris. During your chemo-mechanical instrumentation, you're cutting dentin, you have a lot of... bulk of tissue, of pulp tissue and shredded tissue, as well as dentin that we shave off during the instrumentation process, that should be cleaned out. That's macro debris. And that should be removed from the canal. Now, what you're left with at the very end, which would be your completely shaped and finished canal, that space should be fully now disinfected. And the problem is that by kind of... mixing these two things in one word we've kind of conflated the importance of each component and forgotten to use you know the different modalities that might be best in doing each And that's why I think cleaning is probably best done with some type of a kinetic energy in a solution. And that solution could be anything. It could be even water, because at that point, we really don't need to disinfect because we're just removing debris. And in fact, you could make the argument that water would be safer to do that. However, water does not have any antimicrobial component, which is, again, what we need. So then we need to replace that water with a disinfectant. So the way I look at it is if we can break it down into these two processes. And we know that using some type of a safe method of activating a solution to remove the macro debris while we're doing instrumentation, and then while later on then coming back and replacing whatever solution, if it's inert, with a disinfectant, then we would be able to kind of kill two birds with, well, not necessarily one stone, but we could do these two more effectively by using... applying the specific modality that would be best to maximize their goals of removing macro debris and then disinfecting the space. So what do you say to those dentists who are super focused on efficiency, and you can't blame them for that, that during their instrumentation, they incorporate irrigation, and as they move through their instrumentation process, they're constantly irrigating, and they're using sodium hypochlorite. So they're doing two things at once. They're cleaning. and they're disinfecting. So there's no real disinfecting process that's needed at the end of the instrumentation. What's your response to that? Yeah, so I mean, there are multiple ways of doing this. Obviously, nobody really has the answer as to what is the perfect way of doing it. You know, everybody is essentially creating a mental model of what's happening, and they're based on that trying to optimize what makes the most sense. For me, the idea of having the powered flushing with a safe... solution is better because you could say that, well, why don't you just use ultrasonics and have your ultrasonic push out hypochlorite? Well, that would be great, but it's possible that you could get a little bit more hypochlorite out that way through that kinetic energy. So that may, in some cases, end up being a little bit less safe. So a good compromise would be the use of a safe solution that could be something... that is not as cytotoxic externally, and activate that with your ultrasonic throughout the process. So you're removing all the macro debris. And then you can either do your full disinfection towards the end, or as I mentioned, you do your powered irrigation, your powered flushing with your ultrasonic that could be connected to either a water base or another solution that's coming out of there that is not quite as caustic as hypochlorite. And then you can easily... out the solution and quickly add hypochlorite or just add hypochlorite to whatever's in the canal and that will overwhelm the solution that's in the canal and that becomes hypochlorite. So that's a very quick way of doing it. It's not particularly cumbersome. It's just kind of understanding the ideas of how this cleaning with the use of some type of a powered ultrasonic device could actually expedite and make you a little bit more efficient in terms of removing the debris. And that debris is really important. The removal of that debris is very important because most people don't realize is that that debris is not just being removed for the sake of disinfection, although it's certainly a big part of it. But the remaining debris in the canal is also an impediment to proper instrumentation because it does end up clogging the space in front of the file. And sometimes by creating too much tissue or too much debris that can get ahead of the file tip, that's how the canal could momentarily get like... up and that file ends up cutting a little bit to the side and that's how you get a ledge. So, you know, making sure you manage that debris regularly and very aggressively throughout the process is an important part of getting a safe instrumentation as well as having a good disinfection and great optimal outcomes at the end. So it reduces your errors. And regarding the disinfectant solution, you're still a fan of sodium hypochlorite, I assume. Although it does become somewhat benign in the presence of dentinal chips, but it seems to have stood the test of time and most endodontists are still using a diluted form of sodium hypochlorite. So, I mean, sodium hypochlorite is still the gold standard, but that sodium hypochlorite can be combined with specific type of chelators. You can have combined chelating solutions that has chelators and hypochlorite at the same time. Hypochlorite does become inactive in contact with dental chips. So if you're not going to use simultaneous chelation with a combined irrigant, then you just have to irrigate more. you know, more frequently with your sodium chloride so that you can counter that effect of the buffering. Now, you know, sometimes you could add negative pressure to your sodium chloride, which means that, you know, you're... to run a much larger volume of hypochlorite in the canal by, you know, suctioning and irrigating simultaneously. And that could overcome this effect of fentanyl chips. But, you know, so there are multiple solutions. You could use combined irrigants for a little bit more simplicity and efficiency. But if you don't want to do that, then if you just want to use, you know, basic hypochlorite, then... You just need to kind of be aware of this problem of buffering and the fact that you need to kind of constantly replenish the hypochlorite in the canal. You know, I've heard of people say that, oh, I let the canal sit and soak in hypochlorite. That just doesn't happen because there's, you know, the surface of high chloride against dentin, you know, usually within a minute or two is turning into salt water. So that's not, you need to have a, you know, a plan to kind of replenish that. How important or how critical is using ultrasonic and sonic agitation in the process of cleaning the canal? Like some dentists just don't use that. They don't have it. They don't use it. Is that like going to affect their outcomes clinically? So, you know, like anything else, it's always the question of the edge, right? Can you have an edge? Because there's plenty of cases you don't need to have ultrasonics. And, you know, historically we've had great success rates without ultrasonics, without any of these, you know, devices and so on. But if you're having a case that is some kind of a biofilm that is very persistent, being able to add some energy, some form of kinetic energy to the molecules that are disinfecting will help break up that biofilm a little bit. better. Agitation, cavitation, acoustic streaming, that are the three main components of ultrasonics, have certainly been shown through research to aid in terms of, you know, not only facilitating, but expediting and then catalyzing the entire process of these irrigants, their chemistry, and so on. So how do we do this clinically? How do we impose this ultrasonic energy into the irrigation solution? Dr. Nasseh will be back momentarily to answer that question, but first... If you're looking to raise the bar with your adhesive dental procedures, you should definitely be looking into Bisco. Bisco is a great company that has an unparalleled track record. I can unequivocally say adhesion is their passion. They are genuinely dedicated to understanding and improving the ability to bond dental restorations. Bisco is a company that places tremendous value on research and scientific knowledge to benefit you and your practice. Being an endodontist myself, my favorite Bisco product is Theracal LC, which hands down is one of the best materials to use for direct and indirect pulp capping procedures. It not only seals the dentin, but offers significant calcium release, which stimulates hydroxyapatite and secondary bridge formation, which is exactly what we're looking for in these kind of procedures. So check out their entire product line of premium adhesive products at bisco.com. So historically, people have talked about the use of passive ultrasonic irrigation, which means that at the end of the procedure, when you're all done, you essentially fill the canal up with the hypochlorite. And then you put your ultrasonic tip in there and you agitate it for like about 20 to 30 seconds. That's kind of an end procedure. And, you know, the research on that is kind of mixed, but it does certainly help. It certainly doesn't. hurt for sure, because it will kind of expedite the chemistry of hypochlorite. But what I use it is what I call powered flushing, which is throughout the procedure between instrumentation, I use that ultrasonic with connected to my... closed kind of a water system, which is kind of distilled water that are iodine-treated lines. And that ends up acting in between files to kind of help remove the debris very quickly. And then I replace that with half chloride in the canal. And so that's just kind of – and that is called kind of interrupted ultrasonic irrigation, if you will. But I call it powered flushing because you're using the power of the kinetic energy and the water to – out the debris, and then you replace that with your actual disinfectant hypochlorite. So when you're applying this ultrasonic energy to the irrigation material through this tip that's sitting inside the solution, how far beyond the tip does the energy go as far as affecting the irrigation solution that's further down the canal? So it actually does go fairly far. The mistake that people make oftentimes is that, you know, scientists like to have very technical terminology for, well, the ultrasonic energy doesn't go that far beyond the tip. Well, it may be true that the ultrasonic energy per se may not go that far down from the tip of the ultrasonic. But when you look at the fluid flow and the... kind of the acoustic streaming and the other forms of eddy formation in these fluid movements, you see that there is movement. many, many millimeters around the curve past the tip of these instruments. Even though the tip is not down at the apex, there is fluid movement at the apex beyond that. It may not be quite having that ultrasonic cavitation going on at that point, but it certainly is constantly churning. It's just basically catalyzing the Brownian motion we've all learned in chemistry and in physics. And you're having a faster... motion of the molecules at that point. So it does certainly help improve flow. So the question, as it always is, the case is, you know, what is enough? And that's the thing that... It has to be established. I think ultrasonics have been shown to be fairly adequate for this type of stuff. Yeah, I mean, I know a dentist who works in a very rural area in New York, and the closest endodontist is, I think, 40, 50 miles away. So he taught himself as best he could to do molar root canal, and he actually bought an erbium-yag laser, and he found that that was the best investment he's ever made. Now, I'm not plugging any particular laser in that area. But he found that using the erbium YAG laser, which no other laser can produce that kind of turbulence where these bubbles collapse and open up and collapse again. And he found that using his CBCT, he can see these lateral canals clearing out where he never got that before. So like you said, what defines enough regarding end procedure? really is the crux of the issue, because certainly there are more and more powerful solutions out there. You could buy all kinds of machines, fairly expensive, spend 80 to 100 grand and, you know, have a lot of disposables that are going to cost you another 50 to 100 bucks per application. The question is, you know, I believe in Occam's razor, you know, if A is enough, B is not necessary. And there's no specific research that shows any of these. Granted, they're more powerful, but you can kill a fly with a fly swat or with a shotgun. The question here is what's enough? Yeah, there's no question about it. And when I practiced endo, which was a long time ago, I practiced for 14 years, our office had, and this is not boastful, it's just fact, we had a 98% success rate on our cases, 97% success rate, which is typical, I think, for an endo office. And we were using sodium hypochlorite. I had no idea that it was being deactivated. into a benign solution in the presence of dental chips. I wasn't aware of that at the time. But, you know, we instrumented the best we can, and we treated these patients using old-fashioned radiography. We didn't have any 3D cone beam, and we got very good results. So, of course, the operator and the diagnostic capabilities are very important as well. Last question as we wrap up this podcast, Dr. Nasseh, and really appreciate a lot of his input. Are the modern irrigation tools... are currently available to us adequate for successful endo? There's certainly, well, I mean, it depends what we mean by successful endo. And, you know, one thing is from a... success failure cities define what are we considering to be actually successful eradication of inflammation and histological success as opposed to radiographic success and there's a peripheral radiographs or cbct so there's a lot of different levels but for the most part if we're talking about retaining teeth and not having active disease and infection and pain in people there is no question that the modern endo and the tools that we have available are adequate in saving a great majority of cases. Is it 100%? Nothing is 100% because we're dealing with a situation that's anatomically difficult to manage. We're talking about different kinds of bacteria. You know, 100 different species of bacteria have been implicated in endodontic disease and the different mixture of these creates different kinds of biofilms that in different... different people with different immunological profiles could be more or less inflammatory and cause more bone loss in some people than others. So it's a very complex problem. It's a host immunological problem and microbial interaction in a very complex anatomy. So we can really not expect to have 100% success. But as long as the success rate is high enough that people can use their teeth, have function, aesthetics, and health going on at the same time, I think we have achieved our main goal. And it is certainly possible with endodontics. And the funny thing, Phil, as you mentioned yourself, is the success rate of endodontics has gone up maybe a few percentage points. But it used to be, if you look at the Washington study, and the Washington study is the endo study that is quoted, you used to be quoted all the time with 94% success rate of all endodontic cases. That was done in Washington University. And that study was done in 1953. People don't realize that. That study is that old. And if that's that old, which is the technology at that time, gave us good enough success rates, All of the technology we have today is helping us achieve maybe a little bit simpler and more efficient methodology. In terms of success, the things that create success still remain the same, and technology hasn't really helped change that. CBCTs have probably helped a little bit be able to see a little bit better so you can find more canals, which is certainly a big, important part of... Yeah, that's a great point. That's a great point about the past because of, you know, the late I.B. Bender, who was a very good friend of mine in our family, kind of the father of endodontics. What was amazing is I.B. bender and he started doing endo what in the 1940 50s something like that like you said he would say the goal is to remove the critical concentration of bacteria and that's what would lead to a successful case that kind of holds true today doesn't it it sure does i mean ivy bender and uh sam seltzer was his partner obviously these these guys two big giants in our field um really describe some of these basic principles that still stand true today. So, you know, sometimes we get lost in the bells and whistles and all the technology and the fact that, you know, everyone is trying to sell us something. Well, that's right. That's right. It's a business. It's a business. And the practitioner has to be careful of that. They don't need to buy every gadget that comes out, but they should, if you could increase your efficiency chair side, that's worth looking at. If you follow the principles of endodontics and you just understand what you're doing, you're kind of set on a path to success. We'll get into another podcast in the future about surgery. That's a whole other topic, and we'll talk about that. But I think you covered this very, very well. Thank you very much, Dr. Nasseh, for your time. Really appreciate it. 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.