Cognitive Dissonance Discussion and Case Reports

Are you blessed with great ideas? In the show opener, Ruddle and Lisette explore the notion that creative thinking is not simply lucky, but rather the result of specific strategies and optimal conditions. Next, cognitive dissonance in endodontics today is discussed, specifically in terms of Seltzer & Bender’s landmark article from 1965. After, Ruddle follows up with a few novel case reports that seem to provoke cognitive dissonance. Finally, stay tuned for the close, “Endodontic Concepts,” in which Ruddle talks about the importance of deep shape.


Show Content & Timecodes

00:09 - INTRO: Creative Thinking
07:49 - SEGMENT 1: Fresh Perspective – Cognitive Dissonance
28:03 - SEGMENT 2: Case Reports – 3 Novel Case Reports plus 1 for Fun
39:35 - CLOSE: Endodontic Concepts – Deep Shape

Extra content referenced within show:

  • New Ideas – Strategies and Techniques Inspiring Innovation Through Creative Thinking, Mind Tools, 10 July 2021 (Accessed),
  • Seltzer S, Bender IB: Cognitive Dissonance in Endodontics, Oral Surg Oral Med Oral Pathol 20(4), pp. 505-516, October 1965
  • Ingle J: Endodontics (1st Edition), Philadelphia: Lea & Febiger Publishing, 1969
  • Siqueira JF, Antunes HS, et al: Microbiome in the Apical Root Canal System of Teeth with Post-Treatment Apical Periodontitis, PLOS One, 30 September 2016,
  • Gutmann JL: Commentary: Cognitive Dissonance in Endodontics: Perspectives and Comments, J Endod 29:11, p. 713, November 2003
  • AAE Discussion Open Forum:
  • Hess W: The Anatomy of Root-Canals of the Teeth of the Permanent Dentition. London: John Bale, Sons & Danielson, LTD, 1925

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    INTRO: Creative Thinking


    Welcome to The Ruddle Show. I’m Lisette and this is my dad, Cliff Ruddle. How are you doing today?


    I’ve done better. [laughing]


    Okay, we’re going to start off today talking about creativity. Because it’s a very desirable quality and most successful people are creative. So it can help with problem solving. It can open your mind and give you a fresh perspective on the world. It can build confidence and it can be motivating and inspiring. And it also encourages self-expression. So you might be thinking, well I’m not a creative person. But really, anybody can be creative; you just need to work at it. And we found this article online that identifies three strategies to boost creativity, but then also gives the conditions to optimize creativity. So we’re going to talk about that briefly, but let’s look at the first list. And these are three strategies to generate new ideas, and the first is breaking old thinking patterns. What does that mean?


    Well, if you want to break old thinking patterns, maybe change your paradigm. A paradigm is a believe system; it’s a collection of assumptions. And a lot of times, we get locked into what I like to say is “stinking thinking.” And so then the years go by and we’re living in that world. So change your paradigm. And how you might do that is you might challenge yourself. I like to always say in a lecture, whenever you hear something, ask yourself, is it true? I mean that should be an ongoing internal conversation; question the assumption. Because it’s easy to fall into yeah, it must be true, we’re all doing it. So maybe change your paradigm a little bit by changing your thinking and your assumptions.

    Reframe a problem. Sometimes when you reframe something, there’s more clarity. In other words, I never get lateral canals on postoperative films. Change it to I will get lateral canals on postoperative films. And then go to those people that are doing it, learn from them, and find out what’s making them creative and what they’re doing and you’ll probably find your way forward.

    Now you can think in reverse. I’ve said for years, that could be like start with the end in mind. So instead of thinking what’s next, what’s next, what’s next, why don’t you just skip all that and go out and say what is the thing I really desire? And then look back where you are and then you’ll have it maybe mapped out for yourself.

    And then find creative outlets; get out there; move, you know? Enjoy life, get your heart rate up, exercise, lose a little bit of weight, hang out with people that inspire you, a sunrise, a sunset. All these things when we disengage and get out of our regular work, they serve to inspire us.


    Yeah, and help you think in different ways.


    Maybe the light bulb will go on for somebody.


    The second thing is make new connections. And the article suggests that you pick maybe a word, a photo, even an object that somehow doesn’t really seem to connect to your problem, but maybe try to find a new way it can connect. And Isaac and I do this a lot when we kind of design the graphics. Like, I’ll Google a word, and then I’ll click images, and then I’ll see a lot of different things pop up. But one idea starts leading to another, and then before we know it, we come up with something totally unexpected. So that is kind of a good strategy, because a lot of times, you can see something and it will direct you to a different – like the way you connect the dots it will lead you to something totally new and unexpected.


    I never actually asked you how you got some of these ideas for the artwork and graphics that appear on almost 50 shows now. And when I heard this part of the script come out and I realized that’s how you do it, I thought wow, that gave me some ideas. Okay, so thank you.


    And the third thing is getting fresh perspectives.


    Well the best way I got a fresh perspective was to get out of my way. In other words, look at people that you admire, you respect, whether it’s somebody that can do really good times on their bicycle or whether they’re doing world-class endodontics, or whether they’re just always inspired, happy, creative people. They’re always – every time you meet them you feel like wow; I feel better about myself. Well those are people to interact with. People like people like themselves, so don’t be afraid to leave your group to get inspiration outside the group.

    Another thing is model success; success leaves clues. So look at those people that you admire or that are doing something, and chances are if you do what they’re doing, you’ll be able to do it too. And then finally I think to get inspired and to get more juice, read. There are so many books out there; people that have overcome things, did things, did things by accident, did things on purpose. It’s kind of like that culture thing we did, intentional versus default. So you can be in charge if you choose to be.


    Okay. Well let’s look at the list; we have one more list, and these are the best conditions to optimize creativity. And the first is believe in yourself. Really, you just need to have faith that if you keep working at it, the ideas are going to come.


    Well, I already said find some down time. But that means it might be really vigorous. You might be doing downhill skiing, but do something outside of the context of who you think you are; in other words, professionally. And when you’re out there in nature and you see a sunset or a sunrise, you’re going to just flood your soul with joy and happiness, and then your mind will begin to open up.


    For me personally, sleep is very important as well. Okay, so #3, vary your environment. We’ve talked about that; a change of scenery can do wonders.


    Conquer distractions. I got a new iPad; my other one blew up. And so I didn’t have it all set up yet, and I was working yesterday and it was dinging every 30 seconds on incoming news from the Olympics and so on and so forth. And finally I had to throw it off the balcony, because it was just too many distractions and I had to focus.


    Okay. And I won’t ask you to clarify what you meant by “your iPad blew up;” we’ll just move on. The last thing is just to have fun, and I think that’s pretty much self-explanatory.


    Well, certainly strategies to find creativity are very useful. And I think that hopefully this will give you some ideas, just to shake it up a little bit. You just have to do little things differently, just a little bit different. And you’ll find your north star, you’ll find the road map, you’ll find the flight plan, the trajectory towards success. So take it.


    Okay. Well we think we have a great show for you today, and hopefully you’ll agree. But let’s get on with it.

    SEGMENT 1: Fresh Perspective – Cognitive Dissonance


    So we first spoke of cognitive dissonance on our AAE special last season, and we spoke of it in terms of it being one of the AAE’s educational tracks, officially called Cognitive Dissonance, the Seltzer and Bender Memorial Track. So the foundation for this track is the landmark article by Sam Seltzer and I.B. Bender, published in 1965 in OOO. And the idea in the article is that as scientific evidence has accumulated, greater and greater dissonance has emerged regarding both the theory and the practice of endodontics. So we’re going to spend some time discussing this today. But first, let’s just review the definition for cognitive dissonance.


    That’d be good.


    It is that – well Seltzer and Bender define it as the existence of views, attitudes or beliefs which are inconsistent or incompatible with one another, but nonetheless, are held simultaneously by the same person. So I wanted to start by asking you why there are so many differing views and beliefs in endodontics. Because science has made enormous strides in the last 56 years. With the great abundance of scientific evidence basically at our fingertips, it would seem that a lot of this dissonance would resolve itself.


    Well, we have a lot of differences in our views and our beliefs because we all carry different memories and experiences. So we all – a lot of us were trained by vastly different people from all over the world. So it reminds me of that old expression “who you are is where you were, when.” So we’re all products of our past and what we learned, and we have a lot of – to your point – incredible, scientific literature on what I would call the biological aspects of endodontics. But we have no consensus in the clinical literature, in peer review clinical literature, on the very things we do clinically that should hopefully guide each case to a successful conclusion.

    For example – are you ready? It’s a long list. Okay, we don’t have any agreement on the best diagnostic schemes. Some people do hot tests, some people do colt tests, cavity tests, electric pulp tests; we’re all over the place on diagnostics. We’re all over the place on the size of the access cavity. Is in a ninja, is it an orifice directed, or is it a traditional access? Or is it something in between, balancing all those factors? We have no agreement. We can read articles that support each one of them.

    After you get your access done, there’s the orifice but we have no agreement on glide path management. Is it manual? Could it be mechanical? Could it be NiTi, is it stainless steel? Do we sequence the prep a little different? Some people pre-enlarge; other people try to get to length immediately. We have no agreement on any of this stuff. We don’t have any agreement on working length, patency. We don’t have any agreement on the shaping. We don’t have any agreement on what is the terminal diameter. We don’t understand and agree on great dissonance on apical 1/3 taper. The capture zone; I’m going to talk about it later, okay, so we don’t have any agreement on that. And of course we have roaring debates on irrigation. Coarse irrigation is what actually cleans the root canal system, but we have no agreement on the concentration of the reagents, or even the reagents themselves, their strength, their temperature, their concentrations, the volume, the frequency. We have no agreement on any of this. Are you starting to wonder why we have dissonance?

    So then we get the irrigation out of the way, and of course we all agree on obturation. Not really. We have a variety of different purported ways. Then it you throw in the sealers on top of that; we jump from Resilon to the bio ceramics to the Grossman type sealers, and we’re all over the place, and each literature that comes brings hope, eternal hope that the light will come on and we’ll finally be successful for ever and ever into perpetuity.

    And then of course when we have it all filled and we look at our post-op filling, the lesion is not responding and now we’re talking about post-treatment disease, do we have universal agreement on the next approach? Would it be retreatment, non-surgical; would it be a surgical approach? Would we extract the tooth and do an implant, or would it just be a bridge if possible? So you can begin to see there are vast differences from school to school, from country to country, and obviously then, from trained doctor to trained doctor, and so it’s no wonder we have a lot of disagreements.


    Yeah. You just basically enumerated a lot of differences.


    Yeah, I’m just exhausted right now.


    Well back to the Seltzer and Bender article. They talk about the endodontic triad – shaping, cleaning and obturation – which they refer to as A, B and C. And the idea is that if a clinician adequately performs these three procedures, treatment should be successful. So the dissonance comes in when a clinician believes that they have thoroughly performed these procedures and done everything right, yet treatment fails. Or alternatively, when clearly one of those three, A, B, or C, is clearly deficient, but then treatment seems mysteriously successful. So what do you think about this?


    It’s a conundrum. And in fact, for a lot of people, it’s a mystery wrapped in an enigma.

    You know, actually, I think it’s not that mysterious for me. And I mean that with complete humility. But I spent probably about three to three and a half decades of my life, pretty much 90% of my practice was redoing other people’s root canals. So I want to just jump right ahead to Schilder’s remark that we took as – I went to Harvard, he was at BU – but I was a student of his because my mentor was his second student, Al Krakow. But he talked about 100% minus X. Nobody in the literature ever talks about X. X is Cliff, okay? So we always try to find – well maybe it was a fractured tooth. Maybe the patient’s medical history is somehow diminished and they’re compromised. Look, I’ve done treatment on people with terminal cancer and the bone is filling in before they die. So I think it is 100% minus X, and I think what I’d like to say is we can always find some fluke case that worked that shouldn’t have, and we can always find failures, and we can scratch our head.

    But that kind of reminds me – well it reminds me of a lot of things, but it reminds me of specifically why we’re blaming it on things when maybe it’s our lack of training. Most dentists think they’re very competent. I mean I had over 1000 dentists come to Santa Barbara and train. Most people came and they were the best of the best, and most of them came kind of from “I know, but I’d like to see what Cliff’s doing.” And it was easy to begin to see how people think, their thinking patterns, how they approach their work, and their rationale for treatment. So we don’t know if they’re using the best and most relevant technologies; we don’t know their belief systems. Like I said, who you are is where you were when. We don’t know how they approach their work. We’ll see this in some cases I’m going to show, but we’re all over the place. And usually it’s anatomically related. Isn’t it amazing when we extract the tooth, the bone fills in? Extractions are 100% successful. So the endodontic procedure should parallel the extraction, because what the extraction does and what endodontics should do is it should serve to remove the pulp each time, every time, all the time, 100%.


    Okay. Well I heard two things you said here, and one is you kind of made these mysterious failures or successes that seem like they shouldn’t have happened. Maybe more outliers than the norm. And so they do say in the article over and over again that more research is needed to figure out what is exactly happening and what are these mysterious variables that are swaying treatment towards success or failure?

    But then I also heard you say that extraction is 100% successful. And so that brings me to today, 50 years from the article. And I think – correct me if I’m wrong – but I think there is general consensus pretty much at this point, that cases fail because of a failure to reduce the bacterial load enough.


    Absolutely. You know, Ingle was very good in his classic textbook, Ingle Endodontics. He talked about causes of failure: short fills, blocks, ledges, transportations, broken instruments, perforations, and he goes on and on and on. What all those have in summation is they have residual remaining bacteria. Even the fractured tooth that causes some of us to go more than crazy, it’s because there’s microbes. So you can say the sum of all failures is microbial; it’s micro-organisms. So that’s why the extraction is so successful.

    But if you look back at the old literature back in the days when they did their paper; in fact, I’ll have to make a confession to the audience. I was the last class at Harvard School of Dental Medicine, graduate school of endodontics, to do culturing. And we threw it out for my first year and my second year because it was so stupid. I mean we used to take paper points right out of a sterile packet, and forget going to the patient and going into the root; we went directly into the test tube, capped it, sent if off to histology, and it would come back positive. And so my mentor finally said, “do we expect the bacteria to jump out of the dental tubule and land on the paper point?” So this stuff never happened, and it was crude. It was a good idea; I mean it’s always good to measure and know what you’re doing. But we had very – it was very difficult to get negative cultures and we thought there were a few bacteria. A few means we thought there might be less than 10 species. Now today we have hundreds of species. You know, we talk about my friend Siqueira, [Jose], and he does wonderful research. I just was looking at a paper this morning that there are 536 species of bacteria. So things have become more sophisticated; our ways of measuring have become more sophisticated.

    Anyway, we had crude testing, our methods were crude. I guess it kind of reminds me of some of these mysterious failures. I have always liked to say this. If you’re in North America, and if you hear the sound of hoof beats, it’s a horse. It’s not a zebra! And dentists love to talk about the zebra; the one case in five years that wouldn’t fail, it’s a conundrum. Oh, it’s a mystery why they lose that tooth! Why don’t you take the tooth and do a post mortem? Why don’t you serially section the root? And most of these mysteries are resolved with education.


    Okay, well it sounds like as far as culturing goes, that a negative culture back in 1965 might not be negative today.


    Oh absolutely.


    But what we’re talking about now is actually what makes Randy Cross’ new disinfection technology that we showed on our show a few shows ago, so exciting. Because he’s identified a biomarker to look for, that when found and then when reduced, really seems to sway treatment towards success. I mean I guess there’s more research needed to determine like how much bacterial reduction is enough. But anyway, back to endo -


    But that’s a good point. You’re talking about the very essence of it. But look. We don’t get everything out every time. None of us do. Even your heroes that walked before you never got everything out. So it is a question of what can the body handle, and that’s where we’re moving to more of biomedical solutions for these vexing, long-term problems of like the biomarkers. This is just a huge jump up in terms of efficacy and giving us more confidence.


    Okay. So back to cognitive dissonance today. I have actually heard you in recent years dismiss certain clinician authors who seem to be promoting a treatment concept that maybe is a little more mysterious and unscientific, but maybe based on a new disease model that maybe takes cognitive dissonance to even a new level that maybe it isn’t even helpful to clinicians. And I know that some of these authors have suggested maybe even leaving some bacteria behind.


    Well there’s many people out there, and when I say “many” it’s a few. In fact it’s actually just about less than ten people on the planet. And we all have differences of opinion, but some people like to take the difference of opinion and create a whole new narrative. And I think because – I hate to say it – but maybe because of trying to be relevant or trying to be important, or maybe trying to lead the charge to a new -


    Trying to be clever.


    Maybe cleverness – to try to define a new kind of endodontics. Recently on the endodontic discussion forum, a colleague whose name will remain anonymous, he said that out of a trifecta – some kind of shaping, some kind of cleaning and some kind of filling – he said yeah, we’re still doing the disinfection. I’ve got my GentleWave and I’m doing that single cone, cold gutta percha with seas and lakes of cement around it. But we’re decoupling the shaping and it's now been removed from the trifecta. But then you look at his post-op films and you see that there’s been some instrumentation. But I’ll argue that most instrument canals are neither cleaned nor shaved.

    So we always want to argue and try to get a new future going, and look over here; my way, I’ve discovered the truth. You know the truth is like the extraction; get it all out. I don’t care how you do it, and GentleWave is a great cleaning machine – and I’m not going to go into that today. But it didn’t decouple anything. You still have to catheterize the canal. Do you think you can get GentleWave to do all this dynamics through a mineralized block of dentin? Hello! You’re going to still grab a file, you’re still going to catheterize the canal, and you’ll find that you’re going to have way more success.


    Well I was thinking about cognitive dissonance the other night, and I was kind of reflecting on how it pretty much permeates every aspect of our lives. And the yin/yang symbol popped into my head, and I was thinking like well, two opposing concepts united in a circle, a part of each included in the other. So cognitive – like conflicting beliefs are with us all the time. And really the cognitive dissonance arises when an individual has a problem resolving the conflict. So maybe you need a change of perspective. And the yin/yang symbol is a good example of that, because it represents the opposing beliefs, but in a delicate and fluid balance. And so I’m thinking maybe the key word here is “balance.”


    Well you know with cognitive dissonance we’re going to always have differing opinions about things. And even internally, Cliff can be conflicted. Do this, do that? I’ve always said maturity is when you can hold two conflicting ideas in your head simultaneously. It’s okay to have conflicts. Conflicts are like a muscle; you get stronger. And if you’re curious, if you’re willing to be wrong, if you’re willing to stay humble, live in the question. It’s okay; that’s science. Live in the question; questions are the answers.


    Yeah. Sometimes it seems like the cognitive dissonance trend in all its cleverness is kind of almost taking away from actually the desire to learn and to think that you just don’t know everything and you want to keep – I don’t know how to say this. It’s like it encourages more research and learning, and just saying like well, I don’t know why this failed or why this succeeded. It’s beyond me; it’s too mysterious; it’s cognitive dissonance. Maybe just like what the author is saying in the article over and over again; more research is needed. You need to just keep learning.


    Forever learning; forever learning. You know, I heard somebody refer to – I just read this two days ago – somebody referred to the cognitive dissonance as a crisis. And I remembered in the Chinese language, crisis has two characters; one is danger and one is opportunity. You’ve explained perfectly the opportunity. It’s before enlightenment, chop wood and carry water; after enlightenment, chop wood and carry water. Do more research, live in the question, be curious. And a lot of these things come to us, and technology now is improvement. But improvement through the technology is not going to solve everything, because we’ll have a whole new set of challenges and disagreements, dissonance. That’s normal.


    Okay. Well when I.B. Bender died in 2003, the JOE republished this cognitive dissonance article as a tribute. And in that issue, Dr. James Gutmann wrote a commentary suggesting that this article is basically a call to arms for evidence-based endodontics. And he goes on to say something very interesting, and I’m just going to read it because I think it kind of sums it up.


    You should read it, because it was a – James Gutmann is a friend of mine, we’ve traveled around the world together, and it’s very lucid. Please.


    He says: “Yet for so many years, endodontics and endodontists have been entangled in the web of anecdotal minutia, empirical diatribes and personal preferences. Without letting cognitive dissonance taint our thinking, what can we agree upon regarding success in endodontics? Rather than focusing on accessory canals and pus, patency or no patency, one type of instrument versus another, the density of the root canal fills, or the use of single versus multiple visit treatment, I believe that this article challenges us today as it did in 1965 to be diligent, to search for answers, to be honest in our assessments as professionals, and to realize that we cannot achieve perfection as defined by 100% success.”


    Thank you, James. I still will come back, James, and challenge you a little bit. It’s nice to keep doing the research, but some of us – James, you did too – made your living in the operatory, serving patients; trying to make sick people well. So my analogy for all this is, in baseball it’s not the bat, it’s the batter. Football: around the world it’s called football, in North America it’s called soccer. It’s not the ball, it’s the foot. And for all of you out there, it’s not the technology, it’s the clinician, stupid. Come on! We’ve got to train up and get better, live in the question, be humble and know we don’t know what we don’t know.


    Okay. Well great. Thank you. That’s very informative information you gave.


    Hope it helps.

    SEGMENT 2: Case Reports – 3 Novel Case Reports plus 1 for Fun


    Well obviously we’re talking about cognitive dissonance. So there’s something that I want to repeat and go back to that we’ve brought up on several shows before, and that’s the Little Green Book. And that little green book was written a lot of years ago, almost 100 years ago, and let’s look at it because it’ll remove some of our dissonance if we let our minds open. You know, there’s an old expression in life that a kite that flies is like a mind, or a mind is like a kite, and it works best when it’s open. So let’s look and see some of the things that might open our minds to greater possibility.

    And that’s Walter Hess, and I won’t go through how he cleared these teeth, 10,000 of them, but here’s just six images showing three maxillary molars and three mandibular molars; and you can see the offshoots, the cul-de-sacs, the anastomoses, the multiple portals of exit. Whoops, okay, it’s all there. And sometimes when you’re scratching your head and you’re wondering why a case won’t work, maybe revisit Hess’ work. So let’s take these ideas and let’s look at just three cases. There’s a kiss-off case at the end, but that’s for fun. So three cases, all treated by endodontists and all failing.

    Well, this is the first case. The endodontist did a pretty good job. You can see endodontics was done on the lingual branch; you can see there was gutta percha in the lingual buccal. About five years after treatment, the patient developed swelling; there were palpation problems in the fornix of the vestibule was what I was told. And so there was a surgical procedure, and the same endodontist then went from clean/shape/pack and that procedural effort, to microsurgery; used a microscope. So this is my pre-op film, and this is about 10 years after the original treatment of the clean, shape and pack.

    What are you going to do? Where’s your cognitive mind? What are you thinking? There’s a lot of different ways you could approach this case. For me, it was very simple. There’s been a lot of work done on this tooth, and if I’m going to get in there and get my name involved, I should probably just pretend we’re going to start from ground zero. So my job is to eliminate the clinical crown. I’m going to take the post out; I’m going to take gutta percha out. I’m going to pack and see what happens against that old retro. And I can tell you right in advance, the retro wasn’t really sealing the end of the root. So here we go.

    So after I took the crown off and down packed, you can see in this buccal branch there is a massive rope of GP. And if you look in the photograph, down in that buccal canal, you can see evidence of that rope in the lateral wall. So I used some solvent to clean this up for photography, and now you can see perfectly a rope of GP going out. And after I packed, of course, I blew out a lot of sealer. And so then we lifted the flap and cleaned up the retrograde, and went ahead and there is a five-year recall.

    So let’s look at where we started. We started like this, and you see a lot of these kinds of cases; you see them every single day that come into your office. And it’s easy to look at them and say well, that should have worked. Well maybe it’s a mysterious failure. Oh, it’s a conundrum. Maybe it’s leaking, okay; so maybe there’s residual microbial activity. We talked about what is the maybe basement level of load of bacteria that can be left behind and still entertain success on a predictable basis. That we don’t know yet. But just going back and doing the procedures, doing them very methodical, doing them with purpose, you can push cases towards success. So there we are on the long-term recall.

    Another case. This was done by an endodontist. You know, we’ve been fighting for decades about let’s catheterize the canal; let’s be patent; let’s use those small size, flexible files to go to and minutely through the foramen to clear the debris out. Past the root we have an immune system. Our job is to remove the contents of the root canal space. So you can look at this film. If there was no massive lesion here with some sinus component, you might just say, well that’s perfect. It’s within the standard of care. It’s 1 mm short. I have made a living out of retreating cases that were 1 mm short, because sometimes in the apical 1/3, there can be multiple portals of exit. So you might think you’re 1mm short, but you might be missing 3,4,5 mm of actual system.

    Well, you might ask, the next conundrum is do we go through the crown and retreat it? After talking to the patient and after talking to their general dentist, get the multi-disciplinary team involved, you can begin to see there were various considerations. And we decided because of the size of the lesion, just going nucleated, so that would be done through flap procedures. So that’s what we did.

    But first, look in the throat. Depress the tongue and you’ll see. Some of these things cause sinus problems and it shows up as discharge; purulence in the oral pharynx. So right along, we flap the case; you can see it’s a massive lesion. Got a nice flap going, sealing off the little collar of crestal bone. And then we have a beveled root and we have the repair material, and then, here we are. And you can see there’s already a lot of healing. This is about one year, okay? So you can see that endodontics is a regenerating procedure, and when we clean out the disease and get the disease at the end of the root, it’s that 1 mm slice and section, you can even drop those in your biopsy bottle and you’ll learn something more about what you’re doing. We’re so quick to want to drop the lesion into the biopsy bottle. Why don’t you just bevel the end of the root and drop that, along with the specimen, into the bottle and have histology tell you what they notice?

    And of course, if we just keep following this on out, you can see then this was one year, this is five years. And you can see the inevitability of the bone to repair itself and regenerate after careful endodontics, and after corking the endodontic root canal system. Of course I might have wanted to redo and retrieve. If you know Ruddle at all, I always worry; well how many portals of exit were missed? How many did we miss over here? But at some point, you have a good conversation, you write it down in your record keeping, and everybody gets on the same page and then it’s one for all and all for one.

    Let’s look at the third and last case. Now I’ve never shown this case ever, anywhere in the world, because it would probably occupy a whole moray of discussion. I can imagine around a conference table of endodontists and specialists, or residents, graduate students, or well-trained general dentists that care. We might have a huge morning session on this, because we used to do this when I was a kid at Harvard back in the mid-70s. And then finally my mentor would go last, and he’d say here’s what I think we should do, based on experience and knowledge.

    Well, when you see a lone canine, that’s a peer abutment, the lateral incisor is missing so you’re looking at a central incisor. You’re looking at two central incisors, the lateral is gone, this is a peer abutment, and the bicuspids are gone, and it goes back to the first and second molar. So it’s a long splint and this is the peer abutment. You should also know the patient is an 87-year-old patient. They’re not – they’ve sat in the chair a lot. You can certainly see by one film alone that this person cares a lot about their mouth; they’ve made a considerable effort, a lot of time and a lot of expense to try to preserve their mastication. So after weighing all this, I actually sat down with the prosthodontist and I said do you happen to have a model? And he said well don’t make a lingual access, Cliff, because there’s almost nothing there. And he got the model out and he showed me the stone dye, and I could see I’d probably break the abutment free. So then it was crazy to think about surgery, but that’s about – what other options do I have? Retreatment non-surgically. I could do a surgical approach. I could cut the root out from underneath, but there’s no anchor there and we’d probably pop the splint loose. So the idea was surgery. So let’s take a look at surgery.

    This is when you want to go in a little bit deeper than normal. You want like a zero-degree bevel, because you want to maximize root. We only have a little bond of root that’s submerged in the bone. You can see a little halo here of soft tissue. So soft tissue, but still that is critical. This is post-surgery and this is one year later. This is one year later. The patient was almost 90 now. And we’re keeping that splint in there. So isn’t that the whole idea? Slow disease down from a gallop to a trot.

    All right. So you can see in these three cases, each one was failing for a specific reason, and in every instance, it was anatomically related. I know a lot of you are going to say it’s not that simple, Cliff; you discounted the fractured teeth. Go ahead, discount the fractured teeth. That’s kind of another whole anomaly; that’s another whole thing in and of itself. But if you discount fractured teeth in medically compromised people, it is – endodontics is 100% minus X, and X is Cliff.

    Well, the last case is for fun. We can debate this all day long; do you do non-surgery, do you do retreatment, do you – what else can you do? You can think of all these things. Get out your CVCT, get the axial slice, coronal, sagittal, all this technology. But at the end of the day when we eliminate the tooth, notice how the bone heals. Notice how the bone comes up to the crest, and it’s inevitable; the extraction eliminates 100% of the root canal system. This was done by three different endodontists. The first one did clean/shape/pack. The second one retreated. Third one did surgery. Nobody could seem to get the result. And finally after all the discussions – because you can see how strategic it is. This is a bridge going anterior, this is a single unit, this is the lone ranger. But that was what we did, so extraction still worked.

    So in closing, my remarks about cognitive dissonance is don’t let your dissonance interfere with your cognitive development. How about that?

    CLOSE: Endodontic Concepts – Deep Shape


    Let’s wrap up Show 49. We have a new close today called Endodontic Concepts, and we’re going to focus on deep shape. So let’s get started.

    Well, you can see we’re going to focus right in here on deep shape. But deep shape is going to influence everything. So as long as I’ve got this slide up – I’m not talking about the trifecta – but how you prepare your canal. And I don’t care; small shapes, little shapes, big shapes, too big shapes, small shapes. Anyway, shaping does influence 3-D cleaning and filling root canal systems. So let’s look at the deep shape.

    You know, I’ll take you back several years. Actually, I’ll take you back several decades. Because this is how I was trained and this is what we did for all those early decades of my practice, is we wanted to fulfill the Shildarian principles of repairing canals. And of course we wanted a funnel shaped preparation, where every cross-sectional diameter got smaller and smaller, with its smallest terminal diameter at the terminus of the canal. Now we have resistance form. Okay.

    So how we did this clinically is a we would a lot of times, settle for like a 20 or a 25 at length. It depended on the case; it wasn’t a cookie cutter idea at all. But if a 20 was snugging in a length, if we could take our finger and tap, tap, tap, and the 20 file couldn’t be displaced through the terminus, it didn’t mean it was circumferentially touching dentin. It might have been two-wall dentin. But then we needed to see the 25 come in. And the 25 might be 1 or 2 mm back, and we’d work it a little bit until it got within about ½ mm. And we’d work the 30 and the 35 and the 40; and we might go through a series of files, where clinically it would look like this. Now I would say to my assistant, show me the shape. And she’d take her sponge and hold it so I could see it, and I would work those files, going through, recapitulating, going through again, until I had boom, boom, boom; just like a man going up a ladder. Okay? Every sequentially larger instrument, uniformly backed out of the canal. So we could actually see this clinically and have a visual in our mind of how deep shape looked.

    Well, they weren’t all 20s were they? So what if you had a younger patient, a bigger system? What if you had maybe some resorption? What if you had a little bit of reverse apical architecture? You’d have to flush those cylinders out if you will, and you might say 35. And then I would ask a question. Is it a 35 at length? Tap, tap, tap. Can’t displace it. Then you’re living in a question. I think it’s a 35. It’s only a 35 at length if and only if a 40 is a half stop back. And the 45 is another half, and so on and so forth up to a 60. Then I could imagine that I was forming some kind of a very nice, deep shape that would give me resistance form.

    Well sometimes they were even bigger than that weren’t they? Especially when you live in the world of retreatment where there’s rips and tears and iatrogenic problems. And so at some point you have to ask the question, well can we just play this game infinitely? No, because you have to be thinking about wall thickness. How much wall do you have left? And are you going to make a preparation that begins to weaken the root? And are the files going to be too stiff, and are you going to end up maybe coming over in here and then you get the big rip and tear, and we talked about transportation or we certainly will. So all this combined together was how we did it, until we got NiTi, and specifically, none of this was possible until we got ProTaper. Because ProTaper built the same kind of shapes that you could see here. And basically, if you think about it, from the 20 to the 30, the difference was 1/10 of a mm – this is .2, this is .3 – and it would be 1 mm. So every even-numbered file, 20, 30, 40, 50, was increasing by 1/10 of a mm for every 1 mm. And if you do the math, that’s 10%. So the aspiration was to get something close to 10% in the apical third. With ProTaper we did that. And we had for smaller diameter roots, thinner roots, longer roots, 7%. A lot of times we ended up with 8% because with new cleaning ideas that we didn’t have back in that era we could perfectly clean, perfectly clean a 25.08. So all this grew up, and all this tedium in using nine different instruments and multiple recapitulations and back through the series again until you had the boom, boom, boom, boom, boom. Okay.

    So what we have to do then is think about how can we go to the modern era? In the modern era the idea was in the ProTaper family of instruments, the deep shape was the major concept. It was the first cutting file, the first file to have progressive decreasing and increasing tapers. The finishers have decreasing percentage tapers. So this was the first idea in the world where you could improve; you could increase your terminal diameter and you could increase your apical 1/3 taper without needlessly continuing to prepare the body of the canal. Nobody has done that before or since. Even EdgeEndo, which says everything replaces ProTaper; their biggest percentage taper is 6%; it’s in their own DFUs. So when they say this replaces that, in their imagination, in their dissonance, that’s what it does.

    Shapers did the body; finishers did the apical third. And so we have three files, an F1, yellow band, 20.07, 25.08, and a 30.09. Those three files in the modern era would be creating the shapes that we saw 9 hand instruments, stainless steel files do; 9, now we can replace with 1 or 2. So that was really good.

    Now what about this deep shape, and we’ve been talking – I’ve been talking about it for about 40-some years and now I hear lots of people talking about it. I guess they like the words, but do they live and walk the talk? What this does for us is many, many things.

    First of all, I want to come back to some famous papers. They mention that you can’t even begin to talk about – this was in the most recent International Endodontic Journal. It was a great paper; you can read it on your own. I’m not going to even give it to you, but it’s there. And it talks about you can’t even really begin to have conversations about cleaning in three dimensions and into the tubules until you get to about 25.06. It’s interesting to note that this instrument right here, the 25.08, creates 19% more volume as compared to the instrument they said was a minimal starting point. So if you have more volume of agents, then let’s start ticking off all the advantages.

    Bam! If you have more volume, you’re going to have more fluid to exchange. If you have deep shape, that deep shape is going to contain and limit your irrigation, so it isn’t getting pushed out needlessly causing an accident. You know, everybody thinks of capture zone. They think this capture zone is for filling. It’s for refining and containing the reagents themselves.

    What else? Boom! We are going to obturate, and hopefully we’re going to use some kind of a warm obturation idea. We want to compress that rubber, we want to press it right up against those walls, wall to wall, and the sealer microfilm should be measured on the order of 6, 7, 8, 9 microns. I show that in my Master’s thesis. I showed that almost 50 years ago. So if you look at the cases that can be done, it’s amazing. All these cases have deep shape.

    When you get deep shape, you’re not going to have so much post-operative problems because you’re not pushing things out. A lot of this minimal instrumentation, this minimally invasive endodontics that’s taken the world by charge; I think it’s a noble idea and I keep saying that; but you still need to fulfill your objectives for preparing canals. And if you do that, you’ll not only irrigate better and safely and have happy patients, but you’ll be able to fill root canal systems, just like you see in all these examples.

    So, I want to say thank you to the team. Pierre and John, we did ProTaper and launched it in 2001. And I want to tell you; we have something coming called Ultimate and it’s going to be a big game changer. It’s not linear progression; it’s going to be exponential.

    May you enjoy your shape!



    The content presented in this show is made available in an effort to share opinions and information. Note the opinions expressed by Dr. Cliff Ruddle are his opinions only and are based on over 40 years of endodontic practice and product development, direct personal observation, fellow colleague reports, and/or information gathered from online sources. Any opinions expressed by the hosts and/or guests reflect their opinions and are not necessarily the views of The Ruddle Show. While we have taken every precaution to ensure that the content of this material is both current and accurate, errors can occur. The Ruddle Show, Advanced Endodontics, and its hosts/guests assume no responsibility or liability for any errors or omissions. Any reproduction of show content is strictly forbidden.

    DISCLOSURE: Please note that Dr. Ruddle has received royalties on and/or continues to receive royalties on those products he has designed and developed. A complete listing of those products may be found at

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