Artificial Intelligence & Endo Questions AI in Dentistry and Some Trending Questions

This episode opens with a discussion of the future consequences of postponing routine dental appointments during the pandemic. Next, Ruddle talks about artificial intelligence and some of its future applications in dentistry. In the next segment, Ruddle answers some recent questions from our viewers, making for an informative Q&A. The show closes with some more of that “Philosophical Wisdom,” this time taking the form of Murphy’s Laws, as well as some important corollaries.

Show Content & Timecodes

00:08 - INTRO: COVID-19 Dental Update
05:20 - SEGMENT 1: Artificial Intelligence
23:31 - SEGMENT 2: Q&A
42:19 - CLOSE: Philosophical Wisdom - Murphy's Laws

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Apr 2010

Virtually all dentists are intrigued when endodontic post-treatment radiographs exhibit filled accessory canals. Filling root canal systems represents the culmination and successful fulfillment of a series of procedural steps that comprise start-to-finish endodontics...

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INTRO: COVID-19 Dental Update


[Music playing] Welcome to “The Ruddle Show”. I’m Lisette, and this is my dad, Cliff Ruddle. Are you ready for a show, a good one?


Yeah. We have some good material today, so I hope everybody likes it.


Yes! Well, we wanted to start off talking about something that a lot of dentists are probably thinking about, right now, and that’s, in mid-August, the WHO, the World Health Organization, extended its recommendation to postpone routine dental appointments. They cite a risk of transmission, due to the close proximity between patients and dentists, and also due to the aerosols that are produced by certain dental procedures. And there are several dental organizations, notably the American Academy of Periodontology, the American Dental Association, and the Academy of General Dentists, are very opposed to this recommendation.


Yeah. The problem is that – I keep going back [laughs] to the ‘80s, but we had AIDS. And so, when we dealt with AIDS in the dental environment, we already got pretty good with all of our personal protective equipment, PPEs. And so, that was goggles and masks and face shields and booties and headgear, all this stuff. So, we got that. We got the, you know, the Christensens, they’ve done a wonderful thing, Rella has. You’re gonna talk about her with the disinfect and some of the surfaces, the sterilization of equipment. So, we feel we’re really good at that.

And so, when they stepped in and made us non-essential, it made us pretty angry, because how we look at it is, there’s a lot of things going on. I mean, you know it, perfectly, but how about all those kids you had in orthodontics? Did ortho just stop, for six months? And we know a lot of people can get caries around an ortho band. So, who was watching them? I don’t think they debanded ‘em. How about just simple caries, tooth decay? Did it get into the pulp? How about broken restorations, and something breaks or comes off, those kinds of emergencies? There’s dental emergencies related to endodontics. So, how about all the people you had in provisionals, you know? Provisionals can leak, they can break, they can come off.

So, there’s a lot of things that we thought we should be open for. We thought we were equipped to be open, and we thought we could do it in a very safe way.


I think the American Academy of Periodontology specifically is saying that oral health problems contribute to systemic problems as well, like --




-- heart disease --




-- yeah. Diabetes.




Okay. Well, I recently, myself, had a dentist’s appointment coming up, just to have my teeth cleaned. And I didn’t wanna go [laughs], because I --




-- was a little nervous about it. So, I called and postponed it a couple months. And without me even asking, the receptionist – well, she postponed the appointment, no problem. But then, she – without me even asking, she explained all of the safety things they had done in their office. And after she explained everything to me, I actually felt like, you know, I’ll probably keep my next appointment, because it sounds like it’s gonna be okay to go there.


Yeah. Well, you know, in life, it’s always what’s not said is the problem. So, a lot of times, we have a habit of stepping over the trash when, in fact, we should just talk to the patient, you know? Do you have any concerns, coming in? Are you comfortable? We’re really excited! Look, we’ve done all these things. We put an air vac system in, and we’re doing this, training. We got a new manual or – I mean, talk specifically about what you’re most enthusiastic about, and that tends to reassure patients. And when you bring it up, then it is a problem, it’s identified, and it’s discussed, and it can be resolved.


Yes. And I know one doctor who was quite opposed to the WHO’s recommendation is Dr. Gordon Christensen, a leader in dentistry. And on his website,, he has a lot of information about infection control. His wife, Dr. Rella Christensen, is a microbiologist and has done a lot [with emphasis] of research in infection control. So, there’s a lot of good information there, if you’re a dentist and you wanna find out a little bit more how you can increase the safety in your office.


And they were very, very vocal, too, about WHO’s recommendation to suspend non-essential dentistry, because we see oral health as related to systemic health.


Okay. Well, we’re gonna – we have a great show for you today, and we’re gonna get going on that, right now. [Music playing]

SEGMENT 1: Artificial Intelligence


Today, we want to discuss artificial intelligence, AI, and its applications in dentistry. Generally, AI refers to a machine or software that can mimic human intelligence. The idea is, by analyzing a large body of data and using certain algorithms, that we can create an AI that will be able to problem solve or predict outcomes. And recently, there’s been more attention on AI in dentistry, and specifically in the area of diagnostics. Last season, we had on our show Dr. Cherilyn Sheets, and we talked a little bit about her Periometer. Can you remind us a little bit about this technology?


Yeah. That was a technology using AI. Cherilyn Sheets, as you probably recall, Season 2, Show 8 [laughs], something like that --




-- if you wanna go back and hear a little bit more about it, but the Periometer was a device that could be put interocclusal, and you can selectively have patients bite on opposing teeth, if there are opposing teeth. And it was able to make several distinctions. She’s a restorative dentist, does big cases, their office does. So, they can have roundhouses and splints and all kinds of extensive dentistry, multidisciplinary dentistry, and sometimes they wanna detect caries that they might find underneath a stent or a splint. So, caries detection. Sometimes they wanted to find out if there was a coronal fracture, as an example.

And of course, as they did more machine learning, Dennis Quan jumped in, and he started – he’s on her team. He’s an executive and resident at Duke, and he’s got three degrees from MIT, mathematics, computer science, and chemistry. So, he’s a data guy, and he just has to collect massive [with emphasis] amounts of data. And so, what he was doing, in the process of looking for coronal fractures, their machine could determine, through computer vision technology, radicular fractures. So, this is a very interesting device, and Earthman, James Earthman at UC Irvine, he’s materials science and bioengineering.

So, she’s got these people on her team, and they’re using the Periometer and artificial intelligence, to be great [with emphasis] in diagnostics.


Isn’t Dennis, Dr. Dennis Quan, is he involved in the project, somehow? Did you talk about him?


Yeah. He is on the team, and he’s the one that’s doing most of her AI for her. And so, when they – I don’t know how it works exactly, but when they map – when they have people bite, it feeds information into a machine. Well, they were looking for fractures, like coronal fractures. Well, all of a sudden, they realized, after thousands and thousands of data bits, they could distinguish caries as – as a distinctive difference from a coronal fracture. And then, all of a sudden, they could determine if it was a radicular fracture, sub crestal versus super crestal. So, they – they’ve – I think she will tell us, when it launches, that they found more things they could do with it than they initially sought to, at the beginning.


Okay. Because I had thought that it was just to diagnose various kinds of fractures, but it also diagnosed – can diagnose caries as well?


It can.


Okay. I was also reading, in Dentistry Today, that there’s a --


Speaking of caries [laughs], right?


-- [laughs] in a Dentistry Today news article that they send out by email, I was reading about an – it was called “Artificial Intelligence Beats Dentists to Tooth Decay Diagnoses”. Do you – what can you tell us about this study?


That was an interesting study. When I first read it -- because you and I have been interested in AI for some time now, and in fact, we’re – we got some really [with emphasis] cool stuff in future shows that’s gonna go beyond the basics. But it was Pearl, Inc. that published the study, and I thought, “Well, who’s Pearl, Inc.?” Well, it turned out that it’s Ophir Tanz and Kyle Stanley. Kyle Stanley’s a dentist, and they’re the co-founders. And both those guys’ dads were dentists.

So, they obtained millions and millions of radiographs, typically bitewings and periapical radiographs. So, what they did is, using their computer vision, they could teach the computer to look at something and then, of course, to observe what it saw, and then, to process what it saw. And what they were able to do is make some pretty astounding connections. Number one, AI is definitely superior to humans [laughs].


Well, they – it was three dentists, looking at the radiographs --




-- and then, the AI system. Okay.


Thank you. Yeah. They’re so – they had three professionals. They were well experienced, and they were – it said in the article, they were very good dentists. And then, they compared them with AI. That was the study. Thanks. And they found out that, number one, the – there was two major points. Number one is [laughs], AI was superior to diagnosticians at looking at tooth decay. They called it tooth decay, or caries. That was the number-one finding, superior, AI was.

The other thing that was startling to me and you was, there’s some real problems in our diagnostic, and maybe that goes back to dental schools or just who was our radiologist that taught us. But they found out that the best was 79 percent of the time, dentists agreed when there was an absence of decay. [laughs] But this is very startling. Out of these 8,767 – 8,767 radiographs that they were all looking at, 3 to 1, 3 dentists, AI, only 4.2 percent of the time the dentists – that was 370 films – only on 370 films did they even agree on caries.


Out of more than 8,000.


On around 8,000, it was 4.2 percent. So, there was a terrible dilemma, because dentists couldn’t agree on caries, except for 4.2 percent of the time.


Yeah. I thought that that was really startling, that they set out to prove the diagnostic capability of AI, and then, their secondary finding was the extreme diagnostic [laughs] inconsistency of human dentists. So [laughs] --


And you mentioned a very important word. It wasn’t just in any given film. It was in the consistency. The AI can see it, every time, because it’s looking at black and white. It’s looking at pixels, and it can start to determine what it sees, better than a human.


Okay. Well, there is another Dentistry Today news article that – about a study done by Tufts University. And that was also developing an AI that can diagnose just more – a broader range of dental problems.


Yeah. The Tufts study, I don’t wanna, you know, be critical, but they looked at 1,000 pantographs, pantographic radiographs, and they were teaching their AI machine to read abnormalities. And the things they’re looking at are more accuracy for the patient and the doctor alike, and then, it would be saving time. Because as we’re doing physical activities in other rooms, theoretically, these x-rays could be observed, and you could get a print-out, and it would tell you places to look at specifically that you might’ve missed, or just things it sees as a diagnostic problem, maybe. So, it’s pretty interesting. They need to do hundreds of thousands, but they are doing 1,000.


Yes, and the thing that I felt was very interesting about this study is that – you said they’ve done, so far, 1,000, and they wanna do hundreds of thousands. But they have the dentists looking at the radiographs, and the AI knows the radiograph, but is also watching the dentist examine the radiograph. And anything the dentist mutters, it records. Anytime their eyes pause on a certain area, the system notes that their eyes paused there, perhaps they should look a little closer there.




So, it was just interesting that the AI is watching the dentist examine the radiographs, to learn [laughs].


Well, that was all pretty interesting, those studies. I guess what that brings us to is, are there other applications that you would say, that we have discussed?


Well, we were – you know, we’ve been thinking about this for a while, as you said. And then, you saw this episode, a 60 Minutes segment, and you talked about it with me. And we started to see this – maybe how it could be used in education, how AI could be used in education. On this 60 Minutes segment, they show how technology has been created, that they can create a hologram of someone, and you can actually talk to this hologram, ask it questions, even have a conversation. And they are using this technology on Holocaust survivors, to preserve their stories. And not – I’ll let you explain more, how it works, but they film the person from multiple angles, with multiple cameras, and they ask them questions over a time period, and it’s a very long time period. And they try to cover every question they can think of, and they use all of this information to create the hologram.


Yeah. It was pretty moving. The topic was “Dimensions in – Dimensions in Testimony”. So, that was the project. So, the project was “Dimensions in Testimony”. But who’s behind that? Well, the – who was behind that was a group called “Conscious Awareness”, and then, they combined with USC, University of Southern California, Institute of Creative Technology. And together, they came together to do “Dimensions in Testimony”. So, they wanted to identify Holocaust survivors, and they found this guy named Pinchas Gutter. He was born in Poland. He had a sister and his family. So, it was a family of four, and they were taken out of Warsaw. And his sister and his parents were killed, but he went and survived six different camps. So, that made him a survivor of the Holocaust.

So, over time, though, there was great interest what happened there. They wanted to have moving memorials, like they wanted to pick this thing up, put it on the road, and take it into museums, into schools, let people interact with a Holocaust survivor. So, he’s not only a Holocaust survivor. He’s a Holocaust educator. So, to get this information and have this interactive, so generations of people could talk to him and find out his experiences, they had a pretty elaborate set-up in LA. I think there were 52 cameras. There were 6,000 LED lights. In fact, it was so hot on the set and so bright, that he had to wear protective glasses, when they took little breaks, so he wouldn’t damage his eyes.

And the things they wanted to do is, they had advanced filming techniques, they had specialized digital display technologies, and the other thing they had was next-generation language learning. And those are the three things they used, and they asked him questions. I think you were right; it was about five days. He did it in three sessions, but five total days, and hundreds of hours. And then, they got all these questions. Well, that wasn’t the end of the project. Then, they gave the questions to many, many groups around the world, and had ‘em ask the same questions in different [laughs] ways.


Yeah. I think each question was framed in, like, 10 to 15 different ways, so that the hologram would be able to recognize the question, basically [laughs].


So, what came out of all that is what I thought was really the take-home message. You can go up – and they made a human, talking hologram, and in real time, groups around the world, it’s real size, life size. He sits there, and it’s black, and you can ask him any question you want, from any direction. You can ask him little trick questions. But he machine learns. And through all this learning, he’s doing deep learning. In fact, artificial intelligence would really be comprised of machine learning, convolutional or artificial neural networks, and then, of course, deep learning. And they used all of those things, together, to have this talking hologram.

And so, it was pretty exciting to think that he could learn. So, even – he’s 88 years old now, and he lives in Canada, but even when he dies, they’re saying that well into the future, he’ll be learning, just like we’re learning. And you could ask him a question from 2025, and he’ll be – he will have learned, too, and he’ll answer you in real time and through his perspective.


Okay. I didn’t know that – I thought this – the holograms of the Holocaust survivors – I didn’t think that they could talk about present things, now. I thought that they only talk about their experiences or the data that was fed into them.


Exactly. In other words, you can’t ask him about, “What did you think of the 767?” That might throw him, a little bit. But if you keep it anywhere around Holocaust or that theme, then he’s prepared to answer.


Okay. So, they’re doing this mostly now for Holocaust survivors, because they’re now getting at an age where a lot of them are dying, and they want to preserve, you know, the memories. But I know a lot of people have approached this group that’s doing this, and they actually just would like this done to their loved one or something, so that when their loved one dies, they could still be able to talk to them and have a conversation with them.

And so, we were thinking, like, what if this – is – like, how could this be applied to general education? Like, what – like, for example, what if we made a hologram of you? And then, you – any dental student could buy the software, and you – that you could be their private tutor. They could ask you questions [laughs] about --


Well, I’d sure get a lot of bull [bleep].


-- [laughs] I mean, that would be interesting. Like, imagine if you – if they had done this with someone like Dr. Herb Schilder, and now, you could have a conversation with him. And say they – he is able to extrapolate and deep learn and all that. You could even ask him about things like what he thinks about GentleWave or something, and he’d be able to give an intelligent answer.


That company, Conscience Aware – or, no, I’m sorry, Conscience Display, that’s the company that combined with USC, they said that these holograms can learn, and they can learn way into the future. So, you could take a new problem that happened – not a problem, or a challenge, or something, or technology, and you could ask Dr. Herb Schilder, who’s been passed away for many years now, you could ask him a question about future disinfection technologies. You could ask him about regenerative endodontics. You could ask him what he thinks about some new technique he’s never heard of, but he would’ve learned, too, see? So, he would be able to answer it.

So, I thought that was kind of -- into perpetuity, to be able to tap into some of the great ones and keep hearing their perspective. It’d be a great influence, wouldn’t it?


Yeah. It would be really a neat thing, if this could be applied to education, you know, not even just in dentistry, but education in – on any field that you’re studying.


You know, you and I definitely feel – and, you know, this hasn’t been talked about a lot in dentistry. In fact, I think when we were doing our research, there’s like 19 or 20 articles, so it’s all in the – [laughs] first was 2018, for dentists’ applications. And 1956 was when the word was coined, “artificial intelligence”, but it’s pretty new in dentistry. But we totally think education will change, because of this. I mean, if I said, “Hey, come here! You’re a great one. You know? You’ve done a lot. You’ve really contributed, and you’ve done it for decades!”

So, if I could get you in a room for five days and be a grueling five days, but we would have all the answers we would need, to have that data, because it’s about massive [with emphasis] – to get machine learning, you just have to have so many questions and data, so you can support that.


Right. And then, the right algorithms as well.


The algorithms – the algorithms. It’s giving a sequence to get a result. So, it’s a sequence to a machine, to get a performance done. So, not so hard.


Well, right now, it’s mostly – they’re mostly looking at the applications for artificial intelligence in dentistry pretty much in diagnostics. But it’s expanding, and we will be doing future shows. We’ll come back to this issue and talk about other applications or maybe even some other ideas we might have. So --


Maybe mechanical solutions, beyond just diagnostics.


-- right now, though, I think we still need human dentists. It’s not – I don’t think we’re to the point yet now, where AI’s gonna replace all human dentists. So, don’t worry [laughs].


Well, we all remember that little clip we saw, about two or three or maybe it’s five years ago, time goes so fast. But it was in China, and a robot placed an implant.


Oh! I didn’t even know that.


Completely placed an implant. There was – I mean, a dentist was there and, you know, it had been programmed --


On another robot? [laughs]


-- [laughs] on a live patient. We all saw that. We thought, “Well, we’re not gonna get replaced. We’ll do other things. More – we’ll be able to be more like doctors of oral health, not in – so, like little mechanics to place an amalgam.”


Okay. Well, that’s our segment. Hope you enjoyed it, and we’ll be talking more about this, in the future. [Music playing]



So, here we are, on our side set. We took a little field trip over here. And we’re going to – we have a whole segment for you on Q and A, because we’ve gotten a lot of questions, lately. So, I have some questions here. We’re gonna get through as many as we can. Here’s the first one. ‘I am a seasoned general dentist’ – not me, I’m reading someone’s question. ‘I am a seasoned general dentist, take a ton of endo CE courses, but I am still confused by terms such as “working length”, “the constriction”, “minor foramen”, “major foramen”, and “suggestions to work to the level of the CDJ”. Would you clear up this confusion and tell me, where is the apical extent of treatment?’


Well, that’s a great question, and I have a visual of this question. And I remember the guy that asked it. So, we’ll honor him and, even though there was a response back, I wanted to help the whole world. I mean, sometimes you sit there – you know this. It – the questions come from all over the world, and you’re sitting there for like 30 minutes, writing an email that goes back to 1 person [with emphasis]. So, I like your idea to get this – that the answers could be relevant to maybe anybody that’s watching.




So, I have to take some questions! Okay. Well, here we go. So, there is a lot of terminology. I’ll just try to do a – kind of a simple drawing. So, we have terminology. We have the constriction. We have the major foramen. The constriction’s also been called the minor foramen. And of course, what we know is -- if I go to another color, this might show up a little better. But we know we have cementum out here, on the root, and it crawls around, and it comes up into the canal, and it comes around, and it crawls up in the canal. The literature says that when we talk about this elusive cemental-dentinal junction, the first, most important thing to know is, this is a histological landmark.

So, any dentist, any histologist, on the bench, in a laboratory, with a microscope, can perfectly identify this. And I want you to know, it’s an uneven [with emphasis] landmark. So, the cementum can move in, anywhere from a few microns, and it can go in as far as several millimeters, plus. So, we’ll never find this landmark. You’re saying, “Well, gee, Cliff, what about the electronic apex locator?” Well, that’s not gonna tell you a landmark that is off by anywhere from a few microns to several millimeters. So when I was a graduate student, at Harvard University, I was told that we work to something very simple, and it would be called the radiographic terminus.

If you extract the tooth, and the file is at the RT, radiographically, I want you to know that you would see a flute or two of the file, extending slightly and minutely beyond the foramen. But important, every canal has been catheterized, and every canal is patency. Can you say “patency”? Say “patency”! Great clinicians have to have it. They strive for it. And if a canal’s not patent, it’s blocked! So, a blocked canal means we don’t know what’s going on, apical to the block. So, if we have a little block in here with debris, we don’t know what’s in this area, and we don’t know, in fact, if this area has – I thought I had lots of colors. Boy, I’m gettin’ colors, now.

We don’t know if there’s pulp, we don’t know if there is bugs, and we don’t know if there’s byproducts. So, we don’t want a blocked canal. So, working length, then, could be thought of as a place to work, to the RT. And every canal is open, and every canal is patent. So, I work not to this elusive landmark. On an apex locator, as an example, you have a digital scale. You know, you’ve seen it. It’ll be like three, two, one, and then, there’s a zero point. I’m working right to this, on the apex locator. So, on the J. Morita, the number one probably apex locator -- ProPEX is very, very good. Anyway, whatever you have, 00 is the RT.

That means your file is minutely beyond the constriction or the minor foramen. Now, some people go, “Well, then, where would you pack to?” Well, what you do, in a big blow-up – so, you might have this go up and might do a little bit of this at the end. More canals are blocked, ledged, apically and internally transported, that is a ledge, because clinicians work short. So, if you carry your treatment to the end, your shape might look like this. Okay? There was a way to remove just the last one, but I don’t remember that one. Anyway, in other words, you can locate – you might have a little bit of this and this, and then, you’ll have taper.

The main thing you want is increasing cross-sectional diameters, as you move out of the canal. This is the capture zone. This means it holds our reagents, inside the canal. This means, when we get on here with a plugger, and we push thermo-softened gutta-percha, we have cross-sectional diameters that hold and control our work. So, that’s a little bit about the RT and the – you know, here’s another drawing.


Is – this is okay to leave this like that, versus having it go out there?


Oh, you’re gonna – you’re makin’ me ask another great one! Thanks, Lisa! Okay. Paper points. Paper points.




So, you have your final shape. And let’s just say for fun, you have a little bit of this, and your file might’ve actually been loose, in here, if I can draw this. Your file might’ve been loose. But you’re working every file to the RT. Now, obviously, I didn’t say 40s and 50s and huge D0-diameter files. But certainly, your patency files, your 6s and 8s and 10s can go there. In the world of ProTaper, I take everything right to the RT. I recognize I’m a little bit long. Now, back to the paper point. That part of the paper point that is clean, white, and dry – so, we have a paper point. If this is constantly spotting, or if you push it against your nail, and it accordions and collapses, then, that part of the paper point that is clean, white, and dry – clean, white, and dry – is that part of the paper point that’s inside the canal. That point that spots red or collapses is beyond.

So, we’ll trim our gutta-percha point, based on paper point drawing methods that I described probably 25 years ago. So, that was a good comment that you brought up about the paper point. So, in closing, don’t worry about histological landmarks. It was crazy! Every dental school, every textbook taught to work to the cemental-dentinal junction. That has led to more iatrogenic events than anything I can think of, after approaching 50 years of experience. So, please work to the end of the root. Get everything out. It’s a surgical procedure. You’re gonna have an amputation up here.

Sometimes you’ll notice your paper points will draw – dry right to the tip, right to the end. Sometimes your paper points’ll spot. That just means that this is probably going like this, and don’t worry about it. You’re gonna pack to the constriction. One last comment. One last comment! We typically see this in the business. One more. This is the RT. That’s the terminus of the canal, radiographically, at the PDL, periodontal ligament. This is the RA. So, I’ve said for years, “The RA does not equal – does not equal the PT, physiologic terminus.” The physiologic terminus is what you discover. This is the secret!

The physiologic terminus is what you discover with the paper point. So, we work a little bit long, like the surgeon. Broad incisions include complete enucleation. The surgeon doesn’t just take out the tumor. They make a broader incision, so when they send it off for a biopsy, they can make sure they have disease, disease, disease, there’s a margin, and everything beyond that margin is healthy. You know you got it all. So, when you work to the RT, you know you got it all. But we wanna be biologic, and we’ll pack it to the consistent paper-point drawing method. So, there is this, and a lot of people say, “I work to the – I work to the apex!”

Don’t talk like that, because how you talk about things is how you begin to see them in your mind! And then, we have a flawed picture! And now, we’re operating on flawed information! So, you don’t work to the apex, you work to the terminus. And the terminus oftentimes does not equal the radiographic apex.


Okay. Incidentally, we wrote a paper, me from an editing capacity [laughs]. But we worked on a paper --


She writes a lot of the papers.


-- [laughs] we worked on a paper called “Endo 101: Back to Basics”, I think.




And it discusses this, I believe.


Oh, very good!


I just remembered this, while you were answering the question.


You know, what you just said is, not everybody reads my papers.




[laughs] Should I say our – okay. So, here’s how a paper goes. Nobody asked this question, but you’re probably wondering.




I sit in my conference room, and she interviews me about an article we’ve agreed that would be appropriate. And it comes back to me. I – she’s just writing, the whole time I’m talking. I go to the board, I draw pictures. It comes back, and I have the makings of a very nice paper. And we did that for decades. “Dentistry Today”, four times a year – three or four times a year --


Well, maybe one decade [laughs], about [laughs].


-- well, for you, and then, your sister before you. So, I’ve been writing in “Dentistry Today” for decades! So, if they don’t read our articles, though – but that’s good information. And that’s free, isn’t it?


Yes. Uh-huh. It’s on our website. You can just download it.




Okay. Maybe we have time for one more question. [laughs]


Oh, there’s another question! Well, there’s a whole – there’s many, many questions. See, when they ask us these questions, they want that kind of an answer. Do you know how long that takes to comprise in an email? I often – you know, I talked to John West. I used to talk more with Steve Buchanan. I’d go, “One of my biggest challenges in life is answering all these questions!” And I think I even offended a doctor a few weeks ago, when I said, “You’re killin’ me!”

Well, I love the questions! Please! What I just meant was, you probably caught me between three articles, two lectures, getting ready for Iffy [sounds like] in India and all that kinda stuff! So, I kinda feel maybe overwhelmed! But no. It’s easier to just pick up the phone sometimes and – or have a nice drawing. So, that’s why this segment’s gonna be fun.


Okay. Here’s – I’m gonna skip right down to the last question.




“When irrigating, do you – do you use a cannula that is end versus side delivery? What is your rationale?”


Oh, I love that question. Well, you know, we have two kinds of examples. We have end delivery, where the fluid goes right out, like that. And then, we have the other kind of a cannula that’s like this, and the fluid goes out, side delivery. So, side vent and delivery. I hate [with emphasis] this! So, let’s have a cannula lesson. Years and years ago, the cannulas were big. They were like 21, 23. Then, you know, everybody said, “Wait a minute! Wait a minute! We have, like, you know, little branches. We have, like, little branches. We have anatomy!” So, we gotta get these cannula – so, we went from like 23 gauge and now, we’re all the way up to 31 gauge.

And these things are so small, you can stick ‘em through the ends of roots, and they can go into the sinus, or wherever they can go. The point is, Ruddle never puts his cannula deeper than just below the orifice. So, when I cut my access, I might be working in the coronal one third. Remember, we said, “Always divide the roots into coronal, middle, and apical thirds.” So, cannulas – hmm, I don’t know if I can do this. This is gonna be really tricky. Oh!




Should’ve cleaned up my board! Well, we’ll make it a really long syringe! Okay. And then, you have your cannula, like that. If you were to do something that I’ve been teaching for years, most of you hold your syringe like you’re gonna give an injection. So, you have your thumb out here, on the plunger, and you’re dispensing your reagent. Okay? I hold it like this. I put the barrel – I put it against the palm of my hand. I take my thumb, and on that wing, I pull. And when I pull, I irrigate. When I push [with emphasis], I aspirate. So, I irrigate, aspirate, irrigate, aspirate, and I bump these solutions.

You cannot do this with a side-port delivery. It’s useless! I have shown, histologically, that I can bump irrigants between six and eight millimeters beyond the end of the cannula. All the literature, 10s and 10s and 10s of papers, say it’s only possible to irrigate. I got one finger up. Yeah. Yeah. One finger. One millimeter beyond the placement of the cannula!. So, everybody cites that. We have a little discussion about cognitive [laughs] bias.


[laughs] Yeah.


So, everybody says, you know, “You can only irrigate one millimeter!” So, get the cannula deeper and deeper and deeper, because there’s a lot of anatomy up in here! So, they want you to get these cannulas up there. That leads to a lot of post-operative problems, because we get irrigant beyond the foramen! Sometimes we have accidents, swollen eyes, puffy cheeks. Those are disasters! Those are libel cases! So, I don’t go so deep. I like end delivery.

I must stress, I can only bump irrigants in a patent and catheterized canal. So, if the canal’s open, through and through, around curves, we have histology showing we can bump our irrigants with a 25-cent syringe, in tremendous volume! We can get those solutions rushing over surfaces that have been prepared by a shaping file. And then, if you throw in an EndoActivator or something like that, you can really get agitation.

But that’s a little bit about – you wanna irrigate a little bit better? They made these for people who are heavy handed. They made side-port delivery to clean up accidents, okay? Well, you don’t have to have accidents. I’ve never had a sodium hypochlorite accident in 47 years of practice. Never had it, because the irrigating cannula is always loose! In closing, so, you gotta – you got a tooth. And let’s just say we’re doing this distal system. And – okay. We’ll put in some more canals. My cannula is like this. It’s – you know, you – after you’ve done a little bit of work and stuff, your cannula’s like this, and it’s like that.

So, there’s reflux. So, if you’re pushing too hard this way, the irrigant can cycle back up, that way. You don’t wanna bind your cannula into the canal and make the canal an extension of the cannula, or when you irrigate, you’re irrigating under pressure, and you’ll definitely drive it out. And that’s when you have a huge problem. So, other thing, keep your hand moving. If your hand’s moving, the syringe is never locked up. The cannula, by definition, is always loose!


Yeah. I’m just – like from a layman’s perspective, I’m just wondering about this side-port delivery. Like, if you were down in the canal, and you’re trying to push it out the side, it seems like the pressure would be all different and everything, because you’re hitting this wall when it comes out, right? I mean, I just don’t understand the reasoning behind why you would even have a side port.


Well, side-port delivery is simply to keep colleagues safe. That’s the only rationale for it.


Just from – maybe because it’s harder to --


They’re afraid --


-- push it through?


-- yeah. Because if it’s gonna be – you know, I don’t have this right. But anyway, just do a really big canal. But if you have a – you know, you have a – and it can come out this way, we even know from Gula Vivolo’s [sounds like] work at the Eastman, in London, that you have areas of the canal that are cleaner, based on the placement of the needle, because it’s comin’ out this way. So, what you prognosticate, if you always came in the same orientation, you might have a really clean spot!


So, you have to turn it around and then, do the other way? [laughs]


Oh, yeah. Just show us your cartwheel. That’s what I do, when I practice. I do cartwheels, and the side delivery hits all the walls.


Okay. Well, I think, actually, that’s all the time we have for questions. But we will do another Q and A segment in the very near future, because as you can see, we did not get to nearly all of the ones on our list.


Well, teachers like to have fun, too!


But please ask questions, because we will get to them all, eventually. You can post them on our website in the comments of this show or pretty much, like, any of our subsequent shows. And then, we’ll get the questions, and if you even want your name, you can even make a note if you want us to say your name when we ask the question.


And don’t forget, questions are the answers! [Music playing]

CLOSE: Philosophical Wisdom


We’d like to close our show today with some philosophical wisdom. Last time we did this, we talked about Chinese proverbs. And this time, our wisdom is gonna take the form of Murphy’s Laws. So, we have a list here of some of Murphy’s Laws, and we each chose a couple of our favorites. So, which one did you choose?


Number one on the list, because it – I could really relate to it. If I read it exactly like it says, it’s “Nothing is as easy as it looks.” I usually say, “Nothing is as simple as it seems.” Well, I’ll – before I relate it to dentistry, let me go outside dentistry, if I may. But if you’re a baseball fan or used to play, we all can relate to somebody, let’s just say an outfielder, racing deep into the alley and running a ball down, you know, on the warning track or leaping up at the wall, and it looks almost effortless.


Or even a baseball swing, like when somebody --


Oh, yeah! If somebody swings nice and easy, and sometimes it’s 450 feet. It’s like a tape-measured homerun. Or how about that downhill skier, goin’ through those gates, and it looks so smooth? I saw Marco Marchioni only one time, skiing down this hill at night, with a big torch. And I mean, I thought it looked beautiful. I got chills down my back. And then, later, I thought, “I would be a paraplegic if I did that.”




So, in dentistry, everybody, I’m an endodontist, so I have a little idea for you! When you look at that preoperative x-ray, and you go, “Wow! Let’s get goin’! That’s an easy one!” Remember, things aren’t as simple as they may seem. And sometimes single-rooted tooth have – they hold – those roots can hold two or more canals, and there can be deep divisions. So, they get it.


-- sometimes it’s the experts that just make it look easy, I guess.


I think all the training and then, throw in [laughs] – get some experience going. And all of a sudden, you’ve seen a lot of things. So, you’re not as thrown by things . But the main thing I heard my whole life, “Cliff, I referred you the case. I’m sorry. I know you would’ve liked to have been in there, first. But I opened it up, because it looked pretty easy to me!”




So, remember we were talkin’ about [laughs] x-rays, earlier? Maybe we oughta use artificial intelligence, because not only was it looking for caries, it was looking for other abnormalities, like extra canals, extra roots, and stuff like that.


Well, that’s interesting that you brought up artificial intelligence, because I actually had chosen another one. But then, I just saw this one.


What’s yours?


“Everything takes longer than you think.” And that’s pretty true --


[laughs] That was my career!


-- about everything I attempt to do, every single day. But I – again, hopefully artificial intelligence will be able to help me out, on that [laughs], in the future.


Maybe while you’re doing something else, you can have all these robotic things going on behind you, you know, doing all those chores.


[laughs] What about – what’s your next one?


Ah! Well, this one’s pretty interesting, because, again, as dentists, “Enough research will tend to support your theory.” Oh [laughs], I like that one! So did you.




You know, a lot of times, we have this word called “confirmation bias”, or it can be “cognitive bias”. But we all are who we are, and we’re products of our pasts. In fact, I like to say, “Who you are is where you were when.” So, you’re a product of all that stuff. And now, you’ve learned something. Well, a lot of times we wanna defend what we do. So, we go grab articles, or we’ll go read something, and the article didn’t agree. I don’t like that article! And finally --




-- you find an article, you go, “Wow! They might agree with me! Maybe in the conclusion, they’re – this is the article!! This is why I do it [pounding fists], because it’s right there!” So, we tend to surround ourselves with higher and higher defensive walls, and all of a sudden, we can’t see the truth if it hit us in the head, because we’re so entrenched in our own thinking. So, I used to say a lot, on stage, “When you’re willing to be wrong, you make your greatest growth.”


Yeah. And maybe not be too emotional about some of your beliefs that should be more scientific [laughs].


Yeah. Exactly.


Okay. Well, I just – wasn’t gonna say this one, but I think it’s kind of fitting, and then, we’ll close on that. This one, “Everything goes wrong, all at once.” Well, I guess that just --




-- reminds me [laughs] of 2020. So [laughs] --


Oh, that is good! Yeah. That’s good. I had one more we can close on.


-- okay.


You know, there was – you know, there’s Murphy’s Laws, as she told us. And there’s a lot of ‘em. You can Google ‘em, and you’ll laugh hysterically, because they’ve all happened to each one of us. But then, they were corollaries [laughs] --




-- to Murphy. And I always – in my – I have an x-ray that I show in my lecture, and I show a big mistake, okay? Huge iatrogenics, and we take care of all of that. And then, the patient comes back, and the tooth just in front of it – tooth – it was a molar that I cleaned up. And it was a second bicuspid. And there was a broken instrument in it. And so, I wrote on the slide that Murphy was an optimistic, because O’Toole’s corollary said that. So, O’Toole said Murphy was an optimist. So, in closing for me, remember, pressure – what? You remember it? [Music playing]


Uh, no.


Breaks pipes, or it makes diamonds.


Okay [laughs]. All right. Well, that’s our show for today. Hope you enjoyed it. See you next time. [Music playing]



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

Watch Season 11


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Avoiding Burnout & Ledge Management

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Controversy… or Not

Is the Endodontic Triad Dead or Stuck on Semantics?


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EndoActivator History & Technique

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GentleWave Update and Intracanal Reagents


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The ProTaper Story - Part 2

ProTaper’s 20+ Year Journey as Told by the Creators, the 3 Amigos


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Getting to Know this Top Clinician, Educator & Researcher


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s01 e03

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What is the Appropriate Access Size?


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The Ruddle Show
Season 11

Release Date Show Get Notified
SHOW 91 - Delving Deeper Again
Financial Investing, the Tooth or Implant, Accessing & Flashing Back
SHOW 92 - Artificial Intelligence & Disassembly
Differentiating Between AI Systems & Paste Removal
SHOW 93 - The ProTaper Ultimate Slider
Special Guest Presentation by Dr. Reid Pullen
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