Advancements in Gutta Percha Technology Zoom Interview with Dr. Nathan Li

This show begins with Ruddle and Lisette highlighting some fun facts about the Tokyo Summer Olympics finally opening this week. Next, Ruddle welcomes a special guest by Zoom, Dr. Nathan Li, founder of Healthdent Technology and an expert in all things gutta percha. Then, returning to the sports theme, Ruddle will close the show by expertly making the connection between various aspects of sports and endodontic procedures. So stay tuned for some fun and laughs!

Show Content & Timecodes

00:09 - INTRO: Tokyo Summer Olympics
06:31 - MAIN SEGMENT: Zoom with Dr. Nathan Li
41:14 - CLOSE: Sports/Endo Analogies

Extra content referenced within show:

  • Special Show Guest: Dr. Nathan Li
  • Healthdent Technology Intl., Inc:
  • Dentsply Sirona:
  • Grossman LI: Root Canal Therapy. Philadelphia: Lea & Febiger, p. 189, 1940

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    INTRO: Tokyo Summer Olympics


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




    Excited about the show?


    Really excited to talk about the games.


    Right. So, this coming weekend, the long-awaited Summer Olympics in Tokyo, Japan, kicks off, one year later than normal because of the pandemic.




    Now the fact that the Olympics are taking place in an odd numbered year, 2021, is already unique, but there are a lot of other unique things about this Olympics, so we wanted to start off our show today talking about them a little bit. To start, this is only the second time Japan has hosted the Summer Games; the first time being in 1964. So, I understand in this Olympics there’s going to be robots involved. Is that correct?


    Yeah, the Tokyo Olympic Committee, in conjunction with Toyota, they made robots, and they made humanoids and they made – what do you call it, car-like robots, and the humanoids are going to meet people. They’re going to be greeters and they’re going to interact with people, and I kind of imagine if I was in Tokyo and I had a ticket and I was going to the game like who would I see first and would they come up and [speaking Japanese].

    Anyway, and then, of course, the car-like robots are interesting because people that throw the javelin or the hammer, those projectiles go out a ways, so they’re going to be retrieved to save time and they’ll be bringing the hammer and the javelin and those kinds of things back to where the athletes are. So, that’s never been done before is my impression.


    That’s pretty interesting. I don’t know, hopefully, no robots like malfunction or go out of control or something.


    Or are they going to be in the events?


    Apparently in – and another interesting thing about this Olympics is that in the Athletes’ Village, all of the beds are made of cardboard. Now, of course, it’s super strong cardboard, but still cardboard. And apparently, they can hold up to 200 kilos which is about 440 pounds, but I don’t know how heavy some of those weightlifters are, and if you go to take a running leap onto the bed, I don’t know if it’s going to hold that.


    You should be more concerned about the sumo wrestlers.


    Yeah, okay, yeah, but apparently the reason why the beds are made of cardboard is so that they can be recycled after the athletes leave. So, that’s actually really an interesting thing. And speaking of recycling, I think you had something to say about the Olympic medals.


    Yeah, they have to have about 5,000 medals to give out the gold, silver, and bronze across all the venues and sports, so I think they got something like 80,000 pounds of electronic gear, and it was like laptops, it was handheld cameras, it was like games.


    Phones, iPhones.


    Oh, and then they got like what, 6 million iPhones, cell phones.




    And what was kind of unique about that is people actually gave up their mobile phones because they understood that they were going to go into an actual metal, so that was pretty cool, so that was probably a first for people giving up their electronic gadgets to actually be part of a medal that would go around somebody’s neck that they’re never probably met in their life, but it would be some kind of a connection, I was thinking, through eternity.


    That is neat. Apparently, also, only the Japanese locals will be able to attend the games because of the COVID restrictions, but Japanese fans are known to be some of the world’s best sports fans. They’re colorful, passionate. They are very well behaved, and they also have been known to organize post-match litter clean-ups. So –


    I like that. That’s why when I go to Japan, it’s so clean. I mean the trains are clean, the cities are clean, the countryside is clean. It is like a place to go. Well, the other thing that I liked is in the big national stadium. It was originally built for the ’64 games, so this is an example – our family is always talking about well how can these cities keep building all this infrastructure, so when you go back to a previous city it’s kind of neat cause they have the infrastructure.

    So, the national stadium was already really neat even though it was ’64 games and 56 years old, but they went around to all the 47 prefectures and they harvested cedar, primarily big timbers, and they dressed out all the soffits around the stadium, it’s five levels, so all – there’s five soffits, and then inside, there’s that hole that looks out to the sky and they have these big beams inside so the light comes through and it filters it as if you were on your patio, and you get filtered light. So, it made it, the stadium – it was to make a connection with nature and to bring the modern steel and concrete with the wood, and it’s really a nice look.


    Yeah, you showed me some pictures of it this morning, and I thought it looked really nice.


    Are you going?


    No, but I’m definitely going to be watching, cause I get really into the Olympics. But yeah, are you going to watch?


    Well yeah, I mean just getting ready for this little skit, I started getting ready for the sprints and the track and field stuff which is kind of interesting to me.


    Yeah, we’ve been seeing a lot of the trials starting now, so it will be exciting. Okay, well we have a special guest on our show today, Dr. Nathan Li, who we fondly refer to as the “gutta percha guru.”


    I call him the father of modern gutta percha.


    Okay, so we are very excited to have a Zoom interview with him, so let’s get started.

    MAIN SEGMENT: Zoom with Dr. Nathan Li


    Today we are joined by a special guest, Dr. Nathan Li, who is a practicing dentist and a dental consultant as well as an expert in gutta percha technology. He is the founder of Healthdent, which manufactures high quality gutta percha product as well as works with international dental companies to research and develop new gutta percha material. So, we are very honored to have Dr. Li on our show today, to talk a little bit about himself, the research advancements in gutta percha technology and also maybe give us a little glimpse into the future of obturation. So, welcome, Dr. Li.


    Thank you. Very honored to be here. Thank you.


    Nathan, it’s really great to have you on the show. We’ve been trying to do this now for about a year, and you have a lot to share with our audience, and I want the audience to really understand that there’s a lot that goes into that little, tiny cone that’s tapered and goes to lengthen the canal, so let’s learn more about that from Dr. Li.


    Okay, well before we get to the latest advancements in gutta percha technology, I want to first ask you how you even got on this path that you’re on now, because as I understand, you grew up in China and went to dental school there before continuing your education in the United States?


    Yes, that’s correct. Yeah. And well, here’s a short version of my long-life story. And yeah, born and grew up in China, and in 1979, I remember, I started my dental school out of Peking U, Peking University. That’s the period right after the so-called “cultural revolution,” so you can imagine the knowledge base and equipment, everything else is – what’s the term, antiquated, to some degree. And then was upset and the teachers were hard at it, very, very devoted to teaching, to the profession, so that put a really lifelong mark on us and the work ethics.

    And I remember that in 1984 – no, in the early – yeah, early 80’s and China started opening up, and we had a First International Dental Trade Show in Beijing. I got ticket and I got in and my lasting impression was I remember the beautiful surgical dental instruments from Miltex, and the shiny gold alloys, lab equipment from Nay [sounds like], I think that’s part of Dentsply Sirona. And I took all the catalogues I could carry and started with them and then started wondering, should I continue my education overseas after I graduate?

    So, in ’84, my Perio, one of my Perio professors, Dr. Tai Fung [sounds like], a periodontist who just came back from UCLA for the sabbatical, that’s what they call it, study, for one year, and I talked to her about this idea. She referred me to UCLA. So, that UCLA Perio Department chair at that time was Dr. Carenza [sounds like] and they accept me. So, I came to UCLA ’85 and studied under him and shortly after that, I joined Dr. George Bernard, DDS, PhD, specialized in heart tissue, histology, cell study, and went to his lab to do the research.

    At that time, around that time, we were very excited looking for the bone regenerating tissue. We didn’t know it was called stem cells. We called it osteoblast. And Dr. Carenza located a similar cell in the periodontal ligament, repair, regrow cementum. And we were very excited. And another team at UCLA tried to use hydroxyapatite to coat the titanium implant in medical school actually just discovered so-called, the bone growth factor, most exciting time. It was say a pre-cursor of the stem cell regenerated dental work.

    Oh, by the way, the MacIntosh 2, the Apple computer, came on the market. I got my hands on one in the lab. Fun. Shortly after that, two years into it, I miss my clinical work, and I asked around where I can go study clinical skills, and found out UOP, yeah, Pacific opened up the international program for first time for the foreign trained dentist, a short program. So, I got in and met Dean Dugoni, and he is a great guy has a huge influence on me. And I would say he’s a great leader and Cliff would agree with me. Yeah, he led by kindness and by example. And so, he held my hand for two years.

    And after that, I decided to raise my young family in the suburbs, small community, tried to join in a private practice to learn everything I did. So, I came back 2000, California, and on the southwest corner of Mojave Desert, small community called Antelope Valley, city called Lancaster. So, I started there ’89 and never moved, stayed there for almost 30 years, finished my clinical career, and also raised my family, lots of nice memories, kind people, down to earth, and I always tease my new patients and telling them, welcome, you know, went to three schools to get a one license practice on you. You still want to stay here? They all stayed. And so that was that.

    And then just a coincidence, you know, early 90’s I went back to China to visit and one of my professors told me, “Oh, Nathan, next time you come back, bring some gutta percha points , they don’t have anything.” I said, “Okay.” And chances are and it just happened, and I came back from China and then I went to Chicago, Mid-Winter Show, and just walking around, wandering around, I saw these little booths and, on the countertop, all piled up was all kinds of gutta percha, a company called Schwed, owner was Michael Sobotka.




    And so, I built up my nerve and I said, “Can you sell me the gutta percha points in bulk because I’m going to donate it to Peking U.” And then I said, “If you have material,” I got – tried to get smart. I said, “You can sell me material; I bring back to China and grow it” and he look at me and said, “Sure.” And everything set up, I said, “Okay, my sister lives in China and she can work on that, and the youngsters need jobs and so, how hard can be?” So, I shipped the material back to China, we start hand rolling and kept going for 20 years. So, that’s how I started.




    So, you started gutta percha master cone business and now with your knowledge of molecular chemistry and maybe some of your background that you got from UCLA doing research there, you began to manufacture a vastly improved line of gutta percha master cones. So, can you share a few major improvements you made that forever changed the way that we view gutta percha master cone?


    Well, first off, after about 20 years of the hand rolling of gutta percha cones, I got kind of dissatisfied, tired of it, and I wanted to quit, because it doesn’t matter how hard one tries, if it doesn’t fit the new NiTi rotary files requirements, especially full taper, full taper universal, progressive tapers. So, I said, “I can’t do it.” And so, by 2011, I was ready to shut down. And I think the early 2012, Dr. John West and your dad, Cliff, seek me out and yank me to Santa Barbara, gave me a lesson, took me back to the history learning and so, asked me, encouraged me, to solve the problem and continued going.

    I remember Cliff said, “Try to identify a problem and then create a solution for it.” And he also said, “Never create a solution, a perfect solution, for the non-existing problem.” Is that right, Cliff?


    Something like that, Nathan.


    Yeah. And so, I explained to those masters and where my frustration was, so we agreed, and we shook hand on three things. I said, “I shall continue if I can, one, to use machine to make those points.” Instead of hand-rolling now it was very labor intensive. And two, okay, “If I can make a gutta percha cone with progressive tapers, multiple tapers, to match, precisely match, the full taper universal NiTi files or any other shapes.” And three, “If I can change the six-year-old formula to better adapt the warm gutta percha condensation technique.”

    And we shook hands, and I asked for six months and six months later, we had a prototype. A few months after that, we’re in business. So, that’s the three things we accomplished.


    I guess I’ll tell our audience, Nathan, that in my mind, you were the first guy in the world to make a multi-tapered cone to simulate the final shape of the instruments used to make the shape in the canal. Probably our audience doesn’t know, but most companies make fixed tapered cones even when they say multi-tapered, and so a lot of times, their cones get big in a hurry and that gives us artificial tugback. That was a great thing you did by changing the taper to get our tugback apically.



    And then with the injection molding now, the tolerances became a lot tighter, right?


    Yes, now we have a same tolerance as the NiTi files. In my engineer terms, they tell me there are two ways to make things. One is just use a milling machine, cut and grind. Another way is injection molding, and so which one has more precise, more accuracy, and with a tighter tolerance. And the two camps always fight each other. And for injection molding the standard is 5 microns. And for the Dentsply Sirona, the NiTi files, is 2 microns.

    So, how can I bring injection molding from 5-micron tolerance to 2 micron like Cliff said and get rid of those false claim of pack back actually located way above the apex. And that was a hard one to do, but we did it.


    Okay, so you made those goals for yourself, and then your company helped then accomplish those goals. And now this superior gutta percha is sold exclusively I understand through Dentsply Sirona. And I also understand that all clinicians can benefit from this gutta percha, whether they use a single cone sealing method or a warm gutta percha – or a warm gutta percha with vertical condensation method, correct? Both will benefit?


    That is correct. If I may elaborate a little?


    Oh yes.


    I even make a little note. I know you’re going to ask those questions. Let’s talk about the single cone or the cone condensation technique. And for the single cone, you just stick in there, one cone, and but the trouble is, Cliff mentioned for the apical region. What is apical, a D0, D20, whatever it is. And the single cone is undersize and the most we make is six percent taper, and the pro taper gold, let’s say, is 8 percent taper, so there’s a gap there, and in that region where the one sealer spread sideways, you got lateral canals and entry portals, apex, all this and that, when you have hydraulic pressure to push the cedar laterally.

    But it’s undersized, under tapered, so we don’t have enough hydraulic pressure in that region, and then yet, okay, in the coronal one-half, somewhere around 8 millimeters, 12 millimeters above the root canal apex. Okay? We have a false pack-back, and you’ll feel like it’s a tight fit, but in the apical, where it counts most, it doesn’t. Okay, so the multiple taper full of the geometry of the ProTaper Gold, let’s say, and has the tightest fit, okay. And Apex to really spread those sealers laterally. And yet okay, not in the coronal portion.

    And if I may, okay, I want to break a little news and now people use bio-ceramic sealers, and those sealers, that takes a long time to set, and so it’s very runny and run out of the root canal, you know, hours later. And the way I am developing a new geometry, and the concept is called Fit to Shape, so I still fit very tight apex and then fit tighter, not as tight, in the coronal portion to lock in and lock down the runny delayed setting bio-ceramic sealers using the benefit of… [inaudible]. And with warm gutta percha, the most important thing we did other than get rid of the false tugback sensation from coronal portion as a tight lockdown in the apex. Other than that, it’s a formulation change.

    And our team actually learned from rubber industry really tight regulate and modify the gutta percha mouth flow rate, viscosity rate, at a different temperature and softened differently and has a controlled flowing character, so can be molded into the three-dimensional root canal space. And also, I want to mention it requires much lower temperature, so that’s a huge plus, and the heat wave travels lot further. So, what we did we tried all kind of materials and found the final solution.


    You know, Nathan, I want to acknowledge you for not only did you do the actual physical work, but you created a new language, and it’s not Mandarin, nor is it Cantonese. It’s endodontic language. And I’ll just say a few of them. You said one. I think you’re the only guy in the world that makes a cone called “Fit to Shape.” Now I don’t know if we got all these things trademarked, and you know how the world copies everybody. We’ll probably see this on the back of another company’s packaging soon.

    But Nathan Li was the first person in the world to do “Fit to Shape”. Maybe you want to tell us a little bit about triple lock, a little bit about the flat end, and we already talked about multi-tapers, but there was a lot of things that Nathan did in the gutta percha region. You’ve heard about the “Fit to Shape”, you’ve heard about the molecular structure, but I want maybe to talk a little bit more about what’s inside that little 25-cent cone.


    Well, let’s talk about a triple lock and a flat end of the percha. The hand-rolled for the percha has a bullet shape, has a point at the end, let’s say at D0, that’s why we always called them gutta percha point. But it’s a bullet nose. And but I made all our cones flat, very flat end. The reason for that is the NiTi files have a so-called D0, and it’s very, very sharp tip, and the so-called D0, size 25, it is projection of the taper from the main body of the NiTi file or endo file. And so, the dentist can use it, that tip, can use that tip at apex and beyond apex, shy of apex, we don’t know where they stop.




    And also, honestly, not many endodontists, forget about general dentists, can agree the definition of apex. So, what we did is we accommodate all the anatomical and the file designs and they make a flat end, slightly smaller, let’s say size 25, and so, each dentist can put it – the cone in there and it will fit in the lock, plus or minus quarter of millimeters, so that’s acceptable clinically. And for the dentist ex-ventilate, okay, and use the file too far beyond apex without knowing it. And also designed master cone, now known as taper cone, from easier on the flat end a really tight lock, and D1, one millimeter above D2, two millimeter above, so it’s three locations. It’s the tightest fit, very tight fit of the entire gutta percha cone.

    So, if the dentist accidentally push the NiTi file beyond apex, okay, and they have – our cone has the right kind of taper, and then you can push that cone one millimeter beyond, two millimeter beyond, three millimeter beyond, but you’re not going to push it five, six millimeter beyond, all the way to the mandible nerve canal, let’s say. Okay. That’s what I meant, triple lock, so it’s really the added safety feature.


    You know, it’s really neat when you do that, because you know, we’re always off course in endodontics, as you know, I mean it’s like sailing. You’re always going towards a destination, but you’re always adjusting. So, I like it that you made the cone that is forgiving, and it allows us to have those little adjustments that we’re always making clinically.


    True, yeah, just try to accommodate everybody and with a little extra safety margin.


    Did you want to ask him about, his opinion, about what most influences 3D obturation?


    Oh, okay. So, people don’t know this about Nathan, so I’m going to now expose him to the world for the man he really is. You know, he’s actually interested in regenerative endodontics, and most of the time, our conversations over the years have always kind of steered back to what will we be doing in five years and in ten years. And Nathan has always said to me, “The obturation is fine, and I’m glad I can help out and we can make that more predictable.”

    But then he’s always looking ahead into the future. And one of the things he understands perfectly is that you can’t really describe regenerate procedures or these new techniques unless you have disinfection. So, Nathan has been as involved in 3D disinfection as I would think he has been in terms of his master cone business. So, maybe Nathan, tell us a little bit, it’s nice to have a cone, but what are the two other things that dictate obturation, the trifecta stuff?


    All right, actually that’s my new interest, my new passion, disinfection. And result A, really good evidence-based cleaning disinfection of root canal system. My gutta percha cone means nothing. It only means locking more bacteria down there. It come back to bite us later. I remember this. Many years ago, when dental microscope came onto the market, I’m the one always to buy the new toys and the wasting lots of money. And so, now I got my interest I went to – I remember it was Newport, Dr. Sheets, from USC, and has a really nice training center there.

    So, I bought a Global microscope and went down there for two days, maybe even three days, very intensive training. The opening statement from the professor – I forgot his name, but from Oregon, and he mentioned that – his opening statement is, “You only can treat what you can see.” That opened my mind. So our disinfection, right, and I’m going to borrow a paraphrase that, we only can disinfect where we can bring our irrigants, our agent, disinfectant, into the place. If we don’t have a disinfectant reagent into the place, it cannot disinfect. I think we all can agree on that, right?

    And so, with the pro taper system, okay, and the deep shape anatomically correct and would bring adequate reagent into the place. Now we need to agitate and activate it. I might just add that minimally invasive shaping, it’s a great concept. We all accept that. But it has to be within reason. Within reason that we can disinfect deep inside. I think it’s overplayed the message by now, okay?

    So, with that said, I think the disinfection of the trifecta endo, okay, is the weakest link of the three. We really need to work on it. It’s not that great. It’s a dark secret by asking how many dentists out there doing root canal treatment use any kind equipment, okay, mechanical and the light or thermal to enhance the disinfection process. So, that’s the same. And we need to work on that. And then I may want to share that with Cliff that I tested the new EndoActivator. We call it EA2, new tip, new motor and a new energy level and a new motion pattern. And works great. I just hope a general dentist will use it to enhance their disinfection process.


    Okay, I want to just tell our viewers who don’t know it, that Dr. Li is also on the trifecta project that we talked about a lot on our show. So, he’s also very active on that in that group.


    So, now I’m going to expose something that maybe corporate doesn’t like to hear, but maybe I’ll just cut you loose and talk about a minute about the tips you and I have been working on. So, you mentioned the power is going to be better, the elliptical pattern, the random pattern is going to be better, the crown-down method. There’s all these things that influence energy transfer and agitation, but maybe tell us a little bit about some of the tips because you were using Crazy Glues and scalpels and you were doing – I mentioned the shark fin. Go ahead.




    Just a glimpse, just a glimpse.


    I can’t remember how many different prototypes you and I did together. I think it – it was not about 20, it’s got to be close. I remember that much. And the bottom line is the way I understand disinfection, the reagents. I understand that it is chemical reaction, kill the bugs, dissolve the protein, right, but I also understand there’s mechanical meaning of it. You’ve got to constantly exchange the fresh reagent with a spent, used reagent, pulp chamber with a root canal space.

    And so, with a new tip, and the way I was thinking about how to design the tip with a different cross-sections, different surface textures, different angles, different curvatures, different lots of things, to agitate the reagent, allow more a lot faster, release more singlet oxygen, number one, so I call that chemical part of the EndoActivator. And the mechanical part of it and is faster exchange of fresh reagent in pulp chamber into – deep inside the root canal space.

    I think we accomplished that a lot compared to EA1 and then also we discovered together, Cliff, that the crown-down technique, when you use it, you don’t force it all the way into two millimeters, three millimeters shy of the apex and activate the motor. You just go like one-third down and activate and suddenly you’ll see was the exchange rate, reagent exchange rate, going crazy. So, I remember the old days, crown down technique of the shaping and this is a crown-down technique, and it helps a lot.


    Okay. Oh, did you want to say something, Dad?


    Well, I want to really appreciate it, cause I didn’t get anybody else on the entire team that was as interested as you were, so thanks for sharing all those prototypes, and I was doing stuff in Santa Barbara, trying to make slits and fins and different stuff. But what Nathan and I were trying to do is we were trying to accelerate and improve the agitation of the exchange of the irrigant at all four corners of the root canal space.


    Yeah, I want to get back to gutta percha now, cause I understand that you are in the process of creating a new state of the art carrier-based obturator. So, to the extent you can, would you share a few improvements you are making to make this filling method, basically bring it to the forefront as a safe and fast way to fill a root canal system in under eight seconds, I’m told.


    Oh, okay.


    Yeah, Nathan, she wants the IP and the formula.


    Just whatever you can reveal.


    Okay, all right, eight seconds. Everything is around –


    Oh no, I mean – and supposedly my dad says it only takes eight seconds once –


    Insertion, eight seconds.


    Oh, you – eight seconds insertion, yes.


    You have more than eight seconds to respond.


    I thought you were putting a gun to my head.


    You have eight seconds.


    8, 7 –


    6, 5 – the clock is ticking, Nathan, you can do it. Try hard, Nathan, don’t give up!


    I want to say we’re on the third generation of a carrier-based obturator, Guttacore, so now same time it costs CBO… So all three generations, everything is around the CBO, okay even be improved generation after generation, but still, lots of things are wrong. But they all go to the single source of the wrongness, the carrier, the core, okay. Everything is wrong today was being that technology as the core. So, imagine we have a carrier, just strip the gutta percha surface, we have a carrier… Number one, it’s rigid, not too rigid, and flexible, not too flexible, so 8-second insertion it doesn’t buckle up, break down half-way down and drive you crazy, right.




    So, if we have that, number one. Number two – number two and then when we do the insertion, okay, this carrier stays in the center, always have the gutta percha or something around it, stay in the center, okay. And also, when you get to the apex, a little shy of it, and you can’t push anymore. How about that? Okay. And then number three, if one day we need the re-treatment, we just put a little instrument in there and pull the carrier out in one piece, okay, forget about dissolving it, just pull it out in one piece and dissolving the sealer, okay.

    So, if we can do that, okay, and then sky is the limit. Forget about putting gutta percha on the surface. You can put sealer on the surface. You can put any kind of bio-material on the surface and then insert it in eight seconds. And we’re working very hard with Dentsply and pretty much spill our guys and we’re working very hard on it. That will come.


    Nathan, I have already seen some prototypes, and they’re very, very exciting, especially as compared to existing current technology.


    Yeah, we call it “auto-lock” because you can’t push it down anymore.


    Auto-lock? Centered obturation. And I want the audience to really appreciate this core he’s talking about is nothing more than the internal plugger.




    Okay, so, we’re getting a little bit long on time, but it’s all good. It was great information, but I just was wondering if you could give us a little glimpse about what the future holds for sealers?


    That is a sensitive topic. I’ll go over it quick, I mean not to offend anybody. Okay. Let’s just say first thing is Dr. Grossman, actually I made a note here.


    Louis the Root Grossman!


    The 10 requirements for the obturation and it is still 100 percent relevant today, I say that, number one. And then number two, I’m going to jump into the bio-sealers, okay. And the solubility in human body fluid. Let’s forget about, let’s say water, okay. The bio-material we use in dental is borrowed from big medicine. In the big medicine, teaching regenerative work, okay, is surrounded by healthy, live, full of blood supply soft tissues.




    Okay. Therefore, they want their bio-material to be resorbable, a better word, degradable. Okay. That’s where our dental regenerative work knowledge is based upon. But in our endo arena, the inside clean the root canal system. It’s a death chamber, okay. We need airtight, watertight obturation. And then the sealer goes beyond the exit portals, apexes and that, meaning live tissue, okay, blood supply and periodontal ligament, based on that in the bone. And that become a bio-inducive to induce the healthy body reaction for self-repair.

    To me, I tend to over-simplify everything. That’s how I see it, the future of the sealer. It should not be sealable. We’re not dealing with a big medicine. We’re dealing with endo; there’s a difference.



    That’s a great distinction, Nathan.


    We have to satisfy both. That’s how I look at it.




    Well, thank you so much for coming on our show today. I really love your story, and it sounds like from what I understand, that there’s been gutta percha that’s been around for a long time without any updates or improvements until you came along, and then just revolutionized so much of gutta percha technology that we have now.


    Because your dad took a gamble on my head in 2012.


    Well Nathan, I want to thank you for joining us. I know you’re a big book, and I really appreciate all your knowledge, and I guess I’ll read you a little quote that I have. It’s from Aristotle. And it reminds me of your journey from the little kid in China to where you are today. And basically, your journey reminds me of, “We are what we repeatedly do. Excellence then is not an act; it’s a habit.” And for you, you’ve made excellence a habit. Thank you.


    Thank you, sir. Thank you, Lisette.


    Thank you.

    CLOSE: Sports/Endo Analogies


    So, in honor of the Olympics starting this week we wanted to close our show with a segment called Endo Sports Analogies. So, I will name a sport or an aspect of a sport, or maybe even a very specific event in that sport, and then you will tell us how it is like endo or maybe dentistry in general.




    So, we actually had some serious fun planning this segment, so hopefully you have fun listening to it. So, are you ready to go?


    They might even have their own analogies.


    So, here’s the first one. Lolo Jones going to Summer Olympics in track, the hurdles, in 2008, then in bobsled in the 2014 Winter Olympics.


    Oh, that’s like a really well-trained general dentist that practices for several years and then decides I really love Endo, I’m going back to post-grad school.


    So, multi-disciplinary training, okay.




    A goal in soccer or a home run in baseball.


    That’s when everything comes into alignment, the training, the experience, the technology and then the right case has to come in attached to a patient that has thrilling anatomy, and when you pack it, it’s like out of the park.


    Okay. So, the world champion skier, Lindsay Vonn, tears her ACL, has to spend time healing and rehabbing, then tears the same ACL again.


    Well, I do a nice treatment, it looks really nice radiographically, but the signs and symptoms persist, and I have to do re-treatment.




    On the same case.




    The same knee.


    Speeding down the track on a luge.


    Oh my, that’s, you know, taking that pro taper file around multi-planar curvature and it’s sailing right through length to termini.


    All right. The sport of curling.


    Oh curling, my favorite sport, grew up on the old ice rink, curling. Curling, I guess for those of you who don’t know curling, cause I had to look a little bit myself, to be honest, you have this 42 pound, what’s it called?


    Curling –


    Curling stone. And you get down low and you give a push, and you release, and it comes sliding along the ice, and if it goes exactly where you want it to go, if you’re the last shot, you would go to the house; it’s called the house. It’s like a goal. And then there’s these people in front, they’re sweeping, and what they’re doing is warming the ice, reducing friction, to help the curling stone, 42 pounds, keep gliding on a straight path to the house. So, if I do pre-enlargement endodontically and get all that stuff out of the way, the curling would be like the RC prep, the viscous chelator, to help that file slide right to the house or the terminus, yeah.


    Okay. Simone Biles giving a winning performance on the balance beam.


    We have a lot of discussion on the set about balancing, you know, the objectives of shaping canals, you know, this minimally invasive thing, with the ability to still three-dimensionally clean, so we have to balance those two things.




    Just stay on the beam.


    Not making the cut in golf.


    Okay, in golf, in professional golf, there’s – you play for four days. Each day is a round, 72 holes, and so Thursday and Friday you have to have a certain score, or you get cut and you go home. So, it’s kind of like you’re not so good at endo and you’re working really hard on Thursday and Friday, but you don’t make the cut and you’re eliminated, and you can’t do anymore endo.


    Okay, or maybe the tooth isn’t even a candidate for treatment and has to be extracted.


    The tooth didn’t make the cut. In fact, the tooth was so, should we say mutilated, from the first two days of golf, that we actually just didn’t make the cut and the tooth is extracted, yeah.


    Okay, a false start in swimming or track.


    That’s like isolating the tooth and you don’t have profound anesthesia. It’s a false start.


    Okay. The Triathlon.


    Oh, where is the Triathlon? Which page? Oh, I get it. A Triathlon, three things, huh? Would that be like the triad or the trifecta, would that be shaping, cleaning and disinfection and filling root canal systems?


    Okay. So, here’s a specific scenario. So, the LA Lakers are winning by 20 points, but then the Phoenix Suns go on a 16 to 2 run and Frank Bogle has to call a timeout.


    Well sometimes I learned from my mentor years ago, you’re searching and searching and searching for the elusive orifice and you can’t find it, so you simply close the case to live and fight another day. So, you take a timeout so when they come back on another visit, a lot of times it’s like wow, I’m surprised I couldn’t see it.


    Okay. In baseball, a perfect fast ball, the batter swings, makes solid contact, but instead of hitting it out of the park, the bat breaks and the batter is out at first.


    Okay, so I’m shaping along, and everything is going absolutely perfect, and I fit my cone. It’s just a little bit short and I want to just adjust the prep a little bit, so I go one more past the length and [snapping sound] I hear that famous old noise and my heart sinks, cause when I pull the file out, the one I pull out is a little shorter than the one that went in.


    So, the Biathlon which is a combination of cross-country skiing and rifle shooting.


    Well, you know, I don’t know if this is a good one, but when you’re skiing, it’s very – it’s a big exertion. I mean it’s like an amazing cardiovascular event to be going up the hills and down and skiing. When you come in, you have to like get down on the ground and take a rifle and you have to hit a target. So, you’re probably breathing pretty hard [panting sound] so, you know, be careful what you aim at. So, in dentistry, maybe it would be like the importance of pre-enlargement; it’s an easier pathway, it’s not so vigorous, but when you get to the apical third, you got to slow down, slow the game down, you got to be very precise, don’t forget to breathe, breathe very rhythmically and meet the apex.


    Okay. The role of the –


    Let me correct that. Meet the terminus.




    Please correct.


    The role of a quarterback in the NFL.


    Well in the dental office, I guess if we do it correctly, we have a leader. It’s called dentist. So, that is the quarterback that quarterbacks the dental team, and so you can set the goals, you can set the expectations, and finally, you can even pass the ball or hand it off to valuable team members to reach the goals.


    Maybe even a referral. Maybe those are your receivers.


    Yeah. Maybe just a referral, good point.


    Okay, so Michael Phelps swimming to victory in freestyle.


    Well, you know, when I see them swimming, there’s a lot of beauty and rhythm, but actually, if you kind of stand back from a thousand feet and you see all the lanes, it’s just flailing. I see flailing arms and legs. They show those underwater shots, and those feet are going like that will remind me of the Endo activator submerged sub-orifice level, agitating the solution to achieve 3D disinfection and get the Gold Medal.


    Okay. A world record is more likely in downhill skiing when the snow is tightly packed.


    Well, when Ruddle down packs and back packs, I want a very tight pack to ensure the seal and to ensure success. And to win another medal.


    Okay. Passing the baton in a relay.


    Passing the baton in a relay. What do you got?


    Well, that’s kind of like interdisciplinary treatment, I guess.


    Oh right, passing the baton. Yes, and so when we have interdisciplinary treatment, we have a team, and sometimes I need you to help out, do something, then we get it over to the orthodontist for eruption, and we go to the periodontist to get osseous re-contouring. And then we go to endo and then finally back to the restorative dentist.


    And then maybe dropping the baton could be like you didn’t transfer the patient –


    Oh, drop it.


    – records or something?


    Yeah, dropping the baton happens in interdisciplinary treatment if there’s a failure to communicate.




    So, not only do we have to communicate among the dentistos, but we need to communicate the dental teams, teams with an “s” needs to communicate with the patient cause the patient wants to know where do I go next?


    Okay. How about the marathon?


    Well, the marathon is you’re in for the long haul, right? It takes a lot of endurance and training, so that’s probably like trying to get through a nuisance – not a nuisance block, a stubborn block, like maybe it’s had – we call it Russian Red, not to offend my Russian friends, cause I’ve been to your country. It’s a great country, but there is some paste that’s dispensed in that country in the older days, and we called it Russian Red, and it was brick hard. So, you’ve got to have patience to sit there and perseverance to get – you have to want to get to length. And of course, you’ve got to have the right, you know, solvents and stuff like that.


    All right. Boxing or martial arts.


    Boxing or martial arts. Help me out on that. Give me a lead.


    Well maybe it’s just a struggle. Everything seems to – maybe you’re ducking the problems and looking for the opening.


    Oh great, and the opening would be discovering the orifice at the ninth hour before you re-schedule for the next visit and then finding the slide path and reaching length. That would be getting a blow-in.


    Okay. Okay, so we have one more, and this one is penalty kicks in soccer or hockey to decide the game.


    Well, that kind of reminds me of a soccer game that ends, and it’s tied, so there’s an incomplete result. So, we still don’t know the outcome. That’s kind of like when you treat a case and the patient has persisting signs and symptoms and you’re maybe not sure should you do surgery, maybe that’s the first penalty kick. Maybe you say no, let’s do nonsurgical re-treatment. That could be the second penalty kick. Let’s extract the tooth. Maybe that’s another penalty kick. Anyway, the outcome is uncertain, just like when the game is ending in a tie. It’s uncertain; we don’t know.


    To me that’s almost like well, treatment ended, but maybe there’s still signs and symptoms like you just said, so maybe you need to do exploratory treatment, which we just talked about on our last show, and maybe you’re going to search for various things. So, those would be the penalty kicks, like maybe there’s a perforation, maybe there’s a missed canal, maybe there’s –


    The outcome is uncertain.


    Yeah, so just some fun, and we hope you enjoyed it and we’ll see you next time on The Ruddle Show.



    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 10


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    What is the Appropriate Access Size?


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    Tips for Finding Canals & the Difference Between a Ledge and an Apical Seat


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    Censorship in Dentistry

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    Endodontic Diagnosis & The Implant Option

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    08.31.2023 Update



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