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…Oral hygiene, so it’s actually going to be very helpful for them.

Yeah, I’m on a permanent mouth rinse with it right now to get around those newly placed implants…

Welcome to The Ruddle Show. I’m Lisette and this is my dad, Cliff Ruddle.

How you doing this morning?

Pretty good; what about you?

Oh, I couldn’t be better because I got an email this morning and it had attached some Indian music from ancient India, the continent, and it was very lively.

Yes, one of our biggest fans.

Yeah, VK.

Well we thought we would start our show off today talking about micro robots. So have you heard about the research that the University of Pennsylvania is doing on micro robotics? It’s an ongoing collaboration between the dental school and the school of engineering, and they’ve produced a micro robotic system of nanoparticles that can perform a wide variety of functions. And it’s going to be pretty game changing; it’s pretty exciting. What are some of the things that these micro robots can do?

Well you know, I guess I should do to the audience what I had to do. Let’s get some scale, okay? So everybody probably watching this show has done some endodontics. I know there are some of you that just watch it for the love of it; you’re not even dentists. But if you did endodontics recently, internationally we use a millimeter; millimeters come to mind. So 1000 microns equal 1 millimeter. 1000 nanometers equals 1 micron. And listen carefully: one million nanometers equal 1 millimeter. Now you have the scale.

So what can they do? Well basically what they can do is they can be guided with precision into all aspects of the root canal system. So if they just heard me, that means they can get into a dentinal tubule. So forget the lateral canals, they can get that; that’s like a freeway. But they can get into tubules, because tubules are about 2-4 microns; 2 towards the cavo surface and 4 towards the shaped canal. So they can be guided.

They can – mechanically and catalytically they can be guided into places and they can do work; minor work, but very interesting work which we’ll describe later. They can transport pharmaceuticals to targeted areas, they can retrieve and take samples that can be looked at under a microscope for cultures. They’ve identified the four bacterium that are most common in the root canal space. They’ve taken them out of simulated models and looked at them under a microscope; yep, that’s what it is. So they can do a lot of things. And then you talk about the brushes, the brushing concept, and one aspect that I’ll talk about it from an endodontic standpoint.

Okay, well like on a larger scale, they can actually brush and floss teeth. And this is really good for – there’s a lot of older people or people with disabilities that have trouble with their oral hygiene, so it’s actually going to be very helpful for them.

Yeah, I’m on a permanent mouth rinse with it right now to get around those newly placed implants.

Yeah, okay. So that’s pretty interesting. In terms of what got me excited about it endodontically – because everybody knows that I’ve tried to make brushes for years; had patents on them and then it became the EndoActivator polymer tip, and then different configurations in the cross-section of that tip. But the bristles from a micro robotic standpoint can be elongated. You can change the diameter of those bristles to do bigger or smaller work, so they can be extended, you can change the diameter. Listen carefully; you can even adjust the stiffness and flexibility of those bristles. So I envisioned this big flush with swarming stuff going on with robots, and this incredibly clean things and we throw away all of our other devices.

Well it sounds pretty amazing. What are the made of and how do they move?

They use iron oxide nanoparticles, so they call them IONPs. And those are about 11-12 microns. And so that’s the building blocks, and then they can put them together into two platforms. And in one of them they can make a whole bunch of them, and they can guide them and they can swarm an area. And when they swarm an area, they can go in and take samples.

They guide them magnetically, right?

They guide them – oh, okay; good. Because of the iron oxide, they can be guided. And they can be guided into electromagnetic fields and they can get different alignments. And you can swarm them into an area – you know, like biofilms might be a sheet or a mat – you might want to get them in there in greater numbers. So that was one idea with one platform is to have them swarm, these nano – these iron oxides.

The other one was they actually built – they did 3-D printing and made miniaturized; very tiny, itsy-bitsy little nanoparticles could be built into like a corkscrew, a helix. And that helix, if you put two of them together; they were embedded in an iron oxide gel. So now they could be guided electromagnetically, they could be aligned, they could perform, do work. And those again could be used to retrieve samples, like of biofilms; to disrupt biofilms and break them up and eliminate them. And then to transport, as we said, targeted medicines to areas.

You know, I think we both could agree that this sounds pretty exciting. Like when I first – I first just came upon a headline that said something about micro robots in endodontics, and so I gave you some papers, some kind of more newsy articles to look at. And then you just really started reading a lot more about it, because it’s pretty exciting. And so I think that in the future we’ll do maybe a much larger segment on this topic.

Thanks for bringing that up, because those papers you gave me, I got pretty excited about it. You know, I’ve been around the field for close to 50 years and it was like the future; now they’re doing it. They showed – actually Penn showed they could track these things with CBCT, so it’s not like they hope they’re going to the terminus of a canal. And they can get around tissue and pulp stones. Because they’re so small, the tissue didn’t seem to influence their ability to move and to guide them.

Well I start to even wonder. Like what if they even combined this technology with AI? Then all of a sudden it starts to seem more like science fiction than reality.

That’s all going to happen isn’t it?

Yeah. I think there’s a movie that kind of reminded you of this whole idea.

1966! The big old sci-fi thriller. Fantastic Voyage. And real quickly, a famous international scientist had a brain tumor and it was inoperable, and they couldn’t use any chemicals to break it down like they can with some clots. So they had the technology in ’66; at least they had the idea that they could miniaturize people! So they miniaturized a separate team of people and their subatomic -

Submarine?

Yeah, it was called Proteus. And so they all were miniaturized. And they could only be miniaturized for one hour. And then they’re in a solution, in a syringe, and they’re injected into the body. And they're traveling through the body and they have to go through the vasculature, and there’s some exciting turbulence.

You can see they’re in probably a vein or an artery or something.

They’re in a big artery, and they almost lose their lives sometimes when they get to bifurcations.

But anyway, this guy is going to deploy a rifle laser; a laser rifle. And he’s going to hit that clot and he’s going to break it up and disintegrate it, and that’s what the movie’s about.

Okay, well you might want to check out the movie, and you might also want to check out more stuff about micro robotics. But for today, we have a great show planned, so let’s get going on it.

Okay, so it’s time for another segment of Knowing the Difference. And for those of you who don’t know, this is one of our favorite segments and it’s inspired by a quote by the 18th century French author, Madam de Staël, who said “Wit consists of knowing the resemblance of things that differ and the difference of things that are alike.”

So today we wanted to approach this segment with regard to making a treatment decision. Specifically, should you work through a restored crown for a tooth that needs endodontic treatment, or should you remove the crown?

So we’re going to start off first by talking about some more obvious considerations. And then we’re going to, through our discussion, come up with some things that maybe hadn’t initially occurred to you. And then finally Dr. John West is going to give us a little help. Right?

That’s it. That’s how it’s going to go. Decisions. Madam de Staël, Knowing the Difference.

Yeah, I decided to talk to John West about this because he’s been practicing like I have, about 50 years. And I thought remember that old expression – I’ve heard it three different ways, but I’ll just say it the way I like to say it. There’s somebody that’s smarter than any of us and it’s all of us. So I got ahold of John and I said John, when you assess a patient chairside and you’re going to be doing endodontics, and the tooth is restored, how do you come to those decisions? And he thought it was – I’ll let him talk about what he thought the question initially was. But anyhow, yeah; I did talk to John.

Okay, we’ll get to that later. But first, when I first started talking to you about what should be considered, there were three things that immediately came to mind. We have a list that we’ll start on. And so what were those three more obvious considerations that immediately occur to you when you’re assessing if you should remove the restored crown?

Good. If you’re going to go into a restorative, of course it comes to mind: does it fit? Does it have marginal integrity circumferentially? So marginal integrity.

The next thing is does it have good occlusion? So when the patient goes into work and balance and protrusion, is this thing working well in that environment? Occlusion.

Contours come to mind, because you can have good margins and have great occlusion, and maybe it’s a bulky crown that creates periodontal problems. So we also have a periodontal situation. We probe around these crowns; we want to see is the biology accepting the restorative? Is it subgingival or if it’s right at the margin. So how does the tissue look; how does it probe?

Okay. And then I guess esthetically. Is it esthetically pleasing as well?

Well thank you for mentioning that. It might meet all those criteria, but if it’s a black tooth, maybe it doesn’t look so good.

So yeah. The esthetics is going to be a big deal, especially in the esthetic zone. So I usually don’t – I always have opinions; who doesn’t? I was going to say something very bad. But anyway, yes; we all have opinions. But ask the patient how do you feel about the esthetics? Especially if the tooth is in the esthetic zone. Because they may say I don’t care how well it fits; I don’t care about the contour, occlusion, periodontal. Get it out of there; I hate it.

Okay. So if the crown fits well, the occlusion looks good, the gums look good and it’s esthetically pleasing to eye; would you say that if all those criteria were in place, you were more apt then to just start treatment by working through the crown?

Yeah. I usually always tried to work through a patient’s crown, because it was about trying to save them money. I mean they were coming to me, and this is probably an unexpected financial event because nobody plans for a root canal. So you’re trying to save money for the patient. But again, the criteria we both spoke about needs to be there. I mean you can’t hope that it’s going to be okay. If it doesn’t fit, it doesn’t fit. So I usually work through teeth if the criteria was met; the ones we’ve been speaking about.

However, I would always want to point out the importance of communication. When you’re chairside, before you ever tip the chair back, before you ever start, have a very eye-to-eye level of contact with the patient and talk about risk versus benefit. And we’ll get to it in a little bit, but materials make a difference. So you’ve got to talk to people about what could happen in the event that you disrupt the crown or you blow off some glass – porcelain is what I’m saying.

Then once you start to get in, you also might change your opinion. You might encounter caries that you didn’t see externally. You might see staining. You might see evidence of delamination; maybe the bonding material is debonding and you’re starting to get leakage from inside that you couldn’t demonstrate outside. It could be fractures running down the axial walls. So in any of these instances, you might have to put the chair back up and say what you found, because you now might want to take the crown off that they thought you were going to work through.

Maybe the biggest thing is there are some removal devices that we’ll get into a little bit later, but it would be retreatment. If you’re doing initial treatment, that’s one idea, but a lot of times in my practice I was re-entering teeth that had previously treated. So you might have to take the crown off, even if it meets all the criteria, because maybe you need more access to get out a post. Or maybe there’s a broken instrument and where it’s lining the canal you’ve got to change the angle of the axial wall, and that might infringe on – porcelain is an example; make it too thin. And then porcelain, you should anticipate. Think ahead; start with the end in mind. Would be porcelain be predisposed to break? So those are some of the things I’m thinking about.

Okay, so we’re adding to the list now. Is it initial treatment versus retreatment? I was actually surprised. You told me that the majority of crowns have not actually had endodontic treatment. Is that correct?

Oh yes. I mean -

This is just a separate thing. Because I had actually initially thought that if you had a crown, you had probably already had endodontics. But is that not the case?

I’ll just say this quickly. Pretty much every tooth I ever go through had a pre-existing restorative crown on it. It probably makes sense if you start to think about it. Why do we even do root canals? Well, it’s a Class I, then it’s an MO, then it’s an MOD, then it’s a Class 5, then all of the fillings are going to Hell in a hand basket and it becomes a crown. Well all those are insults to the pulp and at some point pulp degenerates, and then they become symptomatic oftentimes, and then we’re working through crowns.

Okay. But you can have a crown and just maybe it’s just a buildup of your tooth or something; it’s not had any treatment.

Absolutely.

Now I see on our list that the crown material is also a factor to consider when you’re going to work through it, correct?

You know, that’s a great one that you asked, because everybody out there knows – you’re all dentistos and you work through ceramics. Examples could be zirconium; it could be lithium disilicate. You’re working through porcelain fused to metal, you’re working through gold crowns, you’re working through non-precious. So anyway, all these different materials is what she’s talking about.

But I guess what I didn’t realize is maybe step out of my endodontic shoes and run to Glidewell Laboratories. That’s the biggest laboratory in North America. And you might just say to the owner, what is coming out of the shop? All over the big cities; Glidewell, Glidewell, Glidewell. So Glidewell says statistically, that 87% of all the crowns they deliver are zirconium, and that’s a really wonderful, wonderful material. I’m not going to go into materials today, but it’s a wonderful material; it’s become very, very popular. So that’s slowly replacing porcelain fused to metal as an example. So that’s a ceramic type material; it’s actually aluminum oxide. But anyway, crystal structure is micro robots.

The other thing is if you – their next big crown was the lithium disilicate. Those are very, very esthetic crowns.

Are those materials easy to work through?

No, they’re not easy to work through, and everybody knows that. So these are – I’ll just call them ceramic – zirconium and the lithium disilicate. Those are very hard materials; they’re brittle like glass. And those of you that access through them, know that you can go through a lot of diamonds – brand new diamonds out of the box – to get through. And then keep things cool, because we don’t want the heat buildup as we’re grinding through glass. So yeah, that would be basically it.

Gold crowns are really easy to go through, as you know. Gold, elemental gold has a lot of alloy, so it’s not too soft, but it’s easy to drill through. Porcelain fused to metal, we have some glass, we have to be ready so it doesn’t blast off. And then there’s metal underneath that, but it’s pretty thin because they don’t want to reduce teeth too much.

So anyway, those are some of your considerations. And my whole point here is from reading up on Glidewell Laboratories, there’s a lot more of those ceramic type crowns out there than when I was practicing in the ’70, the ‘80s, the’90s and the first decade of the 21st century.

Okay, well I imagine that the material that the crown is made of plays a role, not only when you’re going to work through it, but also if you’re removing it. Probably some crown materials – crowns are harder to remove of certain materials than others?

Bingo! Yeah, bingo, bingo. If you see a gold crown, there are removal devices. And we’ll let John talk first. But anyway, there are some removal devices we’ve talked about on this show, so you’re thinking I can get a gold crown off. I can probably get a lot of the PFM crowns off. But remember if ceramics flex 1/10,000th of an inch, they shatter. They blow up; they actually disintegrate. Or a big piece, the whole buccal wall will just fall off while you’re drilling away. So that’s why you want to have that communication before you start a treatment plan for no surprises.

Okay. And I guess we’re talking really about three scenarios here; either remove it or keep it on. But then under remove it, like remove it carefully so that it can be replaced versus remove it and maybe it breaks and you throw it away.

You know that’s huge. I don’t know that I as a dentisto – but you made that very clear. So you’re either going through something that’s existing with a plan to keep it in place, or you’re going to remove it. A or B. Within the B, just as you said, you might just saw it off and sacrifice it and put it your jar for a rainy day fund. Or you’re going to take it off intact, as you said, with the idea that when I’m done, I’m going to place this back on and it’ll be serviceable.

Okay. Well maybe now is a good time for us to pause and hear what John West had to say on the issue.

So can I say this? So on The Ruddle Show, here comes Johnny!

[West Segment Begins]

Hello everyone. Some weeks ago, Cliff Ruddle asked me a question. He said what are your considerations when performing endodontic treatment through a patient’s tooth that has restorative dentistry already, such as MOD amalgam, crowns, etcetera? Do you disassemble and do the endodontics? Or do you do the endodontics and then patch things up as you go or afterwards?

I’ll be honest with you. I thought it was kind of a crazy question to start with. Because obviously you’re going to radiographically or visually or manipulating to determine if restorative dentistry is loose. And if so, you want to remove it of course. Disassemble before you do the endodontics because it could cause leakage as you’re doing the endodontic treatment. And also it may be that the tooth is actually unrestorable. So it makes sense to take it apart if it’s already showing evidence that it needs to be taken apart. But like most of Ruddle’s questions, there’s insight into this question.

And so I gave it a little bit more thought, and what came to me is the quote by Dr. Bob Barkley, the Father of Preventive Dentistry. And his famous quote for me is, “Dentistry makes patients worse at the slowest possibly rate.” When you think about it, that’s what we do. If there’s caries on a mandibular first molar, we do an MO restoration, and if there’s caries on a distal, we do an MOD. Then the cusp falls off, so we do an inlay or we do a full crown. And we keep restoring the dentistry as it’s required.

And so that got me to at least think about Cliff’s question about longevity and what Barkley’s comment was. And the first thing to realize is we are getting older. I mean in Roman times, you lived to be about 18 years old, you had a baby and died. And Mother Nature was very pleased, because she could see things born again and die; born again and die. And then we messed her up and now the average life expectancy is approaching 80 years old. And according to estimates, if you’re born in say the next few years, before around 2030 say for example, the predictability of life will be 200 years. And you say wow; how could that be? Because it’s the exponential curve where the tip of the – the period beginning of the exponential curve, because of robotics and bioengineering, we’re living longer and longer. And our teeth have to last longer because we want to look good, smell good, appear successful, and teeth are part of that. And if you think about it, the first person to live to be 150 years old is actually alive today. They just aren’t 150 yet; maybe they’re 120 or something.

Anyway, so what do we need to know about Cliff’s question? So I asked first of all about the longevity of restorative dentistry. And I went to Dr. America, Gordon Christensen, and he sent me some notes; I’ll read them to you.

First of all he said (1), sealants usually last – 50% fail in five years. So if sealants last, 50% fail in five years. Class I, small ones 15 years; large ones 6 years. Crowns if properly done 20 years; 10% die and require endo during the 20-year service period. We also see that if general practitioners accomplished endodontics, that 20% failed after five years, requiring tooth removal. So that was just interesting.

But really point I want to say here also about crowns is the use of the instrument, CORONAflex by KaVo. And it’s a very safe and predictable way to remove crowns and FPD abutments for example. They used to be about $3,000. And if you look online now, they’re less than $450 I think. So if you have never invested in CORONAflex, this would be the time.

He also just pointed out and I’ll share with you. Implants we are seeing at 10 years peri-implantitis begins to set in for many cases, and the implant begins to fail. We have no data on implant removal. So that’s Gordon’s perspective.

So the dentistry has to last a long time and it’s breaking down before the patient is done with that tooth or those teeth. So anything that we can do to improve the predictability and discovery of disease sooner and before it becomes catastrophic is of great value.

I’ll mention two pieces that are intriguing to me and then I’ll let you come back on, Cliff. But one is Logicon by Carestream, and it shows caries before we can see them in normal x-rays. And this has been a real great boon for dentists to again discover things before they become really catastrophic, and maybe even prevent the caries from getting along further based on this kind of software.

The second instrument is Innerview, I-N-N-E-R-V-I-E-W, by Perimetrics, which is a device to discover cracks and loose restorations before we can see them; actually when they’re invisible. And this technology has the capacity I think to be truly transforming, or I guess we’d call it disruptive; permanently disruptive technology. Perhaps the most disruptive technology that I’ve seen since x-rays. But it’s an instrument that looks similar – you can look it up on Internet – similar to a toothbrush, electric toothbrush, and you can tell in seconds whether the tooth has loose restoration. GAFF technology it’s called; it’s oscillations is what it really measures. It’s simple to use and highly predictable, and with the help of AI, it’s really become something that really could be potentially significant. Something to just to look at on the horizon. And keep up with your awareness of teeth have to last a long time; the closer we look the better, Cliff. And as far as access through existing restorations, that also depends on you and the restorative dentist’s relationship on how to deal with that. But more likely than not, if I have any suspect whatsoever that that material is coming out or that crown is going to be tested with the CORONAflex. But often you can see bubbles with a microscope if there’s movement of the crown against the root itself, the prep itself.

So the answer is still pretty straightforward Cliff, and I hope I didn’t uncomplicate it too much. And now back to you, Lisette.

[End West Segment]

Okay, so he does raise some good issues regarding life expectancy and also the life of a crown.

Yep, he sure did. You know, Gordon Christensen, a really well-known, respected international clinician, teacher, researcher, etcetera. Clinician’s Report is the publication, and they have an arm within the Clinician’s Report called TRAC. And I forget what it – it’s TRAC. Technologies in Restorative And Caries Research. I think Ruddle does a lot of that too. But the point of bringing this up is they can talk to their group. They have thousands of dentists in their group and they can find out the average half-life of a crown. So Gordon says about 20 years. And I wanted to mention TRAC so there would be something behind that. I didn’t just – Gordon didn’t just snap his fingers; 20 years.

In California where I have practiced all my career, insurance companies will pay to have a new crown on the same tooth that there was an old crown that they paid for in five years. So Gordon says 20 and 5, and then I have some crowns in the back of my mouth where I replaced a couple because I blew off some glass; porcelain, ceramic, there you go with that brittle stuff. But I’ve had them in there for 50 years; 49 and 50 years. So we can see there’s a big range of half-lives of crowns.

Right. But it’s also not unreasonable to think that if you get a crown when you’re in your 20s, you might have to have it replaced at some point in your life.

That’s a good point, because if I get a new crown today, it better ride me all the way out to the finish line. Of course I got a book the other day in the mail that says how to live to be 156, so I might be 2 or 3 crowns out.

Okay. Well apparently after John submitted this video to us, he was still thinking about the topic for some time afterwards. And he actually wrote an addendum to his video that he wanted us to read on the show. So I’m actually going to read that now.

Yeah, it was really good though, because he said so many smart things to all of us. So he went and like I talked to him, he went and talked to some people.

Yes. And I guess he was thinking a lot about why would a crown need to be replaced in 20 years. So here’s what he says…

“Then I thought just how much ‘beating’ does a tooth take over the average lifetime? The best estimate I have been given is by Professor James Earthman, Professor of Materials Science and Engineering and Biomedical Engineering at the Samueli School of Engineering, University of California, Irvine. Professor Earthman writes: ‘The best estimate I have, and it’s a rough estimate, is about 1 million significant loading repetitions per year.'"

...And then he references the papers that we’ll have in our show notes...

“This means that an 80-year life expectancy and 70 years of chewing on permanent posterior teeth, that the ‘loading repetitions’ to those patients’ teeth could be 70 million impacts! Cliff’s right; these endo teeth must first be carefully evaluated for chewing wear. These combined data has made me think twice about assuming everything is OK with the existing restorative and off I go with my access. No wonder Cliff asked the introspective question of do we endo access through existing restorations or do we disassemble, realizing that invisible loss of restorative integrity may elude us without close inspection. After a little research to Cliff’s question, my last word about performing in teeth with existing restorations is that I better use greater diligence in my pretreatment clinical observations, and that I use every instrument available to diagnose the quality of the existing restorative when planning the endodontic treatment sequence.”

Wow! Well you know, he talked about Innerview. So the thing about Innerview that’s so great – and we’ve had Dr. Cherilyn Sheets on this show, and she is the idea person behind Innerview; and then she has a whole team of AI guys – we mentioned Kwan and Earthman. I was just down at her office this last weekend again to have a little dental work done on those restored implants. But also I had a chance to get in a room with Earthman again, and we had some very fascinating talks. He had his grad student there making all these 3-D models, and they’re simulating cracks in those models so that AI can make distinctions between cracks that propagate occlusally down, or cracks from obturation loads that are generated within the roots and move apical coronal. So it was nice to touch base and see where the research keeps going with this. But he mentions use all the technologies at your disposal.

Okay. So let’s actually bring up a new list because our list is growing. So now we’re also considering the age of the crown as well and how much load it’s undergone. And also the technology, which you were just going to go into.

Oh, okay. I got a little ahead of myself. It’s not so easy to follow these scripts.

I think the age of the crown does make a difference, because we just learned from you and Earthman. In fact, I was talking to him about the things he reported to John West by email. I asked him about that Nalla Study that you said would be posted. But he was talking about these 70 million big loads. Well they saw – Innerview could see oscillations in some of my cemented crowns that are perfectly intact; they seem to be on. But now we can pretty much anticipate there’s some cement failure that’s happening. So you can be picking up things with some technologies that would better help you communicate to your patient about what might happen if you try to go through an existing crown with the idea that you’ll save it.

He mentioned Logicon; that was Carestream, the big company. They have a new software that can help you see caries earlier; that would be under the margins. But I also talked about tomosynthesis. I’m less familiar with that. West was aware of that. I’m more aware of tomosynthesis because we’ve had different people on our show talking about it. So that was a way of showing earlier things quicker than conventional radiography; I can throw in CBCT as an example.

Right, and then also crown removal devices. If you have like CORONAflex in your office and you’re really adept at using it, and you don’t damage crowns really – you find you’re good at taking them off and putting them back on – maybe you might want to just take it off then.

You know CORONAflex, I learned something from John. I think I might have had one of the first ones in North America, because it was given to me by the KaVo Company at that time. And I came home and talked about it 25 years ago; it was $2500. John said oh no, no. I think it’s like $500 or $600 now. So the price has come down; everybody can have a CORONAflex. But it’s a serious device to remove restoratives, with the caveat; be careful with ceramics. You can try. It doesn’t ever hurt to try because you were going to cut it off and throw it in the wastebasket anyway, so what if you could get it off? So if it broke, it’s not such a big deal because you were going to destroy it anyway.

Okay, well then we have our last consideration.

Higa, Kline, Metalift. These are things we’ve talked about on other shows.

Okay. So our last consideration: Who placed the crown. And I know you’re going to tell me who cut the preparation and placed the crown.

I didn’t ask Gordon Christensen, but I bet you if I asked him about longevity of crowns and we got past the materials and the fit and the esthetics, he would say it’s about the preparation, stupid! That would be a really direct comment from Gordon’s mouth to my ears because he talks about the preparations. And here’s another thing. He said that if you walk through a big laboratory like Glidewell, any dentist on this planet, and you just walk through and you start observing what they're doing, he said everybody would be totally convinced the preparations could be a lot better. Think about that. Think about that.

And then he said why is that? And then he had another little list and he said well, in dental school they have too much to teach in four years. I mean when I went through dental school there were basically – we had to learn, I’ll just say five things. Well now they have to learn 15 things. So they don’t have a lot of time, the kids are rushed, they don’t have experience. A lot of kids in dental school do a single digit number of crowns; 2, 3, 4; 8 or 9 would be a lot. So they don’t have experience. And they get out and they have a mountain of debt, and Gordon says they have to really start working. And sometimes when we’re in a hurry, we don’t do our best work.

And then finally I think the last one was they are hesitant to take classes. The younger dentists are more hesitant – he has noticed, I have noticed – to take classes; whereas it’s the middle aged and the older people that are going to the classes and learning how to really do stuff.

The younger people probably feel like I just got out of school. I’ll wait till they update some things.

That is a huge point, and they’ve done 3 crowns.

Okay, well do you have any final comments?

Yeah, I’ll go back to Madam de Staël, and I would like to think that these eight factors that we’ve talked about will open up even a plethora of additional sub-categories and you’ll begin to understand it’s about knowing the difference.

Well thank you. Good Segment!

All right. We’re going to do a little Q&A. It’s a little mini one today and it’s going to be related to thermal injuries. So are you ready for it?

Ready for thermal injuries. Ouch! Oh, I had a thermal injury.

First question. I recently read that lasers used for irrigation can cause thermal burns. If I were to purchase a laser, do I need to be concerned about this when using it?

That’s a great question. In fact it’s being talked about a lot on the AAE Forum, and I’m surprised that some of these fundamental things weren’t understood by our profession maybe a decade ago.

First of all, we’d better just talk about what’s appropriate. Er:YAG is by definition 2940, and we just had a little comment on nanometers, so now everybody’s really up to speed. And then we have Er, Cr, and we have YSGG. Just so you’ll know, Erbium, Chromium, yttrium, strontium, gallium, and garnet. And oh yes, and this is 2780. Why am I making a big deal about this? Because these are really the most important wavelengths for endodontic disinfection. So there’s a whole bunch of lasers, but these two give us the wavelength that can burst a water molecule and blow it up. And water is part of every cell; microbes, pathogens of all kinds.

So then now that we know that – because there’s other lasers, low frequencies. But really then we have the choice of are we going to – we have a canal and are we going to have to put the laser starting down in here? And I could have used a different color; it might have been a little bit helpful. But these wands are to be withdrawn at 1mm; so start pulling up 1mm per second. So you fire it up and you slowly pull out.

Now there’s – when you’re doing this and the depth you’re in, the diameter of the canals, the curve. Those are all variables; I’m just talking about a straight one. But you can imagine incurvature, or recurvature. So if you touch the walls, you can get what is called in the literature a melt or a burn. And then Lisette said well if you burn the inside of the walls, is it going to – okay, we could get into that all day. Does it matter? That’s what she’s really asking. And we don’t know that it matters initially, but we don’t know long-term if it leads to more brittle teeth. The big deal is the transdentinal conduction of heat. And thermocouples can be placed out here and you can measure the transdentinal conduction of heat. And that’s what you have to be careful for.

Fortunately these teeth have PDLs around them. The PDL wicks off heat because it’s got blood; it’s moisture. So even when heat transfers, the moisture can be somehow wicked off.

The one that I think that I would buy in today’s world would be the one that – you’ve got your access up here, and you just hang out in the chamber. And whether there’s 3 canals, 4 canals, you are confined to the center of the chamber, and all of the steam bubbles go out through all 4 corners of the root canal system, and there really is no heat buildup.

So if you’re going to get a laser, I think you want to look at 2940 or 2780. I think you want to look at ones that let you stay up in the pulp chamber, because the money is about the same, so why would you want to have to go down around curvatures and have all those little devices that the difference – is it .2, is it .3, is it .4? You’ve got to have a whole cadre of these little things. Now if you shape consistently, you might be grabbing the same wand every time, but they're expensive; they can break.

I just want to add. If you’re using this one where you’re putting the wand down into the canal, you probably are going to want a more fully prepared canal and not so minimally prepared?

Look. These stunts, GentleWave and lasers, are what we’re really – we’re talking about lasers – they are made for minimally invasive preparations. So their whole surge in the marketplace has come because a lot of people are now reducing the size of their preparation. I love your question; it’s very intuitive; I wasn’t even going to talk about it. You would probably have less issues in all this if you made a typical preparation of about 2508. Why do I say typical? Because it’s all through the literature; it can be cleaned and disinfected.

So a lot of you are doing preparations that are 1704. Well there’s a huge difference in 4%, 8%. So what Lisa is saying is these technologies have allowed us to have smaller shapes, but with the advantage of addressing smaller shapes, we have things about thermal burn. So that can be rectified by just knowing I’d like to get a laser that stays up in the pulp chamber. How about that?

Okay, next question.

Done?

I’ve heard you lecture that ultrasonics can be used to remove a post. But if the post is metal, won’t this cause a thermal burn?

Okay. So you’ve got a tooth in here, and it’s had endodontics, and the apical third is corked with probably gutta-percha. And then there’s some kind of a post system in here that has a retentive head, and this is holding the tooth. And Lisa just said, we’re going to say it’s metal. So metal posts can build up heat very quickly and remember it’s always about two things. It’s about the magnitude of the – whoa, we’ve got a misspell here, coming right off the bat here. We need to have injuries we need to think of them in terms of magnitude and duration.

So the main way we knock posts out is ultrasonics. And we use ultrasonics on the head of the post, so you might even have to expand your access a little bit to get room. You want to move up and down the head of the exposed post with your ultrasonic tool, so it might come out of here and be contra-angled and be vibrating. And as you vibrate, only about 30 seconds goes by and significant heat can come right through the root. And this has been published by Gluskin, Ruddle, and Zinman; Ed Zinman. Zinman. Anyway, he’s an attorney/periodontist. And we wrote a paper in 2005; it was in the JADA and we talked about thermal injury lawsuits, necrosis. But if you get bone up to about 10° and you stay there, even for split seconds, you’ll get osteonecrosis and you’ll get bone – osteomyelitis and bone loss and pus, and teeth will get mobile and the gum will swell facial to the tooth – a lot of times in this zone up here we’ll see it. And it’s catastrophic. The tooth has lost grafting procedures and it’s really nasty. So wick off the heat.

We wrote in this article that you should be using air water. So as you’re vibrating – brrrrrr – the assistant can be using the high speed suction and the water, and she can be wicking off the heat. Now of course we have PDLs, but we know the heat transfer is very quick. You can even take your finger and put on the head of the post if you want to check to see how hot it is. If you’re a masochist you want to get a good burn.

So I would say basically just be aware of heat buildup on all metal posts.

Say you did burn the patient and they don’t feel it because they’re under anesthesia. When the anesthesia wears off, is it going to hurt?

You know what they usually report? The tooth is really quite sore; they’re surprised it’s so sore post-treatment. But then what happens is the tooth starts to get loose. And they’ll call maybe and say you know it feels pretty mobile. And then a little bit later they’ll say it’s a little bit to press on it. And they don’t say this, but it can even start to spin a little bit, rotate. And if you pull the lip up, a lot of times the pink gum, if it’s lining mucosa – attached gingiva versus lining mucosa – that can be all white, just about like the board here. And it’s dead tissue. And then underneath that is necrotic bone. So that tooth is going to be lost; you’re going to have to take a margin to get all of that necrotic bone out. That’s going to be a graft in the best situation; maybe an implant if you can graft and get regeneration at a future site. But you’re going to be wearing a provisional for quite a few months.

Okay, I think maybe we’ll do one more question, but maybe you can do it a little quickly.

Oh, Quick is my name.

I would like to transition from a cold, single cone, obturation technique to warm vertical condensation. What do I need to be aware of regarding thermal burns? Is that a quick one?

Yeah, I can go pretty quick. Listen. When you’re using a warm gutta-percha method, we use things called electric heat pluggers. And I might make a distinction that in a warm, vertical condensation method, there is continuous wave idea and then there is the classic interrupted, or the Schilder technique. I’ll just say this today. The Schilder instruments, they heat in this direction. They have a heat sink here; it’s a bigger bulk of metal. So as this is cooling as you take your finger off the activating button, as this starts to cool, you keep pulling heat down this way. Temperature was measured on the outside of the roots as < 2°C.

In this technique, the instrument comes in; it has a little copper wire in here, and it heats this way. It hits apical proximal. So as you take your finger off the activating button, there’s no heat sink here, and so you have to plunge in continuous; you’re on for 2 seconds during the plunge, and temperature buildup inside the root has been shown to be 8-10°. Now this was done on the bench. That means there was no periodontal ligament around the tooth to wick off heat. But it was a big warning. In some of these techniques, be very, very careful.

You know, I did a lot of workshops – and now I’m over my 3 minutes – but if you hold these teeth and you’re packing, I mean just cutting a post prep; make a post prep in gutta-percha. That root sometimes get so hot that sometimes students drop the tooth. So just think about these ideas. I didn’t get to the squirting devices and backpacking devices like the Obtura, things like that. Calamus is another one that I helped invent.

So anyway, those cannulas that squirt gutta-percha; the cannula you can grab it; it’s not so hot. But the cannula goes up and there’s a wingnut that attaches it to the unit, the handpiece. That wingnut will absolutely give you a 2nd or 3rd degree burn. And if you’re back in here doing this and you don’t realize it; there’s a dam on, we’ve got tissue retraction. And you take the dam off, the patient’s happy, you’re happy, as she said they’re numb, everybody’s smiling, the procedure is over, and you see this huge burn on the lip. Guess what? You just burned them. So you’ve got to be careful; that’s why we want you to take classes, go train somewhere, train up. No burns please.

Okay, thank you. Yeah, I guess I never really worried when I went to the dentist if I was going to come back with a burn. I guess that’s something that can happen.

Anyway, thank you for the information and that’s it for this segment.

Okay, so we’re going to close our show today with a little mini segment on the business of dentistry. Specifically how you can take a good business and make it great.

So maybe a lot of you have heard the expression “Good is the enemy of great.” I actually had heard it even before we did this segment. And it doesn’t mean that good is bad. It just means that sometimes people settle for good, as in good enough, and they don’t put in 100% to actually achieve greatness. So where does that expression “good is the enemy of great,” where does it come from?

All right. Jim Collins, 2001, something like that, wrote the book Good to Great. Chapter I: Good is the Enemy of Great. So that’s where I – you know, I read the book a lot time ago and it just was good to talk about it again because we were talking about business. And we can learn a lot as dentists reading this book.

But I guess you want me to tell you a little bit about what he did.

Yeah.

So Jim Collins is quite a remarkable person. He had a team of around 20 people, and then he broke them into small little groups. And they studied – over 15 years they studied Fortune 500 companies. And over this 15 years, they narrowed it down to 28 companies that they thought really were remarkable companies.

Now they saw lots of good companies. Coca-Cola, IBM, Motorola, Merck, all these were very good companies. But they didn’t make the cut as great companies. So they used a lot of parameters, these researching teams, and they went out and investigated… shook them down. They looked at a lot of factors and fed this into machines, and they started looking for common things that would be identifiable from the companies that seemed to out-perform over 15 years, the good companies, the really good ones. And so that’s kind of what they did.

But what was amazing is that at the end of 15 years, they identified the great companies and they found out that they out-performed almost 7 times they out-performed the good companies. So there was something to that; it wasn’t just luck. And the reason they went 15 years – it’s just like your practice. You can have a really great case, right? I’m just taking it right down to not even a day or a month. I’m saying you can have one great case that you did, and then if there’s four more bad ones after that, you start to forget the good one.

So anyway, they wanted to really look at sustained success. So it wasn’t a new machine, it wasn’t that you hired the Mother of the Year to be your receptionist, you built the Taj Mahal office; it wasn’t things like that.

And it was something like if you invested in one of these companies versus a good company, the investment would turn out to be like 6 or 7 times the amount?

That’s right.

Okay, so how did the companies go from good to great?

You know that was what was always phenomenal to me. I had forgotten some of the reasons, but I have a little list here. The great companies didn’t have a celebrity leader. They didn’t have a rockstar. They tended to have people that were just like you and me; they put their pants on one leg at a time. They were intelligent people; they knew their field really well, so we can say the knowledge was there. But they had experience, they were kind, they were humble, they had a way of working with their crews, their factory workers, that they were all in this together. So that was one of the ideas.

They hired typically people from inside. So they didn’t necessarily go on searches to go outside the culture. They thought that probably the great people were going to be right inside the company; they just needed a chance to elevate and grow.

All companies have strategies. Good companies had really good strategies; good companies had even great strategies. So strategies wasn’t one of the things because everybody had strategies. They really were – the great companies learned what not to do and what to stop doing. Both. They had to learn to stop doing certain things that would sabotage them, and then they didn’t want to do things that would just be wrong. So that was interesting. You could think of your own office and your environment, and you might be thinking about what you should not do versus what you should stop doing.

Technology wasn’t transformational. Technology accelerated their growth – no doubt about it – but it wasn’t the single distinguishing factor. So think about that when you buy all this stuff. That’s not going to be it, is it?

All right, mergers. Think about DSOs and all this is how I thought about it. But if you merge two mediocre companies you get a big mediocre company. If you have a good company that buys a mediocre company or another good company, you’re going to have a good company; you’re not going to have a great company. So mergers wasn’t part of it.

There were no taglines; there was no big launch; there were no big roll-the-snare-drums events. They just kept working and they worked right along happily.

And finally – I liked this the best – because greatness was not a function of circumstances; it was more the function of a conscious decision.

That’s very thought provoking. I guess for me it’s like good is okay for a lot of areas of your life. But when it comes to your passion, you don’t want to just be good; you want to be great. So you want to put your all into it and have the right people around you is what I’m hearing. Because what I’m hearing from you is it wasn’t so much about the technology or the strategy; it was more about the people.

And I think you told me also another analogy this author gives is imagine it’s like a bus. You want to get the wrong people off the bus, the right people on the bus, and you’re driving the bus; it’s your business. And then not only do you want to have all good people on the bus that are working for you, but you want to have them in the right seats; like doing the job that they’re best at.

So if you think about your organization, there’s probably some people that are doing a job that maybe no one else could do; that’s probably the right person for the job. But maybe you don’t want to waste people’s talent either on just having them only be doing a job where they might actually be better doing something else. So know what your people’s talents are.

That’s a beautiful thing. I like that when she said that, because I was thinking about all of my different staffs I had over about 50 years, and it really was important to have people in the right seats.

Yeah. Well I think you have a quote that we can close with. And it’s actually something that he likes to say, and it’s based on a quote by Jim Collins in his book. But he changes it a little bit to make it kind of his own. So why don’t you tell us the quote.

Well I simply made it up… Dentisto. I made it dental friendly.

Okay... "So we don’t have great dental organizations, because we have good dental organizations. We don’t have great dental students, because good is enough. And we don’t have great lives because we settle for good lives."

So I thought as I read those things that he said here, I changed them for dentistry. But having traveled around the world and seen so many dentists in different environments and situations, I found some great, great dentists in some areas you might not expect. And again, I think they had the right people on the bus in the right chairs.

Okay. Well thank you; great show today. See you next time on The Ruddle Show.