Dental Ceramics in 2022 – Which Ceramic Should I Use? – PDP117

Jaz’s Introduction:
None other than Ed McLaren who’s like this most AMAZING RESTORATIVE DENTIST EVER. You may also know him from making these epic like movie trailers, dental movie trailers, a prolific speaker, a master ceramist himself, as well as, being a dentist. He has so much knowledge about ceramics. Where he doesn’t know is probably not even worth knowing. Hello, Protruserati. I’m Jaz Gulati. And welcome back to your favorite dental podcast for your hit of knowledge and clinical tips. The kinds of things I asked Dr. Ed McLaren are like, what are the LATEST UPDATES when it comes to CERAMICS? What are the different TYPES of ZIRCONIA? Let’s take a step back for a moment there, you know. These Zirconias have been there for a while, but there’s different generations. When do we know when to use each generation? Zirconia bonding has come so far. Can we now start doing ZIRCONIA VENEER?

I know some clinicians are. Is that okay, is that kosher? We asked Dr. Ed McClaren. And finally, what is the difference between Emax and LiSi and which is better? Protruserati we’re in for a treat. Now, before we joined the main episode, let’s have today’s Protrusive Dental Pearl. I posted this on social media recently about how to MASK A METAL POST. So, let’s say you’re treating a tooth like an upper central or lower central incisor, in my case, with a existing post core and crown. So, you resection the old crown, and whoa, you have this ugly metal post. And with teeth like lower incisors, for example. Well, crowns are always compromised, right, because it’s such tiny teeth. That’s why, I think vertical crowns are absolutely amazing for this, right. So, in this situation, which I shared with you, and I’ll describe it for my audio listeners, you have a metal post.

For me, a post core is just a space filler, it’s a way to actually have some sort of foundation restoration. So, I sacrifice a little bit of the metal core, i.e, I use a tungsten carbide bur, I drill into the core labelly to create a space. And I use Paracore white opaque shade to completely mask that metal. So, now when my technician is working on it. He’ll have a much easier time to mask the metal. The other way that I’ve seen some colleagues do it is, by using like white opaque tint that you can get. I know Ivocalar do one I think it’s called direct opaque. So, it’s just like a paint on a resin, very thin low film thickness. And it’s like super opaque, super white. And you can just paint that over if you don’t want to remove so much. But in this case, I sacrifice a metal and I use a bright white opaque core material like paracord, which I’m a big fan of. But you could also use the resin like I said. So, now we have masked that metal post and you get a better chance of getting a good shade match.

Now, if you’re thinking, are you concerned? Are you worried about drilling into a metal post? Just think about it. The last time you had to remove a metal post that was bonded in was it difficult? Or is it easy? It was super difficult, right? Like you’re there for a long time with your ultrasonics and your burs and whatnot. I did not worry at all about the post somehow coming loose, it was very secure. So, you have to make that sort of judgment call and case by case but usually these posts are in pretty well. This episode is very kindly sponsored by Enlighten Smiles.

Now, I know episode about ceramics. But a lot of times for our younger patients, composite is sometimes the most appropriate material. And if you think you can’t make composite look as good as ceramic. You just check out the work by Dipesh Parmar. This guy is a master dentists. He teaches his techniques using renamel composite and other brands to give you some amazing results working with composite resin. His course called Mini Smile Makeover. It’s fantastic. I’ve been on it twice now.

 The beautiful thing is that you can go again and again and again. It doesn’t cost you. So, you pay once and if you need to go again, as a refresher, you can go for free, which is just amazing. Which other course offers that? You could check out the course on minismilemakeover.com. Once again that’s minismilemakeover.com.

Main Episode:
Ed McLaren, welcome to the Protrusive Dental Podcast. How are you my friend?

[Ed] 
I’m doing well. Thank you! How are you?

[Jaz] 
No one’s ever asked me. Wow! No guests have asked me how I am. Thank you so much. I’m doing great. I’m all the better to have one of my people I respect so much in the dental education space. But the other thing I really love about you, Ed is not only the clarity in which you educate. You are the finest dental educators out there in my opinion, but your movies that you make are just so brilliant that I want the world to see them. So, tell us a little bit about you for those listeners, very few listeners who haven’t heard of you. And then eventually, tell us about how you got into making these dental, essentially, spoof movies which is just phenomenal.

[Ed] 
Thank you! Yeah, in fact, I just finished one in Egypt that we’re in post right now. Post-production means that it’s been edited at this point, called Ceramist Never Die. It’s a twist on bond, a James Bond movie. My name is Ed Bonded in the movie. So anyway, let’s say I’ve been a dentist for like 38 years, as a general dentist for five years, and then got a little bored with General Dentistry and decided I wanted to be a prosthodontist. Yeah, actually, kind of the real reason I went in that direction. I originally wanted to be a periodontist.

But in those days, in late 80s, there was such a fear of getting AIDS from a patient, right? In those days, I actually thought I just go as far away from blood as possible, and work on, essentially, older people that need a denture. So, that’s how it all started. And actually, that wasn’t all that much fun for me to tell you the truth. So, I searched around and thought, well, what is it I like about what I do, and I really enjoyed the aesthetic aspect. I enjoyed doing veneers, were just starting to hit then. I enjoyed doing veneers. I enjoyed doing more aesthetic work. I still enjoy doing dentures, but it was like sort of gravitated toward people that liked aesthetics, too. That wasn’t just function only.

So, that’s how that all started. And then, I realized when I went to PROSPERO, like I said, my director made us do all the lab work. Everybody thought it was a punishment, except me. I mean, I was loving doing it till three, four or five in the morning, which I still do now, making all the ceramics. So, that’s basically how it all started. And then, it just gravitated more toward, you know, current concepts, minimalistic dentistry.

When you start to understand what things work and why, and what things don’t work and why. So, the movie thing started was, you know, as computers evolved, and we all started moving to computers around 2000. I just started learning programs, how to edit video. And it just started with very simple stuff around 2000 to just take my images of my work or my travel images and animate them in some way, which you see mostly what people do today, right?

So, I did that for about nine years, till 2008, 2009. And I started to get bored doing that. I mean, that was boring for me. And I thought, well, what’s the next level? Create a movie with people in it, right? Keep something. So, I thought, okay, if I’m going to do that, the few other people that I saw doing it, I thought, ‘God, if they don’t relate it to dentistry, they don’t keep it short.’ They don’t keep it interesting it’s going to be a big flop. So, I thought, ‘Okay, I got to do something that’s current, something that’s related to everybody knows, like Star Wars, and come up with some dental thing.’ So, that’s how it started. So, I came up with the first one called Ceramic Wars. What was it called The Return of the Ceramist. And then, I did a couple more of that. And then, the last one I did on Ceramic Wars was called, The Last Crusade. And actually, since now Star Wars seems to be cycling in various formats, MANDALORIA, or NB1 or not, NB1. Anyway, you’ve seen there’s so many variations of that. So I just wrote-

[Jaz] 
For those who haven’t it, they must appreciate that this is not just some like little, like guy on an iPhone. This is really professionally produced and these are just the finest quality enjoyment in terms of entertainment that you find in dentistry. I find-

[Ed] 
Thank you! And that’s why I don’t have a Ferrari or McLaren or you know, because all it costs a lot. I mean, it’s a lot of my time, it’s movies about 1000 hours of my time, but it’s also, you know, I’m spending 30,40, 50 thousand dollars. Normally would have had to spend three, four, or 500 if I didn’t do the work, so it just evolved into doing that. And then I just ideas start to happen. And just like you get creative with something, and I get very creative. And I look for scripts or movies that I think that I can do something that’s kind of cool and short.

And so, I’ve done like four now Star Wars movies, there’s a fifth one, I’m writing a return of it. We won a Raiders of the Lost Ark, a spoof on the matrix, a serious spoof called a source a Down and Out in Beverly Hills movie, where I’m a bum on the street and something like that, and then the James Bond movie, and then just a couple of other fun things. And I’m working on a movie called Cambo for cyber, but I’m not in good enough shape. And I don’t know if I’ve ever had a Rambo character, and then, three or four like that. So, that’s how it all started.

[Jaz] 
Where is the home for all these movies? Is there is it on YouTube or?

[Ed] 
Well, okay, so that’s an interesting question. Yeah, you can go to edmclaren.com. and you can see five or six of them. I’ve made eight, nine now. Okay, that ninth ones in post, and kind of what I decided to do was not put them, the current ones on YouTube because actually, it’s a draw for my lectures. It’s an interesting vibe of stuff. It’s, you know, 20-30% of the people are in the room not to watch the lecture. They’re just there to watch the movie. Which is okay, for me, at least. So, the movie I made just before COVID called Raiders of the Lost Art, I haven’t even had a chance to play it except at one or two venues. And then I’ve got a movie called The Source, I haven’t played anywhere, which is a spoof on the matrix. I’m just waiting as the lecture circuit opens back up, so I can get it out there a little bit and get people to the lectures. And, you know, so go from there. So-

[Jaz] 
It was great that tubules. Well, I’ll put the link to edmclaren.com so people can check out the quality and the caliber of those movies. And that’s something I aspire to that at the moment, I make a few spoof videos, I made the Fresh Prince of Appliances. And that was like a two-minute thing. But what you know what you do? That’s like my goal for the future. So, something to aim at. Ed, I love everything. What’s that? Sorry?

[Ed] 
It’s a full time job. Almost.

[Jaz] 
It sounds like it. All the hours, and then the cost and stuff. But oh, my god, the quality you produce is just epic. So, please continue. We need that kind of stuff. Now, you are well known for many things. But yeah, I mean, the whole play on ceramics in the movies and stuff. So, you are my go-to guy with anything ceramics. What you don’t know about ceramics, in my opinion, it’s probably what not worth knowing about.

So, I’m going to hit you with the first question that I have, which is, is there still a place for feldspathic ceramic? Both in terms of patient demand, dentist skill set, I guess. Are we still being taught it at dental schools? And then thereafter, are there technicians who are still happy to make these beautiful feldspathic restorations? And if you don’t mind Ed, for the younger listeners that we have, just also explained what is feldspathic ceramic and how it evolved within the last 20-30 years?

[Ed] 
Well, given the literal definition of feldspathic or the scientific and that would kind of screw people up a little bit. But just think of feldspathic ceramic as porcelain. The stuff that we layer on the surface. Whether it be layered it on metal, whether we layered it on Emax, whether we layer it on zirconia, or any other version of core. That we also make porcelain veneers out of it. And so the porcelain veneer, basically, is bonded to the tooth instead of being bonded to the metal. It’s bonded to the tooth. Okay. And so, there were several questions in that one question.

The first interesting question was the demand from patients. The interesting thing that demand kind of went down for a while from patients. And because of social media being such an interesting phenomena, it’s actually come back significantly because of people that have gotten famous doing it like the Michael apple’s, as you might know, my gap of my Peppa. He’s becoming very famous, especially in the, maybe more patient world than the dentist world, but also in the dentist world too. Bill Dorfman, who started Discus Dental. He’s basically was in my class, we’re the same age, both a few minutes over 60. And Bill’s known for that too. Bill is probably was probably one of the top guys known for a number of years. And now the interesting thing is, because they’re all posting daily on this, and then you got a few other people starting to do this.

There’s a dentist in Dubai called Duvall Lelouche, who I had the opportunity to meet. And I gotta tell you out there, he’s probably one of the most best dentist I’ve seen for a combination of, if he’s watching and not have your head grown, but for a combination of treatment planning, because sometimes we see maybe good veneers, but we’re questioning the treatment plan, right? It’s not a process of why they did something in the first place. Because first we’re doctors, right? So, from treatment planning from ceramist, he’s got four or five ceramist in his office. So, he’s been posting a lot. And so, what’s happened the last four or five years, from very little requests from patients that I’ve seen, I don’t say for me, but at the school when I was at UCLA and stuff like that, all of a sudden people are coming in now, because they’re so savvy on the internet, they know where to go, they’re seeing this, ‘Hey, whats this porcelain veneer?’ And more than that they even know what it is now and they go, ‘That’s really what I want for my tooth.’ So, I think the market is there. I really believe the market is there.

Then the second question about the aesthetics you know, most of us have all done Emax or Empress or GC LISI monolithic and it’s good. You know, it looks good, but it doesn’t look great. Okay, so the place for feldspathic veneers is where you got a patient that really wants a very natural looking tooth just like you’d layer composite, you wouldn’t use one shade of a monolithic material.

So, now the challenge then becomes, where does it work clinically? So, without getting too deep into material science, it works when we have mostly enamel on the tooth. And it’s not the bond, we all think okay, we get a better bond to enamel then dentin. That’s actually not true. If we have fresh clean dentin, it’s not contaminated. Your bond strength to dentin is actually higher than enamel. But it still fails more on dentin and the reason why dentin is eight times more flexible than enamel.

So, when you load an enamel ceramics, when it’s on enamel, the stress passes through the porcelain and is absorbed by the enamel underneath just like on a PFM. Why a PFM works is because the high strength stiffness of the metal. So, that’s really the key for long term success. It doesn’t work on a bonded the dentin surer. But you’re going to see maybe 5, 6, 7, 8% failure rate per year. If you’re bonding the dentin with ceramic just because the dentin bends, the stresses absorbed in the ceramic. Where you’re going to see probably less than a half a percent per year, when you’re bonding to mostly enamel.

So, that’s really the key for me. Now, I also did a study that we published because people said, well what if I have a little bit that exposed? What if it’s just 5%, 10%, or 15%. We heard, this was purely speculation, that you could have 50% of the enamel gone from the tooth or 50% dents and exposed and your bond Porcelain is going to pave like 100% porcelain. We tested that. We published it in the JPD and you know nobody-

[Jaz] 
It’s going to have 100% enamel or 100% dentin?

[Ed] 
So, we looked at 100% dentin and 100% enamel bonding too. 50% dentin, 50% enamel and 100% dentin and then we fatigued it and fractured them. So, here was the results, 50% dentin exposed, and 50% enamel basically behaved like 100% dentin. So, that was fascinating to us. In fact, a three-tenths of a millimeter veneer bonded to 100% enamel, was stronger than a 1.2-millimeter-thick veneer bonded to half dentin, half enamel.

So, enamel really is keen because it absorbs stress. It’s a stress absorption phenomenon. Okay, so where does that leave us if you can’t do it with 50%? So, we also tested if we’re missing 10% enamel, 20% enamel or 10% dentin exposed, 20%-30%, so, it’s about 30%. Where there’s about 30% enamel missing and dentin expose your bonding to is where that dynamic changes where the stress starts absorbing more in the porcelain. But I’ll give you another good article.

The best article I found clinically, that’s obviously a laboratory article, Glebe Grill. Many of you know in Turkey that published an article just last couple of years. He’s published several things over the years, where he followed literally about 1000 veneers and bonded to enamel, bonded to dentin, margins and enamel. And here’s what he found with clinical data, good clinical data, well documented clinical data, that as long as you have at least a periphery in enamel but dentin exposed, it does pretty well. Your failure it maybe percent and a half per year, okay. But when you have full dentin at your margin, that’s when you go to an eMax, that’s when you go to maybe an empress. Empress still works, but non-layer. Don’t layer your Empress. If you feel like you have to layer for whatever reason that’s now in Emax or as Zirconia

[Jaz] 
Amazing! I love those guidelines that you gave in terms of 30% and dentin and 70% enamel and all those studies that you referenced. I’ll make sure I get them in the show notes. But that’s a very helpful answer. But with the labs, now massively uptaking and going into CAD CAM and in a way I do find they’re encouraging them to say, ‘Oh you know what, let me just mill this for you’, kind of thing. So, did you think there was going to be a shortage of skill set from dental technicians in the future who can hand layer beautiful porcelain?

[Ed] 
Yeah, let me distill down one maybe into one or two sentences my clinical thought process, okay. Obviously, if I have 100% enamel to bond to an anterior teeth, I’m doing feldspathic. When I get close to 50% dentin to bond, then I go to a glass ceramic and make a decision, is it an Empress or Emax? I still like Empress. It looks a little better. It’s a feldspathic material that you machine.

Then when I can’t bond, so the time to go to zirconia is when I can’t bond and, you know, basically, it’s going to be sort of a conventional crime. So, that’s the clinical thought process. So, your last question about the laboratory. That’s been the biggest problem. And as you know, I ran a laboratory school at UCLA, unfortunately, we had a bad fire that closed it. I have to tell you, I get called literally daily now, and several emails a week for, ‘Hey, I need to find a ceramics that can do veneers. I need to find a ceramics that can micro layers zirconia.’

So, we as a dental professional organized dentistry, we’re really dropping the ball on teaching people how to do that. So yes, that is a challenge. That’s a challenge to find a somebody that can do a feldspathic veneer, well. I can tell you, one of the laboratories tell me that one of their biggest concerns about doing this is the time involved, it’s a three, four or five times more than machining something and finishing it because the model work is so different. And so, actually, my partner in crime and digital as Jed Archibald, who works with Gordon and Rella Christensen.

Actually, we’re working on, we’re trying to come up with a full digital workflow to get the model work done. So, the model work and then a machinable refractory die, and we’re really close. So, that it’s easy and easy for the technician, all they got to do is layer a little bit like they were layering zirconia crown. So hopefully, that’s done in the next few months. But yes, we got to train technicians, you gotta find a decent technician who can do this. And it’s harder and harder. Yeah.

[Jaz] 
On the other side of things, when you look at the dentists, especially the younger dentists, I’m pretty sure this is also happening in the States as well. But definitely the UK, composite veneers have been really taking off, where do you think that there’s gonna end up in the future? You know, 10 years down the line, are we expecting some sort of a great boom in these composite veneer failures? And then, perhaps a rising of them being converted to ceramic?

[Ed] 
Yeah, I mean, I’m all for that. Okay. I think it’s great because you can be a little bit more conservative with your composite prep. Now, I can do almost a no prep. I’m back to the phase where I’m just prepping just a little bit. Because I find if I do no prep, I can make the veneers but the margins aren’t what I’d like to have, you know. So, it’s very difficult to make perfect margins of blend in the tooth. So, even if I think I don’t need a prep, I’m still putting the latest chamfer on. So yeah, that’s the biggest mistake that most dentists make that are doing veneers. They grossly over prep for a veneer.

So yeah, I think developing the composite skills is a great thing and composites done well. You know, they can last 7, 10 or 15 years if you buff them up a little bit. But I gotta tell you, I see so many veneer cases coming over, composite bonding cases come in. And I would say if I see 20 cases, I might like one or 30 cases, might like one. Usually, when I see a veneer case from a decent ceramics, I like more than a half, let’s say. I’m going to hard on myself in art and other people. So, you got to get the skill set. It’s a skill set.

Now, one thing of truth in advertising, because I used to do a lot of bonding and I was pretty good at it actually. And I know how to layer composites. I don’t do it much anymore. Unless I teach a course just for fun. I know all of these guys professional friends the Newton Fahl’s, the Didier Dietschi’s’s and all this. And when you get them off the record, you say, ‘Come on! that stuff that you’re showing with all the little effects and the mamelons and the perfect surface texture. It looks like God made it you know and stuff like that. How long did you really, how long did that work?’ And they said, ‘An average of 2-2 and a half hours of tooth.’ And I said in one appointment,

Your 10 teeth are spending 20 hours?’ No, we never got it done in one appointment, two, maybe three appointments. So, we’re building it up, shaping it, sending the patient home, they come back little tweak here, little addition there, little subtraction there. And then the third visit is to polish and surface texture. So, that type of composite that you see in the articles is not a simple thing. Okay, it’s a wonderful thing done well, but it’s not a simple thing.

[Jaz] 
A little industry secret share there by Ed. Thank you very much. Very good to know. Next question then is, some docs are anecdotally using zirconia for veneers. Okay, now this seems a little bit absurd to me. And then on that vein, and we can probably venture out and digress into zirconia for partial coverage posteriorities. But let’s just stick on this veneers topic. Are we yet at a stage using the Markus Blatz APC protocol, for example, that we can predictably bond zirconia? And, is this something that you condone?

[Ed] 
Yeah, okay. So, let’s maybe step back in our space for just a second because I was just talking, doing this to Egypt yesterday, exactly what we’re doing here. And because I’m gonna go there and teach a course on there, they said, ‘Hey, listen, we want to learn how to match zirconia next to eMax. So, we can do an eMax veneers and zirconia or something like that. I said, ‘Why don’t you just use eMax?’ So, one of the first tricks that I tell people, when you’re matching restorations next to central lateral whatever, you use the same veneering material on both materials.

So if I got to do his zirconia crown, on one, two, okay, one, one, excuse me and I got to do a veneer on two-one. I’m going to use the same porcelain for the veneer on two-one that I did on one-one. And that’s also a problem right there. It’s a very simple technique, but more specific to your question. Okay. So, I’ve been sandblasting zirconia for years. I’ve been using MDP primer for years, both back on alumina, when we were going to look concerned about sandblasting some things could potentially weaken it, okay. But when I bonded, it didn’t fracture when I used conventional cements I had more fractures, because there may be you start some cracks. But it’s an interesting thing. It was a very good paper and you might want to look it up. I believe it was in dental materials by Matthias Kern. He did looked up all the cohort studies and did a meta-analysis of several different studies and 2015 and hasn’t changed that much was sandblast-

[Jaz] 
That was for resin bonded bridges, right? That was for resin bonded bridges, right? I think that-

[Ed] 
Right. But still for resin bonded bridges, okay. Even if we had a phenomenal bond, it shouldn’t come off. Several studies had very low clinical success. Alright, so yes, I could demonstrate and I did some work with John Burgess and Nate Lawson. I was part of their team or they were part of my team; we’re all part of a team for a couple years. Had an opportunity to look at it. You can get phenomenal bond strengths on day one, when you sandblast Zirconia, put an MDP primer on, it looks good. But when you sheer it off, okay, even though the bond strength is very high, it’s an adhesive failure. It’s always an adhesive failure, and it’s not ripping out the ceramic on one side. And Burgess also did a study where he looked at sandblasting and no sandblasting. So, super smooth zirconia. T

hen when he sandblasted, which is gonna give you a little bit of roughness. Nothing like sandblasting the glass and give you a little bit of roughness. All right, then, he used an MDP primer on both. And basically, what he found was about 70% of the bond strength. So more than half, let’s say for sure, more than half was because of the chemistry of the MDP primer. All of these primers can dehydrolyze in the mouth; they can break down in the mouth. So, if we see some leakage, which sometimes happens, okay, that’s the reason for failure.

And by the way, about roughly about 10 to 12 years after sandblasting my Procera crowns and using that original MDP primer, which is still the main one everybody uses. I had a few crowns start falling off, just because the cement hydrolyzed broke down. So, I’m giving you a little scientific perspective. I worry about the long-term clinical bond strength for Zirconia until we can effectively etch it and effectively get a really good micro mechanical bond. So, I gotta agree with you. I don’t see the rationale of doing Zirconia veneers when we already have somebody else, something else that works that doesn’t break. So, eMax, Lithium disilicate, GC LiSi, Vita has Supremity. They have Ambria.

There’s one out of Korea that looks really nice. There’s 6, 7, 8, 9 products on the market; the monolithic look better than zirconia that won’t break that we can etch. So, that’s what I would recommend today. Now, having said that, there’s a company in Korea that makes a product, and you may want to make a note of this and look this up for your viewers, called ZIRCOS Etch for etching zirconia. It’s a very caustic acid. In fact, you have to have a special vent in your lab to etch the zirconia and it will etch a five line material; it will etch the cubic form of zirconia.

It won’t etch the 3y, the pure to trigonal, but we’re only going to use five line, right. We’re gonna use the more translucent cubic material. So, you may want to look into that, and it’s a very caustic acid. You could not put your hand in it without severely burning yourself. So it’s called ZIRCOS Etch. And I happen to know it works, because my colleagues tested at UCLA. So, if I was going to do a veneer, for whatever reason, and here’s the one reason I might do a zirconia veneer, I’m going to do zirconia monolithic everywhere else. And I got one or two teeth, that I just feel, ‘Oh, I don’t want to prep it. I mean, the inner proximal is good; the lingual is good, but I want to have the same material, then I would do it.’

[Jaz] 
Amazing! That is really useful. And I never heard of this Zircos Etch. I’ll look it up. That’s very fascinating. So, the future potentially, is looking good, but I like how you answered that. Okay, maybe at the moment where we are in the long-term, sort of follow-up isn’t there yet. And so, you’re a little bit hesitant to make that recommendation.

[Ed] 
Let me just add, so if you feel compelled to do that, for whatever reason, maybe your lab does it. I would think a little bit more with adding a little retention and resistance form back to GV Black, meaning a few may be a little bit of a retention groove, mesial distal, something like that. Just to give it a little bit more resistance form. So, that’s if you’re gonna do it, okay?

[Jaz] 
Well, that lends itself next to the second part of the question where I have some colleagues who are doing posterior zirconia onlays. Now again, once again, I’m very much like, okay, if it’s an onlay, I need to have an enamel. If I have an enamel, I’m going to be using lithium disilicate. So, do you have similar thoughts about zirconia monolithic onlays that are bonded posteriorly?

[Ed] 
Well, I mean, it’s the same thought process. We were one of the beta test sites at UCLA for eMax and we started using it in 2004-ish, I think. So, we are graduate students because it was an aesthetic program. We had multiple chairs going and 2-3 year graduate students. So, we did a ton of posterior eMax, and we did roughly three thousand. And I had a deal with the patient because, at UCLA is very protective of their IRB, Institutional Review Board.

 And I wanted data, and I didn’t want to go through all of that. So, I just figured I’d present all the data, okay. So, after over 10 years of doing three thousand restorations onlays with graduate students, not me, graduates. So, we had a whole bunch of graduate students. So, my poll, I probably did two 300. And they did fail 2700 or so. We had one known fracture in 10 years, one known fracture of bonded, bonded, bonded, bonded eMax.

And the average thickness we measured them were right around a millimeter. So, I don’t believe we need a millimeter and a half. I think a millimeter is fine. Maybe even eight-tenths because that stuff is so strong. Of course, this was non-layered, and it was all well-bonded. And it was all, I believed early on and sealing dentin I learned from Pascal Magne and John Sorensen, by the way. To give him a little credit, my mentor believed in sealing dentin back in the 80s. But he never published anything about it. And obviously, everybody knows Pascal, who’s done the most work on it over the years.

So, we were sealing dentin back in the 80s when I was in my process program. And for lots of reasons sensitivity, we had a good idea that it increased bond strength. But Pascal shows that roughly doubles maybe even Quinn topples bond strength if you feel dentin at the preparation appointment. So, when you factor all those things in, we had one restoration fail that we know of. Somebody could have moved to China and fell out of the study. But we offered them a free renewal if it came back, if it failed in less than five years, which we never had one. So, I can tell you, since that works so well, and it looks so good in the mouth. Why do something that you’re not sure about?

[Jaz] 
That’s so true. And I agree totally with that. Just interesting question for you. I also asked this to Chris Orr, many, many episodes ago, just to understand your philosophy. That, let’s say you’re gonna go to eight-tenths of a millimeter or a millimeter monolithic eMax, for example, is your decision-making tree anyway, influence by the biomechanical risk or the biomechanical status of the patient, i.e, large masseters, known bruxist, would you then, perhaps sink your burr in a little bit deeper? Does that deserve an active aggressive bruxist influence your material thickness or not?

[Ed] 
So, the first thing I’m looking at is kind of the amount of remaining enamel. So, let’s say you got that eight-tenths, whatever you’re at, whether you’re building up the teeth, right, you’re gonna open the vertical, restore the vertical, whatever you want to say that is, okay. And you get that eight-tenths. If there’s some enamel there, I’m not worried about that, okay. There was a study done by Gordon Christensen, and a couple of others followed up over the years that they went into laboratories, measured the average thickness of porcelain, on a PFM. The average thickness was a half a millimeter thick. And we didn’t see a fracture that much. Maybe a marginal ridge somewhere, but the occlusal didn’t pop off. Why? Because the metal absorbs the stress, the stress passes through the system into the metal. So, the first thought process is an enamel.

So if I’ve got an enamel, great, I’m not worried about being eight-tenths. If I’m completely indented, I’ll probably go for that millimeter. I think it’s a little thin. I might just take an extra millimeter or two off of that tenth of a millimeter or two off the dentin. Okay. Now, having said that, that’s an interesting concept that comes up about biomimetics. I love that concept. Just in medicine, whether in dentistry, yes, we want to mimic structures as much as we possibly can. Okay, and that’s whether it’s aesthetically or functionally or biologically.

But we truly need to be able to do that too, right. So, we have not been able to reproduce the dental enamel junction as it forms; it sends fibers into the enamel and it sends fibers into the dentin. So, when you look at a tooth, you see all these little fracture lines; those pieces of enamel that are being held on by things that we haven’t created yet. Okay, we haven’t been able to create that. And enamel is a very different material in ceramics. It fails in a very different way than our ceramics. When enamel fails, it starts on the occlusal surface or facial and goes right to the dentin and stops. When our ceramics fracture, it fails like a spiderweb called Hertzian cone fracture.

So, we do have to think about thicknesses. And one of the things that’s bothered me that I’ve seen that’s come out, when people are carrying anything too far, whether it’s aesthetics or whether it’s biomimetics. I see, you know, you’re looking at it tooth. So, imagine you’re looking at tooth, if you remove all of this tooth structure, okay. So, you got three millimeters of dentin. Maybe you’re missing a millimeter and a half of enamel, typical thickness of an enamel and the thought process is okay composite has about the same thickness or thing physical properties as dentin. So, let’s build up a dentin the core, the shape of the dent, save for the missing dentin. And then we’re going to bond some ceramic on that because that’s perfect biomimetics that composite the same as dentin, the ceramic basically the same as enamel. I can tell you that will be a disaster clinically.

Okay, that sounds actually been done over time. Dominique of  came up with what he called the Encore Crown, or something like that where he made crowns. So, missing dentin, missing enamel, he made copings out of composite. Then put ceramic on top, goes in the mouth, sounded like a good idea, bonded the composite bends, bends, bends, bends, bends, bends like the dentin would then bend, and the ceramic peeled away. Alright, so I understand the thought process, you want to minimize or mitigate the stress to the tooth by putting composite on there. Okay, that’s kind of the goal. Okay, the next question is great, but do you need the four millimeters for a composite? So, I talked to some engineers and understood, ‘No, no, no.’

If you’re missing some help to even stress out, about a half-millimeter composite is all you need, you don’t need four millimeters to even the stress out on the surface underneath. So, the light bulb goes on. We fractured a couple of teeth. Pasquale, I think he published something on this. So, let’s imagine you’re missing four millimeters, or three millimeters of dentin. Just a little thin layer of composite to even out the pulpal surface or whatever. Then fill in the rest of the space with three or four millimeters of ceramic and you’ll get the best of both worlds. The thicker the ceramic is, the less likely it is to fracture. You only need about a half a millimeter of composite to dampen the stress on the tooth. There’s no difference in stress to the tooth if the composite’s a half millimeter, 1, 3, 4 or 5. You’ll only need about a half millimeter and so that it makes it easier-

[Jaz] 
I’ve been doing it that way since Mahul Patel, who you may even know in the UK, a very good prosthodontist. He actually told me he learned that from you and was influenced by you, and then he passed it on to me. And so yes, I don’t build the sort of foundation or core composite. I just add the thickness to my lithium disilicate restoration. And that’s a good thing to do, I think.

[Ed] 
You do want to add about maybe about half of it. If your goal is to dampen the stress on the tooth. If the thought process, well, I don’t want to wedge the tooth or I want to even out the stress on the tooth, then either a structural flawable, will mean a strong flowable, okay, that has high flexural strength.

[Jaz] 
I use g-aenial flow like g-aenial injectable, highly filled. But even then I do my IDS. I do my immediate dentin sealing with it, and that for me, kills two birds with one stone. Is that reasonable?

[Ed] 
Oh, that’s great, that’s exactly how I think, now too since we now have very good flowables that have high compressive strength that aren’t like rubber. Okay, that’s exactly a great technique that saves your time, too.

[Jaz] 
Amazing! Brilliant. I’m loving the pace of this week. We’re covering a lot of ground here. I’ve got two more questions here of general themes of this valuable time that I have with you. Okay, so now let’s think about the topic of posterior ceramic onlays, lithium disilicate onlays. I want to know your opinion, your clinical opinion, or any expertise or studies that you’ve seen comparing an Ivoclar product, eMax, versus I believe, is LiSi, GC? Is that right?

[Ed] 
GC LiSi

[Jaz] 
Yeah, GC LiSi, so.

[Ed] 
I have not seen it. That somebody has compared it directly. And I’ve done a few GC LiSi, but not enough to say that hey, like the 3000 eMax. I can tell you; I have friends that I trust that would tell me the truth. Okay, that had been working with the product since it was launched. And they’re having very similar success rates as long as it’s not a layer. If it’s just a monolithic, well bond at GC LiSi, they’re not seeing any particular issues, with failures coming back and things like that. When they start to run into failures. Here’s where people start to see failures, where they’re doing conventional cementation, it’s a little thinner. And, you know, because then the ceramic absorbs all the stress and or incorrect preparations for this type of material, which would be very soft and round on the inside, just pretty much following the anatomy of the tooth the best you can, with no sharp internal line angles. You don’t need any retention resistance form if you have a periphery of an enamel and both seem to be equally successful to me.

[Jaz] 
Is there any anecdotal aesthetic advantage of either?

[Ed] 
I think where people run into problem with Emax and you hear some people say they love it, they say it’s gray. Emax is an interesting material and GC seemed to have solved the problem and I don’t know, they won’t tell me what they did. In Emax, you can’t fire more than about two or three times when you fire a third and the fourth time-

[Jaz] 
It goes gray.

[Ed] 
It goes gray and I think what’s happening is the pigments burning out. The pigment, whatever pigment was in there, it’s like table glass. If your table in your living room and you look at it as a greenish gray look, so it’s just burning out the pigments. So, I think if you can keep it to one or two firings, essentially a glaze, right, if monolithic little pain glaze, I think you’re fine.

[Jaz] 
Hey guys, I know Dr. Ed McLaren has covered a lot here but if you want a simple one page summary of this podcast episode, so you got like a different which ceramic, when kind of thing, when would you do what, then we’ve made a one page infographic. You could download it on protrusive.co.uk forward slash ceramics. That’s protrusive.co.uk forward slash ceramics. Back to the main episode. Okay, fascinating.

And so the last question is to just discuss zirconia. I know, you could probably speak for like five days in a row, a full day’s couple of movies of yours in between, to keep everyone occupied on this topic. But I love how you were able to grasp this big mammoth topic, and how well-read you are into just a couple of guidelines at general dentists can apply. And I love how you did that with the first question. So, I don’t want to really put this complex question for you because it’s oversimplifying it.

But if we had to, suggest a guideline for the selection of the different types zirconia, you mentioned earlier, 3Y, 5Y, if you don’t mind a bit of revision, firstly, on what is the difference and then, when to use? Which zirconia? Essentially, the question, and when should you lay in, when should you use monolithic form?

[Ed] 
So 3Y means 3% of the molecules are Yitria oxide. Okay, and then 97% are zirconia. And the original materials like Lava, most of you remember that name were very opaque materials to trigonal zone. When you have 3% Yitria, you have mostly 100% to trigonal shape crystals zirconium. It’s very opaque, but very strong. Okay. Ceramic engineers have known for years, and they started to apply it to dentistry 5, 6, 7 years ago that you increase the Yitria content, you had three oxide added more Yitria, a little bit less zirconia.

The final material had a phase shift, the crystal shifted to a cubic form of crystal, okay. Because there’s actually about four or five but three main ones, three shapes of zirconia, which actually kind of behave like three different materials to tell you the truth. So, this material has been people been calling it five mole or 5Y’s. So, what they mean is 5% of the molecules when you hear a 5Y are Yitria.

Which creates a material, it’s about 50% cubic zirconia and 50% trigonal zirconia. A fake diamond is 100% cubic zirconia. You have to put about 8% of the molecules in there at Yitria. There’s one thing that comes up because people have asked me they said, ‘Well, I open up this little thing that I get from the manufacturer, and I don’t see three or four or five Y, I don’t understand. I see 8%, 7%, that’s by weight. Okay, according to the FDA, they have to report the different amounts by weight. So, volume is different. That same thing with our composites, right. We got a 70% weight filler, but by volume, it’s 30%.

It’s just a different each molecule has a little different weight and that’s what that means. So, the newer seven years will be put on the market roughly. Cubic containing 5Y materials are much more translucent, we’ve all seen that. And they’re very temperamental, because you’ll get from one lab a little opaque-ish. And one lab, it’ll be beautiful. So, it’s part material and part firing. These materials are very, very sensitive to fire and actually more than porcelain.

So, if you fire them wrong, they can look like a marble or they could turn gray to like eMax example. So, where would I use those today? Those materials are strong enough for single crowns anywhere in the mouth. There are about 750 Mega Pascals when you’re done centering them. Now, here’s an interesting thing about a 5Y material. We were the first one publishing on this, when you sandblast the inside of a 5Y material, okay. The cubic crystal, it does not strengthen, like a 3Y, you probably heard that you can sandblast a 3Y material, it does not weaken at all.

 Because it’s a little micro crack phenomenon. There’s a phase transformation and blah, blah, blah. Okay, so the functional strength of a 5Y material is not 750 MegaPascals. When you’re done processing the inside, it’s about five or 550. Perfect! That’s plenty for a crown. 550 Mega Pascals is plenty for crown but not for a bridge. Okay, so the 3Y materials were originally for layering. There’s a material it’s in between called a 4Y material. It means 4% of the molecules or Yitria, 96% of the molecules are tetragonal. That 4Y material forms a material that’s roughly 30% cubic, and 70% to tetragonal. Two good things about that, it’s almost as translucent as the 5Y, not quite, but almost. Here’s the nice thing about that material, the flexural strength is still up very high around 1000 MegaPascals but you can still sandblast it so when you sandblast it, it’s still 1000. When you sandblast a 5Y material, it goes from 750 to 500 because you weaken it, just like glass, okay. So, where do you use that? So, anywhere in the mouth that I wanted a monolithic restoration, single tooth, I’m going to use a 5Y material.

Okay, STML from Noritake, most people know, or the super the high translucent, but you need to ask those questions if they’re 5Y materials. The lab will know, or they should know that anyway. Okay. So, I’m using the single restorations, anywhere in the mouth. Maybe for a small three unit monolithic bridge and the anterior part of the mouth 500 Mega Pascal’s probably okay. Okay, the ADA says we need six, maybe 800 for mega Pascal’s for longspan bridge. So, for any bridgework, I use a 4Y material. That’s the material, it’s 30% cubic face. Here’s the nice thing about that, it’s translucent enough that it looks decent, monolithic. I wouldn’t say great, but decent. And the reality is most of our patients are fine with decent aesthetics, right. Especially, if they’ve got such bad teeth, they’ve walked around with that, we’re doing an all on four and all in six or none on one or something. Okay, so for any bridge work, I would use a 4Y material. Here’s also the nice thing about it, it’s strong enough to layer if you want to. You can cut it back and layer like a 3Y material. I don’t know that I would layer a 5Y material. Maybe a little bit on the facial, but I would not cut it back to a thin coping and layer. You’re probably gonna see some fractures down the road. So, simple 5Y monolithic, okay, 4Y monolithic for bridges, and micro layering.

[Jaz] 
Got it. So, instead of 5Y for any monolithic crown anywhere in the mouth, including anterior, probably don’t layer it unless you have to build in the facial, 4Y bridges. Maybe for a crown, it’s overkill, because you got the 5Y anyway, and then you can layer that with a bit more predictability and less risk?

[Ed] 
Yeah, so let’s maybe look at it from a different perspective. A lot of times, you know, a lot of smaller labs or dentists don’t want to have 5 million materials in the drawer because you got to pay for all that stuff. Can you distill it down even more? So, here’s what I would do, you could do easily use 4Y material for your crowns, okay, for posterior crowns monolithic or something like prime, which is 3Y, 4Y and 5Y from either car. They’ve made a gradient of Yitria and thus a gradient of cubic face in it, which is a nice material. Use that for your single crowns, use it for your bridges, and then do Emax or GC LISI or Suprenity or Ambria, any of the high strength glass ceramics you like on anterior teeth. And then for the right case of feldspathic veneer, the right case.

[Jaz] 
That’s such a brilliant real world application. Keeping in mind that we don’t want to be stocking all these different types of ceramics and materials. So, I like that real world recommendation, I think we will all gain a lot from that. Those are the main questions I want to cover and you covered them so wonderfully. So, thank you so much. Are there any other things that based on the questions that you’re thinking, and you know what, it’d be really good on this topic to get these nuggets to these dentists all over the world. A lot in UK dentists listen to this one. And also US and Australia. Anything while you have the microphone before I want to know about, how we can learn further from you?

[Ed] 
I think I’ve covered it all. I mean, you’ve got the you know the simplistic idea of how I do a case and basically feldspathic veneer anterior, usually Emax in the posterior, okay, that’s usually what I do. If you came walking in, and I knew you were a patient of mine, unless I can’t bond. If for whatever reason, maybe sub gingival margins, or maybe I can’t isolate, they’ve got a tongue the size of a horse or something like that. Then I’m going to use zirconia and then for bridges I’ll use zirconia, okay. So, that would be the basic thought process there.

[Jaz] 
So, no more PFM for you?

[Ed] 
Now I haven’t done a PFM in ages. I don’t have a problem with it if you want to do a PFM. But, you know, conservative prep with this zirconia crown, take advantage of the substrate a color to bleed through, you know, the only time I might consider a PFM is where I’d maybe I had a completely black tooth. And I wanted to just make a thimble as thin as possible mental framework that I could go and coat so I could get a little warmness to it. So, that I had as much room for porcelain because I had a completely opaque the two that might be the one reason for it. Okay.

[Jaz] 
How about gold, and are you using much gold?

[Ed] 
Personally is, I used to love doing gold work. I did a lot of gold and I made it myself. I, my own, I do all my ceramics today and I still I have for a number of years. I don’t have a problem with it. But I gotta tell you that once you start getting known for doing, you know, nice looking aesthetics, I find people won’t even go like this if I used to make a gold occlusal, like that. You know, they hated the label. So no, I think it’s a fabulous restoration. Absolutely. If patient doesn’t care about aesthetics, and you like doing it. Absolutely, especially with some of your older patients that are bruxers. Oh here I was gonna go to an interesting place. Thankfully mentioned that. So, pop back in my head. So then, one of the questions related to this, what do you do on a significant wear case? Like you said, for your bruxers and you got to restore them, right?

Now, let’s start historically for what people would do, is they somebody come in with a lot of wear and a little short teeth and they want to have new looking teeth. Typically, what do we do, we cut all the rest of the tooth structure down, and we make crowns and maybe we open the bite depending on your belief system. I’ve been doing this long enough to know that I completely disagree with the Dawson philosophy. That vertical dimension is stable through life and teeth are supra-erupt at the same point. I completely disagree. They treated enough patients over the years, that there wear exceeded their super eruption. Then I was able to restore their vertical and they did fine. And obviously some didn’t. But think about that for a second, the concept for patients 50 years old.

Over 50 years, they’ve worn off 50% of their tooth structure. So, you’re going to treat a wear case. They walk in the door and your mindset is, you’re going to take off the 30 or 40% more of their tooth structure. You’re going to destroy 30% more in the next couple of hours and that’s a treatment? Okay, so you know that early on, in fact, right when Emax came out, that popped into my head. This is the material to use for wear cases. So, if I can restore vertical, great. It open as much as I can, I feel functionally, of course, you’re gonna test it out with your temporaries, your aesthetic prototypes and mock ups, whatever you want to call it.

See if they re-establish some closest speaking base, vertical dimension of rest. See if their muscles are fine here. You test that first then you go to the final and then basically I just go for one millimeter thick Emax. So, I prep through my mock-up when I get a millimeter great, if I already have a more and more than a millimeter of composite acrylic and they’re wonderful. It’s even thicker then. Okay, so that’s how I would restore a wear case. And of course, I’m not going to do porcelain veneers in wear case. I’m going to do bonded Emax on those those types of cases. But I never liked how that looks, to tell you the truth. It just looks different to me.

[Jaz] 
Amazing. Thanks for covering that guideline for wear cases I’m sure we gain so much from today’s episode at your place is called is it Art Oral America?

[Ed]
Yeah, so you can find my courses on AOA, it’s ArtOral America and I kind of partnered with DTG, dental technicians guild, aoadtg.com And then I have my own website called Edmclaren.com. And then I got all keep all my articles and crap on there. Actually, it was interesting you bring that up. Some marketing people said, you’ve created so much confusion in the marketplace because you’ve got names everywhere. Names for think blue, you’ve got names for black back and black now, you’ve got Art Oral America, got this. So, this you need to settle on one name. So, I actually just hired an IT guy and about a month or two, it’s everything’s just going to be in Ed McLaren’s. You can find everything under aoadtg.com. But next month, it’ll be just my name, so you can find it.

[Jaz] 
And the courses that you run. Are they catered for dentists or technicians or both? Who are you mostly teaching nowadays?

[Ed] 
D. All of the above. So, I’m a dentist and a prosthodontist. So, I have courses for dentists. I have courses for technicians. And I have courses for teams and I just restarted a course. You’ve probably seen this course called Full Digital Workflow for Milos Li culpa, I did that in 2008-2009. And then same period, I did it in 2013-2014. And it stopped for various reasons. And we just started again a month ago with John Archibald. So take a patient, start to finish. We do everything digital, but I had to call the digital dental team because I don’t believe purely digital restorations look that good. I believe that we have to add a little human touch; we change a line angle, we paint a little bit; we put a little surface texture, we do a little something to bring that good to great. And so, that’s basically the course that’s called the Digital Dental Team, where we treat a live patient. I actually let the participants machine some veneers. The dentists get to try theirs in and play this texture and stuff like that. So, that’s a fun course.

[Jaz] 
And that’s all in LA?

[Ed] 
Well, it’s all in my facility here in Park City, Utah. Okay, and because if I’m going to treat a live patient, I gotta have a good facility. I gotta feel comfortable because we got to start and finished in three days. But yeah, I mean, I do courses all over, you can just check my website or my social media and usually I post where I’m going to be if I’m going to be in Egypt, or I’m going to be in England or something like that. And so-

[Jaz] 
Well, I’d love to catch you in us one then I’ll put the links on the website so everyone can check out and it guys if anything, right I’m going to try and summarize this in the notes in a PDF format, or the list of guidelines recommendations. But do check out Ed McLaren’s website as content and do check out the movies. I’m telling you the movies, you know, keep me saying it, they are something else. And thanks so much for everything you do for the profession and really appreciate one of my heroes give me some time today. I really appreciate it.

[Ed] 
Thank you. Yeah, in the videos, five of the videos are on YouTube on Ed McLaren. Okay.

Jaz’s Outro:
Perfect! There we have it guys, the epic, the one and only, Ed McLaren. Wasn’t he just awesome? He’s a top guy. I’d love to go to the states and learn more and spend some more time with him. It makes me feel really great when these amazing clinicians give up their time to come on this show. So, thanks for listening all the way to the end. I know you’ve gained so much from that as it I once again. If you want to download the infographic, it’s protrusive.co.uk/ceramics. That’ll take you straight to the page where you can download the infographic PDF and it was just like a helpful aide memoire to summarize the findings from this episode. So anyway, thanks so much for joining me. If you found this useful, or if you know the dentist, your colleague who’s also struggling with ceramic decision making, please send them a link to this podcast. Share the love. Thanks so much. I’ll catch you in the next episode.