Dentistry Uncensored with Howard Farran
Dentistry Uncensored with Howard Farran
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1138 Dr. Nate Lawson DMD, PhD, Director of Biomaterials UAB School of Dentistry talks dental materials : Dentistry Uncensored with Howard Farran

1138 Dr. Nate Lawson DMD, PhD, Director of Biomaterials UAB School of Dentistry talks dental materials : Dentistry Uncensored with Howard Farran

2/11/2019 6:18:14 PM   |   Comments: 0   |   Views: 206

Nathaniel Lawson completed a DMD/PhD program in the field of dental materials at the University of Alabama under the mentorship of John Burgess.  After a stint in private practice, he returned to UAB in 2014 to teach and perform clinical and laboratory testing of dental materials.  In 2016, he became the Director of the Division of Biomaterials and the program director of the Biomaterials Residency program at UAB.  He performs research for most of the major dental manufacturers to test the properties of new dental materials both in the laboratory and in the clinic.  He has written over 150 published journal articles, textbook chapters, and abstracts. 

VIDEO - DUwHF #1138 - Nate Lawson


AUDIO - DUwHF #1138 - Nate Lawson

He serves on the editorial board of Compendium, Dental Products Review, and the Journal of Adhesive Dentistry and was recently elected to the ADA Council of Scientific Affairs.  He was the 2017 recipient of the 3M Innovative Researcher Award and the 2016 Stanford New Investigator Award, both from the ADA.  He lectures nationally and internationally on the topics of dental ceramics and direct restorative materials. He works as general dentist in the UAB Faculty Practice.  He can be reached through his website at and you can follow his team on Instagram at dentinaltube.

Howard: It is just a huge huge honor for me today to be podcast interviewing Dr. Nate Lawson who completed a DMD PhD program in the field of dental materials at the University of Alabama under the mentorship of John O Burgess. After a stint in private practice he returned to University Alabama in 2014 to teach and perform clinical and laboratory testing in dental materials. In 2016 he became the director of the division of biomaterials and the program director of the biomaterials residency program at UAB. He performs research for most of the major dental manufacturers to test the properties of new dental materials both in the laboratory and in the clinic. He has written over 150 published journal articles textbook chapters and abstracts. He serves on the Editorial Board of Compendium, Dental Products Review and The Journal of Adhesive Dentistry and was recently elected to the ATA Council of scientific affairs. He was a 2017 recipient of the 3M innovative research award and the 2016 Stanford new investigator award both from the ADA. He lectures nationally and internationally on the topics of dental ceramics and direct restorative materials. He works as a general dentist at the UAB faculty practice. He can be reached to his website at or you can follow him like I do on instagram at dentaltube. It is a huge honor to have you on the show today Nate how are you doing?

Nate: Great thanks so much Howard, thanks so much for having me.

Howard: Well my gosh you're 35 I'm 56 so I'm 21 years older, I could be your dad. I'm telling you when I was your age the new thing was pfm and I never thirty years ago thought I would live old enough to see that come and go kind of like Dell computers. You know it was the biggest IPO and now it's not even publicly traded. So I'm wondering to you what is my pfm to you what is growing now that you think probably won't even be there in 30 years?

Nate: Oh wow okay that you know to the original you are saying like with it with the pfm even so I graduated from dental school in 2011, when I graduated I had done one all ceramic crown and now when we look at our dental students now I mean you know they're doing a ton of full contour zirconia crowns. I mean I would say predominantly full contour zirconia crowns and I could probably count on like one hand how many pfm crowns that I've done since I've been in the Faculty practice. So yes I think it's if you look at some of the numbers like I think there's a something from Gordon Christensen that was published in Giada and 2008 Glidewell is I think doing about 24% of their restorations were all ceramic and then when you jump to 2013 it's about 78% of the restoration.

Howard: So say those numbers again what year was the first year you said?

Nate: So in 2008 I think was about a quarter of the crowns they were doing more all ceramic and then when you go to 2013 it was about three-quarters of the crowns they were doing more all ceramic. So five-year jump where we saw just this big increase in the number of all ceramic crowns that were being made and yeah even for someone like me who graduated in 2011 I mean I wasn't trained in doing all ceramic crown there we had lectures about them and I didn't do a lot of when I graduated and now I mean that's predominantly all that I do. So it's kind of crazy to me how quickly that transit transition happened and then you know and even to think how recently that transition happened but yeah as far as things that are changing rapidly, I mean I feel like now I wouldn't when I'm looking at this going Chicago middle or meeting and some of these communities that these digital dentures seem to be so huge you know all the lectures about digital dentures I was at a digital dental lecture maybe about two weeks ago listen about that not something I work out a lot in myself but it's crazy to see that's I feel like that's one of the big new hot trends of 2019.

Howard: Does that mean you follow a denture queen on Instagram?

Nate: Yeah we shared a cab one time before I knew who that she was denture queen and then I saw the I actually watched your guys's podcast and I follow her on Instagram as well and yeah she's got some really cool stuff.

Howard: Well you know it always comes down to you know you have the very rich dentist treating the lifestyles of the rich and famous then you have the whole flyover middle country like you know I was born in Kansas went to undergrad in Nebraska went to dental school in Missouri now I'm living in Phoenix which is the Florida of the West and so you know Henry Ford said you make a car for the masses you'll get so richly with the classes and you make a car for the classes you'll be like the other eighty-five car companies that have come and gone. So it always comes down to you know that is is done digital dentures bleeding-edge high price or is it actually do the Fivefinger will make it faster easier higher quality lower costs and more miniature. Do you think digital dentures is bleeding high cost high tech lovers love it or do you think it's really for the working man to get a better denture a better price?

Nate:  I think it's starting to I mean the first time I'd heard about it there was somebody lecturing about digital dentures at the dental school and she was going through and show me this showing the steps and it seems so complicated I couldn't you know wrap my head around what was going on and again I mean now I do very few dentures so something that that clinically I wasn't paying attention to as much as a you know thinking about how to incorporate in my practice but as I listen to the steps I thought okay this is something that actually makes sense to me something that and the final products that they were showing look like they were pretty good. I mean depending on how they were fabricating them but it does seem like it's just like anything you know the first time that I saw we used to have these old CEREC 3 in the dental school and to watch one of those things work I thought you know I would never want to do that and then now if you have like a Trios or an Omnicam or look at one of those. I mean it's so much simpler to use and the technology's come so far. So I think that you know that's maybe that's how what's happening with digital dentures like

Howard: I bought a CEREC one in 1989 and it and it was worse than my temporaries that I could make in five minutes oh my god it's come so far. So I would my first question to you is you know natural paths are really taking off because about 1/4 of America has lost all faith in government in institutions like the CDC and the World Health or anti vax and a lot of them are just anti metal and I see a lot of people saying we're gonna do metal free crowns and then they're doing zirconia all day long. I mean when you look at the periodic table is zirconia a metal or is it not?

Nate: That's a good question Howard so a funny story about that was I was out lecturing and in DC and I had one of my friends come up to me afterwards and she had told me kind of funny story where she had been seeing a lecturer who had come and said that zirconia was a metal I said wasn't a ceramic zirconia is actually a metal and you should treat it like that and she went home and she started billing out all of her her full contour zirconia crowns is as metal crowns based on that lecture but it's definitely it's not a metal my background was in engineering so and if I was sitting there in my first day of engineering class an engineering 101 my professor would have said everything in this world everything we could feel in touch has made up with three things they could be a metal a polymer or it can be a ceramic. So ceramics are just a very basic kind of material it's a combination of a metallic and nonmetallic element and so there's materials that are like what aluminum.

Howard: What are the three things it could be what

Nate: The three types of materials that are metals polymers and ceramics so ceramics just the very basic kind of material it's usually something that's an heat insulator electrical insulator is also brittle materials and they're composed of metallic and nonmetallic elements and so this is kind of this is something I learned when I was in grad school from a guy who was in grad school with me and he taught me this kind of neat nomenclature thing. So zirconium is a metal it's a shiny lustrous metal and it's it looks like a metal but zirconia is a ceramic it's a combination it's zirconium dioxide so it's a combination of zirconium and oxygen and sometimes that could that's confusing. The one that I think it's easy to remember if you think of like aluminum like like an aluminum can we know that aluminum is a metal it's a shiny lustrous metal like aluminum foil or aluminum can and that's the metal as compared to alumina which was like what the old procedure crowns were made out of and alumina is a ceramic. So same thing zirconium is a metal and zirconium dioxide is zirconia which is a ceramic material.

Howard: and what would a polymer be, like a temporary?

Nate: Yeah like a resin like the resonant are composites or the polyvinyl siloxane or so many of our materials they are actually polymer materials and in the metals you know a lot of those as well so yeah at first I thought I would just like a silly nomenclature thing until I had the story with my friends who told me about billing out all of these metal or zirconia crowns is metal crowns. I thought those kind of funny of the danger of misinformation in a CE course so.

Howard: Well it's really tough some one of the one of the viewers on Dentistry uncensored sent me an email and she was asking me if she thought water fluoridation she knew that i-40 to Phoenix and I 89 with Jackie O burg and she's asked me if she should do it to her City and I said well the truth be 1/4 of Americans are have lost all faith all trust they think. I mean these people were telling me that I'm fluoride is so toxic that they when it's a byproduct of the mining and it's so toxic they have nowhere to put it. So they bribed the government to slowly pour it in our drinking water because there's no other place they can put it and I said well why don't they put it where they exploded 1800 and 50 nuclear bombs I imagine you could sprinkle some fluoride juice in some sites in New Mexico and Utah. I mean so it's tough and and on this metal thing and vaccines do you think do you think ceramic implants are going to take off because of the demand by holistic people that don't want metal?

Nate: You know that makes me nervous about zirconia implant is still just the the brittleness of the material. I don't know I mean that's not something that we've ever looked into and I know that is that is something I was at the holistic dental association last year and I heard them talking you know their vendors there with the ceramic implants but you know from like people standpoint it makes me a little bit nervous so...

Howard: My buddies here in town in Phoenix that have sunk ten thousand implants that's what they say they they don't they don't want the brittleness the fracture they don't want to removing them they have no interest in them but if you money's the answer what's the question, I've noticed all the big implant players, Straumann all of them have a bought a ceramic implant company they all have one in there and supply catalogue now.

Nate: Not something we've looked into to be honest but yeah and it's funny that you about you know talking back to the water fluoridation I just saw that they had Repub you know because one of the one of things we talk about here in the dental school is a lot of dental students are very Pro fluoride and then we have the discussion about you know what it what are the advantages of fluoridating the water supply if you have toothpick if you have a thousand parts-per-million in your toothpaste versus having one part per million in your drinking water but then we go back to this issue of well you know maybe it's the the people that don't have the access to the fluoridated toothpaste that need the water fluoridation the most and the topical benefits of water fluoridation.

Howard: Exactly ding ding ding that's what I always tell everybody the middle class doesn't drink water out of the fountain when I grew up in Kansas the most tasty delicious drink in the world was out of your garden hose you know it was hot outside you turn on the hose that's not reality all the middle-class drinks bottled water and so who's drinking fluoridated water the bottom 20% there in public schools they didn't brush your teeth before they went to school and yeah so it's just do you want to do you want to give them fluoridated water and prevent decay at 15 cents a year per person or do you want to pay $500 through Medicare and Medicaid and giving some kid a couple paw bottom using chrome steel crowns. Is you know there I'm a big fan of you and you say there's three types of zirconia, what do my homies listening and when I talk about this I want to be clear I always tell you leave a comment in the YouTube section you know give me your name or your age or what country you're from or email me and they're 25% of all the emails are from dental school the rest are all 13-under only one guy a week since me an email says he's as old as me and when you look at these kids when they come out of dental school 80% of all their dentistry is gonna be on the for first year molars. I mean what tooth is most likely an mod filling a crown a root canal an extraction and implant so when I talk, I just podcasted a the Delta CEO from Rhode Island I mean those guys do a billion a year in insurance but when you look at insurance claims over the 32 teeth it's just four huge spikes on the four six year molars. So on a six year molar what do my homies need to know what types of zirconia on there and talk about you know their first molar they're gonna do an MOD composite or an inlay or a crown so what are the types of different types of zirconia?

Nate: Okay so yeah that's it that's a great question so you know when I when when we talk about that you know 2013 when we looked at the 70% of single-unit crowns that were being done by Glidewell were being done at all ceramic materials the of zirconia that was being done back then was the kind of what I call actually call that second generations of zirconia that was when we had these what the one that everybody knows is Bruxier and that's the was the full contour zirconia crown I call that second generation because there's actually a first generation of zirconia which was the zirconia but you had to put felt back that porcelain over so like a lava frame material and those materials weren't they weren't considered a full contour because they didn't quite they were considered just too white opaque to be used as a full contour crown. So the Bruxier generation the ones that are Bruxier they're a lava plus those kinds of zirconia materials what I call second-generation.

Howard: What was the first generation one called?

Nate: First generation would be like a framework zirconia like a lava frame I think was was an example that and it's something that you had to put feldspathic porcelain over.

Howard: Okay

Nate: and that the change was I mean you know getting into the science of the change was they took out some of the alumina content there was 0.25 percent alumina in the first one and the second one went to about 0.05 percent alumina. So they took out some of this alumina I made it a little bit more translucent and that was the kind of the Bruxier lava plus generation of zirconia and then I would say about five or six years later they started coming out with these newer generations of zirconia that were even more translucent what they're calling anterior or translucent zirconia. So materials that were they were they were thought to have this kind of they were kind of made to compete with Emax something that you could put in an ant for an anterior monolithic restoration and when they the one that the first one the first ones that come out was Bruxier anterior katana you tml katana STM el lava aesthetic materials these were all the more translucent versions of zirconia. The change there was they increased this molecule called utria they went from a three mol percent utria which was in the Bruxier type zirconias to a five mol percent utria. So these are a whole different microstructured like if you look at the way if you looked at the an SEM of a crown that was made from these newer types of zirconia it looks totally different the grains are larger in this got cubic zirconia in it. The same thing the same kind of cubic zirconia that you'd have in a in a fake diamond well those that cubic zirconia is in the newer types of zirconia crowns that's what makes them a little bit more translucent. So I call these the third generation of zirconia so the first again was that framework that had a porcelain over it the second was the ones like a Bruxier crown that was a monolithic full contour crown and but it was still kind of white opaque and then the third generations are these more translucent or even more translucent zirconia crowns that they say could be used for an anterior type of restoration.

Howard: So on Glidewell what is their are they still mostly doing second generation Brooks er already they what is their third generation anterior translations zirconia called?

 Nate: So their third gen would be like the Bruxzir anterior that's what that's

Howard: What they're calling it?

Nate: Bruxzir anterior and the most part yet and

Howard: So would you and then Ivoclar they have their what is Ivoclar is their Zeno star is that there's eNOS star zirconium system

Nate: I should know this because I was just out there two weeks ago

Howard: Oh yeah you went up guy you went the wrong time of year man never go to Buffalo in the winter holy moly first time I went there I swear to God the Niagara Falls it was like almost completely frozen over but back to the so do take Glidwell's advice were that anterior zirconium is for anterior but use regular brooks ER on the on those four six year molars?

Nate: Yes so i mean for my patients in alabama for a you know the far for molar esthetics isn't very high. So I mean a second decoration is a you know I think more than good enough I mean this little white opaque but I think for posterior units and particularly if there's any posterior bridges the second generation is totally cool and then maybe moving a little bit more anterior when I want to think about doing a more and an anterior zirconia a 5Y or the ones containing cubic the ones like the Bruxzir anterior katana UTml st ml type crown.

Howard: but wouldn't you wouldn't these people that just came out of dental school and they got an associate job and they're they're doing you know they they need to get a hundred molar crowns under their belt. I mean you know this is gonna take some time for him but wouldn't you rather be cementing a Bruxier on a first-year molar than then bonding lithium disilicate on a molar I mean then the bonding an Emaxs on on a first molar bring a lot more complications and possible problems with isolation following the instructions. You know when these when these guys are bonding you can stand behind a hundred dentist and only see one guy with a timer you know that's why I learned when I went up to Ivorclar, you know they're saying you know when we say brush this on for ten seconds we we really mean ten seconds and all the hardcore guy is like so so would you rather would you recommend cementing it Bruxier over bonding on a first molar? Especially since these people don't follow the instructions they're a doctor of everything they mix kits that blows my mind they use a bonding agent from a 3m kit and a composite from I you know and Ivoclar or Altradent and I'm like you know are you are you sure someone with the DMD PhD like Nate has signed off on this new technique.

Nate:  I think so there's this I have to promote this locally because it comes my department chairman is the head of this thing called a practice-based research network and I think he might have had someone from them on the show and so they did a survey where they just sent out a survey to a couple thousand dentists ask them for first molar crown, if you had a picture restorative material what material would you would you choose and by far the well I wouldn't guess one say by far was things about 30% of the dentist for choosing full contour zirconia 30%  we're doing a pfm and then a smaller setting it was around 17% we're doing Exams for the first molar. So yes I think it's far more common to do a zirconia crown for that first molar and another we just recently did a kind of follow up with that where we looked at between zirconia and Emaxs how many of people were bonding versus cementing them. So with Emaxs yeah it was 70% of people that were using that material were bonding it and you know with zirconia about exact opposite only 30% of people were bonding the zirconia crown. So and most since most people are cementing them it does make it a lot more it means a lot easier to so if you're gonna cement that and I think a big thing too is cementing and bonding is part of it is technique but the other thing is isolation. So I mean if you're trying to do a first molar crown or any part of the any tooth in the posterior mandible trying to keep isolation for bonding that crown can be challenging. So you all think about isolation we're doing composites but you know when we think about bonding a crown that's also a resin, so we're trying to achieve isolation while we're at while we're doing that technique and I think well I saw the study that I always quote that I think is really interesting and that is if you're if you're going to be bonding to dentin like if you're bonding a crown if you bond to uncontaminated surface so if you get really good isolation if you use a resin cement you get a much higher bond than if you're using an RMGI but as soon as you get contamination on there actually your RMGI is got a better bond than the resin cement because your the bond is just completely destroyed by that Salaberry contamination so yeah I think that that's a (inaudible 24:00)

Howard: and so much of that is culture I mean I'm convinced so much of what everybody believes  just what their culture is what they're born into their language or politics. I mean I see glass ionomer and Australia, New Zealand ,Japan and I just don't see it in the United States and why do you think North America is so different with glass ionomer than Southeast Asia?

Nate: Yeah I have to say yeah when I when I graduated from dental school I hadn't used a lot of RMGI or GI for I knew talking for direct restorations

 Howard: Yeah

Nate: I think for force imitation I think RMGI cements are by far the more popular type of cement but as far as you know restoratives it's not as common I wasn't taught a lot about doing direct restoratives with RMGI or GI when I was in school and I actually I used to work on this practice of at Chicago and I'd see all these kids come in with these restorations in their mouths and I from the dental school up there and I'd be looking at them I said these are really they really this is a really challenging patient how did they how are they able to place restoration than this kid and I didn't realize it took me a while to realize they're placing a lot of GIS and RMGI for in the primary dentition and yeah when you can't get great isolation down at the for some of these classify restorations using an RMGI and GI material is great. So I don't I don't know we just weren't I think they're teaching it more now but I don't know.

Howard: So if she's driving to work her down she says hey Nate if you're gonna cement a zirconia on a six year molar or a Emaxs on a six or molar. What would you what would you seem at a Bruxier with and what would you bond a Emaxs with what would you what's your choice cement for Bruxzir on a first year molar you're gonna see my sofa

Nate: So on a first term well I mean basically with me with I'm doing a Bruxier or zirconia crown I I'm gonna go with an RMGI cement most of the time so never

Howard: Give them a name,  they get mad at me when they don't give it a specifics. They want me to hold your foot to the fire and say give me the actual name.

Nate: I think the two most common would be where we have relaxed looting plus the school

Howard: You have what?

Nate: Relax looting Plus, three amble and then the Fuji stems the other really popular RMGI cement which we've tested them both and they're pretty similar and something that's relatively new coming out at the market is the Calibra bio which is their calcium alumina cement which is

Howard: From who?

Nate: Dentsply

Howard: Oh Dentsply has Calibra bio... that's by Sirona

Nate: Sirona, sorry

Howard: You forgot the marriage

Nate: Yeah

Howard: So that three four is zirconia, 3M's rely ex, Fuji SEM and a Dentsply Sirona Calibra bio.

Nate: Yes the most the time with the with a first molar if I would just use an RMGI there's a couple that you know the one time where so I've got one that I've got to do tomorrow where I'm gonna bond a zirconium crown and that's for me that happens a lot for these second molars so when I got these second molars that are real short and I got kind of a limited occlusal space so I'm picking zirconia because I'm I've got kind of this limited material thickness I want something really strong so I'm using zirconia but then that my prep is just short because I'm trying to keep things relatively eques gingival. So I'm thinking I don't have great retention on my prep and I pick zirconias my restorative material and those ones out those ones all bond so if I'm doing you know cuz people you know there's a lot of controversy over can you bond or can you not bond zirconia you know I think that you can but it's not like I do it for every case I just do it when I need it and that's that's generally when I need it the most is for these short second molar crowns. So yeah and then I guess if you want me to go back with the with the Emaxs bonding an Emaxs crown so do a lot of these um we're starting to get into some of these more conservative preparations with these I did a I think next week I have to deliver this onlay that we're doing it with the zirconia I sorry an Emaxs onlay and for those ones the labs generally fetching it for me so they're planned to hydrofluoric acid etch try and clean it out with phosphoric acid applying styling primer and then we've got you know as far as with the cement options with if you're gonna be bonding a crown I think of them in two categories like how involved you want to get there's the ones that have a that have our self adhesive so you don't have to apply any kind of primer onto the tooth like the panavia essay is popular or unison two pretty good self adhesive resin cements and then there's the one that's kind of a bump up where you apply some kind of primer onto the tooth surface before you apply the cement like the relaxed ultimate with Scotch pine Universal on the tooth that's one we have here at the school that we use a lot. So you know I kind of think of them in those two different levels.

Howard: Man love your amazing mind this is on this is great um so I hate to say this to you because it sounds commercial and these I called you you didn't call me then it nobody pays me money to talk about anything on my show but what are the different brands of zirconia I mean there's you know powders there's all kinds of things and what are your thoughts on the different brands?

Nate: Yeah that's a good question so I guess taking a step back it's kind of interesting to look to what you know you missed another step back up when I was practicing up in Chicago I think one of the neatest things I ever did was I call it the lab that this I was working for DSO actually and I called it the lab they were using and I asked them if I could just go by and see the lab to see how things are done and it was interesting cuz my actually my grandfather was a laboratory technician and I you know used to go into the garage and see him working. So I thought a lab would be you know full a bunch of sweaty guys working like Mike you know grandpa making dentures and waxing and stuff up and I just wanna know there's a whole bunch of machines just milling things printing things. So it's a really educational experience for me to learn how my restorations were being made and they were really nice about showing me how they did everything. So zirconia the way that its manufacturers milled what that means it starts off with this thing it's kind of like this big oversized hockey puck of white powder and they take that they put it into a machine and they drill it down into a crown shape it's kind of this oversized crown shape and then they put it into a furnace to Center it and those pucks of zirconia can be made by several by many different manufacturers. It's interesting like with lithium Basilica people know the brand names like they know Emaxs or it's you know Celt repress or obsidian or any of the types of lithium disilicon materials or lithium silicon materials but you know zirconia there's so many different types of zirconia that you know many people I wonder if they know the name of their zirconia. I think that there are some differences in like a high quality zirconia versus zirconia that's you know just bought on the internet somewhere some of the things are the the way that they actually fabricate the disk so it starts off as like a powder and they actually have to press it into that shape and so how they press it into that shape can affect the deformation of the eventual crown that's being made. So one of the things that I that I think is a differentiating factor between different brands of zirconia is if you can either press it from the top and the bottom and they call that ice they call that uniaxial pressing or you could put it in like a ziplock bag and a pressurized can kind of container and press it from all directions and that's called isostatic pressing. So if you have something that's isostatic pressed then all those particles are more evenly condensed and so when you what that could ultimately translate to us is the clinician is let's say you have like that I had this happening one time for unit bridge went to go try it on and the thing when a fit, I was making adjustments after adjustment it was a headache, it was expensive lab bills I really wanted to make it fit and just never fit. Sent it back to the lab didn't change didn't same repression everything like that just confirmed about which material they were using got the crown back in it with a little bit adjustments to things seated. So I don't know if I mean it just one that was one anecdotal experience but that's the if you have a puck that isn't pressed well that the disadvantage is that you could it could lead to some deformation when they actually go in center that restoration. So I think that but you know that's that's one differentiating factor between a well made and not well made material also nothing getting a chance that you know now and what I do I get to visit actual dental manufacturing companies where they make stuff and one of the things that impresses me with high quality manufacturers is how much they do quality control. Like I see them they pull these things off the line and they go take them back to testing and I keep it you know just to make one little testing specimen I think man like you give me there you know I hate to see them waste that you know perfectly made product they just made to test it but you know they do a lot of testing other products to make sure that they're all kind of uniform and this centering is even and they don't deform so I think that that's you know another reason that you know I feel better about going with a high quality manufacturer for the for something like zirconia so.

Howard: I love your amazing mind you're a double doctor your doctor dental surgery and a PhD that is amazing. We have so much in common I asked my four boys on every summer on family vacations we visited several dental manufacturing places my dad did that we were a little wheeze too and we he loved the Six Flags Over Texas, arenas and when we would go to that city we'd also go to anything available that would give tours like car companies you know Budweiser tours all these things and I tell these dentists you know they want to learn how to place implants they think they got a fly across the country or fly to another country and drop all this money and there's a periodontist you know five miles away that would teach them everything for free, going down to the labs I did that what I got a dental school i'll never forget it a German guy and in Continental and I called him up and he told me to come down there and seems like. I mean it's free you would go down there and spend an hour an afternoon and you'd learn so much I drove to Nogales which is the largest removable partial framework lab in the world and just one day down there I learned more about removable partial dentures being in a place that makes a thousand a day than I did in all my years of dental school in college and these companies it's just amazing how you can walk into one of those companies with your four kids in a and a what is the thing called the the the pushing a baby in there and they'll just a stroller and they'll just spend hours with you teaching you all of this stuff and I also think the human mind you know when you're trying to teach my granddaughter all right I got five grandkids are you trying to teach them show touch feel just learn so much faster and when a dentist goes into a lab and they show touch feel you get to see your crown impression but to go to the table and see a thousand impressions in a row sent in and look at the model. I mean you just learned so much fast so kudos to you. When you see zirconia break what are you actually saying is that when they're adjusting it and cementing it do an injunction is it in bridges where do you see a break?

Nate: That's a great question so that was one of the fun things that when I first started teaching here at UAB is I went and talked to some of the prospects and I said if you you know if you if anything fails in the dental school I'd be really interested to see the failed restorations to see you know what happened and so I got a couple of these cases back and I remember one of the first ones they have to do 35 crowns to graduate at UAB and I went downstairs and it was one of the dental students fourth-year dental students and I think she was it was crown number 34 and kind of number 35 she was going to try them in and they fractured. So she's like crying and I'm all with my camera all excited to you know take the pictures of these failed restorations but what had happened was it was a second molar it was on the distal marginal Ridge where you know the manufacturers it's how you can get 0.6 millimeters of reduc are point six millimeters is their minimum occlusal reduction that you can get. So this was probably reduced 0.6 millimeters and then after the adjustments when we were made the crown was something like point four millimeters thick so it was you know it was after adjustment during trying wear this thing fractured and so we kind of changed though recommendations at UAB to try to get everybody to do a millimeter occlusal reduction with their zirconia crowns which built in a little bit room for error in case there was any of these adjustments made where they got to be a little bit too thin. So that's one place but honestly you know not that many zirconia single-unit crowns have fractured within the squad. I just haven't seen it that much what does what I have seen more of is fractured of fixed partial dentures. So with the fixed partial denture the connector is supposed to be they have this thing called the rule of 27 which is which means that if you you multiply the height or square the height of your connector and multiply it by the width of your connector an easier way for me to think of it is basically the most important thing is the height of my connector and I need to have three millimeters of height of my connector. So and usually a lot of times the problem with the height is coming off of the more distal abutment so if that if I've got a Schwartz you know if I'm using a second molars as a abutment too thin if it's real short and I don't have three millimeters I'm not going to be able to have that three millimeter connector height and so then probably a zirconia bridge is not the best solution.

Howard: Are you talking about all on fours?

Nate: No I'm talking about four just to fix a fixed partial denture like a bridge

Howard: Okay

Nate: If like a bridge if you have you can't get a the connector you know that the junction between the ponic and the abutment.

Howard: You know there's a lot of extremists in dentistry like there's a lot of dentists who say I will not do a bridge it's like well you're a doctor the average doctor is 2,000 patients you're saying you have 2,000 patients and not even one of them has an indication for bridge. You hear it all the time with general dentists who do ortho and say they they will never do an orthodontic extraction case, really seven and a half billion people and according to 23andme we're all a bunch of mixed Heinz 57 muts. You're telling me there's never there's never a mom and dad that get married and make a baby that's got two bigger teeth and two smaller jaws I mean it's just extremist thinking even amalgam. I mean even amalgam, I'm out here in Arizona where there's just a gazillion retirees from up north and if they're they have dementia they have Alzheimer's they don't even know their name and they get a an on average one root surface cavity per month in the nursing home and you're gonna do that with inert plastic composite when the wouldn't the amalgam you're a PhD all shut up what would you do if it was your grandma complete Alzheimer's didn't know your name was Nate and had a bunch of root surface cavities would you do amalgams or would you do direct composites and which one would last longer?

Nate: That's so it's funny because my grandmother has Alzheimer's doesn't know my name and she actually lives in Scottsdale so it was like a perfect later but says she so you know for her I keep on thinking about with her as I mean she doesn't have access to dental care so like with her I the one thing I can think is about silver diamond fluoride because I'm I didn't have a chance to take a look in the mouth in her mouth last time I was up there and I saw her but I can imagine that she's you know she's got her full she doesn't have dentures he's got a full mouth of teeth and for her with all those route carries I'm thinking silver diamond floor cuz we can't get her I mean to move her to take her to a dentist office is just impractical so to also just do just limited mobility problems but you know I keep on thinking about silver diamond fluoride for her. I mean also I mean if you had a pick between a mouth and a composite I agree if you can't get good isolation I think that composite is a bad idea but for that type of patient I keep on thinking about the that just being great indication for a silver diamond fluoride.

Howard: So are you that that's it's kind of funny because because the 31 years I've been atout of school you know there weren't any arguments and Peter pediatric dentistry I mean they that was a group it's not like TMJ where every camp has a different view but now the Pete Adonis actually have a controversy with silver diamine fluoride. Are you a big fan of that I mean do you what do you think is better silver diamine fluoride on your grandmother's if she gets a root surface cavity or are physically remove it with a burr and place resin-modified glass ionomer or amalgam?

Nate: I mean I think for a long-term solution if you if we could place something like an RMGI on for that root surface caries but I just you know for her I keep on thinking you know it would take me two minutes to apply silver diamond Florida and a lot of those route carries surfaces versus you know I could be done right in a nursing home versus having to try to take her out and do the restorative work on her so for me I feel like SDF it's just you know even if even if the RMGI is a more permanent solution for people for people like her it would make a lot more sense to be able to do the SDF but yeah we it we use a I'm a fan of SDF for me since I don't see kids anymore it took me a while to figure out where am I going to use SDF and an adult population. One application is for geriatric patients the other one where I've used it is so my faculty practice I have some patients that have come in with just ramp and carries with maybe 28 28 surfaces of carries and so you know with faculty practice you don't have you know not like a full-time practice I'm seeing these patients very slowly so I'll do SDF everywhere I kind of to rest everything and then restore over it with GI or with composite, so yeah I'm a big I'm a and for those patients that's worked great. So I've have I've become a fan of that material.

Howard: Well I'm if you ever you know there's always Mobile Dentistry of Arizona if your if your grandmother needs anything in Scottsdale, Mark Hank and Gregory Pifer, they got a hygienist Anne Ross, Renee Taylor they're good and and if you're ever in town visiting her and you need a dental office on you got mine 24 hours a day seven days a week ever ever need to see her. So how old is your grandma?

Nate: She was born in 1930

Howard: Wow yeah that's almost 90

Nate: 88 yeah

Howard: Yeah that is amazing silver diamond fluoride is a it's interesting times let's just say that interesting times. So we still do bridges what do you think do you think i'm a dentist should have amalgam in their office or do you think it's just it's just too controversial tap mercury you don't find mercury in a multivitamin would you just axe it out or and replace a glass reza modified glass armor or silver diamond fluoride or is there still an indication for the average dentist in america? Well let me answer this is a the DMD pc if it was your boy he's six years old and the center molar is the most i mean it's the unluckiest tooth in the mouth i mean it like saying it's good tooth it's gonna get an MOD filling a crown a root canal extracted replace an implant and your boy there's to start this whole thing gets an occlusal cavity on number three would you put a direct composite there or when you put an amalgam and which one and how long would how long would occlusal the composite last versus an occlusal amalgam it was your own six-year-old boy?

Nate: Howard that is such a hard question, i mean to say predict the longevity of those restorations i mean i'm not opposed to amalgam even though you know we do a lot of studies about  bonding and when I practiced we had amalgam you know I think that composite is a tricky material to use in order for it to do well you really have to use it well and I you know I thought I'd learned a lot about placing composite restorations when I graduated then after practice for a while and then when I come back and like now you know the more I the more I see like I realized that you know there's still so much to learn about do it just doing something as simple as the class to composite restoration to do it really really well. So I mean from caries removal to isolation to the bonding agent to how you place your restoration how it's finished so like I think that you know I think maybe amalgam is a little bit less technique sensitive and you know and it's hard for me to argue you know I see a lot of these pay a lot of my patients come in that are in their 70s with these amalgams that have been in there for 40 years that are still functioning. So it's hard to argue against the benefits of amalgam. I mean I would like to think that if it was you know my six-year-old or my kid coming in to have a restoration down in the sixth year molar that I would be able to do a composite really really well so that it would last as long as an amalgam restoration but I don't know as far as predicting build the lifetime of the two that's too hard of a question I can't I just be clear the guessing

Howard: and let me just remind people I mean we get emails on this show from you know countries all around the world and and I've been to a lot of those countries and my gosh if you don't have a dental assistant, high speed suction, rubber dams, isolation, there's two million dentists on earth and a million of them don't have the American operatory with a high-speed suction a dental assistant and if isolation is even remotely an issue and its posterior especially on a boy I get it with girls I mean girls girls just want tooth colored it's just their thing but for a boy you know who hasn't brushed his teeth in three days and wears the same damn New Orleans Saints t-shirt four days in a row. I mean on that molar you know it's I just think amalgam is so much better. Let's switch tubers because I remember the first time I had to cut off a zirconium crown I thought I thought the gods were cursing me what what is the best burs for zirconia crowns. What have you got to do a root canal through his zirconia crown what have you have to cut one off do you just like having bite down on the stick of dynamite then leave the operatory or how how do you get them off?

Nate: So actually they started this right before I started working here but I mean but then we continued this and we have a machine downstairs it's kind of a burr testing machine that we use to test a whole bunch of different burrs for cutting through zirconium the way the machine works is you've got this bird put in this turbine and you press a piece of zirconia against it with the controlled force and time and you see if it makes a real deep cut in the zirconia then it's a good burr and if it doesn't really do anything then it's not it's you know not a good burr. So when we did that test we just went and found like 10 Burrs I think they ranged from very fine to coarse burrs someone was recounting cutting Burrs just randomly put them in the machine and tested out a whole bunch of them and there were two that tested really well there was one from some company that I couldn't never even find the website for again and then there was a southern one which was this burr that was made by Comet it was just zirconia cutting burr and a lot of people say oh it has to be a fine diamond this happened to be a coarse diamond zirconia cutting diamond it was a road but what it used to be called they changed the name of it now to something called 4zr and again...

Howard: Comet does 4zr

Nate: 4zr, it's there it's there cutting burr and so we you know again I hadn't know I didn't really know much of anything about Comet at the time and then we made this YouTube video about how I did the test and put it out there and a bunch of people watched it because it was called how to cut off a zirconia crown

Howard: Did you post that video on dental town

Nate: I don't think they did I think it's on YouTube but

Howard: How do I actually find it on YouTube what's it called what

Nate: I think you just google how to cut off a zirconia crown and it's an older video, it just has that shows how we did the test and it shows that Burr and I don't know if it's coming up

Howard: Would your name be on it

Nate: Yeah if you put Lawson and how to cut off a zirconia

Howard: Put what?

Nate: Lawson and how to cut off a zirconia crown

Howard: Okay How to remove a zirconia crown by Nathaniel Lawson

Nate: Oh there it is

Howard: This is god he got twenty six thousand views on that good luck that's amazing yeah yeah so I'm subscribed to you on YouTube hell you have eight hundred subscribers that that's that's huge in dentistry. I mean most dental website you go to have three people on their YouTube channel but if you ever were to explode a video let like on Dentaltown I love your signature you have your Instagram link so you can just go right to click that but you should on what what thread should I put that on your site reply to you I'll just reply to that Bruxzir zirconia versus zirconia. Bruxzir zirconia versus zirconia thread are you a familiar is that thread and

Nate: I am

Howard: Yeah Bruxzir zirconia versus zirconia that's kind of a weird well what is that about what is there a difference between Bruxzir zirconia versus zirconia crowns is Bruxie just a name brand name zirconia are the properties of both about the same, My lab charges more for the Bruxzir zirconia versus zirconia crowns curious is worth to increase price to contribute so so is using the Bruxier brand name from Glidewell I guess this guy saying it cost more at his lab than a generic zirconium crown is that a difference?

Nate: Yeah I mean I kind of we're going to a little bit earlier like if there was you know if you're buying this puck that that white puck of zirconia from a brand name versus a generic I think that there are some fabrication manufacturing advantages of going with a brand name there's there's other brand names aside from Bruxier that are good a lot of them are from companies that we know because they're also dental manufacturers like Kuraray Dental that makes panavia products they make a zirconia and 3M they makes a zirconia and Ivoclar makes a zirconia and Dentsply makes the zirconia. So like you know a brand name zirconia I think is gonna be manufactured a little bit better and you'll see differences and strength and possibly defects or also deformation of longer spans stuff. So but I think actually one of them you know going back to the zirconia I think one of the big the biggest thing if I you know if I had to go out and talk to a group of practicing dentist is knowing the difference between the second generation and third generation. So I was given the talk at a dental association two weeks ago and I was talking all about this cubic zirconia and 5y zirconia and then I asked you know is anybody using this and nobody said anything and then I hear like a voice from the back of the room and it's their lab and the in the lab was saying yeah actually didn't you guys notice that all your zirconia started looking more translucent a little bit nicer he's like I switched it out so this is the stuff you're using now and so you know I think it's it's important for people to realize the difference that it's there's usually there's the 3Y it's stronger it's white opaque but it's stronger so that's the advantage that so that's what I would use for a posterior 3 and a bridge or you know if I had limited occlusal clearance and then the the newer stuff the 5y the anterior Konya is more translucent but you lose a little bit in strength. So I just realizing that there's a difference between those two types of zirconia

Howard: Yeah and back to extreme is some of these people you know they're they got their AACD they're cosmetic dentists all that stuff that's really important to women it's really important that people with high aesthetic needs, anterior teeth. Like the whole time been talking to you I've been you know I've been a dentist 31 years I still haven't seen one of your molars I see your Elvis Presley hair you know I see all these good looks but oh my gosh when people are making aesthetic health compromises on posterior teeth in men and boys where a dentist could talk to you for 40 days and 40 nights and ever see your molar. I just don't get it like like I have actually at least once a decade some woman you know wants all porcelain all that but it's a second molar I can barely get any reduction and I just say its maxillary and I just say this needs to be a full gold crown do the full gold crown and she's a patient ten years later and still doesn't know she has a full gold crown, only I'm the only person and maybe her ear nose and throat and my assistant that know she has gold in her mouth material you know there's a lot of a lot of emotions and I want to speak to another emotion that's bothering me in dentistry I see it all the time is when Europeans and what you weigh on this there they are unlike bonding agents just like I don't know if we'll ever be better than a third generation bonding agent I mean just your regular Bisco or whatever but these people are saying well I don't want to do two steps I just 1 steps like how would you like to be getting a bypass and the cardiovascular surgeons as well I I don't want to do a two-step stent I want to do once. I mean I mean come on dude you're a doctor are you really gonna change materials because of one step versus two I mean do you think sometimes there's a real compromise and trying to do everything too fast and easy and sometimes it's just better to do an extra step?

Nate: Yeah so there's this thing called fear this thing called the ACE panel it's the ADA clinical evaluators so they replace the professional project report with this ACE panel now. So it's surveys dentist I think that when the first ones is about composites and they did one about bioactives and the most recent one they would did was about adhesive. Sso they surveyed the ad members about what type of adhesive what generation of adhesive that they're using and it's about 75% of dentists are using the single bottle either a self-etch or total etch, single bottle and still about 25% of dentists are using the two bottle systems. Which I didn't I hadn't I wasn't aware of that data before I think that you know there's these newer universal we've done a lot of work we've got a five-year clinical with Scotch pine Universal where it actually competes with a two bottle system it competes with the multi-purpose as far as retention rates and what we call ring around the restoration, that marginal discoloration but you know you know when I sit when I suddenly think about it really hard you know is can we ever have a one bottle system that's as good as a two bottle system that actually it's funny you bring that up because I've been thinking about that a lot because the with all I think the disadvantage of the one bottle system they say is longevity because if you've got a two bottle system you've got the primer in the first step that's this hydrophilic step and then you've got a hydrophobic adhesive that goes on top of it. When you have a one bottle system you have to put usually put some kind of heme in there making it somewhat hydro a hydrogen somewhat sorry hydrophilic layer which can attract water and eventually lead to degradation that bond. So I don't know like can you our one bottle is gonna be as good as the two bottles I don't know but it seems like that's the way the markets going let that's we're about again 75 % of the dentist and that ace panel survey.

Howard: Incremental layers of a posterior composite are these new filler up in one gulp.

Nate: So yeah that they posed the same question for the ACE panel and it was it was actually surprisingly see that only 25% of the dentist and that ACE panel report we're doing the bulk fill composites and I just you know in my filling with bulk fill composite I use bulk fill composites for primarily you know all of my posterior restorations. With the bowlful composites what they are they're a little bit more translucent they allow a light to go through usually four to five millimeter depth of cure but just because they're bulk fill doesn't mean that I'm gonna mash it in there no matter how big the prep is and then care from the top and call a day. I would rather it just means that I can get away with a little bit thicker increment so we did we're doing a clinical trial we started measuring the depth of the boxes that we had in this trial and found out that there was about 20% of the restorations who are doing had a box that was six millimeters of deeper. So that would mean you know a traditional two millimeter cure composite that we'd have to be doing it looking at like four increments of composite and I don't know about you Howard but I like the who measures the first whoever measures their preps and who's gonna place for increments of composite so my thing with both fills is it just allows you to have larger increments so you can have a you know I usually I'll do one on the floor I'll do one to build up the marginal Ridge so this for class two and they'll do one from my lingual wall a one for the buckle wall and in that way you know I'm using a both full composite off I feel pretty good that even if there's part of that increment that's you know four millimeters deep at least it's getting cured. So that's that's kind of my my feeling in the bulk fills.

Howard: Well dude congratulations on getting on twenty eight thousand people to watch out YouTube video I'm and I get a post it on Dentaltown on so I'm Dentaltown when you go to youtube video share it shows you a copy of the link but if you click the next button embed it gives you the code and then you copy that code then when you go to Dentaltown when you make a post you hits a YouTube button and everybody that does that their YouTube channel explodes because you got a quarter million people on Dentaltown and Google says there's 1.6 billion websites half of them eight hundred million have monthly active users and so there's a lot of noise out there on the internet so by posting your YouTube videos on Dentaltown you get a ton of people subscribe to it and like I doing with your Instagram and I you should tell yeah so my gosh I can't believe we already been talking for an hour I can talk to you forty days and forty nights. What else do you think what else if we go to a little overtime what what else do you think these young 25 year old dentists have just walked out of dental school needed now about dental materials?

Nate: You know I think we've covered the main things we talked about our ceramic, cement, adhesives and composites I think we've covered those all pretty well and one of the things that I thought about that we had didn't get to finish a conversation about was we're talking about you know the way that our restorations look you had mentioned something about how you had never seen my molars when we're talking and then as dentists we have this need to make our our restorations look really nice and some of anything comes from like this Instagram and this social media where we have these great pictures of the dentistry we're doing and sometimes that can be sometimes to me that can be overwhelming. Where I see these restorations that look you know ridiculously nice you wonder if they're photoshopped don't wonder how they do it but in other ways it can actually be good I think dental photography has been one of the things that helped me grow the most is the clinician, this came from having to do these clinical trials where we took pictures of all of our work and looking at those pictures at first it was mortifying it was terrible I saw all these lines all these things all these contours I didn't know were there and if you know we talked about the technique sensitivity of doing direct composite restorations. I learned so much from those pictures and showing them to other people and the other people that I work with here at the at the dental school and helping me improve my composite restorations. Yeah that's it and then the like I said we have a team guys that I work with them that dentalube Instagram account I got a guy who's a for certified prosthodontist named LeeAnn RSA had an operative here a guy named Augusto Robles and then a master dental ceramist named Hernan la Sevilla and so it's a kind of a group effort we've had a lot of fun with that Instagram account is a combination of materials and photography and dentistry.

Howard: Well you do it real well, I hope you get John O'burges to come on the show think you can ever talk him into it?

Nate: I thought he did has he not has he never been on the show?

Howard: No he's never been on the show, he was a legend he'll he was a legend when I got out of school. I mean he's just an amazing man did you see him much?

Nate: Yeah so he actually we actually started working together it's been like 14 or 15 years now so I met him when I was in college and he's the one that brought me here. I mean he's been a great a great mentor I mean he he's the one that brought me to Alabama the one that got me this job here so he's actually I think he's right across the hall right now in his office, so yeah he's been he's just a really terrific guy and taught me you know most everything I know.

Howard: Well you got you gotta tell him I on to come on the show because I just love that guy just love him to death but man thank you so much I know you're a busy guy and my gosh it's not every day we're gonna have someone come on who's a double doctor a DMD and a PhD the kudos to you man and thank you so much for all your posting on dental town and dentinaltube on Instagram and his website is and next time you're out and visiting your grandma in scottsdale like I say if you want to have a hamburger will do it or if you need a dental office just bring it on my place.

Nate:  That'd be awesome thank you so much Howard a big fan big fan of the show thank you so it's a real honor to be on here so thank you.

Howard: Thank you so much they have a rockin hot day.

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