Proven Workflow for Try-in and Cementation of Lithium Disilicate Restorations

You're listening to The Dr. Phil Klein Dental Podcast Welcome to Dental Talk. I'm Dr. Phil Klein. Lithium disilicate restorations are the most popular aesthetic ceramic restorations being placed today. In this podcast, we'll be discussing the materials and time-improvement techniques used to deliver restorations made from lithium disilicate and how they can decrease problems and increase longevity of your restorations. Our guest is Dr. Gary Radz. who maintains a cosmetic-focused general practice in downtown Denver, Colorado for 25 years. He has extensively lectured and published on restorative and cosmetic dentistry. Over the course of his career, he has worked with manufacturers and laboratories to evaluate and improve dental products. Before we get started, I would like to mention that Dr. Radz’ webinar titled Proven Workflow for Trion and Cementation of Lithium Disilicate Restorations is now available as an on-demand webinar on vivalearning.com. Simply type in the search field RADS, R-A-D-Z, and you'll see the webinar. Dr. Radz, it's a pleasure to have you on Dental Talk. Good to be with you, Phil, as always. Thank you. Why do you think it's important for the restorative dentist to get a full understanding of lithium disilicate restorations? Well, Phil, lithium disilicate is probably... the most commonly used material for crowns and bridges. It's right up there with zirconia right now. Lithium disilicate, for some who may not be aware, Emax is lithium disilicate. So a lot of people know the Emax name because Ivoclar has done a wonderful job putting that product out and promoting it. But there are other lithium disilicate competitors out there, especially in the aesthetic arena. It's one of the most common, if not the most common restorations we're doing in our practices. So understanding the material and how to handle it and how to deliver it, I think is critical for most dentists. So we're going to be talking today predominantly about lithium disilicate. And as you mentioned, there's other materials that are out there. And again, synonymous with lithium disilicate is really Emacs to almost everybody's mind. But zirconia is also... I don't want to sidetrack off of what we want to talk about, but zirconia is becoming more popular. But I think that people or dentists in general may be underestimating some of the benefits of lithium disilicate and they're kind of jumping into zirconia and maybe abandoning lithium disilicate to some extent when they really may not need to or maybe they shouldn't. So hopefully you'll enlighten us on that concept. going forward feel free to comment on that now before i hit you with the next question yeah well just so i don't forget um certainly zirconia is this incredible material it's becoming really popular uh worldwide and the high strength of zirconia makes it very very attractive and cost also makes it attractive but zirconia to date Although significant improvements have been made in the last decade, zirconia still is not as aesthetic as a lithium bisilicate restoration. And someday it will probably pass it up. But where we are right now in dentistry, at least to my clinical eye and the labs that I use, lithium bisilicate in the anterior region is still my first choice. There may be factors that make me go to zirconia because of strength-related issues. But when I'm looking for the most aesthetic thing I can put in the front of somebody's mouth, I'm still thinking lithium disilicate first. And you probably use it for posterior restorations, too, in cases where the occlusion isn't a factor. Exactly. Exactly. Now, when occlusion isn't a big challenge, lithium disilicate in the posterior is an excellent choice for many years. before zirconia got from being really ugly to being somewhat aesthetic. I was using it in the posterior for a very long time. It has a lot of indications. Yeah. So in most cases, you get years and years of success, even posteriorly, except for those cases where the occlusion is just really overbearing. So if you would, tell us why the conditioning of the lithium disilicate chairside process is critical to the cementation process. Yeah. Lithium to silicate still needs to be bonded to the tooth to have the ultimate strength of the material, not just retention, but the bonding of the cement to the restoration to the tooth will give the restoration even more strength. So it's critical that the proper steps are followed to maximize not just the retention of the restoration, but also the strength of the restoration. So could you run through? The conditioning of the actual lithium disilicate before cementation, just run us through the process of what you like to use. And even talk about light-cured versus dual-cured resin cements, or you can hit that a little bit later. Okay. All right. Yeah, the conditioning part is actually pretty simple, but before you put in a restoration, cement a restoration, we're going to try it into place. Going to remove the temporary. You're going to clean the prep. You're going to make sure you've got no bleeding and circular fluids. And then you're going to try in the restoration. And then I'm going to evaluate not just the fit, but also the aesthetics. With a cosmetically critical restoration, I'm having the patient evaluate the aesthetics with me. So once we've tried it in and I approve it, the patient approves it. Now we're taking it out of the mouth, putting it on the counter. And we have to get it ready to cement. Now, during the try-in phase, we're going to contaminate the internal portion of that crown, bridge, veneer, whatever. So we have to clean out the inside of that to expose the fresh porcelain so that we can get the ultimate bond strength. The process itself is pretty simple. Back in the old days, we would take that restoration, put it in an isopropyl alcohol, put it in the ultrasonic for 30, 60 seconds, and then clean it out. Nowadays, we don't have to do that. We have cleaners that we can use. Ivoclar came out with one that was very popular, Ivoclean. It's gained a lot of traction. A lot of people use it. I use a product called Xerclean by Bisco because I also use Xerclean for cementing zirconia. So I have one material that I can treat both restorations with. So that's my reason behind that. The Xeroclean or the Ivoclean, either of the products, you just place on the internal aspect of the crown. You let it sit there 15, 20, 30 seconds, power rinse it off with your air water syringe, and then dry off the interior aspect. Now, what I like to do is I like to re -silinate the interior aspect of that crown. So I've just got chair-side silene. I use the Biscos, and it comes in an A and a B. Any two-part silene product will work fine. But I like to re-silinate it. And I say re-silinate it because if you're using a good lab, they've probably already silinated the porcelain anyway. But no harm can be done by re-silinating. In the silination process, what that does is it creates the ability to have a better bond of your cement to your porcelain substructure. That's why we're re-silinating. Clean it first. Rinse it. Air dry it. Resilinate it. Let the silene sit on there 20, 30 seconds. Air dry that. Now you're ready to cement that into place. Do you do that or does your staff do that? That's a team thing. That's what we train our team members to do. That's what I'm checking emails to see. If you sent me something, I had to respond to. Okay, so your staff is doing that, but then where do you come in? Because the next question is, I want you to talk about the light-cured versus dual-cured resin cements that you use. So tell us about that, if your staff is doing this, and the handoff into the cement, or do they cement it in as well? No, no, no, no. The cementation process, to my knowledge, Certainly in the state of Colorado or North Carolina where I used to practice, the dentist has to cement that into place. That's something I would never delegate, even if it was legal for them to do. Too many things can go wrong. So once my team member has prepared that, they come find me, say we're ready to go. I sit down with the patient. We isolate the area because we're bonding these restorations to place, so the area has to be isolated. You know, any bleeding has to already be under control. If I didn't do that, my team member's doing that at the same time as they're preparing the restoration. I'll come in, and then we are either going to etch prime M bond, or we may use these universal bonding agents we have now. I may skip the etch part and go straight to a self-etch mode of the universal bonding agent, depending on the different situations that exist. We'll have it isolated, etched prime and bond or prime and bond, and then we're going to cement into place. Now, you're asking about light cure versus dual cure resin cements, yeah. And self-cures, too. We'll talk about that in a second. Light cure resin cements with lithium disilicate are pretty limited in use to when you're doing a very thin veneer, okay? Your light has to penetrate the restoration to get to the cement to cure that cement. If your restoration's got any dimension to it at all, you don't want to risk your light not penetrating far enough. So with my lithium disilicate veneers, I pretty much will use LightCure resin cement. They're about a half millimeter thick. I know the light can get through there. And I like the little bit of extended working time I can get from a LightCure resin cement. So with my veneers, which typically I'm going to place 4, 5, 6, 8, 10 at a time, that little bit extra working time is advantageous when i'm doing a crown or a bridge i need a dual cure resin cement because i'm not confident my light will penetrate all the way through that thicker dimension of porcelain so i'll use the dual cure resin cements for that and now we kind of stumbled into self etching self adhesive resin cements those if i have a crown that has really good retention and resistance form I will use those products. So the Therasim by Bisco is the one that I use all the time. So if I have good retention and resistance form, and lithium disilicate is strong enough premolar forward that I can use the self-etched self-adhesive resin cements. The difference is dual-cure resin cements have a higher bond strength, categorically, all of them, than self-etched self-resin cements. categorically not manufacturer by manufacturer just as a category so if i need the best adhesion to bond that crown to place if my prep is short or tapered or both i want a stronger cement so that's the dual cure resin cement if i have good retention and resistance form i'm very comfortable using a self-edged self-adhesive resin cement what do you say to a dentist who says well why don't you just use the dual cure process for everything. So you get a little bit more strength. What's your answer? Yeah, you could. You absolutely could. Or is the answer, maybe you want to remove the crown at some point. That's true. That's true. With any of those cements, getting something off is probably picking up a burr and cutting. All right. So the main advantage of using the self-etched self-adhesive cement when you have the inherent retention, based on the prep design and the height of the restoration, the restorative tooth stub that's there. What's the advantage of that? Just you're saving chair side time. It's less technique sensitive. Less technique sensitive because you don't, you have to isolate that tooth for a very short period of time to grab the crown and stick it into place. As opposed to dual care resin cement, you're etching, you're bonding, or you're just bonding, but there's time. And if that tissue is really irritated and you're having a hard time to control it, if you're just like, I'm drying, I'm drying, I'm drying, hurry up, load it, hand it to me, boom. Okay, so that's one situation. The other advantage of self-etch, self-adhesive resin cements is there's a potential to have less post-operative sensitivity because we're not going through that etching step and that drying step. So one of the advantages there... is you don't have post-operative sensitivity. And then with the cement like Theracem from Bisco is there's a biocompatibility factor of the calcium and MTA that's incorporated into the resin that will actually help calm that tooth if it's been a little sensitive. Or you... You got close to the pulp, had to do an indirect pulp cap underneath your buildup, and you're worried about the endodontic lifespan of that tooth. The Therosem I really like in those situations because now I've got more chemical help trying to calm that tooth down. That's a big factor, actually. Yeah. I mean, I'm an endodontist myself, so I hear what you're saying. Okay. Yeah, we try not to keep you busy. Yeah, exactly. Well, I'm not practicing right now. I like the term endodontic lifespan. Believe it or not, all the years I practice, I'm not familiar with that term, but that's an interesting term. All right. I thought endodontic lifespan would mean after the root canal treatment was finished, how long the tooth would stay in the mouth after the root canal. But you're looking at it from the other side of the coin. How long I can keep it from going there. Yeah, right. Endodontic lifespan before you get to the endodontist. Really great stuff, Dr. Radz. You've always been a leader in teaching. We really appreciate all the feedback you've been given the dental community for so many years and Viva Learning, especially your webinars are great. Podcasts are great. So keep up the great work and thank you again so much for your time. Always a pleasure talking to me, Phil. Thank you.