Ceramic Cementation.pdf

And what I'll do today is finish up this discussion or this topic a little bit earlier than normal. And then I'll spend some time going over what you need to do to get an A and the exam next week. Of course everyone, everyone will get an A, right. All right, all right. So remember that there are two...

And what I'll do today is finish up this discussion or this topic a little bit earlier than normal. And then I'll spend some time going over what you need to do to get an A and the exam next week. Of course everyone, everyone will get an A, right. All right, all right. So remember that there are two different types of cementing in dentistry today. This conventional cement which we talked about in the last couple of weeks using things like resin modified glass, iron or polycarbonate, light cement, zinc phosphate cement, that was conventional cementing. But then if you're using a resin cement, then it's referred to as adhesive or bonding restoration to place. So you're either going to adhesive cement something or you're going to conventionally cement something. All right. So let's move into the discussion of what if you had a lithium D silica. Only something like that would fit the preparations you did a couple of weeks ago. You really shouldn't cement that with resin, modified glass or any other conventional cement for reasons that I'll go into in just a little bit of detail. All right. So just be aware that there are in fact two different types of cement. Now there are some restorations, some crown restorations that can be cemented with either either the bonding technique and or the conventional technique. But I'll give you a little bit of information about that, and hopefully Dr. Brown's course will go into more detail on that, because that's his job. All right. Now, this is an important statement to make if you're using a bonding technique, if you're using a resin cement with adhesive bonding of an inlay and inlay, a crown of bridge of veneer, you're actually doing two things. That bonding is providing retention for your restoration. And that's that's obvious. Everyone could should be able to figure out, because it's pretty intuitive that the cement will help retain the crown. But more important, or as importantly for ceramic restorations, the ceramic inlay on the Crown et-cetera is actually stronger if it's bonded to place. Now, let me give you a really good example. Everyone in this room should know what a ceramic veneer is. So let me ask you this question. It's a ceramic veneer. Strong or weak? And the answer is it depends. Okay. But before you cement it, how strong is it? It's pretty darn fragile. Trust me. I've broken some with my fingers and I'm not that strong. All right, so ceramic veneers. Remember, they're only like a half a millimeter thin piece of glass, especially the early ceramic veneers that were feldspar like porcelain. At least now we have a stronger material, like lithium silicate. But. But a thin veneer is actually very weak prior to cementation, but once it's cemented to place, it survives extremely well in the hostile environment that is our patients human being mouths. Right. So the same thing happens with inlays on glaze crowns, etcetera. The whole issue of adhesive bonding something in place not only helps retention, but also adds strength to the restoration or fracture resistance, especially if you have lots of enamel to bond to. It's a little bit not quite as good as if a lot of your preparation is indented, but you actually improve both the strength and the retention. So this is a critical think about next Monday, next Tuesday fracture resistance and retention and marginal seal of any glass ceramic like lithium by silicate or feldspar, porcelain or IPS. Empress are all dependent on how well the material is bonded to the substrate. So good bonding means both strength and retention and marginal seal. So again, lots of things are happening if you adhesive bond something to place. Tell them I'm busy. All right, so I've already talked about. Well, this is the wrong slide. All right. So I'm going to show you a picture that will clearly demonstrate to you how adhesive bonding works. And here's the picture. Okay. So what is this. This is a this is a microscopic slide of properly etched ceramic material. So it could be lithium by silica. It could be feldspar like porcelain. It could be IPS Empress. It could be any of the glass, ceramic, abominable restorative materials. And as you can imagine, and you should remember this, that the whole secret of bonding anything to anything in dentistry is three things. Making lots of little holes, making sure those holes are attractive to resin, and then flowing the resin into those little holes. Right. So you see a lot of little holes okay. So lots of spaces here. And before this, this tooth or this restoration was etched. It looked like this. It wasn't blue but it looked nice and smooth and no porosity at all. So proper etching of glass ceramic materials provides lots of holes which inherently are already attractive to resin and can be even made me even more attractive to resin by the addition of xylene or MDP. You know other things in the primer that's used. All right, so here's the secret of adhesive bonding using an acid, which is much stronger than the phosphoric acid that you're all used to. So this is hydrofluoric acid. And in most ceramic materials it's hydrofluoric acid, either about 10% or 5%. It's important to know the concentration because that will dictate how long it should sit on the on the restoration. But this is what's going to make all the little holes. And this is what's going to make it attractive to resin. All right. So think of this is somewhat similar to bonding to two structure. This is similar to using phosphoric acid on enamel and dentin. This is similar to using a primer a enamel primer. But of course it's a different substrate. We're we're not dealing with tooth anymore. And the reason why anybody tell me why why this is in bright yellow. Why do you think hydrofluoric acid, a very strong acid, very caustic to soft tissue, by the way. Try it. Put a drop on your tongue and see what happens. All right. Don't tell anybody I told you to do that. All right, so why do you think it's in bright yellow? And the answer is so you don't confuse it. Or your dental assistant doesn't confuse it with phosphoric acid. Okay? Because most phosphoric acid today is blue. There are a couple in purple, but there is no phosphoric acid that's bright yellow. So this is almost neon yellow simply to remind you that oh no no no no, this is not phosphoric acid. Don't you use it on your class one and class two preps? Okay. This this will probably burn right through the tooth. All right. So it's a very strong acid. And you must follow the instructions for the time that it's applied to the internal surface of your restoration. The time is extremely important. And as I said, there's almost 10% and there's almost 5%. So again the 10% is a little bit shorter. The 5% is a little bit longer. So make sure that you know what you're doing okay. And again this also if this is used is only allowed to stay on the tooth for 30s it doesn't work. Well. 60s is the minimum that this should sit on the properly etched internal surface. So bottom line is absolutely certain that you know what material you're using. You know what the restorative material is that you're using. And make sure you follow the instructions because it might be a little bit different if using this on false plastic porcelain, it might say 60s if if you're using it on lithium silicate they might say 20s okay. And it's you know, you might think that, well, if it says 20s, I'll just go for 40s it'll be better. Right. And the answer is no. Okay. So all of these steps here are designed to to make certain that you follow the instructions. And if it says 40s, do it 40s not 42, not 40 3940 40s. All right. So the best bond, remember, that's what we're doing here. We're bonding to both substrates or bonding the tooth on one side. We're bonding to the the internal surface of the restoration on the other side. All right. And again the best bond would be a really good prep because again the prep is going to add some macro mechanical retention. The prep is also if the prep is mostly enamel, you get a better bond than if it's mostly dentin. And that's that will give you a better bond. If it's mostly like a core material, okay. And some things don't bind well at all. If you were cementing a crown over a cast metal post and core, you're not getting very good bonding to the cast metal post and core, because bonded bond of resin cement to metal isn't anywhere near as good as a bond to enamel, right? So hopefully you have a beautiful preparation that has a little bit of macro mechanical retention and is has a fair amount of enamel margins especially, especially, I'm sorry, a fair amount of enamel on the prep, especially at the margins. Okay. Now both substrates, meaning the tooth on one side and the restoration on the other side have to be made micro porous. Okay. And then you have to make certain that both of these substrates are attractive to resin cement. Okay. You also want to make certain that the cement space is small. So can and should you use fit checker like we talked about last week or the week before. And the answer is yes. Fit checker is always a good idea for ceramic restorations. They actually make fit checker in a different color than white. So what I showed you last week or the week before was was white fit checker. Remember fit checker simply gives you some idea of of how well seating, how well your seating is. But it also could give you information about why it may not be seating properly. So again, fit checker can be used for both metal based restorations and ceramic ceramic based restorations. And for ceramic you could use white. In fact, I think the white looks just as good as blue. For a while. They actually made it in black and that was a mess, right? So Fit Checker is available in different colors and you can use it just like you used it. Or I described a couple of weeks ago. And again, the best bond is if the cement is perfect. And of course most of the cements now are on the second generation, third generation, fourth generation. So most of the cements are are improved versions of their earlier cements. And the resin cements today are incredibly good. And as I may have alluded to last week, may be too good, especially when you have to remove the restoration 20 years from now, or if it's chipped or broken or especially. If you're well, it's important to know that maybe the cement is too good. If you have excess cement into proximally, it's so good that may be very difficult to remove. Right. So and again, just like any composite because remember resin cement is what the answer is. It's composite. It just has a different working properties, different viscosities and different filler particles. But it's designed it is essentially a composite okay. And it's either going to be dual cure like cure or auto cure. So as with any composite. Always important to avoid contamination. So would I do a bonded restoration on tooth number 32? A patient who can't open their mouth very wide. And the answer is no. I wouldn't, simply because I know I'm going to get contamination during the during the multiple steps of etching, priming, sealing, you know, all of those kinds of things. All right. And of course, this is very important. That's all important. But just like any composite is very important to understand that if you mess up, if you don't follow the instructions carefully, and if you mess up a little bit, it's not going to work because it is technique sensitive. That's what the test stands for. Very technique sensitive. Okay. And remember, one of the big differences between resin cementation and conventional cementation is technique sensitivity. Your technique sensitivity simply implies that if in fact it's not done perfectly, it's not going to work properly. And you can in fact be a little bit sloppy because resin modified glass is a little bit tolerant of moisture, it a little bit tolerant. It'll still probably work even if you get a little contamination. But bonded restorations? No. And that's especially problematic when you have multiple steps. All right. And here's just another example of a properly etched internal surface of ceramic okay. So it's very similar to what I talked about before in terms of conventional cementation. I always recommend that you inspect the restoration as soon as you get it back from the lab to make certain that's what you want, okay? Because every so often a patient will be in the chair. You open up the package from lab and say, this isn't the shade. I wanted something like that. So make certain that it's exactly what you want and make certain of that before the patient is in the chair. Because who wants to send the. Especially if you anesthetize the patient, then it's a wasted anesthesia, right. So make certain that you inspect before the patient sits down. I strongly recommend that you anesthetize the tooth. Unless it's a very super gingival margin on an endotoxin treated tooth. You know, you can use common sense here. But most patients today expect nothing to hurt. Okay. Too bad. I wish they did 1 or 2 hurt, but they they don't expect it to hurt. And as I've mentioned before, most of our patients continue to come to us because we don't hurt them. You know, it's not because they love our margins. It's not because they love our our line angles and point angles and things like that. It's because we don't hurt them. And we have nice music on the stereo and there's parking in our office. That's those are the probably the most important things in terms of building a practice right now. The other next thing that's really critical is don't force it in, try it in gently. Because remember, this is a piece of glass that hasn't been bonded yet. Just as I mentioned the veneers that I could crack with my fingers. Okay, so it's very fragile. So if you had an mod ceramic inlay and you push it with a lot of force and let's say there's a little undercut, a little, it could actually crack right in half when you're trying it in. So don't force it into place. Make certain that you try it in with finger pressure only. Okay. And again, just like we did with with conventional restorations, assess the proximal contacts because remember. A bulky proximal. An exam question, by the way. A bulky proximal contact is the most common reason for something not seating the first time you try it in. All right. So again the same thing applies to a ceramic inlay or only or a veneer for example. Or an anterior posterior crown. Make certain that the proximal contacts are perfect before you check it with fit checker. And as I mentioned earlier, this is available in blue. Okay, then of course the preparation is going to be cleaned and prepared. And I'll talk about what preparation means in a second. But this is important especially for small fragile little inlays and analyzes. Don't check the occlusion until after it's cemented. This is a little bit different than than what I do for crowns and what I do for bridges. ET cetera. I don't even look at the occlusion, simply because if the occlusion is a little bit high and a patient bites down with firmer force than you hope, because some patients say, I want you to gently bite down and they go, where am I? You know, they bang their teeth together. Advanced accidents that ever happened to you say, oh no, no, no, don't bite so hard. All right. So so when you say bite, well, first of all, don't say bite down. Say bring your back teeth together in a nice comfortable bite. You know, listen closely to what I'm about to say. Do not bite down. I want you to gently, you know, those kinds of terms. But for ceramic inlays and on lights, do not check the occlusion, especially if it's one of the weaker ceramics, like feldspars, like porcelain. All right, so check it on the dye. Make certain that the margins of what you want etcetera. And this is what it will look like coming back from the lab. Or if you're really good at staining and glazing in your own office, if you use milling technology and you have, you know, porcelain ovens. ET cetera. But the external surface of this Molle inlay should look like a tooth. It should have little pits and fissures. It should have a nice glossy surface, but the internal surface will look like that after it's been properly etched. It will not look like that before. It's etched. All right. So it has this classic frosted appearance. Okay. If it's etched properly with the right solution for the right amount of time. Okay. Now who's going to etch it? You or the lab? And the answer is either one. It doesn't make any difference as long as you know which ones. Don't assume that the lab will match it, because in many labs they won't etch it unless you ask them to etch it. All right. So I routinely, in my prescription form will say please etch the internal surface with and they know, you know, the appropriate time. And one of the nice things about having the lab do it is they probably have unexpired hydrofluoric acid. They probably have all the right solutions and they do it all the time. You know, if someone does it routinely, that's their job. They probably because of added experience, they probably do a better job than someone who does it once a month, a couple of times a month. And they probably have brand new unexpired material. So this is what you want. Okay. Now this should also be inspected. Take a good look. Because sometimes if you have a sloppy lab technician, there might be a little error there that's not etched properly. And this is really, really critical because if there's one little spot. You can. You only want to reach right there with that spot is because you don't want to double edge everything else. Right. So if the if the instructions say for lithium silicate, etch it for for 20s. Okay. And you reach it now it's 40s. And if you etch it too long, you will not get that nice micro porosity pattern that you will if you adjust the appropriate amount of time. So this is me trying in that mol inlay. You can see the margins because it's not bonded to place yet okay. But you should be able to tell when you seat it if in fact it looks like it seats. Because again for an inlay, if it doesn't seat, this is going to be a big ledge all the way around the margins. Okay, but double check it anyways. Use dental floss by having a dental assistant take a ball, burnish her and put put it right in the middle of the central pit area, and then check it with wax floss to make certain that the proximal contacts are okay. Okay, now let's talk about surface treatment. I'm not going to go. I don't expect you to know all of this, but I just want to stress the point that different ceramic materials may require different surface treatments. So feldspars like porcelain, good old fired porcelain and IPS Empress, which was very popular, let's say ten, 15 years ago with 5% phosphoric acid, a 60% second etch, now lithium based silicate like Emax. Most of you have heard of Emax. I assume that the instructions are very different. 20s if you're using 5% phosphoric acid. If you're using enamel, which I've never used but is somewhat popular here at the dental school because Dr. Giordano invented it. Do you know, Dr. Giordano, if you had biomaterials yet? Okay. You will. All right, so biomaterials, the director of biomaterials, Dr. Russell Giordano, actually invented this hybrid. Somewhat like composite, somewhat like ceramic material called Namik. Not very popular, but it's popular here because he invented it and he wants us to use it. So put up your hand if you ever heard of anemic one two. Yeah. So next year you'll hear about it. So all right cell to do is another one. The reason why we use this is because it's. It's dense splice erroneous product that so they like to sell us blocks. But again, the only reason why I'm showing you this is to impress on you that different materials will require different etching times, with either 5 or 10%. Hydrofluoric acid. Not phosphoric acid. Okay, now what is Evo clean? Evo clean is relatively new, and it's not the only one in the market. Katama, which is a brand from from Japan, is also makes a very good product, very much like a clean. Now I have a clean is a cleaning solution that you use after it's been tried in. Okay. And I'll go through details in a second on what it actually does. But I have a clean it's like a super cleaner making certain that all of the contaminations are disappeared and use it properly. And then this is the primer that you're going to use Modern Plus for at least 60s. This is what we use here at the school, and it's probably the most popular, at least one of the most popular in the world. So this is the thing that makes the ceramic surface attractive to the resin cement. Okay. Just like a tooth. Make holes, make them attractive. Okay, now I've mentioned the pick and stick. When I talked about Temporaries, I used picking sticks all the time when I'm when I'm inserting ceramic restorations. So invaluable. So hydrofluoric acid is going to do that. And this is the appearance. Obviously this is a full crown and the outer surface looks just like enamel. It's nicely polished and the internal surface has that beautiful frosted appearance. Okay. And again just another crown with an internal surface that's nicely frosted. All right. Now let me talk a little bit about Iva clean because this is a relatively new product that is critical to use. If you're going to be bonding zirconia restorations, that's an important statement. It's critical to use this product if you're bonding zirconia restorations. Now, I'm not going to talk too much about zirconia because you don't do inlays inlays. And it's Dr. Brown's job to talk about full crowns and bridges. ET cetera. So I'm hoping that he'll go through lots of detail on why this is so important for zirconia. But let me tell you what it is. It's an optional material for cleaning out glass ceramics, like our inlay products, but it's a mandatory product for for cementing, for bonding zirconia. So let me just digress for a second. I do a lot of zirconia crowns. I do a fair number of zirconia bridges, although I don't do any very many bridges anymore because implants are pretty much replace bridges in my practice. But but every time I use zirconia, if I have a choice of either bonding it or cementing it, okay. And I almost always 95% of the time will cement it conventionally with resin modified glass cinema. That's the norm. I think. However, it can be bonded to place. And there are some people who say, oh, I think I'd rather bond it to place, even though it's much more complicated and a little bit more steps, etcetera. Because using conventional conventional cements like resin modified glass is so easy and so technique insensitive. But anyways, most of us most of the time will use resin modified glass on my physical. Okay? However, if you feel a need for bonding resin bonding, zirconia restorations okay, zirconia is a totally different ceramic. It's a non glass ceramic that is unreachable. So remember that. Ah that photograph that I showed you. It's all little micro porosity. If you took hydrofluoric acid and put it on the internal surface of a zirconia crown, what's going to happen. Nothing, okay? It does not etch. It does not form that microprocessor pattern. However, you can get it to chemically bond to resin cement with certain types of special zirconia primers. Okay, anyways, that's all I'm going to say because again, it's more in Dr. Brown's realm of topics because it really isn't used for inlays, inlays, veneers, etcetera. It's only designed for zirconia restorations. All right, now let's get to I.V. clean. The purpose of eviction is to is to eliminate any phosphate contamination from the internal part of the Crown. That's important. I've a clean is designed for removing any phosphate contamination. Now, the typical source of phosphate contaminations is spit. Okay, so saliva has phospholipids in it. And if you try it in and you adjust it and try it in again, try it in again, okay. It's bound to pick up some saliva on the internal surface of your restoration. Okay. Now if you try to bond it and there are phospholipids inside the crown, it's not going to bond well, right. So you need to get rid of the phosphate contaminants in the internal surface of the Crown Bridge. ET cetera. I've clean does it beautifully, because what I have a clean is, is a suspension of little particles of zirconia. Now, why is it so important for zirconia? And the answer is phosphates have an affinity for zirconia. Right. And phosphates interfere with polymerization of resin cement. So for zirconia you need to get rid of the phosphate contamination or phosphate contaminants inside the restoration. Everybody got that. That's important okay. And this if you try to sand. Well first of all don't sandblast because you've already etched it with phosphoric acid I'm sorry. Hydrofluoric acid. You'll really screw things up if you sandblast. You know, you're not going to you're going to sandblast away the micro porosity so you don't sandblast anything that's going to use hydrofluoric acid. All right. So think of this as a phosphate vacuum cleaner okay. You put it on, you shake it up first like vigorously. You shake it up, you put it on the internal surface for 30s or so, and all of the phosphates will immediately be attracted by the little particles of zirconia in here. Okay. And then when you rinse it away, there's no more phosphates. All right. So what I just said is critical for zirconia restorations. Now can you use it to clean out the internal surface of, of lithium silicate for example. And yes, the answer is yes you can, but it's optional whether it's necessary or not. Probably not. It's sort of like wearing belt a belt and suspenders okay. You only need one. But some people are so compulsive they want to use both. Okay. Just to make certain that their pants don't fall down. All right. So this product right here is a suspension of zirconia particles that attracts the phospholipid contaminants from the spit okay. And it's really, really, really needed for zirconia. Is it really needed for anything else in. The answer is no. But a lot of people use it and it does a good job of cleaning it. It's just not necessary. And I've cemented thousands of of porcelain veneers and thousands of IPS, Empress crowns and thousands of of lithium silica crowns before I ever clean was invented. And none of them fell off, so I don't know whether it's really necessary anecdotally. Okay, so what we've done so far is the lab is probably etched it with the appropriate time, etcetera. If the lab is etched it or you etched it, then you try it in, okay. Make certain that you make any adjustments as necessary except for the occlusion. Do not check the occlusion yet. Okay. Okay. And then when you're happy with the with the fit. ET cetera. Then you clean out the internal surface. Could use either clean or you could just use water if it's a conventional cement. I'm sorry if it's a conventional restorative material, but now you have to add the primer. And primer used to be just mono bond, which is just a saline. But the plus means it's a sideline and it's MDP. Okay. And we'll talk about MDP a little bit later. Okay. Okay. So mono bond plus the plus makes it contain both sideline and MDP MDP and following the instructions that comes with this bottle. It has to stay on while I say on the restoration, I mean on the internal surface of the restoration for at least 60s and then don't rinse it off, just blow it dry. Okay? And now it's ready to go. Okay, well not quite. You have to pick it up with attach it to a pick and stick. Okay. Just as I mentioned with Temporaries, pick and sticks are simply plastic sticks with little soft wax on the end that can be attached to the occlusal surface of your inlay, or only make certain that the soft wax does not get on the internal surface, because then it's going to interfere with your your bond. All right, so this is the stick. I don't know why they made it in green for a while, but anyways. And obviously this is a two surface inlay. The internal surface has been actually the external surface has not been etched. And I use this not only for temporaries, not only for restorations like this. I use it for veneers. They use it for, you know, I don't think I could do dentistry without picking sticks. It's one of the cheapest things I buy. All right, so that's the surface treatment that has to be done to the internal surface of the restoration. What about the surface treatment of the tooth. And the answer is well, you already know this. You know that it has to be bonded to place with etching, priming and sealing. But because it's a dual cure resin cement, it's going to be used. You have to have a dual cure. Binding agent. That's an important statement. It was learned the hard way that if you use a likable, binding agent with a dual dual cure cement or dual cure core materials that we'll talk about when we're talking about individually treated teeth in their restorations, okay? They don't bind together. They don't bind well together. So it's important for you to know that whatever cement you're using make certain that you're using the appropriate bonding agent. The good news is that all of the cements, when you buy them, they come with their own bonding agent. Okay, but don't mix and match. Don't say, well, this is called a bonding agent, so it must work like any other binding agent it may not. So make certain that you're using an appropriate bonding agent with the with the type of cement that you're using. Okay, so the tooth treatment after it's been tried in remember you've contaminated like crazy. If you try and you've probably got a little bit of bleeding, you probably have a lot of saliva contamination. But after it's been treated, you're going to re clean it with flour, pumice and water. Okay. Remember you already hit it with flour improvements to water when you took the temporary off okay. But now you're going to do that again okay. Now isolated as well as possible. There was isolated time where you can use a rubber dam, but most people don't. But even people who who routinely use a rubber dam usually don't for indirect restorations. But it does work. Or you could use a mister thirsty, or an ISO light, or an ISO dry. Anything. You know, a good dental assistant with good suction techniques, flour, cotton rolls, saliva injectors, all that kind of stuff, whatever it takes to isolate it so it has to be cleaned again. Isolated. Well, you may need retraction cord if you have any, any suspicion of bleeding or if you have any if you're slightly sub gingival in any of the margins. Retraction code is always a good idea. Properly and carefully placed retraction cord okay. It doesn't. If it's an inlay, it doesn't have to go all the way around the tooth, just in the area where you want to make certain that you avoid any sulky fluid or bleeding contamination. Now, I put a question mark here because 50% of the restorative dentists use phosphoric acid, 50% don't. Okay. So most of the bonding agents I'm sorry, most of the resin cements that are available recommend etching enamel. But then they'll say it's optional. Okay, in my opinion, shouldn't be optional. Okay. Because if you selectively and carefully etched enamel and rinse it off, it takes a little bit more time and you have to be a little bit more careful, but you'll get a better bond to enamel. Okay. How much? How much better? You know, it's arguable some people will say, no, no, you don't really need that. Okay. But I like to selectively etch the enamel, rinse that off and then apply. If I'm using this system and I'm going to show you what this looks like in just a few minutes, then you usually have to mix the dual cure bonding agent, which is a combination of primer and bonding agent or primer and infiltrator. Okay. And remember, it's going to infiltrate into the little holes in both the ceramic and into the tooth structure. Okay. But most of these kits have their own bonding agent. And as you can see, when you have to mix two things together, it's not just like durable. You have to mix two things together. It's probably either dual cure or maybe even auto cure. Okay. And again apply the mixed primer A and B equal amount. Let's say one drop of a and one drop of b, or two drops of a and two drops of B, depending upon the size of the of the preparation. Then you apply it and then carefully with no water in your air water syringe, you carefully dry it, dry it, but you're not really drying it. You're evaporating the solvent. Remember, primers have things like acetone or alcohol in it, and there may be some remnants of a little bit excess water into the dental tubules. You want to eliminate that by using the proper appropriate primer. Now for this particular kit, the multi-link kit that we have here at school. That's why I'm stressing this particular brand, although there are others okay. It says don't cure it. Okay, so you do not cure the bonding agent. After it's been applied, you immediately put the cement into the crown and then inlay online and cemented. Okay, so get it isolated. Maybe with a rubber dam, maybe with a retraction cord makes it that you clean it with. Not with coffee paste, but with flour, pumice and water. And I just put this slide in because this is what I use for a little to clean out a little inlays and inlays. It's called an intra coronal bristle brush. And it's a tiny, tiny little brush. You know, I don't even see it. But this is what I use with the with the prepping. Okay. Now it's also a good idea to place a barrier so you don't bond the tooth that you're restoring to the adjacent tooth. And a Great Barrier barrier is Teflon tape. Also known as plumber's tape, because plumbers use it to create a great seal around their pipe fittings. Okay, now. I should say this a lot of dentists just go to Home Depot or Lowe's and buy plumbers tape. You probably shouldn't do that. Okay. Because again, it doesn't feel right. So you can get plumbers tape. They'll charge you a little bit more if you go through a dental supply store, so you can get plumbers tape that is designed for dental work, but it's probably they probably get it at Home Depot. I don't know, so I'm not really sure. All right. But this is this is actually. Very thin plumber's tape. If you've never used plumbers tape, the beauty of plumbers tape is it's incredibly thin, but it's a very effective barrier. All right. So I've talked about multilink so far. And the reason why I want to concentrate on this brand is this is what we use at school. This is what I've used in my practice for 15 or 20 years. So it's a really good, well respected cement from Vivint. And in my opinion, I've Vivint is one of the top 4 or 5 companies for making resin cements. There are others. Three makes a great brand is a really good brand. So there are other brands. Biscoe makes a brand. So this is a good one. But it's, you know, just the one we decided to use. It's one of the few products that's not from dense ply Sirona. So. So they're all right. So and again, you can see that these two things have to be mixed properly, which is pretty simple. Then apply to the to scrubbing the tooth for at least 30s or so lightly blown dry not cured. And then this is automatically mixed because of this little baffle tip here. You know, this is a base, this side is the catalyst. And when you plunge this in, the properly mixed stuff will come out here with no streaks and no bubbles. Remember sort of like compression materials. Very linked to is another very good one. This is a great one from from curare. And again it's a great company. But you can see this is fairly similar to the primers come in two bottles that have to be mixed together. And the actual resin cement is in this auto mixing thing and they actually have applicators etcetera. All right. So this is me. You can see everything is well isolated. I'm doing an MOH inlay on this particular tooth a placed a barrier of Teflon tape on the adjacent tooth. So I don't bond two teeth together. Okay. And then my dental assistant is mixing these as I'm getting everything ready. Just to stress this, where I haven't shown you here is I would have selectively etched the enamel too. So selective etch. But again this is considered optional. I know many dentists who don't do this. Many dentists who do do this do do this. Okay. And again, it's auto mixing. And how many times have I said how wonderful it is for dental assistants nowadays? Because all you have to do is squeeze things and push things and, you know, no skill. All right, now, just as I'm ready, getting ready to to work on this, I'm also taking the overhead light, putting it into composite mode of. Also, I'm also putting the orange filter on my headlight simply because especially when you're using resin cement to cement something. If you if it starts to prematurely polymerize, you're in big trouble. Okay. Because again, you have to be able to seat it when it's totally unset. It hasn't even. Remember when when resin cements it goes through three stages. It's the liquid stage and then the gel stage and then the solid stage. Okay. So don't don't wait until the cement is in the gel stage. When you're trying to seat it, it has to be in the total liquid stage. All right. Now once it's properly seated, then you can take your curing light and do something called a wave cure. And a wave cure is simply kind of waving it over the tooth for a couple of seconds. And what this does is it brings all the excess cement into the gel stage. Okay. Then it's easy to remove the excess. Okay. So as soon as it's properly seated, you can see all the excess cement that's oozed out beyond the beyond the margin. Do a wave cure just a few seconds from a few different different areas, and then take either a scalpel blade, dental floss, and or a scalar and remove any obvious excess. Don't wait until it gets fully set. It will be a nightmare. And if you wait until it's fully set, you got about a 90% chance that you got to leave some excess cement mid proximal. All right. So again now's the time to remove it. Okay. And again scalpel blade scalers whatever whatever it takes. But again remember you want to be doing this when the cement is in the gel stage okay. So make certain that after remove the excess then go back and cure it some more. Now this is a dual cure cement. So you might say, well, if it's dual cure cement, it's going to chemically cure no matter what. But sometimes the chemical curing takes a long time. So it's better to do as much light curing as possible because light curing is rapid. Okay. And again, you don't want to wait for it to chemically cure. And then especially if you haven't isolated properly, get some contamination or a bleeder at the gingival margin. Right. So. Concentrate on mostly light curing. But again, don't worry about the deepest part because there anything that hasn't been cured, it will eventually chemically cure. But it might take 10 or 15 minutes for that to happen. Okay. So again, here's just some clinical examples. This is an inlay only that's replacing just the medial buckle cusp okay. And that's what it looks like after it's cemented. Now I didn't use a rubber dam here but I use cotton rolls I use a retraction cord. I use the the Teflon tape. Okay. I attach the restoration to the pick and stick like I showed you before. Okay. And again, if you squint a little bit, you can't see that the restoration is there. That's really the beauty. The only downside is it's a lot more expensive than a composite. But they're beautiful restorations. If you have a patient population who can afford lots of indirect restorations. All right. Okay. And again, I think this I don't know. I can't remember whether this is before or after I cemented in a place. Now this is a full crown obviously, but this is a great vindication because all of the margins are in enamel, okay. And it's easy to isolate. You can see what looks like Santa Claus beard up there. All right. But that's a cotton roll. That's a two by two. You can see that I have retraction cord all the way around that. So I isolate it. Well I'll use a Teflon tape there, Teflon tape there. And I'll etch prime and seal selective. It's just the enamel. Use a primer A and B on everything else, including the properly etched enamel. And then I'll seed it. Okay. And again the beauty of this is this. There's the margin right there okay. Now. The primary indication, in my opinion, for inlays on leis and crowns that are bonded to place are when the tooth allows super gingival super margins. Okay. And the tooth down here is a normal color. Okay. Because again, what if this was done 30 years ago and your only choice is porcelain fuzed to metal. You have to. You have to go sub gingival. And I guarantee that ten years later the margin is going to be visible. Okay. If I ask this question before, is there anything uglier than a 30, a 20 year old person fuzed to metal crown or tooth number eight? Okay look beautiful when it was cemented, but several years later, not so pretty. Okay. All right, all right. And now's the time to adjust the occlusion. Now this is going to change because the the ceramic materials are getting stronger and stronger and stronger. So at this point, I don't even know I don't want to recommend it because the evidence isn't really there yet, but it's likely that lithium d silicate restorations, you can check the occlusion before. Okay, it's probably strong enough. But again, to be safe, my recommendation is to wait until after it's cemented. Now, if you have to check in, I'm sorry if you have to, obviously you have to check, but if you have to adjust the occlusion when it's all done, you have to finish and polish it properly because there's nothing more damaging to the opposing tooth than a finished but unpolished occlusal surface of your restoration, especially zirconia. Okay, but even lithium by silicate, if you take a football shaped diamond and do some occlusal adjustments after cementation, and don't refinish and polish it with rubber points and rubber rubber wheels, then and soft flex discs if appropriate, then you're leaving a very rough surface, and it's sort of like the patient will be eating or grinding with one, with one tooth being like sandpaper. Okay. They're simply going to wear away the opposing tooth. Okay. So a quick review before I give you a break. And then we'll go over the preview of the exam okay. So restoration should be very gently tried in. Do not check the occlusion yet, although that's probably in the process of changing or going to change as the materials get stronger and tougher, prepare the internal surface of the restoration and then put it on a stick a little pick and stick. And again remember what prepare means. It depends on the restoration. But essentially it means making holes and making them attractive to resin. Okay. Then you're going to isolate and prepare the tooth. And when I say prepare the tooth it means etching the enamel, rinsing it off and then using the appropriate dual cure primers. Okay. Then you apply the adhesive. And this is usually the in combination with the with the primer. And then you're going to bind it to place with a dual cure resin cement. Remembering that the using a dual cure resin cement is pretty technique sensitive. So you have to follow the instructions carefully okay. And then clean up hopefully timing yourself so you can clean up the excess resin in the gel stage. Not waiting till the late stage. Now why can't you remove the excess resin right away? Because sometimes if you seat it, remember it's still in the the liquid stage. If you try to remove it in the liquid stage, you might actually pull some of that that cement out from the margin. So and plus because of the air inhibited layer it may not be fully cured. So it's always a good idea to wait until it gets into the gel stage. But don't wait too long because now it's in the fully set stage. And then you can adjust the occlusion. Although as I said earlier, that's probably changing protocols, probably in the middle of changing. And then don't forget to replenish it with the appropriate instruments. And when I say appropriate instruments, remember there are rubber or rubber instruments that are designed for lithium by silicate. There are rubber instruments designed for empress or rubber instruments designed for for zirconia. So make sure that you're using the appropriate. And of course, you can't use the big wheels that you would use for extra oil finishing polishing. You have to use points and cups very similar to the Enhance and Pogo kits. But remember enhance and pogo are not designed for ceramic restorations. You have to buy special, special things. All right, now let's talk about the midterm after I do the QR code. So let's do the QR code next. I got it. It's. Okay, here we go. Okay, let's only take about 5 or 6 minutes because I want to give myself plenty of time for any questions. Okay, back to work. All right. So several things about the exam. If you're a DMD two student, all you have to do is remember what I did last year because the format is relatively the same. But of course, you took so many exams last year, you probably forget an individual exam, but they're all case based. And what that really means is that you need to start at the beginning and go to the end. Don't start at the end and go to the beginning. Don't start in the middle and just do something because it will confuse you. What I'll do in this exam is talk about a clinical situation like your patient is Jo. Jo comes in with a medial lesion on tooth number three. Your decision is to do an amalgam on tooth number three okay. And then I'll ask a bunch of questions about the momentum you're going to do on Jo. And they're all true false questions. Right. So. True or false? The best matrix for an amalgam is a sexual matrix and a separating ring. No. They're tough of. The best. And again I could say the same thing about the composite. So. So I'll probably begin by giving information. I might ask a question about the rubber dam. And I might ask questions about the prep. And then I might ask questions about the matrix. Then I might ask questions about the insertion and then maybe the occlusion and the finish and polish etcetera. So I follow a normal sequence and then I'll introduce another patient. Okay. So that's the format. That's what I mean by case based it. There are like I think our eight or 7 or 8 different patients that you're going to be treating in this midterm exam. All right. That's important to know. And they're true. False I'm sorry. Two false questions and answers. And I do use exam soft. There are paper versions of my exams out there. Because for many many years I use the old fashioned paper. We didn't have exam soft so I did bubble sheets and things like that. Okay. And I always gave my exams back to the students. So they're out there. If some senior comes up to you and says, do you want to buy some exams? So don't spend a lot of money because he's or go ahead and buy them because you're not breaking any law or breaking any rules unless it's this year's exam, obviously. But there are paper versions. The only thing I'll warn about if you find some old exams that you want to study from, the content may have changed. Okay, so for example, if it's a ten year old exam, the information about bonding agents might be significantly different than the information I'm going to ask you in this year's exam. All right. So and I never give out the key either. Right. So some student might, might sell you an exam or give you an exam with what he or she thinks. It's the right answer, but it's not me thinking it's the right answer. So again, just be aware that the real value of old exams is to really just know the format and the style of my exams, not necessarily the content. All right. Now, if in fact, there's anybody in this room who's going to be given special permission to make this exam up, and I'm not talking about, oh, I got to see, I want to get a B, I better make it up. You can't do that. Okay. But if you're if you get sick or you're in a car accident the night before or you're stuck in some airport in Singapore, you know, you just can't can't make it back, then you'll have to take a make up. I just want to stress to you that my makeups are short answer exams. They're not. They're not the true exams. That. But they're they're not easier. They're not more difficult to simply differ. Okay. And the exam that you'll take next Tuesday is a 90 minute exam, but most people finished anywhere between 30 and 60 minutes. Most people. All right. So let me describe your patients. And this is the important part of this session right here. All right. One of the patients. It's actually in this exact same sequence, so you might as well remember that the first patient is simply a patient. You're going to have to polish a complex amalgam okay. So you need to know all of the steps of finishing and polishing an amalgam. You need to know what greenies and brownies are. You need to know why you need to finish before you polish. You need to know that polishing really isn't all that critical, right? But you need to know the steps and the rationale for finishing and polishing. Another important thing to note is that if the carving has been done well and you're using a good, high quality amalgam today, okay, finishing and polishing is nowhere near as important is if you did a bad job carving or you're using an old fashioned, you know, low copper alloy like we had in the 1970s, but nobody should be doing that. Remember the story I told you about a student who was a really good student who polished some amalgams? Okay. And then I came back and found them dulling them up because the patient didn't like the glossiness and things like that, because way back then, when I first started teaching, we couldn't give students credit for any amalgam unless they were finished and polished. And of course, they can't be finished in Polish on the day of insertion. Right? But again, some patients didn't like the high gloss and the finish in polish. All right. Now many questions. Hint, hint. There'll be many questions on everything about ceramic inlay online. It's not going to be a pure inlay. It's going to be an inlay only replacing at least one cusp, maybe two, right? But when I'm even from start to finish, I'm talking about, well, maybe a little bit of treatment planning, maybe a little bit of actually a lot of preparation design. You need to know where the path of insertion is. You need to know why minimum thickness or minimum depth and reduction of your preparation is so important. You need to know why opposing walls should diverge. All of those kinds of things. You need to know what an undercut is. So the basic things you also need to know everything about. Final impressions and you need to know the different impression materials you need to know. Poly ether and poly sulfide. I'm sorry. Poly ether and poly violence lock chain especially. You need to know how to compare the two. Which is more palatable. Which is more palatable. Palatable means what it tastes like when it smells like. Oh, you should remember that. Ah. All right. I'll make sure I run right. So polyester is not very palatable. Poly violence. L'Occitane is by far the most palatable. Meaning? It looks pretty. It smells nice. It doesn't taste all that bad compared to some of the other impression materials. Which one is more hydrophilic? Polyester. All right, all right. So you need to know some of the differences. Are they both dimensionally accurate. Are they both dimensionally stable? Yes. Give me an example of something that is not dimensionally stable. Alginate. Okay. A poly sulfide rubber. You go to old fashioned stinky stuff. The poly sulfide rubber. It's not so good. So you need to know about elastic impressions. You need to know the tray the the double chord technique, everything about tissue management. All right. So why the you know what is the purpose of retraction cord. Remember the the four things that are really important with any retraction technique is you want to take the free gingiva and have it shrink. So it goes both apical and laterally. So it allows you to get a good impression of not only your margin but a little bit beyond the margin. Okay, good impression material has to be elastic. Don't forget how important that is, because when you remove it from the mouth, you don't want it to distort, okay. It has to maintain that, that that dimensional accuracy. Now dimensional stability simply means that once you take it out of the mouth, it never changes its shape. Okay. Or maybe when I say never, I mean realistically, never, because maybe 30 years from now might change. But both of those are important. But dimensional accuracy is definitely more important than dimensional stability. But dimensional stability is really nice to have. All right. The other issue with cord retraction is you also want to make certain that you minimize the possibility of bleeding. And when you get tissue vasoconstriction, you're not going to bleed as much. You're going to get that classic blanching. The two core technique is what I strongly recommend. Know the difference between epinephrine and the non epinephrine treated cords. They're both really good like things like ferric sulfate and aluminum chloride. Those are non epinephrine and they're pretty good. Epinephrine is probably a little bit better. But you worry about epinephrine with certain types of patients. Again that's important to note okay. Another very important property of good retraction techniques is recoverability. I want the tissue to go back to where it was in a healthy state I don't want. That's why I don't really love to use electro surge or lasers to to kind of get the tissue out of the way, because it doesn't necessarily mean it's going to come back to the right shape. All right. Continuing on the inlay and on lay everything I just talked about. Well, a little bit of information about temperature. You know, what the difference between the different temporary materials but not a lot of questions on temperature. But there are a lot of questions about what I just talked about earlier today, the triad and the cementation of these kinds of restorations and the difference between conventional bonding, conventional cementation and adhesive bonding. All right. And then everything about a class two composite, starting with comparing it to a class two amalgam. Continuing on, what's the difference between a preparation for an amalgam of preparation for composite? What are the important properties of preparation? What about extension for prevention? What a prior is those kinds of things. And then lots of stuff about sectional matrices and tooth separating rings, stuff you've already practiced in the SSC, so you should be very comfortable and very familiar with that. Okay. And then using a bonding agent and everything about especially especially hint hint, the fourth generation bonding agents, the ones that are available in three bottles and three steps. Okay. So that's the one I'll really focus on. But you need to know a little bit about the difference between etch and rinse systems and self etching systems and universal bonding agents, the newer universal bonding agents. So you need to know a little bit about that. But a lot of stuff on the matrix systems that's used and why everything about flow, well the good things about flow, all the bad things about global. What are some of the good things about flow? One is it flows really well. Two and it shrinks because it's elastic. It has a high I'm sorry, a low modulus velocity. Excellent. You know the difference between a high and a low modulus velocity by the way. All right. So everything about a flow of all the good things. Now the bad things is they don't have good mechanical properties because they're less filler loaded. So you don't want to use a flow where you have, where you have a need for high filler loading, like on an occluding surface or a stress bearing area. That's the bonding agent and the flow able and then incremental curing. You better know where to see factor is the fact that a low C factor is better than the high C factor, and then how important the curing light is. Depth of cure. What does the curing light really do? Okay. The whole issue of there are photos receptors in every light curable material. And it's critical to get the light to hit that. And a little bit of a few questions about bulk filling or bulk curing. I'm sorry, bulk fill composites because we're transitioning. We're at a point in time where I guarantee that in the future we'll all be using what's now referred to as bulk filled composites. But they're not really bulk filled because it doesn't mean you can fill any size restoration. The only thing that will where you can fill any. I'm sorry, the only material that you can bulk fill any size restoration is dual cure composite. Okay, but nobody wants to use dual cure because dentists like to be in control of the curing. So. So there are dual cure materials that can be bought, but this isn't on the exam. So I'm not going to stress that anyways. And then you know sculpting wise sculpting more important a little bit about surface sealers. You better remember what that is because we don't use. We haven't used that in the SSC. But it is something that you should know about for next week's exam. So when I say everything, I mean everything. There are a lot of questions on class two composites, because that also includes things like bonding agents and flow and the properties of composite in general. I'm going to talk a little. There are a few questions on class five restorations, especially composite, but also a little bit about amalgam. Also, you better know where the retentive points go in a class five amalgam and the class five preparation, you better know where the bevel goes and where the bevel doesn't go. Okay, those are important things to know. All right. Know what a NCC, NCC is so that you know a non carious cervical lesion. Know what it is. And I know I'm pretty sure I asked you this question before, but this is an important thing for you to answer to do. All non carious cervical lesions need to be treated. And the answer is yes. You figure out already. Okay. Next question is they all need to be restored. No. So because sometimes treatment is showing a patient how to brush better and throwing away that hard bristle toothbrush or sometimes, you know, don't drink so many cans of Coca Cola a day. You know, those are all things that contribute to non carrier cervical lesions. So maybe the treatment is simply controlling the etiology. So yes they all need to be treated but they don't all need to be restored. That's an important statement okay. Not only for the exam but for life. All right. Now a lot about this one patient who's going to present with a broken cusp. And you're going to have to answer a lot of questions about treating it with a complex amalgam. Okay. And that includes all the information about pins. So you did a complex amalgam in the SSC but you didn't place any pins. All right. So anything that we didn't do in the SSC because I'm assuming in the SLC, you probably already know what to do. But the stuff that wasn't done in the SSC, you may have to study a little bit harder for including everything about self threading pins. The newer pins, which are much better than the old fashioned Miles Markley pins, the cemented pins, etcetera. They weren't all that good. But no, you know, the countersink and the depth of the pin hole and the fact tha