Transcript for:
Lecture on Designing a Single Unit Posterior Crown

Good morning you filthy animals. Today I want to give you guys something different. Yesterday it became apparent to me that... Not everyone is looking for videos on how to design multiple unit anterior cases. There may be some of you Syracusers out there that are still struggling with just single unit posterior crowns. And today, in this video, I want to walk you through the basics of designing a single unit posterior crown. And I also want to outline the techniques that I use to make designing these crowns as efficient as possible. Get them done as quick as possible with perfect contacts, perfect occlusion. Let's dive in. Well, before we dive in, I also want to discuss stain and glaze techniques, how to go about choosing shade. For this case, we're going to imagine that we're milling an Emax crown. I'm going to show you how to go about choosing which shade, how to go about choosing which translucency of Emax, and also some stain and glaze techniques. I will share that all with you in this video, so follow along. We're going to imagine that in administration we have this selected as Emacs. I don't really want to take the time to change it, but it doesn't apply. It won't matter as we proceed with the design. Everything is going to be the same. So we've got a single unit post year crown here. We're going to set our model axis and basically what we're doing is we're trying to align for a posterior crown. We're trying to align the occlusal plane along this horizontal line and along this horizontal line. You can incline the jaw slightly. That's how it seems to be naturally positioned in the mouth. But if you don't want to do that, it's not all that crucial. The set model axis is definitely more... You need to take that more into consideration when you're doing a small design case or a multiple unit anterior case or single unit anterior case. Posterior, it's not all that relevant. But still try and get the arch within this outlined horseshoe or this outlined arch. So let's click OK. Let's move on. We're going to then mark our margin. We can skip the trim the trim die process. I usually just leave it untrimmed and mark my margins that way. This case the margins were already marked and also with this case I imported it as a.dxd file. Sometimes you lose the color in the impression when you import a.dxd file. Not always, it's only sometimes and only under certain circumstances, but the color was lost in this impression. But you're then going to go around your margin, you're going to mark that, and when you're marking your margin, keep a couple things in mind. You can switch back and forth between the auto and the manual. So you've got two options when you're marking a margin. Do you want the software to automatically mark it where it thinks it is as you move your cursor along the margin, or do you wanna manually do all of it? I use a mixture of both. So I'll take away this margin and I'll show you what I mean by using a mixture of both. I like to use the auto option when I see a margin that's super gingival or a margin that has just a really distinct ledge. So like right here, I would like to use the auto tool because the software is gonna. easily detect that. But then once you get to these areas where the margin meets the tissue, that's when the software can get a little bit confused. It did a good job there, but sometimes it just goes haywire, starts marking the margin on the tissue, and it's just a total mess. So like in an area like this, I can't see the margin all that well because there's no color in the impression. That's why it's so important to have that. But what I would do when I get to a messy area like this is switch. See, you can switch back and forth. I would switch to manual and then I would finish up my margin. Wherever tooth meets the tissue, I'm usually using the manual option. When there's no tissue around the margin and it's super gingival or there's a distinct ledge, use auto. And that's going to make marking your margins much more efficient. And as you're marking the margins, I'm not just looking at the prep from one view. I'm not just looking at it from this view or this view. I'm looking at it from every view to make sure that at every angle the margin is sealed up and I'm making sure that there's no undercuts. But we're going to make sure that there's no undercuts in the next step, in the set insertion axis phase. So when you're here, you're trying to minimize the amount of yellow that's on your prep. So as of right now, there's no yellow on the prep. If there was yellow on the prep like that, we don't want that. That's going to prevent the crown from seeding or it's just going to make it difficult to draw on and off. And it's only going to prevent the crown from seeding or it's going to make it difficult to draw on and off the prep if that yellow is near the margin. You can have yellow along the radial walls of your prep. It's just you want to avoid the yellow near the margin. So... We're good here. Everything's squared away. We're going to click OK. We're going to proceed. Now, this is what the SERC software is going to do. The SERC software is going to immediately take you from the model phase to the design phase. But when it takes you to the design phase, it's going to immediately give you an initial proposal. Now, we're going to disregard that first initial proposal that the computer proposes. So as you can see, when we move from the model phase to the design phase, Follow my cursor. We've gone directly into the edit restoration portion of the design phase. But you can see there's four portions to the design phase. When the software goes right to the edit restoration phase, it's bypassing these other three portions or other three phases that are going to help you get a better proposal. So when you go right into the edit restoration phase, we're pretty much working with what the computer thinks the tooth should be. And if you're working that way, you have no control over your proposals. But what we're going to focus on with this technique that I use is we're going to gain control of our proposals and the types of proposals that we get. So let me share with you what I do. When I transfer from the model phase to the design phase, I immediately, after getting that initial proposal, go back to the parameters. Make sure that I have my parameters dialed in. When I'm doing an Emax crown, a posterior Emax crown, I'm going to set my spacer to 100 to 140. 100, you're going to get a more snug fit. 140, it's going to be a more passive fit. But 120 is that happy medium. It seems to work out good. That's just been the feedback that I've gotten. I'm going to set my occlusal contact strength and my dynamic contact strength to negative 175. So after we've set those, we're then going to go to minimal thickness. Now, minimal thickness... I like to set my minimal thickness to a parameter or setting that's the actual minimal thickness like I don't want to take this restoration below 0.5 millimeters anywhere around the tooth so I'm gonna set my minimal thickness to 500 because that's gonna give me a minimal thickness bubble of 0.5 millimeters all the way around my prep if I have it set to say a thousand, that's going to give me a millimeter of minimal thickness all around my prep. And maybe in some areas of the crown, I can afford to not be one millimeter in thickness. Maybe it can be 0.7 millimeters in that certain area. Maybe it's along the buckle wall or whatever, or maybe there's just no... contact, occlusal contact in that area. Whatever it may be, I like to set my minimal thickness to the actual bare minimum so that that way when I do start to see a minimal thickness bubble, I know, okay, now I've gone past the bare minimum. But just for the sake of this case, I'm sure that a lot of you guys are using somewhere around 1,000 for your parameters. Maybe some of you aren't even adjusting your parameters. When you don't adjust your parameters or when you don't have them automatically set, when you go into the parameters, they're going to be locked like this. and you may be like, hey, I can't move it. Well, you have to unlock it. You unlock it just like that, and then you can adjust it. So just for the sake of this case, we'll put it at 700, which is going to give us a minimal thickness bubble of 0.7 millimeters all the way around the prep. So we've got it set to 700 for the occlusal, which is going to be obviously the top portion of the prep, and the radial, which is going to be the sidewalls of the prep. And then for your marginal thickness, the factory usually has Emacs set to 50 for the default, meaning that it's set pretty thin. What I like to do is increase that just slightly, maybe to like 90, so that... we can prevent chipping at the margin at all costs. Even though the margin may be slightly thicker, it's still going to help us prevent chipping at the margin. And especially if your preps may be a little bit jagged at the margin, maybe you just graduated dental school and you still need to improve on your preps. Set that marginal thickness a little bit higher and you'll be set. You won't have any chipping at the margin. I like to set it to 90 even with all my regular restorations, especially with veneers. With veneers, it's typical to get... a little bit thinner at the margin, so set the marginal thickness a little bit higher, and you can avoid that chipping at the margin. So, 90. Let's recap. These would be my default parameters for an Emax posterior restoration. I'm going to scroll through this a couple times, take a look at it, and we're good to go. God, I am jacked up on this Americano. But okay, there's our parameters. That's the first step we're going to tackle in the design phase. And if I wasn't explaining all this, that's a 10 second process. You just go through your parameters real quick, boop, boop, boop, and you're off to the races. We're then going to go to adjust morphology. Now this phase only comes in real handy when you're doing a small design case, multiple unit anterior case, and sometimes even a single unit anterior case. For posterior cases, we're going to just bypass the adjust morphology phase. The next thing we're going to do is go into the positioning phase. Positioning phase is very crucial, you guys. Some of you may have not even known that this was here, but it's here. And I highly recommend you start doing, taking care of the design in the positioning phase. What you're going to, by... By adjusting the tooth in the positioning phase, you're going to really, really take control of your proposal. Let me show you. As you can see right now, our tooth isn't quite aligned at the margin. You can see that there's some margin exposed right here, and if you look at it from this angle, you could see other areas where this isn't quite aligned with the margin. That's going to create discrepancies in your initial proposal once you get there. So the objective here is to line up this shell of a tooth. That's what I call it, a shell of a tooth, because it's not quite a tooth, it's a shell. Our objective here is to line up this shell of a tooth as best we can on the prep, on the margins, and fit properly in the jaw. So if we look at it from this angle, our buckle looks good, and now we've got this lined up with the margin. As you can see right here, we have a contact that's open. Maybe if we move it over here this way, I was going to say maybe if we move it over here this way, it would take care of the margin on this side, but now there's margin exposed on that side. So we're going to go over to scale and we're going to scale this shell of a tooth out to that margin. Just like that. And we're switching back and forth between scale and position. Scale and position. We're going back and forth. Positioning is going to orient the tooth the way that you want it and scale is going to make it bigger in any direction that you want it bigger. Like for example, on the lingual here, it can be bigger. So we're going to grab this arrow in the scale tool and bring that back to that margin. Now we're set. We've got this lined up with the buckle margin. This is close enough. It doesn't need to be, not everything needs to be precise, but it just needs to be close. That's going to give you a much better proposal. And right here you can see that it's overextending that margin. We can afford to leave it that way just because we've closed this contact. Secondly, our occlusion looks good, but when we're designing a posterior crown, what I want you guys to do is get the occlusion red. Make the occlusion red. You can even make the mesial and distal contacts red and I'm going to show you a technique that will simplify your lives tremendously. So for this case, while we're in the positioning phase, we're just going to make this occlusion a little bit red by moving this arrow up, bringing the tooth up, the entire tooth up. Now our occlusion is red. and that's where we want to be. Last but not least, after we've positioned and scaled the tooth to fit on that prep, to fill in that contact, we're then going to uncheck constrained adoption. That's the last thing we're going to do. Constrained adoption is going to basically give you a proposal that resembles what we've done in the positioning phase, or unchecking it is going to give us a proposal that resembles what we've done in the positioning phase. God, that train. I don't know if you guys can hear that. If we leave constrained adoption checked, the software is pretty much going to disregard everything that we've done in the positioning phase, which we don't want. We want the software to take into consideration what we've done in the positioning phase because this is the closest thing to ideal as far as the position of the tooth. So we're going to uncheck constrained adoption. That's all you need to remember. Just uncheck constrained adoption if you've positioned the tooth the way that you want it. Uncheck that. We're then going to go into edit restoration because we've already got an initial proposal what we're going to need to do is recalculate and then that's going to give us a proposal that resembles our new proposal. There we go. So that's our initial proposal. As you can see, contacts are red, yada, yada, yada. There we go. Now I'm hearing a lot of, uh, a lot of, I have marshmallows for a design. I've been hearing a lot of that on social media. My tooth looks like a marshmallow. It doesn't need to look like a marshmallow. Leave the marshmallows to the smartest. Your tooth can look like a tooth. It can have nice anatomy. It can be all of that. Now. The burrs of the machine may limit you from actually milling out that anatomy, but it'll get close. I've done thousands, thousands of posterior restorations, and if you get it right in the design, it can look really nice right out of the mill. If you want it to look really, really nice, then do some post-mill contouring. But if you want it to look nice in the design, maybe as of right now, you're just leaving it like this. You're doing your contacts, you're doing your occlusion, and you're going to mill. But what I want to show you guys, and this is my design technique, this is my protocol. First thing we're going to do when we're designing is choose our anatomy. How are we going to do that? We're going to use the biogenetic variation tool. And read the description of this tool. Tool to adjust the morphology of the restoration. If you don't want it to look like a marshmallow, adjust the morphology. We're going to use this tool first. That's the very first step in our design. Use biogeneric variation for a posterior crown. And watch what we get when we move and scale this tool. We're now getting this beautiful anatomy, beautiful cusp tips. And you could just stop wherever you want, whatever anatomy that you like. You could stop there. Let's just stop there for the sake of this video. Okay, so now we've got this beautifully shaped tooth. It's just absolutely gorgeous. Second thing we're going to do is now fill in the contacts and adjust everything the way that we need it to be adjusted. When I'm working with the tools, when I'm manually working with the tools, I like to make sure that I'm working with big movements. If I'm working with small movements, and what I mean by small movements is either using the circular tool, which is only going to target specific areas, a small area, a small movement, that's not what I want to do. If I'm working with, say, the form tool and I'm using add to add whatever I want to add and it's set to a small degree, that's going to be a small movement. And then we're going to start getting these designs where just too much is going on. The design is getting chaotic. Keep it simple, folks. Keep it simple. Keep it efficient. Let's work in big movements. So what's a tool that's a big movement? Well, the positioning tool is a big movement. That's going to move the entire tooth wherever we want it. Maybe we don't need to move the tooth though. The buckle wall looks good. We don't need to bring that out. We do need to fill in this mesial contact though. So how are we going to do that? We can move it that way. And just a helpful tip. When you're using the move tool in the CEREC software, uncheck this keep contacts button. Most of the time when you leave the keep contacts button checked, things are going to go haywire because the software is trying to keep this tooth in contact with whatever it's trying to stay in contact with, either the mesial or distal interproximal contact. If you uncheck that, the software, as you move the tooth, is going to maintain the overall shape of the tooth, which is usually a better option. We don't need to use the positioning tool to move this into contact. That's how we would go about doing that. Just move it over. And now we filled in that contact. We don't need to use that though. Another big movement tool would be the anatomical two directional. And as you can see, the entire portion of this tooth is highlighted. And you can see the direction that we're moving the tooth by the arrow. So whatever is highlighted, it's going to be adjusted in the direction of the arrow. The arrow is pointing towards the distal contact of the adjacent tooth. So let's take this portion that's highlighted and move it over. Now our mesial contact is filled in. Now with the same tool, we can see that these lingual cusps are a little bit high. We could bring those down. Bring that down. And then the middle portion, we will need to use the circular tool. But just when you want to work with a big movement, adjust the size of the circular tool. You can see circular and anatomical within the shape tool. Just adjust the size of the tool to be a bigger size. You can either adjust it right here or you can hold down the right click or the right button. You can hold that down. and just scroll your mouse up and down or scroll your trackball up and down or the trackpad. You're just going to scroll up and down while holding down the right button, and it's going to increase or decrease the size of the tool. So let's increase it to about there and bring that portion down. There we go. Now our lingual cusps are lined up, which is nice. Our marginal ridge is even lined up. Our mesial contact is filled in. Maybe we could fill in this area right here with the circular tool. But this design is just about done. It's tooth shaped. It's beautiful. All that we have left to do, let's bring the contacts into play. Is adjust the occlusion, and if we remove the lower jaw, we need to adjust the mesial contact. So, life is about to get really easy. All we've done so far folks, is we used the Biogeneric Variation Tool. Then we use the anatomical two directional tool to adjust the contact, fill that in, and bring down the lingual cusps, which need to be brought down because the adjacent lingual cusps were at that level. Now all we have to do is use this tool. I don't know if you guys are familiar with this. I don't even know if you guys have seen it. I've seen so many SEREC users have this only displayed for their tools. How many of you guys out there have been in your tools catalog and only seen these tools? Well my friends, there are more tools at your disposal. You just have to go to this button right here where it says full view. Right here at the top near the tools. Just click that full view button and now you've got access to that biogeneric variation tool. Now you've got access to a reduction tool if you want to reduce the tooth and layer it with porcelain. We don't want to do that. We want to keep our lives easy. And then you've also got access to this tool. This is a beauty. Read the description for this tool. Tool to adjust the restoration such that it has optimal contacts with its neighbor or the antagonist tooth, whatever. Basically, this is an adjust contacts button. We've got our occlusion red and we want it red because now when we click this button, occlusal. It's going to bring the entire occlusal surface down to the occlusion that you set in parameters. Now if you remember correct, in the parameters we have the occlusal contact strength and the dynamic contact strength set to negative 175. So when we click that button, it's going to make our occlusion negative 175 wherever it's red, wherever it's green, wherever it's not negative 175, it's going to make it negative 175. which is ideal occlusion for a crown. It's going to be slightly out of occlusion, but it's going to be perfect. It's just going to be perfect. In my experience, negative 175 works out perfect. So there we go. That's how we adjust our occlusion. Same thing with the mesial. We've got a red mesial contact. Click mesial. Voila, it's a green contact. Maybe you want to fill it in a little bit right here. We'll go to circular tool, adjust the size to be proportionate to the area that we want to adjust. We only want to adjust this area to bring this into contact. So make the size of the tool that size and then bring it into contact. Now you've got a green mesial contact. You've got perfect occlusion and you've got beautiful anatomy, a beautiful tooth morphology. You're off to the races. This crown is ready to mill and I guarantee you. this crown will drop right in the patient's mouth and it'll look beautiful. If you guys are getting marshmallows, say goodbye to marshmallows. Use this design technique. Replay this video a thousand times if you have to. I promise you, if you use these techniques, you're going to have beautiful posterior restorations. Maybe you're not happy with the way that they're turning out as of right now. Use these design techniques and you'll think you're a genius. You will. So, we've got the design portion taken care of of a posterior design restoration. A posterior restoration. Now it comes time to mill. I want to go over some shade selection concepts with you guys. And I also want to show you some stain and glaze techniques. Although I can't show you actual techniques on camera, I don't have a porcelain oven. I don't have any of that. I'm a designer. I work off my laptop. But I know how the process goes. I've worked in a lab for four years before starting this design service business. My grandfather was a technician. My father's a technician, master ceramist actually. I still have a lot to learn from them, but I do understand the concepts. I do understand the process. I've stained and glazed hundreds of teeth myself. I will share with you all of that in this video. Let's move on to my pad. Okay everyone, so here is a photo that I pulled off of Google. It was the best example that I could find. It's actually not all that easy to find these kind of photos on Google, at least with what I was searching. It wasn't the easiest, but I think that this is a typical example of what a lot of us are working with when we're doing our Cerak crowns. Let's imagine that we're, or we've designed tooth number nine. And you can see that the shade is off for tooth number nine. These same concepts that I'm about to share with you apply to posterior restorations as well. So if we're designing tooth number nine, we've got it ready to mill, what shade are we going to go with? Well, first of all, you can see some incisal translucency down here. So maybe we want to work with an empty block. But as far as choosing the shade, what shade would you go with? You can see that, say this was a Cerak crown. Say you did this crown. Say someone else did this crown. Whatever. You could see that the shade they chose for this crown, it's off in chroma. The color doesn't match. But also, it's too dark. They looked at this shade. And they decided to choose a block that matched this shade. the body portion of the crown. When really they needed to choose a shade that matched this portion of the crown or this portion of the crown, we want to use a shade that matches the lightest portion of the tooth that we're trying to match. So say this is an A2 shade right here. they milled this in an A2 block. And now it looks too dark because this right here, this shade down here, is BL3. Does that make sense? So for a case like this, if this is BL3, we want to mill in a BL3 block, say a BL3 MT block. That's what we want to mill this in. Maybe we even want to mill it in a BL2. Go a little bit lighter, and you could always use stain and glaze to darken it. If you go too dark, you can't use stain and glaze to make this portion lighter to match this portion. I'm going to go to my eraser and erase some of what we've got here. So this is a very valuable concept to keep in mind when you're choosing the shade to go with for your restorations. Oof, so much. and say this is a posterior crown say the incisal cusp of tooth number 19 the crown we just designed say the incisal cusp is bl3 like it is right here the gingival is a3 you're not going to mill this crown in a3 because then you'll end up with an appearance that looks like this yeah this may match even though this doesn't this is way too yellow that's the more orangish brown but say those match, but these still don't match. You have to mill it in a shade that matches the lightest portion of the crown. This is so valuable, you guys. If you're using Emax HT and you're trying to match BL3, say you're trying to match BL3 and you're using HT, most of us are going to mill in a BL3 block. But when you're using HT, it's going to give you that gray look. It's going to look too dark. So when you're trying to match a BL3 shade and you're using Emax, I would mill it in a BL1 or BL2. Go shade lighter. Go shade lighter and then stain it to BL3. Same concept applies to matching a tooth that has a lot going on. Say your posterior restoration has everything from A4 to A1 and you're using MTE Max, then mill it in A1. Don't mill it in the darkest shade, mill it in the lightest shade. When you're staining the crown, there's a couple things you can do. You're first going to have your glaze, you're going to have your stains. When I've stained a crown or when I stain a crown, I'll layer. I'll put a layer of glaze on the entire crown, just a thin layer of glaze on the entire crown. Then what you're going to do is you're going to take your stain and you want the consistency of the glaze to be like a honey or like an egg yolk consistency. If it comes out of the tube, let's imagine we're using the Emax Stain and Glaze. If it comes out of the tube and it's a little bit thick, take your diluting liquid or your glazing liquid and dilute it a little bit. Make it a little runnier. Not too runny though. About honey, egg yolk consistency. You're going to do a layer of glaze all around that crown. And then you're going to take your stain. Say you've got an A3. You're trying to match an A3. You've milled it an A1. Take the A1, A2 stain or I don't know how it works. That's how it works with the EMAX stain. But just take the color that best matches the color you're trying to match. Take that color, mix it with a little bit of glaze. So that way when you apply the stain on top of the glaze, you're not replacing glaze with stain. You're replacing glaze with stain and glaze so that everything is still glazed but now you're adding some color. So you've got your glaze, you've got your stain mixed with glaze, about a half and half ratio, and then add color wherever you need color. And then throw that bad boy in the oven. Another technique, you can apply glazing liquid all around your crown, not glaze, just glazing liquid. You can then add stain to your crown, cook that, and then add glaze to your crown. So you've done two bakes now. You've done one with only stain, and that may give you a little bit more control of where you want to put your stain and your color. You can then add glaze to your crown. And then after you bake that you'll then do a layer of glaze on top of that So that would be your second bake and remember we're doing all of this after we've crystallized the crown As far as other techniques, I would say that those are really the only two techniques you're going to be using on a day-to-day basis for most of your bread and butter, post-year crowns, in fact, probably all of them. Another thing you can do, say the tooth is a monochromatic tooth, it's A2, then mill it in an A2MT or a BL3HT or B1HT. And then just polish that bad boy. If you mill it in an HT at a shade lighter, then you'd want to add some color. But if you're going for just a monochromatic appearance and the tooth isn't all that translucent, I would go with like an MT, same shade, and just polish it. Those are pretty much the finishing techniques that I would be using. Maybe some of you guys didn't even know of these techniques. So if I introduce them to you, I'm glad that I was able to help. I wish that I could go more in depth with this stuff, but... I can really only talk you through it. I don't have the kind of equipment to be doing video of the techniques that I would use, but I hope that this video was helpful. If it was, please comment, please like, do all that. Let me know your feedback. Goodbye.