SEPT 8TH 2023.pdf

Because as I told you last week, we're going to typically start lectures at the 8:00 lectures. We're going to start at about five after. But as long as it looks like most of you are here, let's take just a moment to talk about what we did last week in lab. Just to take a second, some of you probably...

Because as I told you last week, we're going to typically start lectures at the 8:00 lectures. We're going to start at about five after. But as long as it looks like most of you are here, let's take just a moment to talk about what we did last week in lab. Just to take a second, some of you probably found that the preparations you made were surprisingly good. Some of you may have found them to be disappointingly bad. And I saw a lot of preparations last week. And so what I just described is quite reflective of what we saw. Some were surprisingly good, great first start, others, you know, really that like my dog ate it kind of thing. And that's okay. What we would encourage you to do as far as that goes is no matter how good or bad it is, make sure you take pictures of the early preparations because we are going to want you to have some way to remember and frankly, memorialize what you did to start and what you do at the end. And that's going to go back to that. ePortfolio There's actually grades involved in it. Dr. Lidman and I will spend a lot of time describing that to you later in the year. So just for what it's worth, no matter how ugly it is, take pictures. Frankly, the uglier it is, the more desirable it might be to save somewhere so that one day you can look back at it and laugh because that's how a lot of things happen in life. What I did want to say while we're waiting to start today's material, though, is to talk a little bit about why that was so difficult last week. Right. And let's think about it for a moment, because it really is a difficult skill. We were making some lists of the challenges involved in doing fixed preparations as opposed to things like Operative. Not to say that operative is easy. It's not by any means, but you're actually trying to do more things at once when you're doing a crown preparation. And that's where the challenge well, one of the challenges comes. So we were making this list. One of the things had to do with you have to pay attention to how you're angling the burr, how you're holding the handpiece. So on a crown preparation, you're really very, very deliberately trying to follow an anticipated long axis of your preparation. Now, the good news for you in this class is on your typing on the long axis of all these teeth is quite ideal. So from the start of this class to the end, if you follow the long axis of that tooth as it presents in that arch of teeth, you can't go wrong. That'll be especially important to you at the end of the course when we do preparations for a three in a bridge because you want the path of insertion, withdrawal of the two teeth to be coincident. The good news is on your type on if you follow those long axes, you can't go wrong. So that's the first thing. But you're concentrating on that, right? That's one thing you have to pay attention to. Then the next thing you're worried about and this is a little different than with operative, you're looking at where your finish line goes. Remember, we were talking about our desire for you to place your finish line one half to one millimeter away from the tissue with the idea that by doing that and following the tissue it gave you a target, gave you something to strive for, and it gave us a way to measure whether you hit that target. So later on when we have examinations, we're going to be able to see, could you do what we asked you to do? It's something we can test again, As a reminder, in the real world, that means nothing. The real world. You put finish lines where they need to be. In our case, they need to be there just for us to look. But So now you're trying to hold the burr angled correctly and you're trying to watch where the tip of it is going near the near the gingiva. Now, the other thing about prepping with diamonds as opposed to carbides is as you're working it, some of you may have noticed if you hold it in one spot too long, it heats up, it starts to burn the plastic, it clogs and makes a mess. So the way you prep with a diamond differently than a carbide is you brush with a diamond. I'm not sure another way to say it. You kind of move it along, brushing the tooth as you prepare with diamonds. And that'll apply later on too, when you're prepping natural teeth. But that's a different motion than you've probably been making. So again, something new to do and a little different. One of the things you struggle with in many cases is whatever speed you are prepping in operative, however, you set the high speed to cut that may or may not be a good speed. As you're prepping for the crown, you might find that with the diamonds prepping, you'd rather perhaps have the diamond running faster or slower. That's something for you to kind of get a feel for. But again, it's a new thing in the old days where we worked with an air driven handpiece and we had a rheostat that controlled that, that was like that extra thing. We were controlling the speed of the burr that way. In your case, you're doing it with a button, but you still have to figure out what works. Another thing you're working at is you have those depth cuts you've made. Okay, that's fine. But now you're trying to work to prep away this stuff in between the depth cuts and you're trying to do that while not accidentally having the brief fall into the depth cuts and deepen them and therefore make the prep overprepared. And that's again a new skill. It's difficult and it can be a challenge at first. And let's see, what else do we have? Oh, and then finally, we were talking about one of the big challenges of watching the bird self, because you probably all had the experience of the bird clogging, starting to burn. It's a challenge. All these things add up to a different skill, a new skill, no matter how many teeth you've prepped an operative. And for many of you who certainly the D two class who have not prepped one of these plastic teeth for a crown before with diamonds, this is all new and these things are more difficult. What that adds up to is, you know, be fair with yourself. It. There's nothing wrong if it's not perfect the first time. In fact, it may not be perfect or it may not even be great till the end of the class. But if you keep working at it, eventually you'll get it. But it is a very difficult skill at first. And so what we would say is just accept that it's going to take time. It's fine if it does. That's what we expect. We see it year after year and it's fine if that's the case. Before I get into this other material, does anyone have any quick questions about last week's material stuff we covered that, you know, you're really puzzled about and need covered. Okay, great. All right. So last week what we did is we talked about the principles that we follow when we prepare Tooth for Crown. What we wanted to talk about today was. Why do we crown teeth or when do we crown teeth? What are the actual indications? Because that's really the first question, sort of when do we do those things? And it's kind of a simple rule we might think about in terms of when we would crown teeth. We're only going to crown teeth if we have to. I think I tried to describe that when we talked about preservation of two structures as a principle, and there's different ways to think about that. So one way to think about it might be that any time a tooth isn't going to be strong enough to sort of survive in that mouth in the occlusion it's going to be subjected to, that's when you need to provide coastal protection to make sure the tooth isn't going to fracture. That's typically when we start to crown teeth. Another way to think about that and these are all interrelated, of course, is the more tooth structure that's missing. Bless you. The more two structure that's missing, the more compromise the tooth is, the more likely the tooth needs to gain strength and protection from the restoration. That's kind of our our kind of hallmark phrase about crowns. So we might say if we need to gain strength and protection and we have to consider that coupled with, say, the occlusion or what forces the tooth is subjected to, that's when we need to crown teeth. And let me see if I can back this up a little bit. And so a kind of shorthand way to think about it are obviously is that the last two structure there is? Obviously the more likely you might be to need a crown. So these are simple ways to think about it. Now, related to this, just as a way to hopefully elaborate on this a little bit, when we talk about the need for strength and protection from our restoration. Coupled with the question of what the occlusion will be that the tooth is subjected to. There's ways to consider. You may have heard in removable class already and certainly for the students, you're probably well aware of this, that patients can't bite very hard on a denture, can they? Did Dr. Schnell express any of that about the efficiency of chewing with dentures as opposed to natural teeth? Did it come up a little? Not yet. All right. Well, here's a preview. When you talk about patients having things like removable restorations, dentures, full dentures especially, well, it's resting on soft tissue. People can physically not bite as hard on that as they did on the natural teeth. So one of the challenges for patients is the ability to masticate, to chew their food properly with dentures. Where that matters in a case like we're talking about is, well, you could have a tooth that's missing. Some two structure has a pretty big filling. But if what it opposes is a full denture as opposed to a natural tooth, we might very well question the need for a crown. Whereas if it was a natural dentition opposing it, we might know instantly that we need to crown that tooth. Right. So you're always looking as a first step. Anytime you're thinking about fixed prosthetics, you're looking at the patient's occlusion, you're looking to see what what's going on in there? What are the forces like? You're looking at wear patterns, all that stuff. We'll talk more about that next week when we talk about diagnosis. But as it is, you're going to look at the situation the tooth is in, how much tooth is missing, how compromised the tooth looks, and you make decisions. Does it require something to protect it, to maintain it in the mouth? So that's going to be kind of our first sort of thought about that. So what are we going to look for? I guess we might say as we're going to try to judge those things and there's going to be a variety of indications, a variety of situations we look at. The first one might be in the most basic situation where a tooth has an existing restoration in it. So the question for us in a tooth with an existing restoration is always going to be how much does that restoration compromise the tooth structure? What we're looking at is how strong will the remaining cusps be. So what we're looking at here would be actually kind of an upside down upper tooth, right? Buckle and lingual. But as we look at that and so we're looking at how much of the two structures are missing, how compromised is it? And the general rule we're going to follow here is we look at the position of the cusp tips themselves. And we ask ourselves what percent of the space between the cusp tips and this is again a general rule. Does the restoration occupy? And our rule is going to be when it exceeds half? Well, actually, let's say one third to one half the space between here. So if we have some space between here. Right. And our restoration starts to exceed, you know, one third to one half of that. That's when we begin to think a crown might be warranted or some other form of coastal protection, something to hold the tooth together from breaking. Now, again, this are general rules because occlusion has a factor to play. It can also be a question of sort of the condition of the restoration, how the tooth presents in terms of whether it looks invisibly good condition or not. We'll look at some slides in a bit with cracks. It can also have a lot to do with how the restoration was done. There's operative situations where there's a lot of decay and you end up with quite undermined cusps, where a lot of two structures are moved, undermining the cusps and other situations where there's not that much missing. This also points to where we try to be more and more conservative with our operative restorations. I'm sure Dr. Mcmanaman expressed to our desire to keep these, you know, as only as big as they need to be. And that's what we're going to look at when we consider these. So as these go beyond that sort of one third to one half of the intercostal width, that's when we're going to start to worry about crowns. And the reason we start to think about has to do with what can happen with these cusps being undermined in the two Thunder function. And our big fear is about the tooth fracturing. So we worry about teeth breaking because we see that quite regularly in dentistry and it isn't so much that a tooth might fracture, you know, like this where they lose a cusp and so this ends up gone. If that happens, it's not usually a very big deal. It's relatively easy for us to fix. We remove the old restorative material, we place a little bit of a core material and we prep it and make a crown simple enough. What we really worry about is what happens as it starts to break in a more significant way. So as it breaks a little bit under the tissue, are we getting, say, deep enough that we're going to start needing that crown lengthening surgery to get a proper relationship for our crown and the tissues? Or even worse, does it fracture in a really horrific way and teeth can fracture in a sort of catastrophic fashion where you are going to lose the tooth, it becomes non restorative. So when we see situations that the tooth looks undermined, that it looks appropriate for a crown to be made. That's our job as the dentist to inform the patient of what we found and when it's appropriate to recommend constable protection to recommend a crown on the tooth. Right to avoid these possible problems. One thing to mention to you, as long as we're talking about teeth fracturing. And you'll see this constantly when you're in practice. Patients will come in all the time. One of the most classic emergencies you see in your practice is a phone call that my tooth broke and I need to be seen. So they come in, there's a cusp missing classic. You see it all the time. And and the patient always says the same thing to you. You'll hear this all the time. For those in the ass class who practice some dentistry, they probably had this experience repeatedly. Patients shakes their head and they go, You know, I wasn't even eating anything hard. Like it's inconceivable to them. And the truth is they weren't, because teeth don't usually break on hard things the way teeth cusps come flying off of teeth. And you'll see this all the time. Something like a nice, thick piece of bread is a great way to pull a cusp of a tooth because you start out with a tooth that's undermined and it already has cracks in it. They don't just happen all at once, but there's already some cracks. No pain, no problem. And something sticky. Essentially as the patient sort of grinding or chewing up that thick piece of bread or something like it that's sticky bread, grabs the cusp and kind of rips it right off of there much more frequently than hard things. So you're going to hear that all the time. And it's actually I don't know if it's amusing, but it strikes you that way. Another thing that that is hard, though, that is damaging to teeth is ice. So if you ever have patients who'd like to chew ice and they tell you that, tell them not to because ice is a terrible thing to chew, you know, if you think about it, it's an awful, awful thing. The inside of the mouth, very warm. Ice is very cold. We know that when when temperature changes occur, hot to cold, you know, physical objects go through dimensional change. Right. So now you have the tooth at a certain temperature. You get some ice on it so that the tooth structure itself is physically changing its dimensions. This might be microscopic, but as that's happening now, they're crunching this hard stuff. It's a good way to put cracks in teeth. So if you see patients who are who make it plain to you or admit that they like to chew ice, it's a good idea to tell them not to do that. Any questions about this notion? Great. Okay. So let's let's go on. And so another sort of category, another indication for a crown would be a tooth that already has a fractured cusp. And you'll see this a lot. Patients come in. The cuss broke off didn't really hurt. They didn't bother to go to the dentist and they show up and you look in their mouth during your initial exam and you find fractured cusps, you find missing cusps. Sometimes you'll find situations where they did have it restored. But what was done was some sort of amalgam buildup or perhaps a composite resin buildup. And you look at that. And the question for you then is, will the tooth be better served by being left that way or by providing customer protection to try to make sure that the other cusps on the tooth don't break off in the future? Because that obviously is a compromise tooth. You know, long term studies have shown that, you know, the ten year survival rate for teeth is higher with crowns than with leaving some sort of a buildup. Have you done buildups yet? Inoperative? Not yet. Okay. Well, you'll get to do that. And we're going to ask you perhaps in second semester to bring up one of those teeth with bring in to us one of those teeth of the buildup and prep it for us. We'll explain that when the time comes in the second semester. But those are situations, again, where it could be an indication for Crown. It's up to you to look at the situation, the occlusion, everything you can sort through. And very often a crown is indicated there. Another situation that can obviously require crown might be a tooth that presents that severely carious. You're looking at the radiographs. There's just a huge amount of decay in the tooth and it doesn't take a great deal of of ability to look into the future. You don't have to be a fortune teller to look at a tooth like that and know that by the time you remove all those caries, the remaining two structure is going to be quite minimal. It's going to be very compromised and you're going to have a tooth that's going to need a crown. So arguably, when that presents, you want to let the patient know right from the start that you're going to need a crown on this tooth. By the time I clean out the decay, if we're lucky enough not to need root canal treatment, lucky enough not to need crown lengthening surgery, all that stuff that ultimately we're going to end up crowning the tooth and that's fine too. And that's a kind of simple thing. It's just a matter of you looking at it. And as you gain more and more experience in dentistry, you'll get a better sense of what a radiograph tells you about the amount of decay that's present and how much to structure is going to be gone by the time you've prepared all that, cleaned it out and restored it. Bless you. Now, related to that, it's not about caries, but related to that could be sort of the abstraction lesion. Has that been covered in operative yet? No. All right. We're getting ahead of all kinds of stuff, aren't we? I guess it's all right. So you might be familiar with these. This is a rather extreme drawing I made, but you've probably heard of, or certainly the advanced standing class would have heard of fraction lesions. These are those situations you see on teeth where very characteristically along the gingiva you'll see kind of a groove in the tooth. And there's a lot of theories about how these are formed, and they're probably all partly true. But without getting into that, you'll see these kind of grooves. And when they're really minor, in most cases we just ignore them. If there's no symptoms associated with them, we might just try to get the patient to stop grinding their teeth and to get a better brushing motion or maybe use a less abrasive toothpaste, things like that. But when they start to get rather extreme, you could imagine in the drawing I made here how this cusp begins to be rather undermined. We may not have a big filling in it, but we start to worry about when is that going to break? And so as we see these things, we also might have indication to consider crowning a tooth because we can start to look into the future for the patient for that tooth and see where there's going to be a need perhaps to protect it. And ideally, it's better to do these things before they break. That goes back to the first stuff we were talking about, where when a tooth fractures in an uncontrolled way, we don't know what's going to happen until it's done. And in some cases it can be catastrophic. In other cases it can just be a hassle. One of the things that you try to do for your patients is you try to save them aggravation now. What I mean by that is you try to. Try to see things into the future a little bit for them, warn them of what's going to happen and let them plan treatment when it's as convenient as it can be for them. As opposed to having to do treatment when it's an emergency. So whether that's a situation that looks like there's apt to be an infection that's going to happen and you want to save them, you know, swelling antibiotics, the whole hassle that way, or whether it's a situation where you look at something and say, if we wait long enough till it breaks, all of a sudden you're going to be calling me one day. It's an emergency, you have a problem, why don't we do it when it says convenient as it can be now, of course, it's never convenient to anyone to go to the dentist, but there are times that are better in people's lives to do these things. So by letting them know what they could anticipate and hopefully letting them choose the time of their treatment when it's convenient, it's a real service for your patients. So you want to try to do these things when you can. Okay. Any questions so far about any of these things we've talked about? Terrific. Great. All right. Another situation where teeth tend to require crowns or cusp protection are going to be teeth that have ed and treatment. So you may be aware of this already. We're going to have a general rule at Bu and I'll go over this in greater detail at the end of the course because we're going to actually have a week or two of material on restoring and identically treated teeth, but teeth that have had root canal treatment do have a tendency to fracture more than teeth that have not. So because of that, our general rule and again, this is like all rules, a general rule is going to be that all posterior teeth that have had root canal treatment are going to require crowns or other coastal protection. You know, the the variables that crop up are things like, well, if there's no opposing tooth, you don't need to crown it. You know, if it's opposing removable, you may reconsider. So there's always those little variables. But for the most part, posteriors that have had antibiotic treatment require coastal protection and then anterior is are going to be a much more variable circumstance. And we'll talk about that later in the course in greater detail. But that's going to be another one of our basic indications for crowning teeth, teeth that have had root canal therapy and a dike treatment. Did you guys start that class? You started it. Cool. Okay, good. Good. All right. And just to give you a little point of why that happens, I mean, if what you probably learned already in India is that teeth require endo most of the time because there was a lot of decay, right? Decays infects the pulp. You do. Endo Well, if you have enough caries in a tooth that it's going to get deep enough to infect to public. That goes back to an earlier indication we had where there's going to be a lot of missing to structure. So even if it wasn't going to be apt to fracture because of the antibiotic treatment, it's going to be up to fracture anyways. And that's why we're going to typically crown those teeth. Another circumstance where we're going to want to very often crown teeth that have had well, another circumstance for needing to crown teeth are going to be teeth that are exhibit what we might call crack tooth syndrome. And this is a kind of interesting situation, and it's one that a lot of people struggle with. So a cracked tooth is one that a patient presents with letting you know that every time they eat. It hurts that essentially they can't chew on a certain tooth. And the reason they can't chew on the tooth is that every time they're eating on it, they're getting pain. Right now in terms of understanding what's going on here, It's actually pretty simple what happens with a crack tooth. Is that when there's some food present. Let's say this is their food. That food acts essentially as a wedge. It's something to wedge this tooth apart. So as they're chewing on it, there are forces that are pushing the tooth apart. And if there's a crack in the tooth. Some sort of crack running down internally. Where that crack can be felt in the pulp of the tooth that will exhibit. Cracked tooth syndrome. Now, it's actually very, very easy to diagnose because there's some simple questions to ask. If the patient comes in and says, I can't chew on this tooth, it hurts whenever I eat. First thing you ask him is you say just bite your teeth together. Does that hurt at all? And if the answer is no, you pretty much already know what's going on. So if they can bite normally and they don't have any pain and they only have pain when they're chewing on some sort of food, then typically you have some sort of internal crack, a crack tooth. So it's kind of a simple thing. So when you have that kind of circumstance, what you know is that over time that crack will get worse. In some cases, it'll exhibit by a cusp breaking off. In other cases, it just gets worse and worse till they finally can't ignore it. They can't just chew on the other side and they come in for you to treat it. Your goal when you're aware of a cracked tooth is to do something about it sooner rather than later. And this goes back to what I was saying about trying to save patients trouble, because if you deal with this fairly soon. Bless you. What you'll try to do typically is put a temporary crown on the tooth. And your goal with that is by covering the tooth, by providing customer protection, you're trying to hold it all together so that those forces that would wedge it apart no longer can that the forces are dissipated on the outside of your temporary crown. Now, if the tooth exhibits no symptoms anymore, once you have the temporary crown, that would be your indication to just go ahead and finish your crown because it looks like crowning the tooth alone will resolve the problem. And there's different ways you can sequence. Some people would like to prep and temp the tooth, leave it for a while, get the patient back and discuss it. In other circumstances, if it didn't seem too bad, you might prep and temp it, make the crown and then temporarily cement the crown before you decide to final cement. And then if there's no symptoms, you'd say, okay, this looks like it solves the problem with final cement. If you put either a temporary crown or your finished crown temporarily cemented and there continue to be symptoms, they continue to have some discomfort when they chew on it. Well, you go to the next step in treatment, which would be if we can't control the discomfort by covering the tooth with the crown alone, what do you need to do? Well, we need to get rid of the the pain, which is feeling it in the nerve in the tooth and the pulp. So you send the patient in for root canal treatment. The tissues are removed. Now the tooth can't feel anything and you can go ahead and finish your crown. But a lot of times you can test that first. You don't necessarily have to send every one of these patients for root canal treatment, but that would be your your kind of basic crack two syndrome and how you might go about approaching it. What becomes much more problematic for you as a dentist? Much more challenging to sort through our circumstances where the patient might have kind of asymptomatic cracks in a tooth. So perhaps you have a patient in. And they have an old amalgam. You see what looks like a little crack on the marginal ridge. They don't have any symptoms when they chew, right? They just have an old restoration that you want to change. So you remove the old restoration and now you're looking into the tooth and perhaps you see what looks like a little crack in there. So then the question for you is, what do you do about that? There are no symptoms. Do you crown it anyways? Do you just restore it and wait for symptoms? What's the right solution? And the difficulty there is that it's hard to know the right solution to any of these things. Until whatever you do has some time to judge it. You know the old saying, hindsight is 2020. So these are the sort of circumstances that are trickier. What I do with these circumstances, and this is for each dentist to choose on their own, how they want to deal with their patients. What I would do is inform them of what I see. I'd say the tooth looks like it has some cracks in it. Hard to know if these are ever going to get worse or whether they won't. It's hard to know how long they've been there. You know, it could be that had we pulled this restoration out two months ago, I want to see the cracks at all. And it's getting worse in a hurry. Or it could be that 20 years ago those cracks were there and they've not changed at all. It's very difficult to know. So what I like to do is inform patients of what I see and what the possibilities are for the tooth and give them a chance to participate in planning their treatment. So some patients might say, you know, I want to be proactive, let's crown it now. That way I'm not going to worry about the likelihood of it breaking down the road or the possibility of it breaking. I'm not going to worry that it starts to hurt and I need to root canal treatment down the road. I'm going to try to be proactive and get ahead of it. So for people who approach their lives that way, great. You offer them that opportunity and they'll seize it. For other people who might be like, You know what? It's not bugging me today. What's the least I can do with it? Do that. So you put the filling in it. They're happy. Good for everybody. As long as your patients are informed and hopefully understand the implications of the choices that you and they make together. I figure you can't go too wrong that way. The challenge is that it's often difficult for them to really understand everything that you're trying to present, but that's arguably a much more challenging situation, the sort of asymptomatic crack. And then when we talk about crack teeth, there's another circumstance that. That comes up and that's a tooth that's really fractured. Where a tooth has a vertical root fracture, it's really split. Typically that will present where the patient calls and says, you know, it hurts when I chew. It's hurting over there. And you get them in and look and they tell you they can't chew on it. If you have them bite straight together, that type of situation sometimes will hurt. And the reason it's hurting is there's a fracture running down the side of the tooth vertically through the length of the root. And it's kind of, again, easy to diagnose for you as the dentist. And I just wrote out some stuff here for you. So typically it's easy to figure out because you start to probe the tooth and it'll probe in a very typical way, maybe 2 or 3 or whatever. And then where the crack is, where the actual vertical root fracture is, your probe just sort of drops right down. It's like there's a seam running right down the side of the tooth. And that bless you. That's your vertical root fracture. Now, a tooth like that is hopeless. That tooth is going to have to be lost. Typically, though, the patients are always going to say, well, can we get an x ray of it? And the answer is no, because it'd be well, in some circumstances, if it lined up perfectly, you might see it. But it's very difficult on a conventional x ray to see this. You could see it on a cone beam scan, but you may or may not want to bother. And typically, what's the point? You already know it's a hopeless tooth. A lot of times these will present if, say, that fracture is out on the buckle or something where the tissue is a little swollen, there's a little something going on there. How you handle that is up to you depending on what you do in your practice. What I like to do because I'm a dentist, I don't I don't do typically extractions and I don't place implants myself. I work with oral surgeons and periodontist for that. So typically what I like to do is tell them that it looks like the tooth has probably a root fracture. It's probably hopeless. And then I send them to the periodontist I work with and I let them give them the final bad news. So they're the bad guys. But the good news for the periodontist is after they pull out the tooth, they can place the implant, which we can restore later. So but that's a circumstance you'll see as well. And in many ways that vertical root fracture is the ultimate disaster for a tooth that might have been crowned years before and avoided this. So when you're seeing situations where a tooth has indications for a crown, this is where they could lead to as sort of the ultimate disaster for a tooth. Let's do this right now. One of the things we're we try to do here is our attendance. So we're going to start doing that. Let me get this thing up and see if we can make this work. Uh, so you guys have your phones because this has worked in other classes, right? There's your code. So that seemed to be working for you guys. It takes a while. All right. Hopefully we can get it. 40s. If it doesn't work, we'll do it again. 189. Okay. You guys have that. Very good. But once you do it, it's captured. It should work. Yeah. So you're telling me this system we have isn't perfect? I'm shocked. Shocked? I figured by the time we started our class, they'd perfect it. You guys did do another one. All right. So let's go on to you guys. Good. You all scanned? No. To the other monitors work better. The side ones. Maybe they're better. But we did not. Oh, it's not this. It's the. Yeah. Yeah. You know, you have to make sure that I know with these it's a good idea in some cases to, like, turn off the Wi-Fi and turn it back on in this room to make sure that it's really running. All right. Well, I'm going to start to go on with some of our stuff. So there are some other indications for crowns. Another indication would be a circumstance where. Yes. Yeah. How long to wait? It's a good question. What was asked was how long after we put a temporary on it? Or maybe we put the regular crown on and we're just watching it. How long do we wait? And I don't have a perfect answer. A lot of times it's just guided by what the patient experience is. If we put, you know, the ideal circumstance from the dentist and patient's perspective is whether it's a temporary or the regular crown temporarily cemented, you put it on and, you know, they call the next day and say, I don't feel a thing. It's great. And then another week or two goes by and they say, it's perfect. You fixed it, doc. You're like a, you know, a genius. And and when that happens, it kind of tells you right away. What's more problematic is, well, it's a little better, but I sometimes feel stuff and then it can drag out. So there's not a perfect answer. A lot of times you just have to see how it plays out. So, sure, you know, while we're talking about cracked teeth, let's go to this for a second. Let's see. I'm going to let me just show you a couple things. No, wait a second. Where's our. No, no. Here's what. Sorry. Here's what I'm looking for. Okay. All right. Let's look at a few slides real quick. That might be might help illustrate this real quick before we finish the other material. So when you talk about crack teeth, because this is an area that we find confusing, you know, here's a very typical circumstance where the tooth presents and you can see these little cracks in the marginal ridges. You would look at this tooth typically and say, all right, it's not that deep or big a restoration. Would you crown it? And typically you wouldn't feel that it has an indication for a crown there in a lot of circumstances, except if the patient's telling you that whenever they chew, it hurts. They can't chew on the tooth. That's a cracked tooth. Right. And that's a circumstance where you have to start to seriously consider what to do with it. This isn't the same tooth, but here's a circumstance where you can see what a tooth that's been prepared for, a crown that has a really solid fracture in it. Right? You can see things like this now when you see a fracture this distinct, you have a hopeless tooth because this is a real fracture, this tooth. If you start pushing on it, you could practically pry it apart yourself, although ideally you wouldn't want to do that sort of thing. More typically, when you have an asymptomatic fracture, you can see a little bit of a seam, but not quite as wide and distinct as this. Here's an example just real quickly of something that came up. This is not a wide restoration. This would not inherently need a crown, this tooth. But you can see there's a little fracture here and the patient has pain. When they chew on it, it hurts to chew on the tooth. They can't chew on it. So you prep and temp it. This is just the preliminary preparation. And then what we're going to do is remove what's left of the old restorative material because we don't want to ever leave behind any old restorative material. The reason we don't do that is we don't know what's under it, right? That amalgam looked clean, but it could be that under the old amalgam was a bunch of caries. So you always remove every bit of the old restorative material. This goes into that rule that as a dentist, once you touch the tooth, as far as the patient's concerned, everything that happens afterwards is your fault, right? It doesn't do you any good to have say, prepared this put a crown on it and later on they need root canal treatment. In the end, Adonis goes into the tooth and finds a huge amount of caries that were underneath there. And you say to the patient, well, the previous dentist did a terrible job. They left decay under, you know, in your tooth. They won't believe you because you were the last one to do it. So it's your fault. So for that reason, we have to make sure these are clean. And it's not just to protect yourselves. This is for your patient. By cleaning that out, we make sure it's okay. What you see here, though, is once we clean that out, we left a little bit of a box that adds retention resistance. There's no reason to fill that in. We can just leave that. So here's our preliminary prep and then we're going to just go ahead and make a temporary restoration on it and send the patient home. Bless you to see how they do with this. All right. So we have this is a block temporary. We're going to do this in our class in a few weeks. And so here's just the sequence we followed and we'll see what happens. If this resolves the symptoms, we're going to go ahead and do our crown. If it doesn't, we'll go ahead into root canal treatment and other things like that. Okay. So just a few quick slides there. Let's get rid of this and go back. Here. All right. So to go forward with what we're talking about, some other indications the last few before we wrap up what we're doing, another indication for a crown would be a circumstance where we have to provide maximum retention for the restoration. Replacing this would come up in a circumstance where you're thinking, well, it's a kind of short tooth. Can I get away with an on lay or knowing that a crown providing more surface coverage, more surface area is more retentive, you might need to do a crown because the tooth is just sort of too small. Or it could happen in a circumstance where you're going to be making a crown or other restoration on the tooth and that tooth is going to serve as an abutment for a partial denture. You haven't really studied partial dentures yet, I don't think. But when you do, there are going to be circumstances where the clasps of the partial grab onto a tooth. That's what will retain it. If the tooth that's going to be grabbed onto has to have a restoration on it. If you need a restoration to be maximally retentive so it doesn't get pulled off, that's another indication for a crown. So that would be a circumstance where you might have to do that. Another circumstance where a crown is indicated could be esthetics. You have a patient who presents they don't like the appearance of their teeth. And in some circumstances, the only thing that's going to really allow you to kind of make them look right is to crown the tooth. You might be grinding away a lot of two structure that you didn't want to touch, but in some cases, if the overriding concern is that esthetic result, that can be an acceptable reason. That could be an indication and to to crown a tooth. Another indication for crowns could be where you have to restore function. Sometimes teeth are compromised in such a way, whether it's from where or previous fractures, and you have to sort of rebuild what's there. And in certain circumstances, the only way to control that, to rebuild the function, as it should be, can be with crowns. Basically what that gets down to is as much as you might be able to do building up something in Operative, it's not quite as controlled or effective as when something is done in the laboratory so that your technician can restore teeth to a proper function and proper size and shape and all those things. So this is one of those circumstances where a crown or crowns fix prosthetics could be well indicated. The last thing to talk about in terms of indications are going to be indications for a fixed bridge as opposed to, you know, leaving a space when a tooth is lost. So as a quick reminder, and this would go back to your dental anatomy class, I believe we know that teeth exist in the mouth in what we might call static or excuse me, dynamic equilibrium, get the opposite. So they're in a dynamic equilibrium, which means the teeth stay where they're at because they're hitting other teeth. If something changes in that state of equilibrium, things move around. So if a tooth might be lost, things shift. So if a tooth, a first molar is lost, we might have the one behind it. Tip forward, the one above, go down, and before you know it, what we've got is a circumstance where we've kind of violated our. Occlusal plane. We've got kind of a mess there. And in some cases that could turn into a problem, not always, but in some cases. So this would be an indication when a tooth is lost for our desire to fill in the space. So as a general rule, when teeth are lost, we would typically recommend that they be replaced. So there's different ways to replace teeth. We can do them in two different ways with fixed prosthetics. One is with a fixed bridgework. We'll talk about this more in a couple of weeks. Another way can be with dental implants. You're going to have a whole course on that coming up later in the year in our class will come up repeatedly. But, you know, talking about them a little bit, we are going to spend more time in our class on fixed bridgework. And the last thing I want to cover before we get out of here this morning is just to sort of show you the basic nomenclature we're going to use for our fixed bridgework. So when we have a missing tooth and we're doing a replacement in this case, what we might call a three unit fixed partial denture or a three unit fixed bridge. We have teeth that's supported on either end, the crown on the on our support teeth are called retainers. The teeth themselves are called abutments. These are the same terms we use when we talk about a partial denture or something, teeth that support things or abutments. I don't think these terms are in any way unique to dentistry. If you look at the Tobin Bridge in Boston, it has abutments that support it. It doesn't have a Pontiac, though. The replacement tooth is a pantech, but it does have abutments. It covers a span between our replacement tooth. The Pontic wear that's connected to our retainers is kind of a simple term that's called the Connector. So they're very that's the nomenclature we use. It's kind of straightforward. Later in the course, in a couple of weeks, as I said, we'll talk about fixed bridgework, indications, things like that. And later in the course, we're going to spend a lot of time, the final portion of our course, the last third of the course or so or a quarter of the course is preparing and temporary housing for a three minute fixed bridge. So we'll spend a lot of time on that. Any questions about any of this material today before we wrap this up? Great. Well, yes. How do we decide when to crown? All right. So the question was asked was was a good one. And I, I kind of went right by that real quick. It was it had to do with when we have root canal treatment on anterior teeth, how do we decide when to crown them? We don't when we get to that part of the course late in the course, we're going to spend some time on it. But in shorthand, we're going to decide to do it. Again, the first things I said today when we have to, but we don't always have to on an armchair. What it's really going to come down to is how much two structures missing and what is the function look like. So if you have a situation where the patient has an anterior open bite, the answer is never. If you have a situation where the patient has no say. They needed that index because they were playing basketball, took an elbow in the face, pulp died. Tooth isn't really fractured. Everything's intact. There's a tiny axis opening on the lingual. You'll never crown that tooth unless they keep getting elbows in the face, right. And eventually they'll break it. But until then, you'd leave it. If you have a tooth, though, that had to say a huge amount of decay in it. A lot of missing two structure, same reasons as before. You'll crown it because there's there's no two structure. So it's a little more nebulous than posteriors. The reason being that posteriors, because of what we see as a proclivity to fracture. And we know that they're going to be under a lot of function. Those you got to crown them, you don't want them to fracture anterior is because the function is so different unless we're really compromised on the amount of two structure, very often we can get away without crowning them and our basic desire not to drill on two structure kicks in and we try to avoid it late in the course. When we talk about this, I'll try to cover it in a little more detail, if that's all right. Hopefully that's enough of an answer for today. If there's nothing else for the A's class, we'll see you guys over in the lab in 15, 20 minutes. Something like that wasn't working. Can I?