CLASS II COMPOSITE.pdf

So let's look at posterior composites in 2023, 2023, and probably for the next few years. But composites are still changing. And I'll talk a lot about that. I really like these. These are brand new, these screens. They're actually not projection screens, but they're nice. Take me a while to get used...

So let's look at posterior composites in 2023, 2023, and probably for the next few years. But composites are still changing. And I'll talk a lot about that. I really like these. These are brand new, these screens. They're actually not projection screens, but they're nice. Take me a while to get used to this. All right. This is one of the nicer rooms to go to lecture. Some of that lecture rooms are not so nice at all. All right, so where Where? Class one and class two composites are excellent is for small to medium sized restorations. They're really not capable, and it's extremely difficult to get a good result with very large restorations. Okay. It's also important to note that probably the biggest single contraindication for posterior composites is when you can't get good access and you can't get good visibility and you can't get good isolation. Every textbook in operative dentistry will say that that's the number one contraindication for using composite. And if composite isn't isn't indicated, then you have to think of other things, maybe even amalgam, maybe even ceramic inlays or on laser crowns. ET cetera. Some people feel that if you can't get a rubber dam on it, you probably shouldn't do composites, you know? And there are you know, I have a private practice as well. I only work there one day a week now. But my last patient last night, I had to take care of a restoration on the distal of tooth number two, and his mouth opened like that big. All right, So is it physically impossible to do a composite? Well, I probably could have done a composite, but Iwouldn't have shown it on a on a screen here because I probably would have been embarrassed and I probably would have had a 5050 chance that it wouldn't have wouldn't be all really acceptable. All right. So I ended up doing an amalgam. All right. So class two and class one composites are really indicated for small to medium sized lesions where you can, in fact, get good access and visibility. All right.And probably the the ideal indication for a class one or class two composite is when you're placing the first restoration in a tooth, because then you can take advantage of the fact that the preps are more minimally invasive and I'll use the term minimally invasive dentistry over and over and over again in that in this course. All right. So obviously, if you're replacing an old amalgam with a composite, you can't be minimally invasive because the prep has already been prepped or the tooth has already been prepped for an amalgam. But for brand new pit and fissure carries small proximal lesions that you're restoring for the first time.I think composite is by far the best, the best choice. It is important to note that it's definitely more time consuming and more technique sensitive compared to amalgam. So if we were comparing amalgam to composite, I can do a class two amalgam in 15 minutes. I can't do a class two composite in 15 minutes. It's much more takes much more time and much more attention to detail. Now what does technique sensitivity really mean? I don't want you to say anything. I just want you to think about what your definition of technique sensitivity would be. This is an intentional pause, by the way. I didn't forget what I was going to say. Our technique. Sensitivity implies that if you don't do everything the way it's supposed to be done, if you don't follow the directions carefully, if you mess up just a little bit, it's a failed restoration. Okay.A technique, insensitive technique or procedure would be one that you could be a little sloppy. All right. So if you're a sloppy dentist, do a lot of amalgams. Okay. If you're a meticulous dentist, do a lot of composites because it does require more tech, more attention to detail, and there are more steps, especially in the in the adhesive aspect of Class one and class two composites. So it's more time consuming, more technique sensitive than amalgam. Right. Now, this last bullet here, still evolving, is really important. I want you to think about this. Where are we as a profession? Where are we in the evolution of amalgam? Now, evolution by definition, would be from the very beginning to as good as it will ever be. Okay, so where are we in the evolution of amalgam? And the answer is we're done. Amalgam is not going to be improved. There are no scientists. There are no chemists who are working on coming up with a better amalgam. First of all, there's no money in it because no one doesn't want it. Plus amalgam has been around for so long that if it was going to be any better, it would have already been changed. But there hasn't been a change in amalgam since the 1970s when high copper alloys were invented and different sizes and shapes of the the particles. But the reality is, is that composite where are we in the evolution of composite? Is there anything still changing with composite? And I'm talking about everything about composite like matrix systems and bonding agents and those kinds of things. So it's important to note that composite today is better. And again, I'm talking about everything about composite is better than it was five years ago, and five years from now, it'll be better than it is right now. So composite is still evolving. That's why if you ever saw if you looked at one of my lectures from ten years ago, don't pay any attention to it because things have changed in the last ten years. And it seems like like every six months or every 12 months or so, there's some new advancement in composite dentistry. And we'll talk about whether or not that's better or worse, because sometimes newer materials aren't as good as some of the older materials. You know, I love like gold crowns. I think gold crowns are phenomenal, but nobody wants them and no dentist wants to pay the lab fee. That's another story. But I love this screen so much bigger. All right. So take a good look at the slide on the left. This is the very first. Material. I'm not going to call it composite because you'll notice you don't see the word composite anyplace on this label. All right. So this is the first material that was designed. It is a composite, by the way, specifically for posterity. It's called P10. It's from 3 a.m. now it's three MSb. But the original posterior composites were I was going to use a swear word, but I'm not going to use it. But they were really junk. Okay. First, the early days of posterior composites were not good. This is fairly embarrassing because I actually did this restoration over here in the early days, like in the early 1980s. And it's an embarrassment, I say, to even show something like this, because this is after 3 or 4 years in the margins of breaking down. Obviously, the surface texture is no good. The contact is flattened out because it's worn down there. So just be aware that, like I said, in the evolution of posterior composites in the early days, it was real bad. Then it got better, a little bit better, a little bit better. And we're probably 90% of the way there in terms of its evolution. You know, we're getting closer and closer to perfection. I shouldn't use the word perfection, but we're getting getting better, but we're still not perfect yet. All right. So this is the way I typically lecture. I lecture the same way I will do a procedure. So I'm going to lecture about diagnosis and treatment planning first, and then I'll talk about isolation like a rubber dam. Then I'll talk about the preparation, then I'll talk about the matrix, then I'll talk about the insertion and curing, all that kind of stuff. So it's typically how I organize my lectures. All right. So as I said earlier, one of the most important things about a class one or class two composite is getting good isolation. For what reasons? Why is it so important? Wonderful. All right. So, again, if you get contamination, so contamination control in general, because contamination, especially at certain points in your procedure, probably the most important time to not get contamination is right after you etch something with with phosphoric acid and before you apply the primer, etcetera. If you get contamination there, you got at least a 5050 chance of having a patient with post-operative sensitivity or failed restoration. So isolation is important for that reason. Why? What are other reasons for good isolation? Pardon? Visibility, access and visibility. Absolutely. It gets the tongue out of the way. It helps you focus with your eyeballs because if you have a lot of stuff in the periphery, you're getting distracted. But with a rubber dam, you're really able to concentrate and see what you're doing, especially with loops on it. Okay. But other things like patient safety, if you're removing an old amalgam without a rubber dam, you've got shrapnel flying all over the place. Little particles of amalgam are all over the place. And of course, you know, especially during Covid, there was a lot of discussion on aerosol and how important it is to minimize the aerosol. You don't want to get Covid or any other problem from your patient because if the aerosol is flying all aerosol are going to work their way around your mask and around you, around your gloves. But there is no real aerosol with a rubber. Of course there is an aerosol, but it's all non biologic. It's all water and pieces of two structure. It's not blood and saliva, etcetera. All right. So protection for you and protection for the patient, for a whole variety of reasons. So this is a good view of an old fashioned rubber dam. Nowadays we're using non latex rubber jams. So if any of you know that you're allergic to latex, be aware that especially in the SSC we only use non latex gloves and non latex rubber Dam. And this is a really good rubber stamp. All right. So just as a quick review, if I'm working on this tooth, for example, this is a good isolation. You always want a couple of 2 or 3 teeth anterior if possible, 1 or 2 teeth posterior. Of course, sometimes you can't have two, 1 or 2 teeth posterior because of what there is no tooth posterior. So if you're working on if you're doing a restoration on this tooth, obviously you can't isolate teeth behind. And you'll notice and this is also while everything's important, it's going to say this is important, but everything is important. You'll notice that there's a wax floss ligature and the clamp just in case. When you're trying in the clamp, it falls towards the back of the patient's mouth. You can grab it and retrieve it before don't wait until after it's swallowed or aspirated and then pull it out. You probably pull out the trachea. All right. So it's important every time and you'll be applying lots and lots of rubber in this course. But the clamp always needs a wax floss ligature. And if you're not familiar with this, it's called the wedging. It's really simple and comfortable for the patient and traumatic for the patient way of isolating the anterior parts. So there's no rule that says you have to isolate five teeth. But it's a good idea. Remember, you want to isolate enough teeth so you have good access and visibility, but don't get carried away. When I was in dental school, we had to isolate from the second molar all the way to the canine on the other side. And that was stupid. You don't need to isolate that many teeth. All right. And you also notice that the rubber dam is properly inverted. You'll notice that the rubber material has been snapped through all of the contacts.All right. And again, some of you are very familiar with Rubber Dam I used and some of you are not, but you will be by the end of this course. All right. Let's talk about the prep design I mentioned. There I go again. I'm mentioning minimally invasive. What is minimally invasive dentistry. And again, I don't want you to talk because there are too many of you and I can't hear that. Well, anyways. All right. But what would your definition of minimally invasive dentistry be in terms of prep design, in terms of designing a prep, what is minimally invasive dentistry? Because I could also say minimally invasive dentistry applies to treatment planning. You know, if a composite will work, don't do an amalgam. If an amalgam will work, don't do a crown, you know, those kinds of things. All right. So minimally invasive dentistry in terms of prep design means what? And again, don't talk. I just want you to think about if I said I won't do this, but if I said write down the definition or explain it to a first year student. All right, so here's my definition. My definition of minimally invasive dentistry or minimally invasive preparation design is never, ever removing healthy to structure unless you have a darn good reason for removing it. Okay, now sometimes you have to remove healthy to structure. Remember, if you're dealing with a proximal lesion, the only way to get to it is to remove a perfectly healthy, marginal, you know, a little bit of the marginal ridge, Right. So enable to get in the getting to the problem is also called convenience form. That's one of the black solid terms. But in terms of of removing healthy tooth structure, sometimes you have to but you should have a good reason if you're doing a crown preparation. I can remember the first time back in school I did a porcelain fuzed to metal crown preparation, and I'm thinking to myself, I'm removing a lot of healthy two structures there. That's why, you know, we're lucky now to have material, crown materials that don't require as much occlusal and axial reduction. So that's what I mean by minimally invasive dentistry, never removing healthy to structure unless you have a darn good reason for removing it. All right. Now, why is that important? Can Enamel grow back? No. Are there any amyloid blasts in this room? Let's think about that for a second. Okay. Once in, Amelia, Blast has done its job and this is before eruption. What's an email blast has done its job. It disappears forever. Okay. So I'm sure there are bioengineering people who are coming up with cloning email blasts and maybe rebuilding enamel, but certainly not in my the rest of my career, but maybe in your career. All right. Because of that, we really don't have a right to remove something. You know, compare this to a broken bone. If you break your bone, you go to the emergency room. Hopefully you don't have to go through surgery, but they'll set it, put a cast on it and send you home because the bone will rebuild itself. The bone will actually cure itself. Same thing with the laceration. If you get a cut on your hand, you stitch it up and maybe a little scar, but it will heal itself If you break a distal lingual cusp off tooth off a lower molar, will it grow back? No, of course not. Of course, patients are lucky because they have dentists who can put it back. But certainly, Amelia blasts aren't going to put it back. All right. So that's why we really don't have a right to remove healthy to structure. Okay. Unless we have a reason for good reason for removing it. All right. First of all, does anyone not know who GV Black is? Good. All right. He's my hero, by the way. All right. So really, sometimes I hear people literally, I idolize GV Black and you'll probably hear from as two students from DMD, two students and three students that Mcmanaman really has this thing for GV Black. That's absolutely true. I think he was a genius. And what he did in the early part of the 1900s is that he took a pretty bad material amalgam, okay, and literally told the manufacturers how to make it better and told the dental schools how to teach it better. And it took them he literally almost single handedly took a really bad material, the early amalgams, and made it the most important restorative material of the 20th century. Amalgam absolutely was the most important restorative material of the 20th century. Now, not the 21st century. Just trust me. You know that's not true. And it drives me crazy when I hear dentists say, Oh, that's old fashioned black dentistry. I'm telling you right now, the black were around today. I I'd love to meet him. I bet if black were around today, he would be a revolutionary. He would be, you know, telling dental schools, oh, you're teaching this all wrong. In fact, he would say, I don't believe you guys are still filling teeth. I thought caries would have been eliminated by now. All right. So he's a revolutionary, so don't use his name in vain. Don't bad mouth black and certainly not in front of me. All right. So but what's interesting is we still use a lot of his terminology and an important part of dental school. In fact, tomorrow I teach the first year students their very first lecture in dentistry. They don't know what the word medial means yet. So I have to start very, very slowly with them. Obviously, I'm much more using much more sophisticated language with you guys, but we're still using GV Black's language. I use the term outline form. I use the term resistance form. I use those those terms. Okay. Not because I idolize them, but because he was a way ahead of his time. I also want to stress the next two bullets. Is there an ideal, let's say mo prep on tooth number three for composite, an ideal Mo prep? And the answer is. There is no stereotypical or ideal prep. You really have to use your understanding of the tooth structure. You need to understand what enamel is really like and how it responds. And same with dentin. And you really have to understand the material that you're using. That's why, for example, the purple floor depth on occlusal restoration is different from amalgam than it is for composite, than it is for ceramic inlay, for example. So the preps are clearly different and you have to design use that word a lot. You have to design the preparation based on your understanding of the tooth and the restorative material that you're using. Okay. So I you know, every so often people will say, well, cut an ideal prep. There is no ideal meal prep. Sometimes they're big, sometimes they're small, sometimes a couple floors deep, sometimes it's shallow, Sometimes the lingual width is wide, sometimes it's narrow. All right. So let's pretend now, because what we're going to do is do class one and class two composites. What about the pits and fissures? How should you prep the pits and fissures? And the first answer is, if there's no caries in the pits and fissures, don't prep the pits and fissures. Remember, the only requirement for prepping for composite, The only requirement for prepping composite is if there's a problem there. And the problem is most commonly are either caries or old restorations. Okay. There are occasionally there are a few other things. And I'm going to talk probably starting next week, I'll review a slot preparation or what some people refer to as a box preparation. And this is simply finding and and restoring the proximal lesion and leaving the pits and fissures alone. In terms of your outline form, on the occlusal surface, you're only needing to include the pits and fissures that are not that are carious or if there's an old restoration there. All right. Now, what about the whole concept of extension for prevention, for preparation, for composite? So let's backtrack a little bit. This is actually historically earlier than GV Black. It was a guy named Webb Webb. You don't have to know that unless you're on Dental Jeopardy or whatever. But this guy named Webb actually first published the term extension for prevention. What does it mean? And again, don't say anything. I just want you to think for a second about what what the definition would be of extension for prevention. Now. What is the most. Now you can talk. What is the most vulnerable part of any restoration? What is the the part of a restoration that is most likely to develop secondary carers? And the answer is the margin. More specifically, it's the gingival margin of a class two. You know, you rarely see secondary carers in a buckle lingual margin. You rarely see secondary caries on an occlusal surface of a well done restoration. But even in a well-done restoration you can find secondary carers on the Gingival margin for a whole variety of reasons that we'll talk about a lot in this course. If the margin is the most vulnerable part of your restoration, okay, it's critical to place that margin in easy to clean areas that are not likely to be bathed in plaque 24 hours a day. Right. I'll use the term, especially in the SSC. Dirty places. So what are the dirtiest places in your mouth right now? And the answer is two. One at the deepest part of a non coalesced fissure. It's dirty because you can't get the bristles of a toothbrush there. And based on what you had for breakfast this morning, there's little pieces of food particles there. And this clearly carried genic bacteria there. But more importantly, just below the contact, especially on posterior teeth, there's plaque right now, unless you aggressively floss their teeth in the bathroom just before he came to sit down. There's already the formation of the biofilm, just gingival to the contact points in your posterior tease. So those are considered dirty places, plaque niches, places where plaque will accumulate. And those are the most likely places for caries to start. Now, in a high caries, this patient there, the entire mouth is a dirty place for a whole number of reasons. And we'll talk about caries, risk assessment, et cetera later on in the course. All right. So here's the concept that Webb came up with pre pre GV Blacks. This is like an 1870s, 1870s that he actually published this extension for prevention was based on the fact that if the margins are vulnerable. Okay and there are dirty places in your mouth, don't place your margins in dirty places. Okay. So this is an important thing. Don't put your margins in dirty places. I sound like your mother, right? Don't do that. Don't pick your nose. Don't do it. All right? So don't put your margins in dirty places because if you put your margins in places where there's always going to be plaque, there's going to be secondary caries, especially in a patient with a poor diet, especially in a patient who may be zero stomach. ET cetera. So for a whole variety of reasons, extensive for prevention made sense. Okay, now what about with a typical class one or class two composite? The good news is that, one, the materials are better and the margins are better, especially on enamel. If you bond well to enamel. First of all, let me ask you this. If you had to give a grade to enamel bonding right now, what would the grade be? Enamel bonding. I'm talking about with good technique. Now ten on a scale of what? 1 to 100 or 1 to 10? Okay. So on a scale of 1 to 10, it's a ten. Okay. On the scale of a BCD. It's an a, a plus. If we could give a plus. We can't give a pluses here at the school. All right. But it deserves an A-plus because it's outstanding. It was first used in the 1970s. K and I have restorations in people's mouths where the enamel margins are still beautiful. Okay. That are 30, 40, well, not quite 50 years old, but, you know, old restorations. Now, there may be other problems. So that's the whole concept of extension for prevention now for today's composites. Do you need to follow extension for prevention? Remember, extension for prevention means that you do all the rest of the prep. You find the caries, you remove the caries, or you move on support to structure. You do whatever else is required for that type of restorative material. And then you say to yourself, Well, I haven't broken contact on the distal yet. I haven't broken contact on the missile. Do I need to remove healthy two structure in order to extend for prevention? Think about that for a second. Can you. Do you need to break contact? You know what the break in contact means If you need to break contact for, let's say, a class two composite. And the answer is it depends on the caries risk. If you have a high risk patient, yeah, you should put your margins in easy to clean places. If it's a low risk patient, you don't need to. Now, most of the time, especially with an understanding of where carry is formed, you're going to break gingival contact and most people will say breaking gingival contact is always a good thing. But buccal and lingual you don't need to. And again, it's a minimally invasive dentist. I use the concept of customizing my extension for prevention based on the patient. And what I really mean is the patient patient's caries risk high caries. Patients are prepped more aggressively because I want to put the margins in very easy to clean areas and low caries patients. I don't need to break contact. So we'll talk about that a little bit more detail now in the pits and fissure areas, if in fact this carries in the pits and fissures for a class one or the occlusal portion of a class two do, how deep do you need to go? What's the palpable floor depth? What determines the palpable floor depth of an occlusal composite? A class one composite? How we getting to and removing the problem, period. Okay. So if the problem is a faulty restoration, remove the restoration. If the problem is pit and fissure carries, go deep enough to make certain that you've that you're you've removed the problem. And we'll talk a little bit more later on in the course about the difference between affected and infected dent and you need to remove all affected or infected. I'll talk about that a little bit later. So how why do you is your preparation and again, there's no numerical number here. Okay. I can't tell you all preparations need to be one millimeter wide or two millimeter wide on the occlusal surface because it depends on two things. Once you've removed all of the caries, that's determinant, number one. But you also might need to remove a little bit of unsupported structure on the buckle and lingual of that preparation. So you may need to widen it In general, about a millimeter width will give you access and visibility to make certain that you removed all of the carriers. All right. So very different than amalgam. What about, let's say, an Mot ceramic inlay? How deep does the pulp floor need to be? How wide is the buckle lingual dimension need to be? And the answer is it depends on the material that you're using, but it's generally one and a half to two millimeters deep and wide. And for an inlay you need a divergent walls for path of insertion. All right. So that's why I said earlier, you need to understand the tooth, but you also need to understand the restorative materials that you're using. All right. Now, I will talk about this quite a bit a little bit later on. But when you're deciding on the preparation design for the occlusal surface of an Mot or do prep, when you're deciding that, how do you know that there's there's caries at the deepest part of that fissure. Let me ask you that question slightly differently. How good are we as a profession? How good are we at accurately diagnosing small pit and fissure carries? Give yourselves a great. Five on a scale of 1 to 10. Eight? We're not that good. We're not that good for reasons I'll talk about it a little bit later. But unfortunately, GV Black would go crazy, says, I can't believe you guys can't accurately diagnose small pit and fisheries. But there's a reason. And the reason is is pretty straightforward once you understand the morphology of a non coalesced fissure. Right So for example and this is an important couple of terms to to make certain you understand the definition of a coalesce fissure. A coalesce fissure is where let's say this is a buckle tip, that's a lingual tip, and this is the groove of the area. In between the tips, this is the coalesced fissure, okay, where the enamel on the buckle is continuous with the enamel on the lingual. Okay. What is this, the. Well, it's right there. You can read it. All right. So this is a non coalesced fissure. What's the difference between this and this? And the answer is caries does not form on coalesced fissures. Carries easily forms in non coalesce fissures. That's why many of you in this room had spit and fissure sealants when you were a kid. I didn't have pit and fissure sealants when I was a kid because I'm much older than you. Right? And I had lots of pit and fissure carries when I was a kid. Plus we didn't have fluoride. We we thrived on Coca Cola and all that kind of blankety blank. All right. So a coalesce fissure is one. Unless it's been sealed, it is absolutely susceptible to pit and fissure carries. Right? So why is it so hard to diagnose in the air? Because it starts down here. This is where pit and fissure carry starts. Okay. And you can imagine if this carry genic bacteria here and some carbohydrates and some time remember the key Jordan diagram, Right. So if this is where caries starts, it's going to infect the dentin or affect the dentin first. Okay. Before it starts affecting the enamel. Right. So if, in fact, come on. Whoops, went too fast. Okay. If this is where caries starts. Okay. How do you know that this caries there, can you see it on a radiograph? No. Unless it's huge. Very, very, very large. Peyton Fisher carries can be seen on a right wing radiograph, but not a medium sized and certainly not a small pet and fish lesion. Can you get access to with an explorer down here so that it sticks in that soft dentin? Oh, not not in the early stages because it's enamel is still is still unaffected by caries. Right. So that explains why it's not so easy. Have you ever heard of a diagonal dance or some of the electronic devices that are designed to identify early stages of Pet and Fisher carries? I actually thought that many, many years ago when the diagonal and similar products are introduced, that everyone would be using them. Now, I want you to be honest. Put up your hand if you've used a diagonal or a similar product. All right. So that's why in the early stages I said, Oh, by 2020, the year 2020, everyone, especially if they treat a lot of kids, are going to be using a diagonal dent and almost nobody put up their hand in this room. So it's just not all that popular for a whole number of reasons. So we still need a better way of knowing whether or not there's caries down there or we need to make certain that every child at age six gets their six year old molars pit and fissure sealed. That doesn't happen. When? Skin sealants. You have to be very careful to place. Okay, so seal emplacement. The single biggest problem, in my opinion with salient placement is that a good percentage of them are done well. All right. So, again, that's a that's a lesson from Dr. Roebuck. Rebecca's in pediatric dentistry. He'll talk a lot about sealants. Okay, So let's pretend. Following this course. We've already diagnosis tooth. We've already isolated with rubber. Damn, I didn't talk about anesthesia because that's. We'll talk about that later, but you'll get plenty of that in other courses. Plus I imagine that you've had a lot of experience with that anyways. All right. So. Let me do a little survey here. High speed handpiece. Who in this room has used mostly an air driven, high speed handpiece? Okay. Who has used mostly an electric high speed handpiece. All right. So here's some bad news. I like to camp pieces are really good once you get know how to use them. But for those of you who have never used an electric campus, get ready for today because you're going to be using an electric handpiece for the first time and it is absolutely different. Okay. Some people argue it's better, some people argue it's worse. But the trend clearly is more and more practices are switching from air driven to electric and paces. All right. So when you're prepping this occlusal surface of your meal prep or prep, when you're starting to prep, once you've diagnosed, you at least guessed that there was a pit and visual lesion. What should you use? The burr that I love almost as much as black. The bird that I love is a 330 burr. Okay, so what is a 330 Burr And the answer is it's a small pear shaped burr. Doesn't really look like a pear, does it? No. All right. And it has a slightly rounded end, because the reason why this is nice is that it's small. And again, smaller birds are going to be more minimally invasive. And I'm a minimally invasive dentist. Okay. In fact, for smaller teeth like anterior class threes, etcetera, or tiny little pit and fissure lesions, I'll use a 329, which is actually a smaller version. Most textbooks and restorative dentists or operative dentistry today recommend a small pear shaped burr. So that's why 330 it's essentially the only burr I've used in. A long time. 40 plus years. All right. All right. So that's the birth I recommend. Obviously, you want to adjust the air, water coolant. We have air water coolant in the SLC. All right. So some older simulation labs did not have air, water, coolants, but we do. And one of the first things you learn to do today is adjust your air, water, cooling. All right? So the air spray will come up. Well, actually in your hand pieces, they'll come out from several different places so that the water hits the head of the handpiece I'm sorry, the head of the bur as it's cutting the tooth. But this is a little bit different with a for those of you who've never used an electric handpiece with an air handpiece, the speed of the handpiece is determined by your foot. All right. So, you know, obviously, if you push down on the foot pedal, it'll go faster. It's very similar to the accelerator on your car. All right. But an electric hand pace, your foot is only going to turn it on and turn it off. Okay. So you adjust the speed on the unit. Okay. So again, we'll go through lots of detail this morning because in the SSC today, most of the morning will be familiar familiarizing you with the equipment, showing you how it works, etcetera. Okay. And then doing a little bit of practice. All right. So you're going to adjust it to 40,000 RPMs, but you're going to be using a handpiece that multiplies that by five. So our high speed handpiece is a 1 to 5, meaning that the the motor is going to create a speed of, let's say, 40,000. But the actual speed, once it goes through the electric campus is 200,000. All right. So, again, we'll we'll play with that this afternoon. All right. See the electric. And again, this one has a red ring. But again, we'll go step by step in the SSC. So we're going to set it to 40,000, although you can set it to. Oh, gee, I'm sorry. You can set it to 20,000 for the refinement, but most of your cutting with the high speed handpiece will be at the setting of 40,000. But just be aware that it's actually 200,000. And you need to make certain that the air water spray is adjusted properly and you have a nice, nice, sharp 330 Bur So we'll do that this morning. All right. Another important thing in the pits and fishes is your alignment. Remember the problem with with ivory teeth with type it on teeth is they don't really have pits and fissures. Yeah. Can't really do that. So imagining and I'll describe how deep you should go and how wide you should go. But I'm imagining that if in fact there was carries a millimeter half below the surface here, because that's where the deepest part of the pits and pit and fissure would be, it's critical that you align this properly this way, because if you align it this way, you're not going to find the deepest part of the carries. Okay? If you align it this way, you're not going to find the carries. So in order to be minimally invasive but still get good access for removal of the soft dentin, that's at the deepest part of that fissure, you want to make certain that your burr is aligned properly because again, if it's coming from this direction, you're not going to find the carriers. If you're coming from this direction, you're not going to find the carriers. Or if you do find the carriers now, you're going to have to make it a lot wider than it needs to be. All right. So we already talked about that. All right. So I have two preparations. This is a finished preparation for a class one. This is the occlusal portion of a preparation for a class two. You can see the red right there. Now, what is that red? Yeah. Okay. You're going to have to get used to this. In fact, one of the first things we're going to do today is create the lesion. When I was in dental school and for the first several years of teaching, I thought to myself, This is stupid. We're taking typing on teeth and cutting preparations. But there's no caries in these these teeth. Right? So that didn't make any sense. So what I've been doing for the last, I don't know, ten, 15 years is actually having you make a proximal lesion first. Okay. So you're going to be unscrewing that tooth following my directions for exactly how big and exactly where to make this proximal lesion. Okay, Then you're going to take your 330 bur in your hand and you're going to cut the lesion from the distal. Okay. To the depth that I say to the buckle lingual width and the occlusal gingival width. Okay. And then stuff it with red wax. So over in the SSC right now, you actually have red wax in the stations that one of the first things you'll see when you get there. All right. So once the lesion is made, okay, then I have you screw the teeth back in. Okay. Put the assemble the patient's upper and lower jaws et-cetera and then put the rubber dam on. Get ready to go. So here are the two preparations. Now, why is it steep and why is it this wide? And the answer is because this is an old amalgam prep. Okay? So it looks like a big prep. It looks like that's not minimally invasive. But if it's an old amalgam prep, you can't convert a maximally invasive prep into a minimally invasive prep, obviously. All right. So some of your preps will look like this, some of the preps won't. Some of the preps, if there was only caries in the in the medial fissure, the prep would have stopped right there. Okay. If this if you removed all the caries but found a lot more unsupported enamel, what is unsupported enamel? What's that definition? And the answer is enamel. Has to have in order to maintain or to be maintained in order to survive in the rough environment and animal needs. What? And the answer is it needs dentin supporting it. Okay. Enamel is a lot like a piece of glass. Okay. If I gave you a pane of glass and said, break it, this is what you would do. You would simply take it like that and snap it and the glass would break. Right? What if the glass was on this floor right here? It's stuck to the floor. Permanently bonded to the floor. Can you walk on that glass? Yes, because it's supported underneath. Now, obviously, if you banged on it, you might be able to crack it or break it. But enamel doesn't by itself doesn't survive all that well. But enamel supported by dentin does survive. Survive very well. All right. So dentin has to and I'm talking about the internal part of the enamel rods. The internal part of the enamel rods must be supported by good, healthy, resilient dentin. Okay, Now, a common question. Even in courses that I give a common question, especially in the early days when we were doing posterior composites. Did I learn posterior composites when I was in dental school? Look at my white hair. Did I learn posterior composites when I was in dental school? And the answer is no, that's going to happen to you in your career, is that you're going to have to learn something that you didn't learn in dental school. Okay. Just like I had to learn how to restore implants, I had to learn how to do posterior composites. I had to learn how to do veneers. I had to learn all this stuff that I'd never done before or never done in dental school. So here's a common question that I get. Do you need to bevel the occlusal surface of a pit and fissure pit and fissure prep? It's a trick question. Why is it a trick question? Does this prep need to be? Beveled? And the reason why it's a trick question is that it's already beveled. Okay. The rationale for Beveling a prep for composite is to expose the cut ends of enamel rods. You do, in fact, get better bonding, better esthetics if in fact your margins are in are cut ends of enamel rods. Okay, So look at this right. There are these cut ends of enamel rods. The answer is yes. Okay. So does it make any sense to do this? No. As a minimally invasive dentist, you're just removing more enamel and you're widening the occlusal surface. You're more likely to get wear because composite doesn't wear exactly the same as enamel. You know, under especially in a bruxism patient. So the bottom line is, does this need to be beveled? And the answer isn't no. The answer is it's already beveled. Okay. So if I ask this question, do you after you cut an occlusal preparation, do you then need to bevel occlusal surface? And the answer is no. Or Beverly occlusal margin, I should say the answer is no because it's already beveled so don't bevel something that's already beveled. Okay. And again, you could also say that what is the surface margin right there? Is it 90 degrees? No, actually, one of the definitions in some some dictionaries or some even have a dictionary. But if you have ever seen a deck. No, never mind. All right. So so some people will define a bevel as where two planes come together, not at 90 degrees. Okay. Do these two planes, the outer surface of the tooth and the inner surface of your prep, do they come together at 90 degrees? The answer is no. If there was, 90 degrees would be like this. Right. So you don't need to bevel occlusal surface because it's already beveled. And this is from your textbook and again you can see it's kind of a wide preparation but if you can see that there's lots of cut enamel rods and a cut enamel rods bond better than the sides of enamel rods to cut ends of enamel rods will in fact give you a better marginal seal and better esthetics. Okay. We'll talk a lot about that with class threes. Okay. So now let's move into the distill here, because this is only an occlusal preparation. This is a dough preparation and this is exactly what you're going to do this afternoon or today because you'll be doing a dough prep. Now, let me confuse you on tooth number 20. Number four. Everybody know what two number 20 is. Are you going to have to get used to this? Okay. All right. So we're using the universal numbering system, which I always have to say this in the first lecture to advanced in class, because a lot of you aren't used to the universal numbering system. Okay. So for some of you, this is, what, 35? Three. Five. Okay. For some of you, you put a little bracket and say that this is a five with little orthodontist. Use that a lot. So and some people will just say, well, like an orthodontist will say, well, we'll, you know, just put brackets on the sixes. Yeah. Universal numbering system. That's the maxillary right. Canine. Right. So you need to get used to this. So we're working on tooth number 20 today, which is the lower left second premolar. Okay. And we're doing exactly the same prep. We're doing a Doe. All right. So step number one is removing a little healthy to structure because you have to break through some of that marginal ridge in order to get to the lesion. Okay. And you know where the lesion is because you just put it there with the red wax. You just cut the hole and put it with red wax. So this is me getting to it. Now, once I've found all of the red wax, I simply switch to excavating instruments either around burr, excavating at a slow speed on your slow speed handpiece. And I'm talking about very slow, right? So we're not removing much normal to structure. We're only removing with the excavating inserts, we're only removing infected dentin and maybe a little affected dentin. But again, I'll talk about the difference between infected and affected a little bit later. But in the SSC we're simply removing the red wax and the red wax. Will kind of take the place or mimic infected dentin. So it's fine. Now, once I remove some of that excess red wax there, is the preparation finished? No. Well, I removed the lesion. Didn't I say that One of the nice things about composite is really, you only have to remove the lesion, but you also have to remove weakened to structure. What is that right there? That's a lip of unsupported enamel. Okay. It has to be removed. Okay. So that lip of unsupported enamel must be removed. Come out. There it is. All right. So this is the preparation. An ideal. I shouldn't use the word ideal because there is no ideal. But this is a good preparation for a composite in terms of the margins. One. Have I broken contact? Duh. Of course I've broken contact. None of these margins are touching the adjacent tooth. So when this is restored, all of the margins will be an easy to clean areas. Although you could argue if the patient is a non flosser that gingival margin is still susceptible to carries. But if the patient is a good brusher, the buck and lingual margins are easily reached by the bristles of a toothbrush. So what about the surface angle? You can see that these this is not 90 degrees like it would be for an amalgam. Okay. This is a slight flare, not an acute bevel, but a slight flare. And again, you can't really see that there. But this is well planed as well. So slightly different tooth, but I just want to go through that. If the occlusal surface simply represents the removal of all caries and unsupported structure, finding the red wax, removing all of the red wax. The best way to refine the preparation after all the red wax is removed is a hand instrument. Now. This is what has happened historically. Most dental students use hander instruments too much because they're afraid of using the burr. They're afraid of nicking adjacent tooth. They're afraid of cutting away too much. They're afraid of getting a bad grade. So for a whole number of reasons, dental students use handpiece hand instruments too much. I'm talking about hatchets, hatchets, chisels, Ben angled chisels, gingival margin trimmers, etcetera. Now, once people graduate from dental school, they don't use hand instruments at all. So this is the way it should be. You should not remove I'm sorry. You should not use a hand instrument. To remove gross amounts of two structure because you're putting too much force you for a whole number of reasons. Plus the noise it makes drives patient crazy. However, when your prep is almost done and you simply need to remove that little lip of unsupported enamel, hand instruments are wonderful and they're very safe in terms of not nicking adjacent tooth. First of all, how often is the adjacent tooth next? I'm sorry, nicked next. How often is he? Jason Tooth Next in, in real life dentistry. And the answer is. A lot. But it's the patient's fault, right? The patient moved the patient unexpectedly. Did that? Yeah, I wish. All right. All right. So good hands Hand instrumentation is very important, but don't use it to remove gross amounts of two structure. First of all, it would take you like a half hour to to extend the margin a little bit more, buckle a little bit more lingual, use a hand instrument. It works really, really well. All right. In fact, one of the most valuable instruments that I use isn't even a hand instrument for operative dentistry. It's a thin sickle scaler because a thin sickle scaler does a really good job of removing any lip of unsupported enamel on the gingival. You could also use it with a little bit of practice on the buckle and lingual. Right. But this is me with a thin sickle scaler simply going below the prep and almost like scaling using the same techniques as you would for scaling calculus. You bring it up and you remove that unsupported enamel. So from a textbook, if you do a simple mordo prep that enamel right there, is that supported or not? No, it's not supported. So you need to go in there and make it more like this. Now, this isn't great because it's 90 degrees, but you don't want to flare or bevel the gingival margin too much because you might actually end up with a margin that's on past the edge, past the edge and onto root surface. If the margin stays. Which is a better margin, an enamel margin or a root surface margin. I can guarantee that if I could place all my margins on enamel and I'm talking about composite and even for indirect restorations like ceramic inlays and on lines. But if I could place all my margins on enamel, I think that restoration is going to has a good shot of lasting forever, especially in old patients. So but if I had to end this, the surface margin on root surface. The success rate is significantly lower. The long term success rate of root surface margins is not great. Composite doesn't do well on root surface margins. Crowns don't do all that well on root surface margins, but on enamel margins, they work great. All right so I plain away any unsupported enamel on the gingival margin, but I also plain away any unsupported enamel on the buckle and lingual. All right. So now I have a preparation. Whoops. This is a hatchet that I'm using. And again, I want you to be very familiar and very comfortable with hatchets and chisels. Right. Now, what about, first of all, what's the is another GV black term? What would GV Black's definition of resistance form be? I'm not talking about retention form. I'm talking about. Well, let's talk about both of them. Definition of retention form. Retention form is what you do to the preparation to prevent your restoration from falling out. And for crowns and things like that. It's almost the same. But we'll talk about that later. But for direct restorations, like amalgam or composite, it's what I do to the preparation to prevent the restoration from falling out. That is retention form. Now Is retention form important for composites? Another trick question. It's a trick question. The answer is yes, But it's very different than the old fashioned retention form, because if you bond restorations to place, you're actually creating micro mechanical retention. For an amalgam, you're creating macro mechanical retention. You need some convergence of walls, you need some certain things in your preparation that will prevent your amalgam from falling out for crowns and inlays and on layers. There are other things we'll talk about later. But for composite, especially small to medium sized composite, micro mechanical retention is enough. So if I ask GV Black, do you need retention form for composite? He would say, Of course you do. Okay. I say, Well, not really, because your definition of retention form is macro mechanical retention, but for composite, micro mechanical retention is enough. Okay? In most cases, if you have a little bit of macro mechanical retention, that's fine. But what about resistance form? The most important element of resistance form is a flat gingival floor. Think about your gingival floor gingival floor should be. In fact, my opinion must be perpendicular to where the forces are coming from because resistance form is defined as what you do to the preparation to prevent things from breaking under masturbatory forces, under chewing. And remember, it's not just tooth to tooth, it's tooth to food to tooth. When a patient bites down really hard on an olive pit, what they're really doing is taking all of the force from all of the muscles of mastication and concentrating them on one tooth. Okay. Very different to just clenching all your teeth together because then you're spreading out all of the forces. So concentrated forces really require that you have a flat gingival floor that will resist those forces. Now, look at my hands here. Okay. If the floor is like this and the forces are coming from here, this amalgam is not going to break. I'm sorry. This composite is not going to break. Or if it were an amalgam. But what if the floor is like this? When you put forces like that, there's a lot of strain up in here and things will break. Okay, so having a flat gingival floor for amalgam is important. In fact, for ceramic inlays is important, but also for for composite. So let's compare these two preps. This is a conventional prep with a flat gingival floor. This is a minimally invasive prep with a not flat gingival floor because remember, this is where the forces are coming from. What's going to happen to this prep? I'm sorry, this restoration, even if the restoration is done well, except for that floor, what's going to happen to this? It's going to break. It might break there. Sometimes it'll break in here, but this is less likely to break. So is macro mechanical resistance form important for an Mot composite? Yes. Is it important in terms of. Well, never mind. I'm sorry. Is macro mechanical retention form important? And the answer is macro. No. Micro. Yes. Okay. Real important statement here. Okay. Let's take a five minute break. Actually, before we do the five minute break, let me try for the first time the attendance thing. Okay. Brand new set up here. And I have no idea how to turn the lights. How you go do it the old fashioned way. Okay. Bear with me for a second. Okay, here we go. Do it. Black would say. What the world are you doing? This is so cool. Okay, let's take five minutes. So it 9:04, We'll start up again. What's up? For a second. Thank you. Okay, let's. Let's get back to work. All right. I've already answered this question. Do you need macro mechanical attention? The answer is no. Do you need micro mechanical attention? The answer is yes. So just as a review, when you are dealing with composite as opposed to amalgam and ceramic restorations, the depth requirement is only really determined by removing two things Actually three carries maybe a previously done restoration and weakened unsupported tooth structure. You need to remove that. So that's probably the the major and whether it looks like a wide prep or deep prep, etcetera, that's purely based on the lesion and location of the lesion and the size of the lesion. All right. And same thing with outline form, right? The best surface margin for a for composite is anything not 90 degrees. So it doesn't have to be a very acute bevel. But but it should be not 90 degrees and it certainly should not be the opposite. It shouldn't be a lip of unsupported enamel. Probably the most important requirement of any surface margin for composite is don't leave a lip of unsupported enamel. And this is especially important at the Gingival margin, also important in the buckle and lingual margins and the occlusal margin. You know, you already have a bevel simply doing a minimally invasive 330 preparation. Now what about excavation? And I promised earlier I would tell you talk a little bit about the difference between affected and infected dentin. When you find the lesion, what are you actually finding? Are you finding caries? Yes or no? No. Caries is not an entity carries as a disease. Okay. And a disease that does what it is destructive of of tissue. Right. So when when the carious process or the disease known as caries affects enamel, it dissolves it away. Okay. So what is curiously affected enamel look like? And the answer is it looks like nothing because it's all dissolved away. But in Denton there are two major actually three major components of dentin. What are they? Hydroxyapatite crystals, collagen and water. Okay. That's the three major components of dentin. So when caries affects dentin, what happens in the answer is the first thing that happens is the hydroxyapatite crystals get dissolved away. When hydroxyapatite crystals get dissolved away, it's softer and it's a little bit more radial. Lucent on a radiograph. Okay. But if I allow this caries to continue, now, all of a sudden the collagen starts getting denatured and and maybe even dissolved away. All right. So clinically, what happens with enamel is that it's gone. What happens with dentin is it goes through different stages of hardness or softness. So a healthy, normal dentin is pretty hard because it's fully mineralized and it has lots of normal collagen in the right amount of water. Okay. In I'm sorry, affected dentin affected dentin is dentin. That has diminished lysed the hydroxyapatite crystals have been dissolved away, but the collagen is still healthy. Okay. And a question that will or debate that we'll talk about a little bit later is do you need to remove affected dentin? And again, it depends on a lot of different things that we'll talk about later. Now, what is infected? Dentin? Infected dentin is when there are no more crystals, the hydroxyapatite crystals are gone and the collagen is either dissolved or denatured. Clinically, it's mushy. Okay, so let's go through those three things to an explore or an excavator, normal and even sclerotic, and I'll talk about that later too. But when you're excavating normal, healthy dentin or sclerotic dentin is pretty hard and it's very difficult to remove with an excavator. When you poke it with an explorer, it doesn't stick. Okay. It's pretty hard, right? And again, you should all have enough experience to know what I'm talking about. DMD students tomorrow won't have any idea what I'm talking about. That's okay. DMD ones. All right. So DMD two is a pretty smart because they had a nice course last year. All right. That's why you're here because DMD ones have already had my lectures on class two composites. Right now, infected dentin clearly needs to be removed because it's very soft and very mushy and it really can't support your restoration. It doesn't bond well if you're using bonding agents, etcetera. So almost everybody will agree that soft, mushy dentin, parentheses, infected dentin should be removed. And again, when we're talking about pulp capping and, you know, protection of the pulp, etcetera, I'll go into much more detail on affected infected dentin, but that's what you're excavating to make it really simple in the SSC. What are you excavating? Red wax. All right. So you will, if in a final exam, like a summative exam that you'll take in the spring, if you leave red wax, you've left infected dentin. Okay. So always in the SSC, always remove red wax. Okay. Uh, not good. All right. So at this point, I'm not going to go into detail here because you're not going to do it in the SSC. But once the preparation is done on a class two, you would put a matrix on a class one. Obviously, you don't need a matrix, right? So now you're going to use a bonding agent that you have that you're going to use. And there are many, many different types of bonding agents. There are many, many categories or generations of bonding agents. And again, we'll go into lots of detail later, but I'm going to skip over that part simply because you're not going to be doing it this afternoon. I just want to give you the basic information that you need for today's exercises. So after the bonding agent is is a key word here properly used? And again, one of the biggest problems with failed composite restorations is not as etching too long or not evaporating the solvent or or you're not applying the primer properly according to manufacturer's instructions. So you need very, very carefully to follow the instructions for placing the bonding agent system and essentially, well, let me just quickly review it. If you are to explain to a patient, let's say you have a very inquisitive patient and the patient says, what was that stuff you did before you started filling the tooth? I said, Well, I applied an adhesive. I said, Well, I know what adhesive does, but how does it work? And you're saying to yourself, Oh, gee, all right. So but it's simple. If I were explaining it to a lay person or how I'm going to explain bonding agents to first year students in the next couple of weeks, I would say this. The first thing you need to do, although it's not always first, s