NORMAL ANATOMY OF THE PERIODONTUM.pdf

So just letting you know from the information as we talked in the beginning, there is a functional system of tissues that surrounds the teeth and attaches them to the bone and the four structures that make up the paradigm we talked about already in our first lectures gingiva, periodontal ligament, t...

So just letting you know from the information as we talked in the beginning, there is a functional system of tissues that surrounds the teeth and attaches them to the bone and the four structures that make up the paradigm we talked about already in our first lectures gingiva, periodontal ligament, the PDL cement, human alveolar bone. So we're going to break down all those four structures. And how does it work? It's like the cement is connected with the alveolar bone through the PDL and the gingiva covers, then everything and attaches on the coronal part of the tooth. That's how the whole system works. Okay, so let's start with the gingiva. So first of all, we need to understand, like the microscopic anatomy, the clinical features, what you're going to see for your patients. You're having the oral mucosa mucous membrane, as you may see that being written as well, which is continuous with the skin of the lips and the mucosa of the soft palate and the firing. So that's how the oral cavity starts. And this oral has three main types, consists of three types the muscular mucosa, which you see in the heart palate and gingiva, specialized mucosa like the torso of the tongue, the dorsum of the tongue, and finally the lining mucosa, which is like non corona. And we're going to go even over those things in a little bit. So some things I think we mentioned those briefly in our first lectures, but just bringing it up. So what the arrows are pointing here is are actually the free gingival margin. So that's the margin we call it free because it's not like attached on the tooth. It's loosely just resting over there on upper and on maxillary and mandibular teeth as we see over here. The free gingival free gingival margin is exactly the same thing. Then afterwards, right epically to that we have the attached gingiva and that's for both maxillary and mandibular arch as well. Then after that we're having the masticating mucosa. We've got it here, the alveolar mucosa. The alveolar mucosa, I'm sorry. And those are being demarcated by the mucosa gingival junction. I have it here. Yeah. So as a content, we start from the top with a free gingival margin. There's a small groove here. We're going to talk about that later. Then we start with the attached gingiva which is attached over there. We're going to talk about that as well. We have the connection, the nuchal gingival junction, going back to the new cause and the alveolar mucosa. The same thing happens exactly with the upper teeth. Okay. The same thing happens on the lingual of the mandibular teeth. So you're having the free gingival margin the same way you want you know it, and the alveolar mucosa. And those two are being separated and demarcated by the mucosa gingival junction. When you're seeing a patient clinically, you need to identify those structures. You will see when you start doing period charts and evaluations, you're measuring the probing and all those things. You're also measuring how much mass gathering because you have and the presence and absence may or may not be associated with sort of disease or variation. It may indicate the need for treatment or usually like a surgical approach or something. So it's important to understand those things. And the same thing you. Need to do also on the lingual side, which is not always easy. Okay. It's not always easy to find that, but with the exposure and gradually you will understand how those two structures look different. And there are cases that on the lingual area, for example, mandibular interiors, you may have those mucous gingival problems where you don't have enough hair, nice tissue like like attached gingiva. The reason there could be a trauma, there could be ortho, there could be tongue piercing, there could be tons of things that can contribute to that. And these can cause and compromise mandibular teeth because issues with the sensitivity with recessions and things to maintain the teeth. So this is something important to keep in mind. On the other hand, on the maxillary teeth in the pilot, there is no mucous gingival junction. Why? Because it's all nice, it's all masculine. So there's nothing over there. Okay. And that's why we have plenty of tissue when we're doing soft tissue grafts. You're going to learn later on. That's a great source of taking this tissue and enhancing it where it's needed. So obviously, over here we're having the incisive papilla in the center between the centers and the guy and the pilot guy over there that you can see. You can have different variations and shapes of the pilots with higher, medium or shallow vault, depending on the case. But that's something also is a variation over there. There's a question. Nope. You feel free to share a question. It's fine. We said it's a safe environment here. And finally, you can have these. Or both if you see that clinically, they're totally healthy. Okay. These are different variations of normal. And we need to be able to realize and recognize that because every patient is different, every patient will have different clinical features based on also their genetic features. ET cetera. So what's the difference? Like, for example, here you see more melanin pigmentation on the lower one. That's how things are being seen clinically. And we need to be able to recognize in different populations and patient population, especially here, we have like a broad, diverse population to understand if something is normal, variation of normal, what is healthy and what is not. So this is totally like normal representation with the melanin pigmentation being exposed, we're going to learn that it's being synthesized in the melanocytes, in the basal layer of the epithelium it's being produced, and that's how we see it clinically. So let's go like a little bit further down with the gingiva. So we talked about it very briefly, but we're going to have the main four categories of the gingiva, which is the free we talked about it, the cellular, which consists of gingiva in the sulcus, the inter dental and the attached, and regarding free gingiva in a healthy patient. This the color is like coral pink. We have like a dull surface. It's pretty much firm, which you can even see that and feel it with your instruments, your bio probe and includes the entire dental gingiva and the papilla. So over here, as you see, when the tooth is completely erupted and I have those two things. So the free gingival margin is on the top. Sometimes you can see that small groove which we call the free gingival groove before I go that when the tooth is fully erupted, the free gingival margin is usually located about 1 to 2mm, 1.5 to 2mm above the CG, because we're going to learn that the attachment is right there at the edge. So in a normal, healthy, fully erupted tooth, because obviously you can have a healthy periodontal you with delayed eruption, right? Passive eruption. So the association there is completely different but fully erupted tooth normal healthy you. The free gingival margin is always a cap like up to two millimeters or so above the CG. We will see that in the molars where the space is a little bit wider. It can range like 1 to 3mm, but that's something important to keep in mind because when we are measuring around our teeth, the teeth to see if we're having deeper pockets or so we need to understand where these free gingival margin is in relationship to the CG. Otherwise, if you don't have this association, you do not know what you're probing. Is it on the enamel surface, on the root surface? And those two are completely different with diagnosis. The moment you start feeling with your instruments, the root surface, that means you have start your starting losing attachment. And this could indicate beginning of disease like history of disease or anything like that. So it's important to understand those relationships. Okay. So going back now to the free gingival groove, is that like small indentation? You may or may not see that in all the patients and presents and options does not mean that this patient has disease or vice versa. It's usually at the most outside, if I can say so on the label surface, on the most apical border of the junctional epithelium. And it doesn't necessarily mean that it coincides with your sulcus. So obviously this is has to be seen like histologically, which we're not doing for every single patient, but relationship wise, that's what you need to keep in mind. And this part between these free gingival margin in that fragile groove is the free gingiva that we are talking about. Clear. Okay. Um, regarding the circus, as we said over here, that's a shallow groove that's between the gingival margin and the tooth. You can use a probe. We're going to learn about that later on, how you can get in the gingiva and go over there. So again, in a normal, healthy periodontal, there is not like an actual pocket or opening. It's like this free gingiva is just resting there on the tooth and you're just able to separate it without causing any discomfort to the patient. Obviously, if you poke your instrument deeper, that's when you're going to the connective tissue and the patient doesn't like that. So we don't do that, right? So that's how we have this small crevice that it's like kind of in close contact with the enamel surface and you can easily penetrated with your instrument and go inside and see how deep this is going. Okay. And anything else I wanted to mention here? Nope. And the we said about the groove that the presence and absence does not mean that the production is healthy or not, because sometimes you may not be able to see that in some patients. Now regarding the dental papilla, this is the tissue that fills the entire dental spaces. The gingiva, whether it's above the alveolar crest, more commonly in the interiors, it has more like a scalloped architecture in the posterior is more like a flat architecture. But it pretty much this depends on the size, shape of the teeth in their contact. Okay. You can have like anterior teeth which are very square, maybe not having any contacts and the architecture, it's still kind of flatter compared to like a very pronounced scalloped architecture. So that's something to keep in mind as well. So as we said here, that's how the papilla is being formed. Now, the shape of the papilla, we said it depends on how the teeth are being in contact. And you see that in the anterior teeth, which more it's more like a pyramid compared to the posterior, which is more like a flatter architecture over there. And what you actually form here between the posterior teeth, you see like this small valley where the three arrows are pointing. This is like the cold space. C o. L Okay. And I have a histologic picture over there, so that's a very thin non characterized epithelium over there. Does this work? It does. So that's a very thin non epithelium over there. That's right in between. So one tooth is here and the other tooth is right in front. Okay. You see that in cross-section and usually that's where disease can start. This decided not to work. That's where disease can start because as we said, it's thin. Non canonized bacteria can easily colonize their patients, may not clean their adequately. That's why we reinforce with flossing and all these other things and that's where inflammatory cells may start appearing and disease may start into proximally. It does. I'm not saying that all periodontal disease starts there, but due to their histologic and morphologic characteristics, it's very frequently seen that that burden issues and inflammation start in the inter dental spaces. Clear. Okay. And finally, we have the attached gingiva, which is right below this free gingival groove. It's too early to dance. Too early to dance for me. I don't know. Maybe for you it's not. So we're having the attached gingiva, which again, in health is color pink. It may have this stippled surface that you can see like more stippling, which is pretty much the connective tissue fibers that are attaching over there. Firm texture. It's firmly attached. It's not mobile. And it's you see here, that's the free gingival margin, the groove, where you have also pretty much the free gingiva. This is all the attached gingiva. This is the Muga gingival Junction and this is the alveolar mucosa. You can see that also in the color how it works. Sometimes it may not be easy to differentiate between these attach in the mucosa, especially in presence of inflammation when this tissue is very red. And what differentiates those two tissue? The mobility. Okay. This tissue is mobile. It's moving above the alveolar bone. Right. This one is not. So having said that, we're having this stippling, as we said. So the presence of stippling, it's like an orange peel that's I've been told about this thing like since my first year of dental school. So I continue that knowledge. That's how it looks. So presence or absence of stippling does not indicate disease. Okay? You may have a super healthy periodontal, super healthy tissues and they may not show stippling and that's totally fine. I can hear you. So having said that, this is something that you may mark down, but as we said, it doesn't mean that if the patient doesn't have that, it automatically means absence of the presence of disease. It's true that in a disease periodontitis the tissues look like smoother and more, you know, glossier and more edema. Yes, that's right. But you can have a totally healthy you. The stippling may not be that pronounced. So regarding the free the attached gingiva, it's wider in the incisors and molars areas, a little bit narrower in the premolar region sometimes when canines as well, depending on the anatomy. But whatever you're seeing clinically here, that's what's happening. Sub clinically we said this is all the free gingival on that side. That's almost the groove that you may not see that corresponding to the apical portion of the junctional epithelium. The sulcus usually and slightly above the junctional epithelium. That's why I'm saying do not coincide the groove with how deep your psychosis right? Junctional epithelium takes some space about a millimeter or so. We're going to learn about that later on. So this inside is the cellular epithelium that kind of rests and it's in close contact with the tooth, and that's where you can put your probe. You're having your junctional epithelium, connective tissue PDL here bone and then assuming this is the mucous gingival junction, the alveolar mucosa. Make sense how this look clinically. Okay, so I'm finishing up with the alveolar mucosa. We're having the red color, as we said, smooth surface. It's mobile. It's loosely bound to the bone, and it's demarcated between the mascot oral mucosa or the attached gingiva with the mucus gingival junction. Why is it important to know that, as I said in the beginning, when you're doing your dental evaluation, you're measuring pockets, attachment loss and among all the things that you're measuring is how much nice tissue you have around the teeth. And there can be teeth that have no attachment loss, like no recession or anything, but pretty much minimal muscular mucosa that can be that can have like recession. So having lost this mascot or mucosa and ending up to the mucous gingival junction, there can be teeth that can have deep pockets on the facial surface ending to the mucosa gingival junction. So all those things indicate nuchal gingival deformities that you may need to address with a specific treatment depending on the patient's needs at each case scenario. Okay, it's early for dancing, but not early for questions. So let's see. Very straightforward. So the gingiva consists of which type of mucosa? Just tell me the number. Mm. Be right. Okay. Melanin pigment is synthesized. In which cell? Hey. And the mucus gingival junction is absent from which of the following surfaces. Be no C Right. Okay. Let me put the letter. It's going to be on recorded, but you can take a picture now that it's all completed. We got it. Excellent. So moving to a more microscopic anatomy that we're going to go into depth regarding the epithelium. Uh, let's try to make it as simple as possible. So the outside part. So that's what's face is the mouth, right? The cheeks, the lips, etcetera. This is the oral epithelium. That's the free gingival margin. That's the tooth over here. Okay. So that's the free gingival margin. We talked about the small groove that you see here microscopically. We talked about the micro gingival junction that you see here in the alveolar mucosa. So it's going to go microscopically now. So the free gingival groove, that's the sulcus, the circular area that attaches on the tooth and that's part is the cellular epithelium. And then at the lowest part where literally in a healthy periodontal, that's where your periodontal probe will finish. That's where your junctional epithelium starts. This is all magnified. Okay, This is not so long. It's pretty much like maximum millimeter or so over there in the health. So the junctional epithelium attaches on that lower part of the enamel surface and then you have below the connective tissue. Here's the crest of the bone and here is like the PDL and that's the whole of the bone. Let's see that here in a histologic slide. So we have the tooth over here. Okay. It's the tooth that's the enamel, right? That's the oral epithelium. And that's like from the mascot or mucosa over here, as we see these somewhere here, don't have the marking is the alveolar mucosa free gingival margin right over here. You see over that. That's the oral cellular epithelium. Then you start having the junctional epithelium. So there's always a small separation between the oral epithelium and the tooth. You see that with a white space, a line because there's no attachment. That's where you start having your junctional epithelium that attaches directly to the attachment to the enamel surface of the tooth you're having here, your C.J. That's the same thing here, the s.j, which is what the cement enamel junction where the cement and enamel connect connective tissue over here, connective tissue fibers. We're going to learn about that alveolar bone here, crest of the bone here and PDL over there. And route here. Clear. Clear. Yes. Move the cheeseball line. Buccal gingival junction is somewhere low. So, yeah, it was good to. As correct to assume that is in the same level the bone. That's a very good question, but no similar to the groove. We do not assume that the Gingival junction is right at the crest of the bone. Okay. There are times that can be above the crest of the bone, below the crest of the bone. You may have a bone deletions underneath, so you can't assume, oh, where my junction is, where the crest of the bone is. It's a very good question. Okay. You see that outside. And sometimes you can be surprised. You're raising a flap there and you're saying, oh, that's maybe what it is. And you're seeing the crest of the bone to be way more currently. And the nuchal gingival junction. A typical example can be in patients with altered passive eruption, which means that the teeth have another update fully. There's a lot of gingiva, like they call it like the gummy smile. Or so you have a lot of bone way above the gingival junction there. And then there's a different approach on how you treat that. Okay, very nice. So let me move on. Working on my steps. So we talked about those three. And now let's take this small piece and see how this works with the oral cellular epithelium over there. So we see that. Let me go here. Yep. And this is the connective tissue. So we want to see how this connective tissue and the oral epithelium connects. So we take like this small piece and we magnify that over there. So that's the oral epithelium and that's the connective tissue. And you see like those projections over there that we call it like the connective tissue. Papilla as we see those projections and respectively the part of the oral epithelium that gets in. Is we call it that the Red Pigs, as you see over here, the ones that are getting in, that's how they actually connect. What I need you to keep in mind is that there are no red pegs or connective tissue papilla between the junctional epithelium and the connective tissue Over here. You can see it over there. Very lightly on the oral epithelium is going to be, but in the junctional epithelium there is none of those. Okay, So we talked about that. But just to keep in mind what forms the base of the sulcus, we said it's the top of the junctional epithelium. Okay. And where is the most apical cell of the junctional epithelium in a healthy periodontal? At the siege. That's anatomically how I need you to keep that in mind. Okay. And we're going to go over that and we're going to repeat it. So it's going to stick there. I promise. So this is a picture of the connective tissue only. And we ripped off the epithelium to see how those projections work. And you see how this is with the oral epithelium side, how they project with those red bags in the connective tissue papilla a little bit milder on the oral cellular epithelium, but there is none on the junctional epithelium. Okay. What we talked in the beginning. And going more into details about how those like epithelium and connective tissue works. So this is the top of the epithelium and that's how the connective tissue works. So pretty much you're having the basement membrane that's separated, that separates like the basal layer and the underlying connective tissue. And there are two parts of these basal basement membrane, the lamina lucida and lamina denser. So we call it elucidates like it shows like more clear in the microscope. That's why we call it this way. While lamina denser shows up denser in the microscope, then SA has more like type for collagen and the lamina Lucidum is like laminin and other glycoproteins and the basement membrane is attached to the basal cells with connective tissue connecting fibers synthesized by fibroblasts. And we see here that these are connected with hemi desmos forms. Okay. Between the connective tissue here, like those two, the basement membrane, hemi desmos and the epithelial cells. So remember, because we're going to talk about the desmos forms in a little bit. The hemi desmos forms are between the epithelial cells, the last epithelial cell and the basement membrane with the connective tissue while the desmos forms. We're going to check. We're going to see in a couple of slides. It's between the epithelial cells itself. Okay, just remember those differences. So regarding the oral epithelial epithelium, we do know that it's currently stratified Squamous epithelium extends from the Mucus Junction, as we said, to the Gingival margin microscopically. It's a great barrier against mechanical injury and other threats that need to go to the periodontal between the cells. We're having the desmos forms, not the hemi desmos semi desmos forms is the connective tissue. And we have usually those four cell layers and those layers starting from the inside. So that's connective tissue. So we have the basal layer as we see over here, the precursor layer, the granular and finally the nice. And I have the Latin words as well for your reference. And it can be either ortho or Parker. Nice. The differences with the author journeys, as you see in this slide, is that it does not contain any cell nuclei in the cell in the keratin layer, the top layer compared to the Parker Nice, where you can see some cell nuclei in the keratin layer. So that's the difference. So you can have both in the oral cavity over here, the epithelium, the ortho is not that frequent frequent the author nice, but you can have both types of epithelium in the oral cavity. So going layer per layer what we need to keep in mind in case you see also any histologic slide to understand that you're having those cylindrical or cells in contact with a basement membrane, as we said with the hemi desmos forms over there. The last layer of that, these basal cells undergo the mitotic division until they're getting mature and they go on the top layer. That's where the epithelium renewal take place. You need to know the renewal time, how long it takes for those cells to get renewed and have a renewed epithelium and have a full complement of organelles. They are having like those tonal filaments and everything. And we talked about this, the connection with the lamina propria. So with the connective tissue underneath is through hemi desmos forms the membrane. The layer right above this first layer is the pre layer where this is the widest cell layer. You have the most like cytoplasmic processes taking place again, thus junctions and the connections between the cells are mainly with desmos homes. There's a little bit diminished activity, but that's like the biggest layer that you can see in a histologic slide. Then we have the granular layer, which is like a thinner layer. It goes thinner and thinner. This is like the precursor of the keratin as you have with Hyaline over there. You have a lot of ton of fibrils and the cells are getting flatter and flatter until they end up with a nice layer which is the outermost layer over here. As you see, they can have the dense, the cells contain densely packed on filaments. We can still some see some intercellular junctions being present. We're having cells that are filled with keratin and some depending on the membrane. As we said, if it's ortho confused or recognized, you can have cell nuclei in this. Must membrane and knowing the difference between those two and usually the author Kearney's epithelium is better in terms of protection against mechanical injury. So that's pretty much the cycle that we said. We start here with the connective tissue, then basement membrane connecting with a hemi desmos forms as we said, and then we move on. We see this is the biggest, the stratum. Spinoza like that, widest epithelium like layer. Then gradually the cell flattens out until we go back to the top, the keratin layer that you have on the top clear. Okay. And just type of connections you can have. You know, apart from the Desmos homes that we've been talking about, you can have a gap junction or tight connection. Keeping that in mind as well of how cells can connect with each other. So what kind of cells do we have with the oral epithelium? Obviously the majority of the population is keratin producing cells, but we have some other cells as well, like the melanocytes, the Langerhans Merkel cells and inflammatory cells, which we call clear cells, because histologically if you see them in the microscope, there is a zone around their nuclei that appears lighter compared to the ones with the keratin. So that's why they call them clear cells and. Going to more details of what each cell does. As we said, the melanocytes, they are the ones that are responsible to synthesize the melanin and the pigmentation. They transfer it over there. It's like a then 3D cell on that side, the Langerhans cells. Again, it's like a 3D cell plays a role with the defense mechanism, with the oral mucosa, the T cell lymphocytes and response to those. The Merkel cells are more responsible for sensory function, sensory information. And finally, we have the inflammatory cells that play a role in the immunological response, and we're going to learn about those in the host response lecture. So don't worry about that yet. You're going to worry about it in some lectures. So having said that, seeing all the cells here, how they're being represented, the treating cells, you see again, the melanocytes dendritic, the Langerhans cells and everything, and how they are being spread in the epithelium. Something that we need to keep in mind is that everybody has the same number of melanocytes. Okay? It's not that somebody has more or less, it's all about the activity and that's independent of the race. So we all have the same number of melanocytes. So the level of pigmentation is is not a function like of the numbers, but the activity of these cells. So my cells are totally dead during the winter. They're doing nothing. And even if I try to wake them up, they're just sleeping over there, they hibernate. So it's all about that, the exposure and how they're being exposed in the melanin. And that's why you see different variations of melanin pigmentation in different patients. Okay. Going now, we talked about this, gingiva, how it works. Let's go to the cellular epithelium which is stratified, squamous, non canonized or recognized, depending on how the area looks over there. It continues with the oral epithelium and goes to the cellular area and apical it goes and ends to the junctional epithelium as we showed in previous slides. And again, this is a first line again of mechanism in proximity to the tooth in terms of bacteria challenge and everything you will see, we will see later on, and especially in the host response lecture that we have the first line of cells defense over there, that cells are present and if bacteria over populate the area, create these inflammatory response so the body from its nature tries to fight those and still maintain the balance in order to maintain health and and finally, we're having the junctional epithelium which is stratified non camerounais. It's the helium, as we said, that attaches on the two surface, the enamel surface right below that, the most apical portion of the junctional epithelium, the most apical cell is usually at the C.J., the cement enamel junction. And right below that, that's where the connective tissue starts. Okay. Similar to that, we're having infiltration of with inflammatory cells, especially lymphocytes and plasma cells. Depending on the stage of inflammation, we are it's more permeable than the cellular epithelium. That's why we want to keep things before we reach that junctional epithelium. And as we said, the one side is attached to the tooth and the other one is more to the connective tissue. So keeping that in mind how the epithelial works, we're having the outside membrane with the oral epithelium trying to resist mechanical trauma, bacteria and everything. We have the sulcus epithelium which tries, which tries to fight. Then we have the junctional epithelium. Again, we have an inflammatory response, but that's when inflammation starts. It can become more pathologic for the patient, creating the periodontal issues that we're going to learn later on and seeing over here. As we said, that's the most typical cell of that Junctional epithelium. That's right. At the C.J. Yeah, it can vary sometimes a little bit. We're not going to argue if it's so many micrometers above or below that, but usually that's what we say. It's more of the C.J. That's where the connective tissue starts. And just giving you a heads up. We're going to mention that in future lectures too, that this part of junctional epithelium that attaches on the tooth and the underneath connective tissue that still attaches on the tooth on that root surface, this portion, which is barely two millimeters or so, that's what we call we used to call the biologic width. Now we call it the super crystal attachment of the tooth. So maybe in ten years we're going to find a fancier name. You never know. So and that's pretty much how everything that we talked so far with the oral epithelium, the oral cellular epithelium starting here. Remember with the connection here, you're having those red pegs on the oral epithelium a little bit less, but still present on the oral cellular epithelium, but none on the junctional epithelium. This is the first line trying to resist mechanical trauma and some inflammatory response. You can see here the same on the oral cellular epithelium. You can see some inflammatory response as a defense which is more resistant to those bacterial infiltrate junctional epithelium. Again, because all this is connective tissue. All these can have cell infiltration, right? It can still have a line of defense, but it's more permeable than the other two. That's right. At the C.J. over here, you're seeing sometimes it may overlap a little bit and that's where the connective tissue. Starts and right below we have the ball. Clear. Yeah. Okay. Let's see. So. I care to island granules are located in which of the following epithelial layers. I close with B? Okay. That was such a great translation. I'm sorry. Of the various epithelia that make up the gingiva epithelium, which one does not care. Nice. What do you think? Oh, you know, go three slides before. See. And the most permeable section of the gingival epithelium is. We said between the oral and the sulfur and the junctional. I think it's 3 or 4 slides previously. What should I pick here? Mm. B or C? What do we say? See. See. And see. Remember, this is the one that's not the most permeable. The other ones are the first line of defense as much as possible before you enter there. Okay. Very nice. So let's move a little bit to the connective tissue and see what's happening underneath. So obviously, that's the most predominant tissue of the gingiva. We're having collagen fibers, fibroblasts, other different cells, you know, inflammatory cells, ground substance. And the lamina properties of the connective tissue is responsible for the presence or absence of coordination of the lining epithelium. So depending on the different structures that you're seeing in the oral cavity, you have different genetic and biologic features of the underlying connective tissues. Why did they do? Mm. Ah, it appeared we didn't want to talk about the fibroblast, so. So, yeah, there are tricky cells. I know, I know. The fibroblast is the most predominant, you know, connective tissue cell. It's like more than 67 7% of the population. It's produced like the connective tissue, collagen and elastin, like all those tissues that we see over here. And it can secrete MMP the metal opportunities. I know these are like this all sounds Greek to you. We're going to learn more about that in a few lectures. So pretty much this is a very important cell and we're going to learn how the fibroblasts play a significant role both in health, but disease as well. Okay. Because of the balance, you may have different role of this cell. Regarding the mast cells we have, they produce specific components of the matrix. These are active like substances and can affect the functions. They've been like more research on those in these type of cells recently. They're trying to connect with several inflammatory diseases. So you may see that coming up in more recent studies. And especially like lab studies, people are doing macrophages. We're going to learn also in the host response lecture. That's a key cell, especially with inflammation and everything. It has like synthetic functions, phagocytic functions. You have plenty of those in the inflamed tissues and they're derived from the blood monocytes. They migrate into the tissue. So we're going to learn again more about that. But it's a key cell for inflammation and host response. And we're going to keep in mind about this information. And we have now a bunch of other inflammatory cells in the connective tissue like the leukocytes, the lymphocytes, plasma cells and the presence actually know the number of those depends on what state you are in terms of health, like mild inflammation, severe inflammation, present gingivitis. Again, we're going to learn all this information. Just bring it up that we're going to talk about those cells in the future as well. So in the connective tissue, as we said, we have a bunch of gingival fibers that produce mainly collagen type one. And we have also the oxidant fibers, elastic and reticulum. So different types of those. And regarding collagen fibers, I have a scheme here because me as a person, it's easier to see pictures and understand what's going on. It doesn't mean that you have to do the same thing, but that's why I put the pictures on apart from the text. So understanding how those fibers run around the connective tissue, you can understand how what those fibers are connecting. Usually to give you a hint, the name we give to the fibers because we don't have so much fantasy. It's like the two tissues they connect. Like if you see dental gingival, it's the tooth and the gingival dental, the tooth and the periosteum. So it's not very challenging to think about it. Again, I'm telling you how my brain tries to work in order to remember those things, but you need to know those primary collagen fibers. I'm not going to read all the text. I have it here for you for your reference, but you need to know where they are, how they're run, if what they connect, what connects, you know, to the tissue above the bone. So you will definitely have questions about those. So just letting you know and for your reference without being lost in the textbook and all the information. I have the secondary groups, again, very briefly to know I'm not going to read those slides. That's for your reference for easier starting later on. Any questions so far? Do you want to take a break now? Do you want to move on? Oh, what a break. Okay. All right. I'll see you. Let me see. What time is it? Okay. In eight minutes. Eight is my favorite number. Thank you. This. You have help. I don't have to. Just do that. All right, so let's move with the rest. Restructures the PDL. So we talked about the ligament, and I will be calling it PDL. It's exactly the same thing just for your information. So this has kind of and I know it's very tight to see that kind of an hourglass shape. And what do I mean with that? It's like a little bit wider on the crest, narrower over here in the middle and then wider on the bottom. But it's so, so fine. That's different. So usually, you know, the with our eyes, we can see that it's mainly microscopically that you can see that. So the narrowest area is usually in the mid root area. The width ranges from 0.2 to 0.4, but we usually say around 0.25 width. It's very vascular cellular and joins the cement and the bone. It's part of the attachment apparatus, as we said, absorbs and distributes forces on teeth to the alveolar bone, the width height, the quality of these plays obviously a role in the mobility if you're having it too, that has excessive forces, the first thing you're going to see clinically is that the tooth may be moving and radiographic. You will see that space being very, very wide and that's what you would describe in your findings widening of the PDL. It plays a crucial role in the regeneration and provides neuro sensory protection. There can be times that teeth may be unkillable, so you do not see that PDL space. I mean, it could still be there, but obviously if the tooth for some reason is closed, you don't see the PDL. I wish you don't have to extract those teeth. I had to do some of those. I suffered because they literally cannot move in. They can come out and you know, you're trying to maintain the bone to keep it for whatever treatment you may be doing, and then you end up just sectioning because there's no way the tooth will come out. So that's how it looks. Again, we have plenty fibers here and I need you to differentiate between the gingival fibers and the PDL fibers. You will be asked for both. So just make sure you differentiate those. The principal fibers contain and produce a collagen type one. We're having the crest fibers, the horizontal oblique fibers which are here. These are the widest like the the more numerous that you can find in the PDL and the apical fibers in the bottom. And obviously, if you're having multi rooted teeth, you're having some inter fibers right here between the roots. Okay. So just keep in mind those five categories. The most of them are those oblique fibers. As you can see in this picture. And obviously you can have some others oxidant and elastic fibers in smaller numbers. Regarding the ground substance, it's more like gel. Like matrix. The water content is about 70%. You have different glycoproteins, proto glycans, etcetera, that you can see over here information about the PDL you're having. It's like a very neurovascular tissue and you're having, you know, blood vessels and lymphatic vessels and nerves in the loose connective tissue. You can have different epithelial cells, the fibroblasts, all those cells that we can see here, osteoclasts osteoblasts. And like you see how much role you can have in the regeneration. And that's a key I'm giving you like some heads up for later on. Like when we're talking in theory about regeneration, the only thing we care about mainly is periodontal ligament because we have we can have all those different cells and we can try to regenerate. And a lot of efforts with either materials and membranes and techniques. ET cetera is to be able to give adequate time because you need to know the renewal time of the cells, of the tissue, of the gingiva versus the bone versus the PDL, which is completely different. And that's why we use specific materials in order to give the PDL the adequate time to be able to renew and regenerate and hopefully regenerate the periodontal. We can't do it in every case scenario, obviously, but that's something that's presidents have been fighting all those years and still fighting for that to question. Yep. I just got a little sure the ground substance. Yep. Where do we find it. That's part of the PDL there. Yeah. It's so tiny. I know, I know. It's so tiny, but it's there. Okay, so. Something that you need to keep in mind for the PDL is about those Sharpies fibers. You may have heard about those that they are connecting between the bone and the crest. And the easiest thing I can say is like, as you see here, the diameter on the bone side is a little bit wider. And I want you to think they're coming like that's the bone and that's the route right there coming from the bone and the root like a mesh. And they connect like there. Okay, so the mesh is a little bit wider on the bone side. So that's pretty much you need to remember about those and their diameter and how it wears it and how they connect between the bone and the cement. Okay. Regarding the vascular supply of the PDL, we have in those different dental arteries and blood vessels, different anastomosis. So it's a pretty significant and vascular area. As we said, sometimes depending on the procedure we do, we may need to do like some anesthesia in the PDL. It's not the most comfortable thing ever, but some patients may get, you know, and I can have it here. Some patients may get may get like sensory from there. So you may need to do that as well for their comfort. So you're having the nerves that are entering through the apical foramen, they're mixing with other actions and mostly you have those non melanated ones and the nerve endings of the PDL. They register pain and pressure and that's why it's a very vital space. And that's the difference, for example, between teeth and implants. We don't have the PDL, so the implants don't feel, don't have this sensory compared to the teeth clinically considerations that we have about the PDL. What happened here again? Uh, here. So the PDL is thinking in functioning in non functioning teeth. And when we're saying figure we're meaning also wider. What you can see also you graphically as a wider space than the normal 0.25 as we said, and especially in heavy function, that's where you can see more widening over there. The cells are capable of remodeling the ligament, the adjacent bone, because you said you have they have a bunch of different cells included from Osteoclasts and mantle blast, osteoblasts, etcetera. And obviously when the ligament is damaged, these remodeling changes as well. It plays a key role in protecting the tooth from being resolved by normal remodeling processes. And what do I mean with that, we're going to learn a little bit about the bone which undergoes normal remodeling throughout our life, right? So it reserves and forms, again, reserves and forms. So if we didn't have this space, whenever we would have resorption, we could also have resorption of the tooth. Okay. So cases that we have issues with the PDL or other specific pathologies, you may see the resorption that may be root resorption, for example, that may be initiated by those also that you're having over there and contains those precursor cells for the entire attachment apparatus of the tooth, for the symptom, the bone, the PDL. And that's why it's a key structure for guided tissue regeneration. Okay? That's why we're focusing a lot on the PDL. So answering some questions. So the PDL forms from which portion are that was from our first lecture. Of the developing tooth germ. You remember? See. The PDL fibers are anchored in cement and bone by sharp fibers. The diameter of these fibers is greater, where bone size and momentum side or equal a bone side. Excellent. And finally, the width or insularity of the ligament is greatest when the ligament is. Heaven function, right? You're having a little. Okay. Ready? Excellent. Um. Now. I hear I have a question before I even teach you anything. Why is Samantha included in the tissues? It's part of the two. That height, weight of the fiber. The attachment of the fibers. I'll go with that. Okay. They come from the same. And I remember that. That was my very first question. I said, okay, why is it a paradox? It's like part of the truth. They have the same embryonic region, both cement, PDL and bone, as you see here, come from the dental follicle, as we say. Okay, so what do we know about cement? It's a thin mineralized tissue covering root surface. It's a vascular. It doesn't undergo like physiologic remodeling compared like to the bone you're having continuing surface apposition. You're having collagen fibers, hydroxyapatite and attaches the ligament fibers to the tooth, to the to the root, the root of the tooth and contributes to the process of repair after damage of the root surface. So you can see here, like above among those among those structures is the least mineralized among those three calcified tissues. And what we need to keep in mind is that we have those we briefly maybe mentioned also in the embryology lecture, but we have those as cellular and cellular cement. And what we need to keep in mind is that the A sailor is surrounding the colonial aspect of the tooth and the middle third as well. It contains bundles of fibers and connects the tooth with the alveolar bone and with the cellular cement. It's more on the apical third of the root contains both extrinsic and intrinsic fibers and cement decides. And what we need to keep in mind is as cellular cement forms and calcify cement, the blast can become trapped within the matrix. And that's where you're getting those cement sites being formed. And also keep in mind that a cellular cement forms first and then the cellular one develops afterwards and completes when the teeth occlude with each other in the opposite arch. So the cement is produced by cement or blasts and or PDL cell. So you can have both of those origins. As we said, it's wider, a little bit on the apical portion compared to the cervical portion. You can have those extrinsic fibers, the sharpest fibers, and they're oriented perpendicularly to the cement and then conjunction and you have those intrinsic fibers where it's more parallel to the root surface regarding the cells that you're having in the cement area. You're having cement blasts, cement decides, PDL fibroblasts. Remember, these fibroblasts are going to play a huge role, as we're going to see. And the class, which is we call it like cement or class, is the same category over there. So going one cell by cell regarding the cement of glass, we talked about those. They originate from the animal cells in the dental follicle. They may arise from undifferentiated cells of the PDL. So keeping that in mind for the cement room, you can get cells that are rising not only from this momentum area but also from the PDL. They're in close proximity with the cement surface and you can have the production of those intrinsic collagen fibers regarding cement sites, we said about either getting trapped and they reside in lacunae in the cement. They communicate through a network of different cytoplasmic processes and they're important. They play a role to the maintenance of the vitality of the cement and transportation of nutrients through the cement. Regarding the PDL fibroblasts, we talked about those already in the PDL part. They are part of the PDL. They produce the collagen fibers and contribute to the cement agenesis and finally the cement of class Osteoclasts. As we said, multi nucleated giant cells. They play a role with segmental resorption and you can distinguish from osteoclasts sometimes. So that's what I need you to keep in mind in that now relationship between symptom and anomaly disease. So we talked about the two, how it is you're having, the enamel, you're having the root and that connection between cement and enamel. We call it the cement enamel junction. Okay, That's very easy with what we call we just take the one tissue and the other tissue and just make one word out of those. So the easiest way to remember that is wait here. I know it's very old fashioned, but we still say that overlapping first meeting, second gap, third. And now the other question that people get wrong is what overlaps what? He always makes it. What can I make it easier? So the symptom of relapse because C comes before E? Okay, we got it. Excellent. So obviously you can have different abnormalities in the symptom area, like hyper cementitious semantically normal pearls or the piece, the cervical and normal projection. Just briefly mentioning those, we're going to learn more about those in our clinical lectures later on. Regarding hypersomnia and ptosis. It's an abnormally large like cellular symptom area, especially on the apical third of the root. Again, I don't want to deal with those teeth and take them out. I had to do it like a couple of times. It was a pain because imagine like having a tooth and then like a bowl underneath. You literally need to remove all the bone in order to take it out. Okay. So they're very challenging in terms of that, but it's common that those teeth may also exhibit some other root related issues. So keeping that in mind regarding the semantics, there are small spherical particles. They they are a cellular. They can be either, you know, free in the PDL or attached to the cement surface or even embedded in the cement layer. So you may find those as well. Enamel pearls, they look gorgeous, very nice and white and round and shiny in the fractions and they usually contribute to formation issues. But don't all issues associated with the molars, especially third molars, more frequent mandibular molars. And usually if you can't do much with that tooth, you just need to remove them and remove the teeth. Actually trying to remove the pearls is not always predictable because they can even contain tissues, you know, from dentin or even pipe endings or so. So it may not be that easy, but that's something that you can see that when you graphically like a very distinct round sphere on the friction of the teeth. And finally the cervical enamel projections, the keep this is like this kind of line that this enamel just drops towards the friction and you can see more severe. We have a classification from like this 60s when we haven't changed that. And it's like a class one, a small drop. You can see one and three are the more frequent ones, especially those. You can see them very frequently. The class two goes towards the friction, but it doesn't make in contact with that. And class three goes in the friction again, usually teeth with those projections, those seeps may not have a good prognosis because you can't have attachment there. You're having friction issues. So some of those teeth need to be extracted. But there are others like this one that you may lose some attachment or whatever, and you just are able to see that on that side. Regarding clinical considerations of this momentum, it's obviously essential for the normal Anchorage of the tooth. It provides a protective function to the tooth itself and it's less susceptible to resorption than the bone. And that's a crucial role for the ortho treatment. Thin cement layer is removed after SRP and we need these stands for scaling and route planning. And this is very important to keep in mind when you treat patients per patient with periodontitis doing those deep cleanings, as they call them, like those scalings and root plannings, you don't want to be over over instrumenting those areas because you can easily remove it very significant amount and then you can end up with very thin roots and those hourglass shape roots that sometimes are being created. So keep in mind about those things. The, the, the anomalies or other like variations in segmental genesis may have a clinical implication in the prognosis even of the tooth and the new segment information is a key process during therapeutic procedures. That's why when we're doing from surgical to surgical periodontal procedures, we want to make sure that we remove that diseased thin layer of symptom without over instrumenting obviously the tooth in order to have a nice healthy root surface for the fibers, as it was mentioned before, to attach again and form the new attachment. All right, let's see. Cement is produced as a result of cellular secretion by. Okay. Aha. What? See? A. What should I choose? Hey. It's C, Remember the PDL cells in the symptom area and they play a role. If you go back, there are PDL cells that play a role in the symptom secretion. Yeah, both the PDL fibroblasts. If you go back maybe five slides, I don't remember how many. The coronal two thirds of the route is covered, mostly with what type of cement. You don't have to remember. You can look back in the lecture, right? It's not a test. B. We found it. But yeah, it's be. And cement and glass originate from which embryonic structure? See, we. Remember that we're the best in embryology, the one that we don't like. We got it. Okay. And finishing up. It's not going to take long. I know it's a long lecture, but we cover the whole anatomy in one about the I'm sorry, the bone and the alveolar process. So obviously. These are the. Parts like the alveolar bone, proper lines, the alveolus, which contains within the alveolar process parts of the maxilla and the mandible support the sockets of the teeth. It develops in conjunction with the tooth development, protects the teeth. As we said, it's a reservoir of minerals and part of the attachment apparatus like the and the cement. As we said, those three structures and you can have like cortical and cancerous bone. So the cortical is more like the outside part. And you can see the difference between the maxilla and the mandible. You're having more cortical bone on the mandible even here compared to the maxilla, more cancerous bone and the different types know I'm not going to go into all these details now with type one, two, three and four, but the different types of bone that you can have and the implications of those types, especially with treatment, especially with implants, how dense or more or cancer loose the bone area may be for success of your treatment. So keeping that in mind as well. Now between the teeth, we're having what we call the septum, the intra dental septum, the septal area, the crest of the bone is the most coronal part of the bone that you see on the tooth. And going back to a question that was asked about the junction and the bone, this can be wherever you can predict it with where the Gingival junction is. And you can have deletions, as you see over here. So what is the reason is that the crest of the bone usually is about up to a couple of millimeters below the CG. Why? Because we need that space. For the junctional epithelium attachment and the connective tissue attachment that we talked in the beginning of the lecture. Right? So biologically, for this all to fit over there in a normal periodontal healthy Bourdon tube fully erupted tooth no other variations. The crest of the bone is, as you see over here. Maybe that's also a little bit slightly lower, about a couple of millimeters below the CG, the cement enamel junction. Now, if this goes way epically there, that's what we call the decisions. Okay. And the fenestration, I'm not going to be very what's the word doesn't cross my mind. But this is a Greek word. Okay. Yeah. We have it in boats. The finished stream. Right. It's a whole that we look into that. So it's like, I'm sorry. Pete. What? What? Yeah, yeah, yeah, yeah, yeah. But this is a Greek word. So that's what it is. Like, you have bone on the top, bone on the bottom, and you have an opening over here. Okay, so that we call it a fenestration. Now, do we know that per se when we see a patient? No. Can we sometimes suspect that? Sure. If you're having a patient that has recession, maybe you're seeing that you're expecting that the bone, you know, has the hastens over there. And that's why you get that doesn't mean you need to find out for every single patient what's happening. No, but in specific cases and treatment that you may plan, it may have implication if you're having decisions for destinations, you know, in grafting or ortho movement, etcetera, because you may end up with issues that you didn't have when you started with. So that's why we need to keep that in mind. So we have three plates of the bone and we need to know of the alveolar process, the reform plate. And we have the numbers here that's adjacent to the PDL, the supporting plate that's coming like right after. And finally the outer plate facially and lingual that's composed like the cortical bone. And these are continuous with the body of the maxilla and the mandible, depending what you're looking at. So yeah. Question Yeah. Mhm. No. The crest of the bone is in Italy as well. It makes this scalloped architecture only because it's between the teeth. You call it like the septum, the septal area. Yeah, yeah, yeah. And I was wondering if there's a clinical. Or. No, no, you you can't you can see that in these scans. That's where you usually see that especially. It can be related. Either you want to treat and keep the tooth or extracted and place an implant, for example, or anything like that, having those deficiencies in fenestration. We usually look for those when we're planning implants and we want to do like soft tissue grafting, okay, because you can have those when you take a graft and then you may end up with a problem. But the fenestration, you should see them mainly in the cities. You may be suspicious, especially, let's say on the mandibular teeth, where sometimes, depending how they're placed in the alveolar housing, you may see through the alveolar mucosa like the reflection of the root. So you're saying, you know, I'm suspecting there's adhesions here or a fenestration there, but you can't know unless you open a flap or you expose the skull. And that's what's the implication Like if you see that, does it mean that you need to do something? No. Okay. Especially if there is no disease associated with that. But if there is disease associated with that, you need to be careful because this may have implications on the healing and what you end up with. And if you need to do a kind of treatment, let's say ortho treatment and you're having and you're starting like this, you may end up with, let's say, severe recession afterwards, that you're not having it. So that's why you need to assess those clear. Okay. So regarding bone, as