so when we looked at the period on term peri means around or don't come from the word tooth we're looking at structures that are around the tooth and we looked at the gums we looked at periodontal ligament fibers we know that there's bone that's surrounding the tooth now what we're going to look at is cementum and cementum is basically a layer that's covering the root it's a layer that's covering the or housing the cover in the tooth yeah let's put it that way so let's look at cementing more carefully when we're looking at the cementum which is usually a yellowish brownish color that is covering the entire tooth it's basically a mineralized tissue so it's just a tissue or layer that's mineralized it has minerals that's covering the two roots okay so it's only covering the root not the enamel just the root um one of the cool things about it is that it covers or sealed the open dentin materials so if you look at the anatomy of etude um let's see if i can draw it we have the enamel okay so this is the enamel underneath the enamel we have the dentin okay and then we have maybe i can try it in our green then we have like a pulp okay we're drawing but what i want to get at is the yellow dentin that we're going to look at okay so this area over here that i am coloring is the dentin and so what you notice is that the cementum which is the brown that's outlining the root that's the cementum covers the dentin and that's really important because if i were to zoom in i don't know what happened there let's do that again so if i were to zoom into the dentin i'm just going to color that in again the dentin actually has tubules or holes which are known as dentinal tubules and when these holes are or tubules are open we're going to feel sensitivity anytime we have we eat something cold we're going to feel it because those tubules are open so what the cool thing about uh cementum is that it actually covers the entire dentin so that it can seal those tubules so now we don't feel any sensitivity okay so one of the things that is cool about cementum is that it covers those dentinal tubules now when we are um deep writing okay or instrumenting our clients debriding our clients one thing that can happen is as we're scaling or debriding away we can remove sementim and when we remove cementum now the dentin is exposed so now we might feel sensitivity so it's important that we do not need to remove the cementum um to eliminate bacteria it's so important that we keep the cementum we preserve the cementum the cementum has some great uh you know benefits and one of the benefits is that it seals the tubules so do not aggressively deprive the cementum off now we do have layers of cementum or types of cementum we have something called acellular cementum and then cellular cementum notice that the acellular cementum is drawn a lot thinner compared to this cellular which is a lot thicker and firstly the way i remember it is alphabetically so a comes first in the alphabet so that's where i'm going to put a over here c comes later in the alphabet so it goes towards the root okay so a is first and then c so a for acellular and then c for cellular now what i want you guys to know is that the a cellular is um has no living cells and what that basically means is that once the cementum is gone here it's gone for good we can't get cementum back so acellular cementum is the cementum that we could actually write off and we need to be very careful because once it's gone it is gone cellular cementum however it has living cells it has something called cementocytes which we'll look at later on but basically it is present at the bottom okay near the apical and intra-radicular parts of the root okay the apricot is the bottom apex and intra-radicular and this actually um gets bigger you get more and more cementum over time and the reason why we get more and more cementum over time is because if we're grinding or um you know we're clenching if we're we have attrition right so we're grinding and we're putting a lot of pressure on our tooth eventually our cementum has to compensate and create that cushion over here and it'll build more cementum at the bottom so cellular cementum is the one that we get a lot more of so we can get a lot more cellulose dimension throughout our life the older you get the more cementum we'll have because of the constant you know attrition that we get so if the cementum is built to compensate for the attrition so acellular cementum is on the top is towards the enamel and cellular cementum is towards the apex of the root