If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:7:56

Video transcript

so now that we've talked about the mouth in general let's put a smile on that face and take a look at the teeth in a little more depth so what we have here is an image of the lower jaw and another term for the lower jaw is the mandible so this is your mandible right here and then this is your left side of the mandible so I'll put left and this is your right side so you can follow along as we talked about your teeth and as you can notice here things are pretty symmetric right so I can draw a dividing line right down the center and as we go through and talk about every little tooth that we have we'll see that we have the same tooth not just on the other side but also in your upper jaw also known as the maxilla so this tooth right here we have a mirror image of it here and for this pair that we have there's two of them in your upper jaw so keep that in mind we're going through and doing the math at the end all right so every tooth has a specific function to it or every set of teeth so let's go through the different types of teeth we have this first one we have is called the central incisor the central incisor and again we have four central incisors in total we have the one I've pointed out here the second one here and then two others in your upper jaw the central incisor is mainly used for cutting this is the tooth that you use to cut your food the way you remember that is the reason why we call these incisors just like in surgery we say we're about to make an incision is we're about to make a cut so the central incisors make incisions and the same thing is true when we talk about the lateral incisors we've got four of them in total just like the central incisors there's only one on this side so I'll write four in total here and again they're also used for cutting our food and now that we're done talking about our incisors let's move on to talk about our canines so this is our canine tooth and we've got four of them in total and so the canine tooth they're also known as fangs and you'll see why and I'll show you in another image they're the sharpest longest teeth that we have and they're actually used for gripping there for gripping imagine when you're going to a restaurant and they give you a bread basket at the beginning you put a piece of bread in your mouth and you kind of pull away at it and you tear it apart because your teeth the canine teeth that you have all for them are gripping on the bread that's in your mouth as your hand pulls the rest of it away so I'll put pulling in here just as a little cue as well for how we use our canines and now that we're done with our canines we can talk next about our premolars so the premolars we have two on each side which means that in total we have eight of them we have eight premolars and the way to think about what these guys do is in two parts one if you see the word mola over here that's a reference to the Latin word mola which just means to grind or it actually represents a grindstone if you ever look at what a millstone is or a grindstone those were called mola in Latin and that makes sense because our premolar teeth are used for grinding down our food as we chew it the other thing to keep in mind is this first part of the word pre and we call it pre because these two premolar teeth come before these final three molar teeth so we have three molar teeth right here which means that we have a grand total of that you guessed it twelve teeth and just like the premolars these guys are here for grinding as well to break down our food as we chew on it for the same latin root we discussed above and at this point now that we've talked about all the different types of teeth the interesting thing is that this textbook picture of what your lower jaw should look like is actually what it looks like in only twenty eight percent of people in the population now why is that well I've got a nice panoramic image here and you might recognize somebody familiar whose imagers taken here and it's nicely situated so this is your right side and this is your left side and this is actually a panoramic x-ray of me looking right at you so this is the front of my as you now know them the central incisors and these are the central incisors online down here and for reference this top bone that holds your upper jaw is also known as the maxilla so why don't we clarify that so this is my maxilla up here and as you guys already know this is my mandible so I'll write mandible right here and what's interesting is when you look at the teeth that I have here they're a little different from the image we saw previously and it's because if you count them here's my central incisor this is my lateral incisor the canine this is my first premolar this is my second premolar that's my first molar and this is my second molar there's something missing here and it's not just here but it's actually missing on this side this side and this side and I think you guessed it all four of my third molars are gone and the reason why is because they were my wisdom teeth so your third molars are called your wisdom teeth and often people get these removed in fact 72% of people get these removed so 72 percent of our population remove the wisdom teeth and it's actually a pretty simple explanation for why that occurs if you take a look at the gums that I have right here so I'm just going to draw sort of a rough drawing of my gums and I'll try and make sure I exclude my teeth as I do this little tracing right here but if you look at the gums that are sort of surrounding every tooth I have in my mandible or my lower jaw right here they have just enough space for every tooth to erupt or come out let me color that in and the way the tooth comes out is that there's a small designated hole let me just draw one here for my second molar or if I want to draw one in over here for let's say my lateral incisor so that's the hole the lateral incisor erupted or emerged out of the hole for the third molar sometimes ends up being pretty small in fact in 72% of people ends up being pretty small and the problem is that when my third molar is here let me just draw this third molar in and it wants to grow naturally what you would want to see happen is for the third molar to go this way and then out interrupts through that hole but unfortunately this isn't what happens in most people instead the third molar commonly tries to erupt through your gum or through your gingiva which is an important term I'll write that down so your gums are also known as your gingiva and if they try and erupt through your gingiva you can have things like inflammation or tearing of the gum or gingiva or even an infection that occurs if it happens for an extended period of time and this commonly occurs in people within the age group of about 17 - say 25 years old and that's why we call them wisdom teeth by the time you gain a little bit of wisdom start having all four of your third molars erupt right through your gingiva and so you want to get them removed before you can have some type of bad reaction like inflammation or infection that can occur that can mess up the neighboring teeth that have erupted or grew out so well and that's pretty cool if you can recognize that because the same x-ray that my dentist used to see that my wisdom teeth were removed correctly and safely is something that you can now read and interpret by yourself