Purpose Driven Dental Assisting - Lesson #7 of 23 - Radiographs and Dental Anatomy

Okay this is lesson number seven. Thank you for watching. We are going to go ahead and dig into radiographs. Now this is one of the main diagnostic modalities of general dentistry, dentistry and medicine for that matter, being able to see through tissue to hard tooth structure for dentists and the jawbone. So we're going to dig in a little bit and let's talk about what the purpose is. Of course it's all about diagnosis, excuse me, being able to see what's happening, making appropriate recommendations for treatment going forward. It's all about diagnosis and serving individuals through appropriate diagnostic ability, therefore leading to appropriate treatment recommendations. Okay so let's talk about diagnostic need. There has to be a need for a radiograph. We know that these x-rays create ionizing radiation which can be damaging and it is additive. There's no blanket or standing x-ray orders. We should never say to the dental assistants, every new patient gets a full mouth x-ray and a panoramic and all this stuff. We should always make prescriptive x-ray radiations. They must be individual to the unique patient. It's required by law in most states. They have to have diagnostic value. If you're taking x-rays just to take them and they're not useful, if you can't see the root tip, if you can't see what's going on, then yeah, don't take it. My rule is with my dental assistants, the new ones, try once for an x-ray whether it's a periapical or a bite wing or panoramic. If it doesn't come out, try it again. If it doesn't come out, you need to get help. Do not try a third time without someone with more experience helping you. It's just not worth blasting the patient with radiation if there's no need to do that. Positioning, positioning, positioning. Radiographs are all about positioning appropriately either the sensor or the patient in the machine. Angulation, elongation versus foreshortening. We're going to talk about this a little bit later on in the lesson. Basically it comes down to how you angle that radiograph in relation to the x-ray beam that's coming. If the beam is coming this way and it hits it perfectly perpendicular, it's going to be an accurate representation of the height of whatever it is we're looking at. Now if I angle the x-ray sensor and that beam goes through it, that what was normally this size becomes that long which is longer than it was originally. So angulation is important when you're taking an x-ray. This is an intrabony, meaning in the jaw, tumor for a patient that we were tracking. He initially refused a biopsy when I first saw him. He went in for a biopsy. I don't know, I haven't seen him, it's been a couple years since I saw this patient. I am assuming that he had to have most of his jaw removed based on what we're seeing here. This is probably a cancer but I wasn't able to follow up on him because he never came back. This is probably nothing to worry about, maybe a little dense bone there, could be some sort of trauma, could be something sinister. Here's an x-ray of an implant of course. You can see some bone graft placed at the same time. And here's two implants, a post-operative x-ray of the implants. Let's talk about radiation. What is it? Well there's a giant spectrum of radiation, non-ionizing and ionizing. You can see our visible light spectrum, these colors right here, this is what we can see. Well x-ray is way up here and this is the energy, the amount of energy in the rays. Without getting too deep into it, as the energy goes up, the damage to the tissue, the potential risk for either killing the tissue or developing some sort of a cancer increases. And that is also additive. So the more x-rays, even though it's a very low dose x-rays, the more x-rays you throw at someone, that amount of radiation can build up and increase the risk for potential problems with tumors or other issues down the road. So we want to minimize the radiation. As little as reasonably acceptable is what's generally taught in most radiographic schools, courses rather. So here's a list of some of the exposures. This gets really complicated. It's not important for us to discuss that in this basic course. Let's talk about a panoramic x-ray. This is a panoramic x-ray. This also has a cephalometric attachment over here. This sensor right here with the blue dot, this little white piece, click the blue dot, that comes out and goes right here. You can use it to take a ceph, which takes a side view of the jaw, of the whole skull for that matter. This piece can be dropped. So be careful, don't drop that. This side of the machine takes a picture like this, the panoramic x-ray, which shows us everything, the whole jaw, the jaw joints, up into the eyeballs, part of the brain sometimes in a single picture. Here is a panoramic radiograph. And I know we're kind of flying through this. There's a lot of detail in this lesson. But this is a panoramic radiograph. This one normally we take about once every five years, unless there's a justification to take it more frequently than that. This is what we call a full mouth series or an FMX of x-rays. This involves 18 individual films consisting of periapical x-rays and bite wing x-rays. Generally, most of us dentists are taught that you take a full mouth series every two years, depending on the need. So we'll take this set once every two years. We'll take the bite wings, which we'll talk about in a minute, about every six months, sometimes as long as a year, again, depending on the need. And we use this little guy, this little intraoral x-ray tube head to take these individual x-rays. These, of course, are photos which are taken with a camera. So these are periapical x-rays, peri meaning around apex or apical meaning around the root tip. So peri apex, so they have to include the root tip for it to be a periapical x-ray. A lot of times we'll have a dental assistant come and sit down and tell me that you got the x-rays done and I'll take a look at them and there's there's no root tip. They got some of the tooth. It's not a bite wing, but it's not a periapical. It has to include the apex to be the periapical x-ray. So make sure you're getting appropriate x-rays. Again, the periapical x-ray must include the apex of the tooth. It's ideal for identifying pathology or infection. Easy to screw up. Be cautious of angulation problems like we talked we'll talk about a little bit. Foreshortening and elongation all depend on the angulation of the x-ray in relation to the object and the sensor. So these are the bite wing x-rays. You'll notice that they show the upper and the lower where the patient has them. They're ideal for identifying in between the teeth or interproximal tooth decay. They're great for evaluating margins of crowns and fillings. Usually updated once or twice a year depending on the need. Make sure the contacts are open. We'll talk about this in a minute. Avoid overlaps of contact points because it's hard to diagnose tooth decay when you can't see in between the teeth. Do it right or don't do it at all. Like I said before, take the x-ray once. If you get it, great. If you take it again, you can't get it, get help. Don't try it a third time without someone more experienced being in the room with you. So you can see here, this is tooth decay identified on a periapical x-ray. So you can see it here a little bit and then I refine that image with a couple of filters and you can see the interproximal tooth decay. But in the mouth, that looks totally normal. You couldn't see the tooth decay without the x-ray. So that's why the reason we take x-rays. Make sure the contacts are open, not overlapped as you see here. See that white line? That's the overlap of the contacts. If the angulation of this, you have two teeth basically and if the angle is turned a little bit, then these areas are going to overlap. So we have to make sure that the angle is such that the x-rays can go right in between the contact points instead of overlapping it, if that makes sense. So here is my setup, what we use in my office. This is a Schick sensor. This is a complementary metal oxide semiconductor, an active sensor basically, that's waiting for an image to hit it and then it's translated into a computer. So the nice thing about it is this is plugged into a USB port so it's powered. That means the amount of radiation that has to touch that to activate it is much lower than conventional film. This is that tube head again. Here is our panoramic and here's just a quick demonstration of elongation versus foreshortening. So with this particular tooth and this setup, if you had a tooth right in between this tube and this sensor vertically, it would be represented appropriately assuming the tooth is vertical. Now if the tooth is vertical here, you can see that as the x-ray comes across, it's going to make whatever is closer to the top appear longer. That's called elongating and the same thing applies here. Whatever's closer to the top is going to appear shortened. A little bit of physics involved there but that's a very basic description of that. So we want to make sure that our x-rays are parallel to the tooth we're taking the x-ray of, not angled, and that the beam coming in is perfectly perpendicular to that surface. Otherwise things don't look really accurate. All right, so here again is the bite-wing x-ray. We want to make sure the contacts are open and not overlapped. And then we have this great thing called 3D imaging which is really starting to take the world of dentistry by storm. Only big drawback with 3D imaging is the amount of radiation required to get a 3D x-ray. So here's a cone beam 3D x-ray. Here's the type of images we can get. Again, it gives you actually a 3D picture that you can move through. That's really, really cool. Here are some photos. Good photos are really critical. I find that I use photos the most to educate my patients about what they have and why. Like you can see right here in this center photo. I would tell the patient you've got a fairly conservative amalgam filling that has several fractures, recurrent tooth decay. You know, a fracture in between the fillings. Here's a significant failing filling. Same thing down here. Same thing here. And then a composite restoration. Although the color is nice, it doesn't quite blend. That's not a big deal. But we're starting to see fracturing here. Some leaking and recurrent tooth decay. Photos are worth their weight in gold. All right. Now we're going to dig into dental anatomy. Now this gets a little hairy, if you will. Teeth don't have hair. So bear with me for a minute as we jump through this. In the United States, teeth are numbered starting on the upper right with tooth number one. Moving around to the upper left with a wisdom tooth being tooth number 16. Then going down it's 17. Then back around to the other side again to the bottom right with number 32. So the wisdom teeth are number one, number 16, number 17, and number 32. It's really complicated. There are better ways in my opinion. But this is the way everybody's taught in the United States. As you can see here, tooth number one is on the upper right. That's the wisdom tooth. This incidentally is not the first molar. This is the third molar, which is number one. Number 16, 17, 32 are the wisdom teeth. So the front central tooth, this is number eight, this is number nine, and then number 24 down here in the front, and number 25. So they're numbered quite uniquely. The baby teeth are numbered actually with letters, which helps to distinguish between them. But a lot of us don't see a lot of baby teeth. So I and J, K, L, S, T, A, and B are the molars. Again, it's a little bit unique from the standpoint of learning that, but it's definitely learnable. So let's talk about surfaces of the tooth. Mesial means toward the midline. So if you look at this diagram, the mesial surface, this surface right here, which corresponds to right here, is toward the midline. So that's mesial. Distal is away from the midline. It doesn't mean toward the back necessarily, it means away from the midline. But it essentially translates to toward the back. And these are tooth numbers again. So upper right, the wisdom tooth would be number one, then two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, and 15. Cheek side, buccal or facial. Tongue side, lingual or palatal. So let's look at some dental anatomy on a radiograph. The mandible is the lower jaw. The maxilla is the upper jaw. There are two maxillas, the left and the right maxillary bones. One mandible, one mandibular bone. All right, the nasal sinus is the airspace in your nose. Maxillary sinus is basically the airspace in your maxillary bone. The orbital opening, of course, is where your eyeballs are. The coronoid process is this area right here. It's part of the jawbone that comes up that your temporalis muscle, this big muscle that attaches to the side of your head, attaches to. And that's the coronoid process. Ear lobes, sometimes we can see those on x-rays. You can see it right here and also right there. That's the ear lobe on the x-ray. The zygomatic process is the cheekbone. Oftentimes we can see those. The cheekbone is right here and right here, cheekbone. And the inferior alveolar canal is this canal that holds the nerve and the blood vessel that goes through the lower jaw. And here's where they are, the hyoid bone. Oh, I missed that one on the list. Hyoid bone is down here in your neck. Mandible, inferior alveolar canal, maxillary sinus, maxilla, nasal sinus, orbital opening. There's another one over here. The zygomatic process is the cheekbone. All right, a whirlwind tour of dental anatomy. Nailed it, right? You got it all. Let's talk about the teeth. All right, so the crown of the tooth, natural tooth, an unaltered tooth, is the part of the gum line. The root, of course, is below the gum line. The biting edge is the incisal edge. Fossa is a depression, usually on the tongue side of teeth, some teeth. Cingulum is the bump on the tongue side of your front teeth on the top and the bottom. Some people don't have those as much as others. You can see here down in the bottom, you've got a bunch of unique areas, landmarks of the tooth. It's not critical that you know all these things at this point. Down the road, we can certainly dig into these a little more. One fun word that I like is furcation, and that means the space in between the tooth roots. The furcation. Okay, so test, true or false, bite wing x-rays show the apices, the apex, the tip of the teeth. True or false? True or false, panoramic x-rays should be taken every six months. What are the numbers of the permanent first molars and what surface of the tooth is toward the midline? We talked about four or five or six different names, mesial, distal, buccal, lingual, facial, palatal, surface. Which of those surfaces is toward the midline? So pause it, write down your answers. Here is the answer key here. All right, thank you for watching. We will see you in the next lesson.