Occlusal Effect Caries: Caries Caused by Cracks Into Dentin

Treating cracks in teeth can still feel ambiguous for many dentists. Is it better to observe? Is it better to crown? Is there a less invasive treatment option? In this episode, Dr. David Alleman discusses a key piece of research that offers practitioners more insight into crack diagnosis and treatment: cracks that cause decay.

Occlusal effect caries is a carious lesion that forms from cracks that extend into dentin, creating a pathway for bacteria to enter the tooth. These cracks, called peripheral rim fractures, occur mostly around large restorations that leave the surrounding tooth structure unsupported, making crack initiation easier in the tooth. By understanding how these cracks form, practitioners can better learn how to detect and restore teeth affected by peripheral rim fractures.

Articles referenced in this episode:

• Milicich G, Rainey J T. Clinical presentations of stress distribution in teeth and the significance in operative dentistry. Pract Periodont Aesthet Dent. 2000;12(7):695-700.
• Walker et al. Enamel cracks the role of enamel lamella in caries initiation. Australian Dent J. 1998;43(2) 110-116.

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Transcript

0:36

Welcome to season four, episode one of the Six Lessons podcast. Today we're going to talk about the most important year, really in developing of Six Lessons. That was the year 2000. In the year 2000, I had to make a big decision. What was I going to do with cracks? Because in the year 2000, I bought a microscope. Happened to have $10,000 in the bank. What else are you going to do with $10,000? Right. I bought a microscope. I got permission after I had already made the purchase. My wife was very understanding that if I'm going to understand dentistry, I need to see what I'm doing. And so purchasing the microscope in 2000 came at the same time that the most important article in structural Compromise was published. I'm just going to go to the library here and get that article. Just happened to have a couple many copies, but that the article looks like this. So here we go. We got Milicich We got Rainey talking about the manifestations of stress, clinical presentations of stress distribution in teeth, and the significance in operative dentistry. The year 2000, published in PPAD I read that in my office. It explains something that I had always wondered about why patients could come back year after year with no inner proximal decay, and then one year they would come in for a bite wing and they would have inner proximal decay class two lesions. How could that happen? Because the idea in dental school is that you go to class to carious lesion by not brushing, not flossing. And I would look at the patients and they had clean mouths. They were brushing on floss. You know all the sudden they had a class two lesion. How could that happen? Well, when I read the paper by Milicich and Rainey, it entered a new diagnosis into my practice. And every practice should have this diagnosis available. It's called occlusal effect. Caries occlusal effect caries is a carious lesion that's mediated by a crack into dentin. And that crack into that is first recognized as potentially being an avenue for decay, with a new concept that was introduced in that article called a peripheral rim fracture. Now, in dental school, I graduated almost 20 or 22 years before that, 1978. Did we ever, ever talk about cracks in a marginal ridge? And the answer is no. But once you start looking at marginal ridges for cracks in enamel that has an occlusal amalgam, just what you find them all the time. If you have a class two amalgam, look on the distal ridge that was not restored with the class two amalgam. And guess what? You find a fracture in the enamel. But the fractures enamel sometimes are not stains or not obvious. But in the year 2000, the same year that the Milicich Rainey paper was published, I bought the microscope. Why did I buy the microscope? I heard a lecture by Cherilyn Sheets at the Utah Dental Convention, and she was. And it is a Prosthodontist in Newport Beach. She was giving a daylong lecture, and her lecture included the fact that she was using a microscope. So after her lecture, I went down on the floor and there was a microscope company. Tom Sorenson was the salesman and the microscope company was Global Microscopes. I looked at the microscope for the first time. I had had loupes before that time. My loupe magnification was 4.5 with 4.5. I remember I started to use caries detecting dye at that time. That would have been in 1997. So for three years I had caires detecting dye, and with 4.5 loops I could see caries detecting dye very clearly. And I was developing the concept of the peripheral seal zone I had heard a lecture by Jeff Knight, and he introduced the idea and called it a moat an idea of a moat free of caries around the pulp. that evolved into the Peripheral Seal Zone concept that was published. But we started teaching in 2003. But decay steadily caries text and is very easy to see compared to initial cracks. And so in 2000, when I bought the microscope, I could see cracks on all the marginal ridges that had amalgam restorations. I don't know if occlusal amalgam be both mesial and distal. Sometimes you'd see a crack on the lingual or the buckle, but all of these cracks in enamel. Some were sensitive and some were not. Some had symptoms and some did not. My mentors at that time in the year 2000 would include Ray Bertolotti who did not talk about cracks. Gary Unterbrink who did not talk about cracks. And Didier Dietschi who did not talk about cracks. So my three mentors didn't help me at all to understand this, but this published article from New Zealand dentist Graham Milicich good friend of mine, and Tim Rainey, another good friend from Texas, started to demonstrate that there had been publications and articles investigating these cracks. The first one that was very important was published in 1994 by a doctor Walker. I said, no, it's 1998. I'm losing it. But in 1998, this article was published, and all of a sudden we actually had a picture. And this picture was included in color. It's not going to be a color on this photograph, but this black and white photograph shows an internally decayed lesion that is much greater inside than it is working away to the outside. Now, that photograph was published in the 2020 and the 2000 article by Graeme Milicich but this was published two years before by Doctor Walker in Australia. And this crack in the enamel here was a naturally occurring crack that you learned about in dental school and dental anatomy. It's called a lamellar. It's a disconnection of the enamel rods. That is a natural defect. And those lamellae had associated with them that were identified by Walker. Decay. And that decay was inside the tooth, working out instead of plaque mediated decay that would be outside the enamel and work in through the mineralization and eventually reach the dent. Now this is fundamental knowledge on the most important pathology the dentist ever deal with. Decay. I mean, decay has been talked about for over 250 years. It goes back to Pierre Fauchard the father of dentistry, wrote an article in the Encyclopedia, the first encyclopedia in the world published in French. Translated into English. Dentistry is a scientific investigation. Well, this soft stuff inside the two to eventually cause abscess and needed to be extracted. That was the only real process that was available. Had always been filled with an explorer, and so it could be seen as a discoloration in this broken down tooth. In the 1776 period, the time when George Washington lost all of his teeth from decay except one a lower bicuspid. He had one lower bicuspid when he died. But this idea of having dentistry being scientific is really mediated by publishing, about printing, about being able to read articles from people in other parts of the country, or other parts of the world, speak other languages. This is the foundation of science. Have a discussion. Have a dialog. This is what I see. What do you think it is? Let's find out. Unfortunately, the microscope, which is really the fundamental breakthrough first discovered 100 years before the American Revolution, 1676 And so this idea of seeing things with the microscope, you know, it's part of my mind. And when I bought my microscope, all of a sudden caries which is easy to see, was staining with caries detecting dye, which is less than one, spilled over into this second pathology. That turns out to be the third leading cause of tooth loss, which is fractures into the crown, into the root of the dentin, which is non re storable. But again, this is 25 years ago. I'm just looking through the microscope and my three mentors, Bertolotti, Unterbrink, Dietschi can't help me. Fortunately I had a friend who was actually a crack expert he repaired cracks on airplanes. airplanes repaired cracks on actually were very expensive. For 20 years he worked on the spirit B-2 bomber, And so I had discussions with my friend Dennis, and I said, Dennis, I've got these teeth. They have cracks, got this microscope, I'm seeing the cracks, but I'm seeing the cracks. And I understand that if left untreated, they can one create a path to the pulp to kill the pulp. But the second thing is that they can fracture root. So that's unresolvable. And you will lose a tooth from that. And so I'm seeing this, but nobody in dentistry is talking about it. So I kind of feel like Galileo you know I'm looking and all of a sudden I see Jupiter and he's looking through a telescope, which is this reverse order of lenses in a microscope. He just turned the telescope the other way, and you got a microscope. But now, Galileo, you know. What did he say? He knew that the universe was bigger than what he had been taught in his church classes, and. But he got, taken to town by the people who wanted the earth to be the center of the universe. But he knew that, 70 years before that, a very important cleric from Poland, Copernicus, had made the calculation, use the math that he had, and that it had proven that the sun is the center of the orbits of the planets, and not the other way around. The planets don't orbit around the Earth, and the sun doesn't orbit around the Earth. That's a Copernican revolution that took about seven years to get to the scientists in Italy. But once it was there, and once you see it, you can't not see it. But the idea is that seeing things with the microscope is fundamental to understanding dentistry. And so when I got my microscope and talked with my friend Dennis, I said, Dennis, what do you do with these cracks on these airplanes? He says, we repair them sometimes. We observe them. If they're not that big, we can repair them next time or down the road. But for example, he said, if you have a crack on an airplane wing attaching to the body of the airplane wing, you can see that with the normally if it's three inches, you can fly the airplane to go get it repaired. Three inches is okay, you can fly, but you got to get it repaired at three inches because it's seven inches. The wing falls off. So when you see airplane pilots or somebody on the ground going around the airplane just looking at it, they actually have a checklist of things to look for, and they need to look at that part of the airplane to see if there's any cracks there. And you don't want that airplane wing to fall off when you're flying it. So you're glad that there are checklists. You're glad that people understand crack initiation, how they start crack propagation, how they move, and catastrophic failure. When the crack takes off an airplane wing, for example, catastrophic failure in a tooth is you lose the tooth. It's not usually associated with death. And so are dentists. As important as. You know, physician surgeons, well, maybe in most people's eyes are not. But if you have a toothache and you have a dead pulp and you try to get that tooth extracted, guess what? You would have wished that that crack would have been treated before the pulp died, before the tooth was halfway broken off and hurting you in your mouth. But the idea is that this morning, this actual morning, I read a journal of a pioneer who settled Utah, and he had a toothache, and he went to the dentist that he had. The dentist tried to extract the tooth, only got half of it out, and after that half was extracted, it hurt more than it hurt when you went to the dentist to get it extracted. and extractions of teeth safely. It took until the 1850s until people really tried to figure out how to extract teeth without breaking the jaw. But this dentistry and the first dentist, who came to Utah that was trained. He was trained in Germany in these extraction processes that were really cutting edge in the 1840s. But his name was Alexander Navarre, very famous dentist in Utah. The first one. But now we're way past that. And so now we have the ability to take a crack and see it when it first starts. And if you dissect a crack when it's just past the DEJ it's easy. And in fact, many cracks have actually been removed by crown preparations. And I hate to say that because, you know, I hate Crown preparations. But in reality, some crowns, when they're prepared, are removing enough to structure that incipient cracks are removed and the crown actually helps the patient feel better, even though they've had some crack two syndrome. And this causes ambiguity. This causes confusion in the profession. But this last week, Davey and I were in Philadelphia teaching a two day, program. when you teach dentist for the first time how to use caries detecting dye the lights go on, and you teach dentists the first time that they should look for cracks and dissect cracks. The lights go on. And then the other concepts of immediate dentin sealing, resin coating, deep margin elevation, all these fundamental biomimetic protocols, they're all at risk. If you don't take the time to do your lesson. One caries detecting the lesson two crack down section and crack investigation with magnification. So that's the end of episode one. But we're going to continue episode two of season four of the six lessons broadcast. Until next time, get bonded. Stay bonded.