Treating Cracks in Teeth: Propagation, Visibility, C-factor and Composite Layering

Cracks put teeth at risk of infection and fracture if left untreated, but treating cracks in teeth can create many challenges for practitioners. Removing cracks without good magnification, visibility and an understanding of crack propagation puts the nerve and critical tooth structure at risk. Once the crack is removed, the non-standard defect requires specific techniques to bond to deep areas of the tooth while maintaining a strong bond.

Dr. David Alleman, DDS, first began researching treatment options for cracks because he recognized that full coverage crowns weren’t yielding predictable results. Adhesive dentistry had the potential to offer a more predictable alternative, but the protocols didn’t exist for practitioners. So he formulated those protocols for predictable crack treatment himself. 

Articles referenced in this episode:

• Belli S., Et al. The effect of fiber placement or flowable resin lining on microleakage in class II adhesive restorations. J. Adhes. Dent. 2007; 9: 175-181.
• Nikolaenko SA, Et al. Influence of c-factor and layering technique on microtensile bond strength to dentin. Dent. Mater. 2004;20-579-585

NEW: Deep Margin Elevation Online Practical Workshop

On July 25, learn deep margin elevation from anywhere in the world through live online lectures and guided skills practice over Zoom with Dr. David Alleman and Dr. Davey Alleman. Learn more at allemancenter.com/dme-online.

Instagram
@david.alleman.dds
@davey_alleman_dmd
@allemancenter.com

YouTube
@allemancenter

Transcript

0:27

Here we are in season four, episode four, we're going to talk about a systematic approach to treating cracks. And so in the world of dentistry, cracks have been recognized for decades, maybe even 100 years. But the idea is that the treatment of cracks went to a plateau where there was some success with full coverage of teeth that had a crack tooth syndrome, and that was first talked about in the 1960s by Cameron out of USC. other investigators applied this and had some success. Some fairly long term studies, 3 or 4 years showed some success, but when I was taught that system in 1970s for crack tooth diagnosis and treatment, I went into private practice first, I was in the Navy for three years and then into private practice and full coverage. Restorations were the only thing that really talked about. And so that's what I did. If I had a tooth that had consistent pain on biting, I really didn't focus in on cold sensitivity. I didn't really understand source of dental pain at that time. But if a patient had a consistent pain on biting, then we would make the diagnosis crack tooth syndrome. then I would treat pathology with full coverage. their usually was some improvement. quite often, and I'm not getting specific numbers, I don't have a collection of data, but in my mind at least 20% of the time I did not have a reduction of that pain. On biting. It continued, which was very frustrating. But then in dental school and other clinicians that I talked to, if they had a tooth that never settled down, it was always the crown was on pain on, biting was still there. The next step was root canal treatment. Okay. Well, you know, it costs some time, costs some money. Patients not happy about that? I'm not really happy about that. But I get to be really good at doing root canals. I was trained by some of the best undergraduate faculty members in the world, Steve Cohen and Alan Gleason. They wrote the book pathways to the pulp. Our class valedictorian became a world lecture and ended on a Steve Buchanan. Anyway, we had a lot of training, and so that was just something you shrug your shoulders and do the root canal. then ten years later, a number of these teeth failed catastrophically. I can remember one patient specifically, she came in with the crown in her In the crown. She had the buildup and the tooth structure that was holding the build to the roots, which had now been detached. I looked at that and I said, Cindy, wow, you must have eaten something really hard. And that's how much I understood about a fractured tooth. I didn't understand crack initiation, crack propagation, but the main thing I didn't understand is that I had not diagnosed that this tooth had a fracture before I crowned it to treat her crack tooth syndrome, The treatment took away her pain that he continued after the placement of the crown. and then when she came in and it was fractured subjectively. This to the could not be saved at that time with any techniques that I had. So it was Now, She's since passed away. Four years ago I talked to her husband Well, I'm trying to put things into perspective because my job as a dentist is to give options to a patient. And sometimes the option for a patient is I don't want to deal with that problem. Let's just take the tooth out, which can be a real blessing, because a dead tooth can abscess and cause some some more systemic problems. But the idea is that me personally, I hated that Cindy was lost her second molar after I treated it with a crown, treated it with a root canal, then ten years later, the tooth was Now, for most dentists who are more progressive than I am. By the time I had that catastrophic failure, most dentists would have said, well, if you would have started to get trained on implants earlier like I did, then you could have given her the next option, which is an implant. I mean, I'm trying to not be sarcastic. I'm trying not to be bitter. I'm trying not to be jealous. You know, I'm a human being. in my brain, I am looking for either a new profession, which is going to be history. I'm enrolled in graduate programs. I've taken the graduate record exam, I've been accepted, and we're going forward to become a historian, a history professor, and take a minor cut and pay that my wife wasn't going to complain about too much, I think. I don't know, we never did But the idea is that quitting dentistry was more desirable to me at that time because I had an consistent results on treating crack tooth syndrome because I was introduced to adhesive dentistry, the idea of adhesive dentistry actually reconnecting it to was very attractive. the advances in, he said through better adhesive products and then better techniques still led most dentists down the path of saying, okay, we're just going to glue that together. all of a sudden that crack tooth syndrome will go away. And in my experience, it did go away for four years. And then at four years, some of the teeth that I had bonded together started to have the same symptoms of crack tooth syndrome. And again, do I do the endo well, yeah, I want to save the tooth. We do the endo. then at about that time this would be 1999. I was introduced to microscopes by Steve Buchanan. I went to a two day course in university at Ohio State, the Ohio State University Dental School. There were 100 dentists there getting advanced in and onto training. Steve Buchanan was the teacher and he had ten ended on us assisting him. And we each had the opportunity to use microscopes, most of us for the first time. Once I saw what a microscope was going to give me as far as what I was doing and of dentistry, I was sold. so I went home. I'm ashamed to say it, but I had $10,000 in the bank. I'm not ashamed that we had $10,000 in the but I'm ashamed to say that I spent the $10,000 on a microscope without asking my wife. So there is a saying that it's easier to get forgiveness than permission sometimes. and you know, she agrees. Without a microscope, I would not have been able to stay in dentistry, because I still did not have the confidence that this new adhesive dentistry was going to change the profession from the traditional frustrations. But 1999, 2000, January I got my microscope and all of a sudden caries which had been my main focus from 1995 to 1999. Now my main focus became cracks from 1999 to 2003, when I first started teaching six lessons, because now I had that missing link, the missing key to having 100% success because I could see the cracks and my knowledge of engineering, which was basic. But still I had friends who were engineers. I just asked you guys are professional engineers? What if you have a crack? What do you do with And they were taught in engineering school to dissect cracks, take cracks If they working on a bridge and it had a crack, they would take the crack Bridges are made by a lot of connections in those days were metal to metal, and so they would have the rivets these rivets that were connecting pieces of sheet metal, many rivets under micro movements. The cars moving these little micro movements are shaking the molecules in the metal. And pretty soon we get some cracks around the rivets. And in certain situations those bridges failed catastrophically. The bridges collapsed, and then all of a sudden, the engineers looking at this catastrophic failure, they were the first ones to notice that these rivets, some of them had small cracks. Around. And these cracks had grown. And eventually the crack had propagated through the whole bridge and caused a catastrophic failure. So what was their approach to prevent future catastrophic bridge collapse? Early diagnosis. They went and looked at every rivet on every bridge. And guess what? There were some cracks. And what did they do? They took a big drill drilled out the whole rivet with its crack. So now they have a big round hole, then they put a big bolt and they screw it on. That was the mechanical stabilization of this potential catastrophic failures in bridges. The same thing happened with airplanes, airplane wings made of metal, airplane wings made of plastic, airplane wings made out of wood. Actually, wood was the least prone to cracks. Why? Because wood was not a brittle material. It had a nature that is called. Tough. Wood is a tough material, it's not brittle. the difference between toughness and brittleness and plastics is just a function of how the plastics were If they have fiber in them. Another of our lectures will be on this information that I learned from my friends who were engineers was a real eye opener. so I started reading books, engineering books fractures, on cracks and diagnosis and blunting a crack at the tip was the best way to make sure that that cracked had never, would never cause a catastrophic failure. So in 2000, I dissected my first crack using my $10,000 microscope, and when I did, had enough knowledge of adhesive dentistry to know that now I had created a high CPI actor situation. other words, the ratio of bonded to un bonded surfaces on a trench on a dissected crack. The ratio of bonded to bonded surfaces was so high that the C factor stresses. If you restore that with two increments, a four millimeter crack dissection, if you did two increments, then you would have a D bond on one wall of that restoration. at that point, we had resin coating as an understandable application of reducing C factor for the first 90s of a restoration. of course, I was the only person in the world that was thinking in those terms. How did I know that? I talked to everybody for five years that knew anything about adhesive dentistry. Gary Unterbrink was the only one that had the idea of polymerization dynamics, on his direct restorations, he was always putting layer of flowable composite. when he talked in the terms of flow, the next year, after I had met him face to face in 1998, wrote an article with Naren Wilson called Decoupling Approach reduce sensitivity on Large composites. It's not the exact title, but in 2000, in Quintessence International, Gary Unterbrink and Naren Wilson published that paper, that led me to create the decoupling with time that I'm famous for infamous, I hope not. I mean, it's just like science. Why would anybody not understand decoupling with You just have to ask them and then if they haven't talked to me, good luck. Because, you know, we've got 2000 articles here that say time is the missing element of all of your adhesive failures. Well, that time is related to how long you delay the connection of the size of your preparation the way you delay. That is by making them very thin initially, or placing fiber that can allow composites to move in two directions. that science came in 2002. So in 2002, Sema Belli was publishing fiber posts. In 2008, or coot published the scanning electron microscopy that showed the exact movement of the polymers as they were entangled within the Ribbond and all of a sudden we had two ways to decrease C factor with time, and with five replacement and small volume increments. Those three foundational principles allowed us to prevent a root canal failure, because losing a bond or a very narrow, high C factor preparation that looked kind of like a the shape of a root canal being restored in a crack dissection. And so the systematic approach that we developed was based on polymerization dynamics. I learned from Gary Unterbrink reduction by Nikolaenko in 2004, and then in 2006, seven and eight, the fiber placement that Sema Belli, Erkut and El Mowafy published. There's a system that if you do that, then you can have the same results, but you have to dissect the crack, otherwise the crack will continue to propagate. And we will talk about that next time. Until next time, stay bonded.