Stress-Reduced Direct Composite

The tops of teeth don’t matter… as much as the bottoms. The key to any biomimetic restoration is the direct component, which is why I describe biomimetic dentistry as a bottom to top approach. When I first learned of Simone Deliperi’s work and we began working and then teaching together, we both understood how this direct component needed to be carefully managed for a successful restoration. Deliperi’s Stress Reduced Direct Composite technique, which we co-authored a publication on in 2009, is a necessary tool for any dentist who aims for conservative dentistry.

Article referenced in this episode:

• Deliperi S, Alleman D. Stress-reducing protocol for direct composite restorations in minimally invasive cavity preparations. Pract Proced Aesthet Dent. 2009;21(2):E1-E6.

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Transcript

0:40

Welcome to episode six of the Six Lessons Podcast. This week we're going to be highlighting the practical application of decoupling with time how to overcome the hierarchy of bondability. And the paper that we're going to highlight is this paper that I published with Simone Deliperi in 2009. It was in PED, Practical Esthetic Dentistry, and the title of the article is Stress Reducing Protocol for Direct Composite Restorations in Minimally Invasive Cavity Preparations. And so as I beta tested in my own office from 1998 to 2003, the techniques then the question was how do we apply this as far as spreading it to other doctors who may be interested in tooth conserving dentistry? And so in 2003, I made the decision to start teaching. Other doctors made the offer to friends of mine who were interested. The very first one was Dr. Arnoud Noot that we started teaching courses in 2003 and for five years as we taught the courses, the articles we used in teaching, there were first 20 articles and then we added a couple of more, 22 then we went to 25. And of course, every time I gave a course, I was always tempted to add another article or two to make everything clear. Well, in reality, what the dentists really want is a cookbook. They want to know what to do, what to start, step by step. And so their cookbook evolved into 14 or 17 steps that we teach in our hands on programs. But the literature that allows us to say, this is what you should do based on science. It grew every year and continues to grow. But in reality, the growth when it goes to 100 articles or 400 articles or 600 or a thousand or 2000 or 3000 articles, at some point the master teacher has to make a selection. And that selection is based on the knowledge of what's important and the scientific base that needs to be demonstrated, if not totally understood by the student. Well, as this evolution of who's going to be the next generation of teachers and in 2002, I was torn between should I teach or should I just let the young, potentially great teachers like Simone Delilperi take the lead? Pascal Magne already had his book published in 2002 had a lot of good ideas about minimally invasive biomimetic approaches. But I made a decision based on my initial introduction to other dentists and their interest to start teaching, and in 2003 I started to visit other potential leaders in this movement. Many of them were associated with universities, which I traveled to. And Simone Deliperi being in Italy, it was a little bit tricky because the trip to Italy is a long ways and quite expensive. But it did come over once a year to Tufts to give a lecture on his technique that was published in 2002. The technique didn't have a name at that time, but it had the idea of stress reduction and the technique that he was teaching at Tufts would reach maybe 40 doctors a year and that his partner, Dave Bardwell, would teach undergraduate students this technique. But if you only reach 40 doctors a year on a two day course, the impact on the whole profession is small. And a dental school like Tufts has many faculty members, and the faculty members that grew close to Simone Deliperi had great techniques and could teach. But the vast majority of the faculty members at Tufts did not take advantage of that relationship. And that became clear to me when I visited Simone Deliperi at Tufts for the lectures that he was giving in 2007. And in 2007, when I heard his lecture, I had introduced myself through the actually Dave Rudo through email. And that connection from Dave Rudo came because both of us were very interested in some of his published articles in 2006 and 2007 on Ribbond placement in restorations. So we can kind of say that Dave Rudo was the matchmaker between Alleman Deliperi But when I flew to Boston and we started to talk, we went through our lectures that we had been given. I had been giving lectures for five years at that time. And some of these lecture I had just heard and watched his hands on program that he gave to two practicing dentists. We felt like we were very close in all of the protocols and ideas, and these protocols and ideas really rested on the understanding of key factors we've talked about in episode four. And so when we put our heads together, we decided to stay close and made a plan for teaching more or publishing articles. The first article that we published together was published in 2009, and this is the article, and this article gave a title to this new technique. First, we were looking for titles, and the first one that somebody came up with, maybe I came up with it, but we both decided it was a bad title, was a complex composite technique. So we felt like if we use the word complex composite technique, it would be a immediate turnoff because most most dentists want to have their life simplified, right? Of course, the simplification of having successful dental treatments is worth the effort of some of the complexity of some of the techniques that we've developed. But we we made this paragraph. I'll read this. It says, Although the performance of dental bonding systems has improved from early formulation, the stress from polymerization shrinkage and occlusal loadings still challenge the bonds of adhesive systems and the tooth itself. This can cause enamel cracking, cause fracture, marginal leakage, post-op sensitivity and recurrent decay. Nikaido and his colleagues showed that 60% of bond strength can be lost in high factor, bulk filled restorations under functional loads. Such issues of bond strength versus C factor have previously been addressed with three techniques, and these three techniques are still taught and understood by many, but not systematically implemented in the biomimetic restorative dental protocols that are taught or not taught at dental schools. But this is a start. The first approach was by Fusayama and he recommended the use of chemically cured composites with slow setting characteristics that had high flow and stress relief. Now, Ray Bertolotti, my first mentor, recommended this, but there is a major problem, as we referred to last episode, in that the hierarchy of bondability means that with chemical cure you have to wait 20 minutes to overcome this hierarchy bond ability and with bulk fill. Not only do you have to wait 20 minutes, but you are connecting in all of the layers of the hierarchy at the same time. That was Fusayama’s big problem. It always resulted in lower bond strengths in the deep areas of the preparation. But if you had high bond strength because you had a lot of enamel to bond to, that would still be a successful restoration in most cases. The second approach for Fusayama was the published in the book that he published with Roberto Spreafico in 1997, and he suggested a semi direct restorative technique that the polymerization was done outside the mouth to reduce the polarization shrinkage to primarily the looting adhesive agent. Now, this technique I learned from Dietschi himself in 2000 took a two day course at UCLA in Los Angeles. And that technique has a major flaw. And the major flaw is that you have a hierarchy of bondability between the tooth and the pre polymerized inlay/onlay. When I went to L.A., I wanted to see if Dietschi had figured this out, and after two days I said, I think you're, you know, the best dentist teaching in the world right now. This is 2000. But obviously, he had some things that we disagreed about. But I yeah, as a student, I wasn't in a position or it wouldn't have been appropriate to have a deep discussion with Dietschi at that time. The third approach by Dietschi’s protege Pascal Magne used an indirect technique with immediate dentin sealing to increase the strength of the dentinal bonding system. Thus, IDS allowed the dentin bond time to mature before it was challenged by the polymerization stress of the resin cement. Now that's published in the late 1999 by Magne and also in 1998, and they knew it was a mistake. This semi-direct approach without immediate dentin ceiling. So this evolution of immediate dentin ceiling coming in about 1998, that's exactly when I started to understand that immediate dentin ceiling was absolutely fundamental. But I came through literature that was coming out of University of Zurich, not the University of Geneva, but Peter Share. And Stefan Paul had proposed this concept that they called dual bonding and was really proposed to overcome the problem of bonding to temporary cement that was contaminating the dentin when the only was bonded to the dentin. And so they proposed this dual bonding technique where you're bonding the dentin and then you can't contaminate the dentin with the cement. So it's an evolutionary step towards immediate dentin sealing understanding, immediate dentin sealing as far as how bonds test strengths, how bond strengths were impacted. All of that was to come in the future. But around the 1998 in Europe, then the United States, in Japan that had already been published in 1994 by Sato, these concepts that were coming together, Bertschinger was an important researcher out of Zurich, one of the students of Peter Share and Stefan Paul, all of this idea that immediate dentin sealing is the only way to make a semi direct restoration work. So he published an article in PPAD in 1998 that corrected that. It wasn't very explicit article, but it did have that detail of immediate dentin sealing even a deep marginal elevation was had a small illustration in that 1998 article in PPAD but it was a step, I believe, that was understood in Japan, but it wasn't pushed as much as it could have been. But again, hindsight's 20/20, so we talked about Fusayama’s technique, Deitschi’s is technique, Magne’s technique. And now in this article we say this article presents a fourth way to solve the C factor problem via a stress reducing direct composite technique. So that's the first time that the phrase stress reducing direct composite technique was introduced into the literature. Now it's obviously used because it is a fourth way that was introduced to overcome the problems of C factor and the problems of hierarchy of bondability, which I had shared with Simone in 2008. And we started to publish that and teach that when we taught together, we talked together for ten years from 2008 to 2018, but the stress reduced direct composite method dissipates the stresses of polymerization by utilizing precise layering and light curing protocols. This technique is extremely important for minimally invasive dentistry. As a conservative, preparations often have high C factor. In other words, once you make a small preparation, you always have multiple walls to have a large preparation. Then the walls are not contributing to the C factor stresses in a veneer preparation. For example, the preparation kind of looks like a plate. We don't have competing walls that can stress that developing hybrid layer, but in most Class two, Class three restorations, we have multiple walls and this to conserve to structure has to be dealt with in terms of reducing C factor stresses, particularly in the posterior mouth where the forces of occlusion are ten times as strong as the anterior forces. And so by using the stress reducing direct technique, the complex geometry of minimally invasive preparations can be treated in the most conservative manner. Magne has termed all low stress, highly bonded advanced adhesive techniques as biomimetic because they mimic the stress strain neutrality of a natural tooth. The stress reduced direct composite is thus minimally invasive and biomimetic, but the one thing it is is not simpler. In other words, if you take an impression of your bio base, it's simpler, it's easier, cost a little bit more money. If you scan it through a CAD cam, there are costs associated with the CAD cam semi direct technique. But again, you have to have the return on your investment of time with profitability in office. So officers like Simone Deliperi, they're totally profitable with using only the stress reduced direct technique but most officers will use a semi direct made chair side the onlay made chair side or with the CAD cam or an indirect technique taking an impression of the bio base and sending it to the lab for the enamel replacement fabrication. And so these techniques, as they started to become elucidated, it became obvious that certain of the early techniques like Fusayama’s had to be set aside, except in certain cases where there was no hierarchy of bondability. And the example of that is inside a pulp chamber of an indirectly treated tooth inside the pulp chamber. All of the walls have equal amount of hydroxy appetite, so the adhesive grabbing of those walls is equal, and the only stress that can happen is either bringing the walls together, which won't happen in a in a pulp chamber because there's two structures supporting that or the molecules in the polymer will become rearranged. That's exactly what you want with a chemically cured composite chamber restoring an end of be treated tooth. So we do teach Fusayama’s chemical cure approach in ended on thickly treated molars. But you can also use these other techniques to restore endodontically treated teeth. Also, we call that lesson seven. That's beyond the six lessons. But it's a very important technique and we can probably have a whole episode on lesson seven. But the idea is that once this was introduced in 2009 and it was being taught every year in different seminars, in different teaching, I went to Italy seven times. Simone came to United States, Utah twice and teaches at Boston at Tufts every year. And so for ten years, the more aggressive teaching of this stress reduced direct technique was understood as a real option. And around the world where CAD cam access or even lab access might be limited, the idea of a stress reduced direct technique is very attractive, particularly because we had added at that time in 2006 and seven, the wallpapering technique which allowed us to use ribbon to relieve the C factor, stresses to any particular part of the preparation where the ribbond was applied. And when we had our first meeting face to face in 2007, we were talking very specifically about the paper that was published that year by Sema Belli. I told Simone how embarrassed I was when I indicated to Jack that he was doing great research. I really liked his research in Jack, laughed his head off because in 2006 I didn't know if Sema was a man or a woman he knew, and he let me know that she's a woman. But Sema in connection with Simone Deliperi and myself, that connection has been very strong as we've met face to face and the face to face meetings have come at meetings like the International Association Mission of Dental Research. Simone Deliperi and I had a presentation in 2009 in Miami Beach. Back then, I got the year right 2009, 2009 in Miami Beach, International Association of Dental Research. This is when we actually did the final finishing of the article that was published that same year, the presentation that was made at Miami Beach. We had some pretty significant interactions with different leaders in composite dentistry around the world. In Holland, a Professor Nick Opdam was there. He was actually the co-chair of the session that Simone and I presented our research and he's a professor at Nijmegen in Holland. Also, Tom Hilton was there and Tom Hilton's a professor at Oregon. And these two instructors and teachers influenced students greatly. But Simone and I had a different approach that we felt was very applicable and should be taught in every dental school, even if the restoration is not completely done top to bottom with the stress reduced direct technique, the technique needs to be used in these deepest areas where deaden is missing close to the pulp or sub gingival and approximately on a root, because those areas only have 70% at max of the amount of hydroxy apatite that dentin has. That's more superficial. And so we need to separate those bonds from more superficial bonds by this process of decoupling, meaning not connecting them for a certain amount of time. Simone’s first paper in 2002 the decoupling period, it was 3 minutes. We both agreed that 3 minutes was cutting the two close and we would teach for the rest of our careers 5 minutes as a minimum of decoupling with time. And that allowed us to help the bonds strengths in these difficult to bond areas maximize. And then with a layer of ribbond, we were actually able to decouple or even permanently that layer that is deepest to the pulp that has the most importance is saving the pulp cell and it has the ability to stretch. And that stretching is in the ribbond instead of the stretching of the hybrid layer off the dentin which is the foundation of weakening a dentin bond under c factor stresses. So when Simone and I decided to change the world, we needed help. And over the years we have recruited and taught a cadre of teachers of the stress reduced direct composite technique. In 2013, five years after our initial presentation here, we brought Simone over in 2008 to teach her about 30 doctors here in Utah that learn that technique from Simone personally. Ray Bertolotti was in that class. Dave Rudo was in that class. But as the years have gone on, we've seen that the concept that every biomimetic restoration has a direct component is a piece of information that is missed by everyone that isn't trained. They don't get it all. Dentists kind of look at the top of the tooth and they wonder, Wow, you know, how did you get such great anatomy or how did you get such great color match or, you know, the idea that the top of the tooth is what dentists are looking at is a fundamental brain program. You know, you could call it brainwashing, but dental schools really concentrate on how the top of the tooth looks. And no dental school except perhaps Groningen in Holland and Geneva and Zurich in Switzerland and Diego Portales in Chile and Federal University of the Amazon in Manaus. There's probably a universities that dental students are getting. The concept that the most important part of any restoration is the part that's close to the tooth. And so every biomimetic restoration that has a connection side to side, front to back and top to bottom at 30 megapascals or more, they all have immediate dentin sealing and resin coating and a period of time before the next layers are connected to that most important connection of the tooth, which mimics the hybrid layer. So I believe that about wraps up our lecture on stress. Reduced direct technique, publication and history will go more into that in future episodes. Until then, get bonded, stay bonded.