Harvard University
Department of Restorative Dentistry School of Dental Medicine
Okay. I’m going to try to summarize my experience at Bicon. I’ve been here for the last two and a half years. It’s almost going to be my third year already. And I’m going to try to to summarize it in the next half an hour. This presentation usually takes me three hours. But I’m going to try to present as much information as I can. When I first got to the implant dentistry center at Bicon, I was coming from four years as a full time faculty member at the Harvard School of Dental Medicine. A place where I have been working with Dr. Weber, just basically restoring ITI Straumann implants. On my first day there, I remember that Dr. Morgan sat down and he was giving a presentation about the integrated abutment crown. And he presented to me an implant restoration that has no screws. An implant restoration that has no cement, and an implant restoration that is made partly with resin. As a prosthodontist, coming from such a conservative approach, you can imagine I was completely taken aback and I was skeptical. After two and a half years working with this system, and perhaps because of my clinical experience with it, I have completely turned around and I have a completely different view of what this system is all about. Perhaps because I have done cases like this one in which Dr. Daher did the surgery. We had a central incisor in which we had to extract it. It was non restorable. He extracted and placed the implant. Following the technique that Bicon presents and breaking every single rule that I was taught at Harvard, I was immediately loading this particular case. We took the tooth out, placed the temporary or the abutment that we’re going to use temporarily, the temporary coping. We made a temporary and we immediately loaded this case. We placed this and we waited eight weeks. After that, the patient came back, the implant was well integrated, and we took the final impression. We looked at the location of the implant and the health of the gingival tissues. And it came time to place the permanent restoration. As you can see in this particular case, we opaque a little bit the facial of the abutment to compensate for the lack of facial bone in this particular case. We place, this is the final restoration, on the day of insertion. And this is the same restoration one week after we inserted it. On the left side, you can see the temporary restoration. And on the right side, the final restoration. You can see the soft tissue defect that we have in the area. You can see it from the other angle as well, the soft tissue defect that we had in there. Once you have cases like this, it doesn’t matter what they teach you in dental school. It doesn’t matter if you come from where you come. You start believing. There is no question that when you can obtain this type of results and whenever you can do it, extracting the tooth the same day, immediate loading, and then restoration. Then you know you’re in the presence of a remarkable system. You can see here the before and after restoration of the case. And you can see here that with this particular restoration, we can achieve aesthetics. And of course, I’m coming from a very conservative prosthodontic rationale. I’m always looking at how porcelain restorations look. And I’m always looking and trying to improve. But this is a damn good result. Now, one of the questions that I started to come in my mind during this period of time, as I got to restore cases like this, is why can’t we do the same thing with other implant systems? Why can we place a screw retained Brånemark implant in any of these locations? If you place it like this, it will be a highly unaesthetic case. If you place a supracrestal or intracrestal like this, you will have a biologic nightmare. Because Brånemark implant systems have been researched so thoroughly that we know that an implant supported restoration that is screw retained does not seal the abutment to crown interface. Which leads to bacteria in the crevice and leads to bone loss. And as long as there is a screw retained restoration, there is a space. As long as there is space, bacteria goes in and causes troubles. We don’t have the same issues with a locking taper screwless implant. Now, what if I was at Harvard and what if I decided to restore this particular case with an ITI implant? If I do this, because we know that the ITI implants have solved some of the issues with screw loosening and limitations that the Brånemark system comes with. However, we still have to deal with a cemented margin. We know because research has been very clear with this, that margins, you know, lead to bone loss. A gap between the crown and the abutment or the implant has been shown to cause bone loss. So I cannot place an ITI and have an aesthetic restoration in a case like this, unless if I have a lot of the metal showing through the gingiva in a very unesthetic way. But what about cement? Have we thought of the possibility that teeth and implants do not work the same way? How many times have you removed a temporary restoration and found that there is plenty of temporary cement all around the sulcus, despite your efforts of removing all the cement. Well, is clear what happens. And what happens is teeth are not like implants. Unlike teeth, implants do not have one millimeter of attachment zone above the bone. And because of that reason, the cement goes way beyond the sulcus and reaches closer to the bone. So research has also shown us very clearly that whenever the sulcus is deeper than three millimeters, it is almost impossible for the dentist to remove the excess cement. And if the dentist tried to remove it, it can scratch the surface of the abutment and bacteria will follow those scratches all the way to the bone, leading to bone loss. So research isn’t very clear. We just have to look at it. We just have to understand it. So why can’t we use the integrated abutment crown in situations in which we cannot use other conventional systems. We can use it because as Dr. Dibart has shown us, it is a bacterially sealed implant abutment connection. Period. That right there is remarkable. And one of the information I’m going to show you today is going to show you what happens with the bone around that implant abutment connection after a few years that it’s working. Because of that fact, this restoration has some advantages. It has the advantage of being cementless. And because of that, then we can take other, you know, different steps and do different things with this restoration than we can with another cemented restoration. This restoration is also an interesting one because the material it’s made of has the same surface hardness as tooth structure. As you can see here, and much less hardness than porcelain’s. So therefore, will not erode the opposing dentition. It also has the same wear rate. Much less wear rate than the typical composite. And it is fracture toughness is as good as gold’s. But the most remarkable one, and the one I want to continue going back to, is the fact that we need to understand that between the implant abutment connection, there is a very tight seal that does not allow for bacteria to go in. So we have the restoration. Now the question which is which became my biggest effort for the last two and a half years of my life was to show what happens with this restoration in the mouth. Because we know how unforgiving the oral environment can be. And a restoration that can withstand the environment. Now, I had my own doubts. Because I was thinking, oh, for crying out loud. A restoration that’s made of resin, I’m just going to see it break. Well, I will show you what happened. And it was not that it broke. So we devised a retrospective cohort study. And I want you to look at this study with your eyes open, and look at and realize that when they made these restorations, they were not thinking, Dr. Morgan was not thinking that another guy from Harvard was going to come and evaluate the hell out of it. Right? He was just doing his dentistry. And he gave me a door open with no questions asked to evaluate this particular restoration. And that’s exactly what I did. So we performed an evaluation on all these patients. And one of the things I’m most proud of, which probably made the statistical evaluator, Dr. Sean’s life much difficult, is because I had to evaluate every single factor available. So there were more than a hundred variables that we were considering that it had to be taken into consideration. So we looked at everything. We looked at the location of the tooth. We looked at this particular, which became a very interesting part of the study. We looked at whether the restoration had been placed between two teeth, between two implants, between a tooth and an implant, or between only one tooth or only one implant. We looked at the bone quality. We looked at whether they had been placed next to a root canal treated tooth and replacing a root canal treated tooth. We looked at diameter, length, you name it, we looked at it. And I only put here just the most important ones. From the prosthetic part, we went and evaluated just the regular factors that you would expect me to evaluate, like interproximal and occlusal contacts. Like type of occlusion. Like lateral guidance. We evaluated whether the IACs were in function in lateral movements. But of course, because I’m a nerd, had to go and evaluate everything. So I went and I evaluated the type of opposing structure. Were they occluding with teeth? Were they occluding with implants? Were they occluding against porcelain? Were they occluding against everything? Almost, you know, how many times did the patient go into the bathroom? Everything was evaluated in this case. So we had the type also. We evaluated the type of the restoration, how a prosthodontist would. Right? Surface texture, marginal adaptation, anatomic form, and all this. And I was having a field day because I was evaluating the restorations of a general dentist. You know how prosthodontists like to do that. Anyway, in some of the cases, we evaluated things like, for example, these two restorations in the lower right side are IACs. And as you can see in the lateral movements, they are not in contact. On the lower left, the two molars are two IACs. And as you can see, in lateral movements, they are not in contact. Whereas, in this particular case, this is the same patient. You see the two IACs, the two premolars are the ones guiding the lateral movement in this group function. In this particular case, the patient had an upper denture and the two lower molars on both mandibular right and left were IACs occluding against a denture. So does it make a difference? Well, it’s good to evaluate all these factors to really get to know because I need I I told myself, if this restoration is going to work, we’re going to find out. We’re going to evaluate everything and we’re going to see how it works. And if it doesn’t, why it didn’t work. So we looked at, you see these two restorations in here again. You see? I’m showing you that there was every single possible type of occlusal scheme evaluated. Now, we also evaluated some of the soft tissue variables. We looked at plaque index, bleeding index, sulcus, sulcus depth, Whether there had been any bone evaluation before or after the placement. And we evaluated the presence and the type of complications. We also asked the patient what was their opinion. The results, we had one hundred and fifty one restorations that were placed in fifty nine patients. Most of them women, most of them healthy. The majority of the teeth were extracted because of decay, some others because of trauma, and periodontic and endodontic reasons. The survival rate was 96.8%. And that’s because two restorations failed. These two restorations failed because one of them, the implant failed. It was loaded prematurely. So really only one restoration was replaced. And that was in a maxillary anterior restoration that was placed in a patient with no posterior support. Remember, this was done with no planning. This was, let’s restore everything we can and let’s evaluate everything. So there were things that were done that could have been done better. But now, one of the most remarkable results was the fact that I observed no fractures. There was only one small little fracture in the material in an area that was smoothed out and the restoration continued to work. That was, as a prosthodontist, for me, one of the remarkable factors. The other remarkable factor is that with my explorer, I could not find any openings in the marginal adaptation. They are bonded. They are bonded to the metal and and the core material are bonded and there is no space. Only in three cases I could even find maybe a lip and then that’s how I documented it. The vast majority of the cases were classified as excellent or good for all the factors we were looking at. But let’s look at a case. Because when we look at cases, it’s when we get excited and when we get to see exactly what it was on. This was two thousand and two. Okay? And as you can see, there was a failing lower left bridge. They decided to extract and immediately place an implant in the area of the premolar and one posterior to it. But not only did they do that, they bonded them together and immediately load them. If I had seen this picture here coming from Harvard, I would have left Bicon without even asking anything. Because I would have said, oh, for crying out loud, you’re placing this margin here, this implant abutment connection so deep into the bone, how can you? Of course, you can’t do this. So why are you expecting when you see a case like this? What I was expecting is bone loss. This is the day that the crowns were placed. So remember, this is the day, first day that these abutments are placed in there and not removed again. So what happened from here to here, two and a half years later? Well, you can tell for yourself. This is the implant abutment connection. This is the bone. This is the bone. This is the bone. And this is the bone. I could switch this and still tell you that this is two thousand and and two and two thousand and five and you still see no difference. There hasn’t been any bone loss. The bone has grown pretty much all around the implant abutment connection. Look at the tissues around the restoration and look at the before and two and a half years later. This is a restoration that performed well. Another case. This is when the restorations were placed in November twenty second of two thousand and two. And this is this year. I want you to see the pictures of the restoration. I want you to see the pictures of the restorations after two and a half years. Look at the color. Look at the surface. Look at the tissue. But more importantly, look at the bone. Look at the bone. The bone speaks for itself. One of the most remarkable things of this whole study was the bone. I kept looking at it and I kept saying, my God, the bone. Another case, same thing. This was October two thousand and two and this is January two thousand and five. This is a restoration that is made of resin. Right? This is an IAC. This is a porcelain fused to metal restoration. You have an opportunity here to see them working side by side two and a half years later. Well, two years and three months, something like that. So you can see the tissue. You can see the color. You can see the surface. And yes, it has lost a little bit of its shine, right? Porcelain hasn’t. But this is a very good result. But look at the bone. Look at the bone. I just can just go with these slides and keep showing you without having to say a word and you will understand what I’m saying. Because the slides speak for themselves. We are so close to the implant abutment connection. This is where the implant abutment connection is and this is where the bone is. How many years later? So another case, another IAC and another porcelain fused to metal restoration next to each other. So we look at it and we see what’s happened. Look at the tissues. Yes, there has been a little bit of recession in here and we can start to see the metal margin there. But look at the surface, look at the color, and look at the health of the tissue. And one of the good things about this restoration is that if that bothered me, I could remove this restoration, repair that, and put it back in. You can’t do that with any other system. Look at the bone. Do I have to say anything about the bone? Then I continue. Now I’ve been very motivated doing a lot of bone research and doing all these things. And at some point in time, I’ve only done a third of the IACs in terms of measurements. But I can show you, this is one of the first cases that was done. This is November two thousand and one. And this is January two thousand and five. I’m going to show you two thousand and one, two thousand and five. No significant difference. Bone speaks for itself. The stability and the health of the tissues around this are just self evident. This is another case. These restorations were placed in July of two thousand and two. But look at how were they placed? They were placed deep into the bone. Look, this is the margin, the implant abutment connection. This is the bone. They were deep into the bone to begin with and they continue to be deep into the bone and the stability of the bone continues to be remarkable. Without a question, The most remarkable finding of this whole time evaluating this restoration is the stability of the bone around the locking taper implant abutment connection. Now, I found other things. Because as a prosthodontist myself, I was looking at things like this. I said, oh, for crying out loud, this crown is huge. It’s very big buccolingual. So I downgraded some of those restorations because I felt that they were, you know, that thirty five of them were too big. And this turned out to be a relevant finding. Because then when I correlated this to all the other well, I shouldn’t say I. When I and Dr. Sung-Kiang Chuang did it together in many days, you know, at Harvard. Then we found out that it was actually a correlation, but I’ll talk about that later. So we found also some things that we would have expected. We would have expected the restoration to accumulate more plaque. We know from prior research that resin based material accumulate more plaque than porcelain and tooth structure. We know that. And that’s what I observed. In sixty two, the IACs, could go with an instrument and find some supragingival plaque. The majority of the patients, almost one hundred percent, were extremely satisfied with treatment. This is one of the cases in which I saw plaque. And you can see it all around the restorations. But you can see that the tissue is healthy. And you can look at the bone. And again, the bone speaks for itself. Stable. Another of the things that we looked at is Okay, still have time. Another of the things that we looked at was complications. We looked at the complications and we look at them and we said, okay, I wanna look at this. Because since we have so few failures, we couldn’t really do a very nice statistical model. The only thing we had to look for is if we had any complications, that we had some complications. We wanted to evaluate those complications thoroughly. We found that there was pain in one case, in the same patient that had the implant removed, pain was documented. There were four instances in which the occlusion was adjusted, and one instance in which they added the interproximal contact in an IAC, which is something that’s definitely possible. And there were nine maxillary anterior IACs that loosen in that period of time. Now, once we evaluated all those factors together, we found that when I wanted to see these x rays because these are the x rays of the same patient. Left and right. And I want you to see and focus your attention on this tooth here, this lateral. And see the difference between this lateral and this older one right here. The one that came loose was this one. And it happened to be located between a tooth and an implant. We found that if an IAC was located in the maxillary anterior area, and it was located between a tooth and an implant, it was three point three times more likely to loosen. You can see from the space at the well that there is a difference. This crown hasn’t gone down all the way when this one seems to have done. So I want you to pay attention to this because then we’re going to make some hypothesis at the end of the presentation. Now, it is remarkable that only maxillary anterior restorations loosen because this is not what we see in other systems. We see that restorations in posterior mandible come loose, anterior mandible, and posterior maxilla. In this particular system, none of the restorations, except for the maxillary anterior area, came loose. We found that if the crowns had been over contoured in a buccal lingual direction, that they were four point five times more likely to come loose. And of course, this is not a maxillary anterior tooth, but the point I’m trying to make is just the width. Now, we know that maxillary anterior teeth occlude or bite against the lingual surfaces of the maxillary anterior teeth creating forces that are oblique to the long axis of the implant and the implant abutment connection. We know that a lateral load can actually make the crown height act as a lever and increase therefore the forces that are, you know, the tensile and compressive stresses. We know also that wide occlusal tables can have a similar effect and can increase then micro rotation and tipping. Therefore, we hypothesized in the research that we submitted for publication in our prosthodontic journal that the lateral loads present in the maxillary anterior area were increased or magnified by an increase in the buccal lingual width of these restorations, could have caused the loosening of this restoration. Now, we also know that of the nine IACs that came loose, six were located in between a tooth and an implant. So not everything is explained by the anatomy. We found and we hypothesized that because of the different degrees of mobility between the tooth and the implants, it was probably more difficult for the restorative dentist to ensure the complete seating of those restorations. Therefore, we hypothesized that some of the restorations that came loose were not seated properly. Now, because of the amount of evaluation that you have seen in this particular research, for us to come to the conclusion that all these little factors have actually some impact, you realize how thoroughly we evaluated this system. And today, I can stand up here and tell you, restoring locking taper implants with integrated abutment crown is an excellent choice for the restoration of maxillary and mandibular locking taper implants. Thank you.