Dear friends, welcome to this unit where we will be discussing about Implant Placement with simultaneous Guided Bone Regeneration. This is a technique that is very helpful especially in the anterior maxilla, and we will use our examples in this region. As we know, every time we lose a tooth, we're actually missing much of the surrounding tissues. The most pronounced of this loss is actually the loss of the alveolar bone, which shrinks the dimensions we have to place an implant in both height and width. So if we actually want to place the implant in the ideal prosthetic position, we have to achieve primary stability from the existing bone, the remaining bone, and regenerate the missing one. In this technique, the implant is placed usually six to eight weeks after the extraction. In this time, we have achieved only the closure of the soft tissues, but of course, not any healing of the bone. And therefore, the key is whether we have enough bone to support the implant and give us primary stability, or not, because if we do, then we can continue with the Guided Bone Regeneration. If not, we will have to consider other two stages augmentation procedures. So, prior to planning and decision-making for such a case, I think we have to have a very good understanding of the local anatomy. And when we suspect that we will be using an augmentation procedure, Cone Beam CT, a 3-dimensional radiographic representation will be very helpful. I would recommend to take the Cone Beam CT with radiographic splint. That means that we prepare a radio-opaque imitation of the crown that we're about to replace. We place it in the position it should be with the splint, and then we make the Cone Beam CT. That will give us a very good representation of the prosthetic component we're trying to recreate in relation to the existing bone. And of course, this way, we can estimate much better where an implant should be placed, and if this would be possible. Another interesting tip is to make your Cone Beam CTs with lip or cheek retractors. This way, the lips will not collapse on the alveolar ridge and you will be able to visualize much better the oral mucosa, or the gingiva surrounding the alveolar ridge. These images that you see here came from a publication by Januario et al. and the radiographic image on the left is without retractors; on the right is with retractors. You can see how a high-resolution Cone Beam CT can give us a good understanding of the soft tissue anatomy as well when we retract the lips. So, once we have the Cone Beam CT and we have our radiographic examination, then it's time to go in detail through all the slices. There are three major things we have to look at in this Cone Beam CT slice. We have, of course, to look at the height, that we have enough height to place an implant, usually in anterior maxilla, because our primary stability, the good-quality bone is in the apical direction, we might need to use longer implants, maybe 12 millimetres long, or so. The second thing is to see if we have the width throughout these 12 millimetres to surround an implant fully in-bone. And of course, we have to also scan for the relation of anatomic structures such as the incisal canal which might interfere with our placement. So, talking a little bit about the height, in an ideal case, we have enough height to support our implant and width. If we only have enough height but not enough width throughout this height so we have a palatal wall and maybe mesial-distal but we were missing the buccal, this is an ideal case for Guided Bone Regeneration. Now in the case where we don't have height and we don't have the width, then this is when we should consider other staged augmentation procedures. How do we evaluate the width now? Ideally, we want to have our implant fully imbedded in the bone. So we want to have at least one millimetre, maybe even two millimetres, if possible on each side of our implant. That will be the ideal case. But it's not the only scenario. It might be also other favourable scenario. For example, like we see in this image, we are missing some part of the bone, so some part of our implant is exposed. But the critical thing here is that the exposed part of the implant is actually smaller than the diameter of the implant. In this scenario, we can still get primary stability from the surrounding bone, and we can replace the missing bone with the augmentation. But there would be also some unfavourable scenario. And this is mainly when the exposed area of the implant is wider than the implant diameter. In these cases, we are very unlikely to get primary stability. So if the dominant anatomic condition belongs to this category, then probably, we have to consider a staged augmentation. So as a rule of the thumb, it all boils down to try to evaluate how much of the surrounding bone belongs to the ideal or the favourable condition, and how much of the surrounding bone belongs to the unfavourable condition, and then decide if this will be a good case for GBR. My rule of the thumb usually is to divide the implant in three segments: A, which is the coronal part; B, which is the middle third; and C, which is the apical third. Then I will go back to my Cone Beam CT and I will see for each of these three segments of the implant what is the dominant anatomic condition. So if A or B or C, so at least one of your three segments is in the ideal anatomic conditions, that means fully surrounded in the bone, I think then we can get enough primary stability and recreate the remaining missing tissues as long as we have the bone height at least in one wall. Now, if A and B and C, they all belong to the favourable condition where the exposed part of the implant is smaller than the implant diameter, then we can still get primary stability and good conditions for placing the implant, and we will recreate the remaining bone with the GBR technique. However, if A and B and C, they belong to the unfavourable conditions, then this is when we should consider a staged augmentation, or maybe a Block Graft. Let's see very, very briefly some of these in clinical applications, and then the rest you will be able to see in the detail in our procedural videos. In this particular case, we have a big buccal defect, the implant is placed, and the whole coronal segment belongs to the unfavourable bone condition. It's exposed quite a lot. Nevertheless, the two other segments they're fully imbedded in the bone; this is a very good case for a GBR. So once we achieve primary stability, we will cover the implant surface with bone chips from the neighbouring bone and our grafting material. Cover everything with the barrier membrane and this case, leave the implant for healing through the mucosa.
