CEREC TiBase Lecture Series - Post Mill Processing & TiBase Attachment

Hi there, welcome to the post-mill processing discussion portion of our CEREC tie base lecture series. Here we are going to etch, micro-etch with 50 micron aluminum oxide particles. This video is through the little protective window in the micro-etcher. You'll notice I'm only etching above the rim and I'm holding the tie base in such a manner so that the rim protects the rest of the tie base from the micro-etching material. We want to make sure that we're only micro-etching above the rim and it just needs to be a minor micro-etch, just enough to increase the surface roughness so that we facilitate increased retention of the ceramic to the tie base. It doesn't have to take very long, this is real time. You'll notice it's only taking about a minute, maybe a minute and a half. And here is a quick view of what it looks like after I've micro-etched it. Notice you can see the roughness, you can also see the letters and numbers. Certainly you can spend some more time and go ahead and blast all that off, but it's not really critical. We just want to increase the surface roughness of the tie base. Now I'm going to demonstrate my personal polishing technique for just about every ceramic that I use. This is an Emax restoration, so first and foremost we're going to cut the sprue off, then I pull out this gray wheel from Meisinger and go ahead and do a pre-polish on the restoration. Notice I'm using a pen thumb grasp with a very tight fulcrum. My thumbs are touching there so that I don't have to worry about bumping myself. I am right-handed, so that wheel is actually spinning counterclockwise, downward toward the margin. If you do this right, you should generate some heat as you're applying pressure to the ceramic. So you'll have to take it easy, don't do it too fast, you'll burn your fingers off and be very cautious you don't tear your fingers up with the polishing wheel. Normally this will take me about 30 seconds to a minute to go ahead and do this pre-polish with the gray wheel. I'm going to hit all the surfaces of a standard crown or bridge, veneer, inlay, onlay, but with the tie base restoration, with this hybrid abutment crown, I'm not going to polish the flat interface that will touch the tie base. That needs to remain untouched. After initial pre-polish, which again takes a minute, maybe a little bit more, I'm going to switch to an extra stiff Robinson bristle brush and use some fine, not the extra fine, but just fine diashine or diashine polishing diamond paste. Now it should be noted when you're using this paste, you need to generate some heat and allow it to melt into the brush and then the same applies for the ceramic. You have to hold it there. It takes time and pressure for this paste to do its job. If you're doing a once over too fast without actually pushing the brush, you see how much pressure is being applied, pushing almost to the metal hub of the brush. If you're not doing that enough, you're not going to generate the shine or you're just not going to generate it very quickly. Lots of pressure and time to do the final polish on the restoration. Now it should be noted that with this particular example, I did not put any stain or glaze on this particular hybrid abutment crown. I do a lot of staining, not so much glazing. I like to stain and then polish after it's fired. But this particular situation, I did not demonstrate any staining and glazing. We will talk about that in a different video. But for now, you'll notice I'm just polishing all the surfaces that were pre-polished with my extra stiff Robinson bristle brush. And if you're doing it right, you might get five crown polishings out of one of these bristle brushes. They tend to wear out if you're pushing hard enough on the surface. You can see that shine we're generating just from a two-step polish, a pre-polish and then a paste polish with the brush. You can do a really good job of polishing here in a matter of two or three minutes. I usually end up doing my polishing in a couple of minutes or less. And you can see I've left that flat interface untouched. At this point, it would be ready to stain and glaze if you so desired. So I did not stain or glaze it. I just fired it. Now we're going to go ahead and demonstrate the attachment process of attaching the tie base to the ceramic. And I've got a couple of different examples up here. What I like to do first and foremost is make sure that the pieces fit together. Oftentimes after firing, you'll end up with a little bit of object fix inside the interface. So we want to make sure that they seat completely together before moving on to the next step. So I'm trying it in there. Pretty tight fit. Sometimes you have to use an instrument to push it back out from the other end. And if you want to, you can go back and micro etch just the tie base again, not the ceramic. First step is to silenate or prime the tie base itself, the ceramic. Not the ceramic, just the tie base. So I'm using a straight silane on the tie base only. Now the instructions with this particular silane are to apply and allow 60 seconds of reaction time. 60 seconds, a full 60 seconds. My experience generally living here in New Mexico with almost zero humidity is that the silane itself will evaporate. The excess silane will evaporate within about a minute. If it doesn't evaporate, the next step would be to air dry it so it's totally dry. Now care should be taken that you don't get any water on this interface because that could interfere with the bonding protocol between the tie base and the ceramic. So a good 60 seconds of reaction time allowing the silane to prime effectively the surface of the tie base. Okay, after we've allowed 60 seconds of reaction time, the next step is to make sure it's completely dry. You'll notice it looks like the tie base is already totally dry and I'm just using a straight air stream. There's no water, there's no micro etch, nothing in there, it's just air to dry it. Once it's totally dried, once we've dried the tie bases and set them aside, the next step is priming and preparing and etching the ceramic. I like to use this monobond etchant prime which is an Ivoclar product. It basically takes two steps, a separate hydrofluoric acid etch step and a silane step and combines them into one. Now the protocol for this material is to apply the etchant prime which they've colored this nice turquoise blue color, green blue, to the interface which will be bonded. There's a 20 second scrub and then a 40 second reaction time. Basically the 20 seconds allows you to scrub off any impurities or imperfections that may interfere with the bonding and then the 40 seconds allows a complete reaction time for the etchant prime to go ahead and finish its job preparing the ceramic interface. Now it should be noted that when you're doing this you want to scrub all the way up into the area that you're going to go ahead and seal after the implant is placed. That way you don't have to try to prepare it in the mouth. It's already etched and primed and ready to go so when you get your implant placed and torqued you can go ahead and just bond the composite into that hole, the screw access hole. A good full solid 60 seconds of reaction time is what we need with this material. 20 second scrub, 40 second reaction, a total of 60 seconds. After the 40 second reaction time we want to rinse the ceramic fully and thoroughly. So good rinse with just clean, good clean water. There's a sink to the left you can't see and then a solid drying out just to make sure that we get all the excess water out of there. Once it's all dried and totally clean and make sure that you've done your steps correctly it's now ready to go ahead and bond to the tie base. So we're going to demonstrate that now, the bonding to the tie base. There's a specific cement that should be used when bonding to the tie base and that is the hybrid abutment cement from Ivoclar. I would caution you when you go ahead and do your bonding procedure to place the screw in the tie base before you attach it to the crown. The tie base, rather the crown itself, the block is designed to retain a regular platform size screw so it won't come back out of the block. So place the screw in the tie base before you bond it. This is a self-curing, this multi-link hybrid abutment cement, which comes in different opacities. This is a self-curing, not dual cure, self-curing cement. We always want to do a double bleed so I've bled it once before I put the mixing tip on and now I'm going to bleed it again just a little bit to make sure we get a nice clean mixture and then I'm going to apply it to two things, to the inside of the crown which you see here and gently scrub it around with a clean micro brush or a explorer or a perioprobe or something just to make sure that all of the surfaces are coated and then I'm also going to apply it to the tie base. Now this is a self-setting, it doesn't set up, it doesn't set up at all with a light reaction so it's a nine minute set. I'm applying this again to the tie base and the inside of the ceramic. Once you've applied it to the ceramic you want to scrub it around, make sure that we've got it nice and even, just to ensure that we've got a good coating of this opaque cement, which again comes in different opacities to help block out the grayness of that tie base. Next thing is you've got to line up the groove with the slot on the inside of the crown and you can see I'm spinning it around until it drops into place and then I'm going to hold it together. The instructions are to hold it together for a brief amount of time, 10 or 15 seconds, to make sure that we get it pressed all the way together. After that what I like to do is allow it to sit. So we have to be cautious that we don't get any of the cement in the screw interface or up in the screw head. So a good way to protect that would be you could put some foam or some cotton up inside to protect the screw head. A lot of docks will also use wax which is just fine. I've found that if you're careful and cautious when you're applying that cement you don't necessarily have to worry about it too much, but if you do get a little bit that starts to go down into the screw channel in the top of the hybrid abutment crown, once it starts to get its initial set you can stick an explorer in there and kind of pop it off. I haven't had any issues with gumming up the screw at all as long as you you're careful and cautious. So the instructions are to let it set for a couple of minutes. You can apply like a glycerin to prevent an oxygen inhibited layer after you pop off the excess cement. What I like to do now is after three or four minutes, once that cement starts to get really hard, sometimes I'll pop it off and apply a glycerin. Most of the time I just set it aside and go back to my patient work and come back to it 10 or 15 minutes later and then that cement will literally pop off as a ring. It comes off very very easy and then you polish that interface to ensure that we've got the tie base burnished against the ceramic. But the full set time on this cement is nine minutes and it's an auto cure, not a dual cure. Dual cure, it's a self-cure only, so light won't help. I've been asked a lot of times can I use my own cement? I think the answer is yes. It won't be nearly as opaque but it will be faster. I've done it in the past. Ivaclar recommends that we use this particular cement, the hybrid abutment crown or the hybrid abutment cement, as it is designed for this indication and will probably provide a little better retention because it's specifically formulated. So here you see me with a paper towel wiping off that excess cement. Now the cement is not totally set so you want to take care not to dislodge or jar that abutment, the tie base from the crown. So be careful, be cautious, but the full set time on this cement is nine minutes. So set it aside, go back to your work, come back to it once it's cured. So once you're confident that the cement is totally cured, you want to go ahead and clean off that interface and I've got a micro brush here that I'm just going to scrub off the extra cement. Sometimes if you've got a little chunk in the inner surface there or the screw channel, I'll use an explorer to pop it out, break it loose. At this point because of the height of that crown in relation to the screw channel, it's a good thing that the screw is already in place otherwise I would not be able to get the screw out or in because of the way those blocks are designed. They're designed to retain that screw. Now if you have a very short crown on a tie base, chances are that retentive area will be milled out and so the screw will come in and out pretty easily on a regular platform screw. Now a narrow platform screw on the Noble Active implant, the channel is wide enough for the screwdrivers that that screw will come in and out on its own, but a larger 6mm platform on the Noble Active conical connection, the block will retain the screw so make sure you put that screw in before you attach the tie base to the ceramic. So here's our armamentarium for attaching an individual crown to a tie base. Now you'll notice up on the top I've got the separate hybrid abutments with an individual crown. So as you're preparing those it's the same process, you're attaching the hybrid abutment to the crown and then you're cementing the crown on afterwards. So essentially the same process, nothing earth shattering or groundbreaking about that process, it's identical to what we just demonstrated here. Okay thanks for watching, we'll see you again in the next video.