With zirconia formulated by Keating Dental Lab’s research and development team to meet our demanding standards for durability and aesthetics, the KDZ Bruxer® crowns are the most esthetic monolithic zirconia restorations on the market. They are gentle on opposing enamel for bruxing patients, yet strong enough for long-span bridges with an average flexural strength of 1,100 MPa. The KDZ Bruxer® crowns are available in all 16 Classic Vita shades.
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Today I want to talk a little bit about what is an implant and what is an implant crown. Imagine we have two teeth and for some reason we lost this tooth in the middle, whether it be gum disease, whether it be decay or even trauma. We could do a bridge between these teeth, but really in most situations an implant is the best option.
What an implant is, it’s almost like an artificial root. The surgeon basically makes a hole in the bone and then puts an implant that’s made of titanium into that hole. You can see it basically reproduces what your natural tooth roots look like.
After a period of time, typically four or five months where it actually fuses to the bone, then your restorative dentist can place the crown on top of that implant. There are actually threads within the implant. The dentist then will design a crown to fit this space between the two artificial teeth. Then they will screw it into that implant body. This crown can be made of metal, gold, or it could be completely a tooth color, which we prefer.
A new material that we use is the KDZ Bruxer®, which is a tooth colored material that is very, very strong. We can actually put this implant crown to place, and it’ll look just like a natural tooth. You’ll be able to floss around it just like a natural tooth.
The primary goal when you place implants is to make sure we have ideal function so that you can chew and eat properly, and second is that it looks like a natural tooth. We want the implant crown to look like a natural tooth. Keeping that in mind, we may choose different options for our final implant crown restoration.
In the back of the mouth where the esthetics may not be as critical as the front of the mouth, we can actually use metal, even gold, or we can use some of the more opaque ceramics like the KDZ Bruxer®, which is tooth colored but tends to be a little bit more opaque. We can use those because they’re very, very strong. We may have a little bit of compromise in esthetics because of the lack of translucency, but it’s a great fitting material, it’s affordable, and it looks like a natural tooth, especially in the back of the mouth.
In the front of the mouth where want to optimize esthetics, we prefer to use all ceramic restorations. That can either be screw retained, where the crown is tooth colored, it has a little hole in the back and we screw in the implant, or it could be cemented where we actually put what we call an abutment on the implant. Then we actually cement a tooth colored crown. That gives us optimal control in color and esthetics.
Be sure to talk to your dentist about options, again, whether it’s in the back of the mouth or in the front of the mouth. Also where the implant is placed in relationship to adjacent teeth may have some factors in what the final restoration’s going to be. Be sure to ask your dentist about what your options are and what they would prefer in their own mouth.
Today I want to talk a little bit about implant restorations. The big question that always comes up is should it be cemented or should it be screw retained? There’s a lot of factors that go into that. One of the very first ones is was the implant placed in the right spot? If I look at some cases here, and you look at this molar, it was probably placed using a surgical guide. It’s right in the middle of the edentulous space between the molar behind it and the premolar in front of it. This is ideal where I can do almost anything I want. My preference in the posterior is to do screw retained.
If for some reason we had failure, whether it be fracture of the ceramic, a screw came loose, or whatever the factor is, I can go in and I can access it through the access opening, unscrew it, take it off, do a repair, send it back to the lab. I just think it’s easier to get to. If it’s in the center, if it’s in the ideal position, we can either do screw retained or we can cement it. A case like this where it’s a replacement of a premolar, it’s a small implant. The implant was placed really too far distally. This is almost impossible to do a screw retained because the screw hole would come out right through the marginal ridge, and we wouldn’t get enough support of the abutment or the ceramic around that screw channel.
This is a situation where really we need to make a custom abutment and then make a cemented crown. We could go over dozens and dozens of cases, whether it be anterior or posterior, just looking at implant placement of whether it’s mandatory that it has to be a custom abutment versus screw retained. Here in the anterior, two implants. The position makes it impossible for us to do screw retained. The screw channel would come out right through the facial or the facial incisal, so the only way to fabricate a final restoration here is to make custom abutments, angle them toward the lingual, and then we would do cemented crowns. In the anterior, also, we’re going to look at what do we want to have as this final restoration how much control we have.
If we had an implant and we decided to do a screw retained, we can actually have a titanium base, and this would be our screw channel that would go through the titanium base. Then we can have the coronal aspect of that implant crown be so that the lab keeps a hole in the top of the crown. Let me go ahead and erase this. We go ahead and put the crown to place, screw it into the implant abutment, and then we would just fill this whole with a composite so that it blends in. That would be screw retained.
If it was an anterior tooth, let’s say a maxillary central, so we have our implant still, ideally I would like more control of the final restoration. What I would prefer, and I can still have a titanium base … This originally was the UCLA style of abutment. This would be titanium. Then I would have the lab make me an ideal prep, and this could either be zirconia or it could be lithium disilicate, and then they would make a crown to fit over this abutment. The advantage of this is I can actually have this zirconia or this lithium disilicate shaded dentin shade. So this could be like an A2, let’s say. Then this final crown, which could be glass infused ceramic, it could be lithium disilicate, it could be one of the new aesthetic zirconia crowns like our KDZ Bruxer® Aesthetic, then this can be made very thin. In fact, sometimes we’ll even make this at 0.5 to 1 millimeter.
Now it gives us the opportunity to have a very translucent restoration. We’re going to bond this into place, bond it to the abutment. We’re going to bond it utilizing a resin cement. We can actually alter the shades of our final restoration based on resin cement, almost like we’re cementing a veneer.
Two primary factors, where was the implant placed, again, in the posterior I prefer screw retained if I ever need to access those in the future, and how much control we want for esthetics. In the anterior, I tend to do cemented crowns over an abutment.
The question is gold or ceramic for a final restoration? It used to be gold was really the gold standard. It fit well, it was a conservative preparation, and it was durable. Today we have materials that in my opinion are better than gold. One of them is zirconia dioxide. At Keating Dental Arts it’s called the KDZ Bruxer® for the back of the mouth and the KDZ Bruxer Aesthetic® in the front of the mouth.
The advantages of the Bruxer over gold, one is cost. The most expensive restoration that we fabricate in our dental laboratory is a gold crown, which means our patient is going to have to pay more for that crown. So, number one is cost. Second is conservation of tooth structure and durability. The nice thing about the new zirconia, it’s basically a gold-like prep. It used to be when we had metal and we overlaid it with ceramic or some of the weaker ceramics, we didn’t have a very aggressive prep. Sometimes it was a millimeter and a half, even two millimeters, where gold was .5 to a millimeter. The new Bruxer zirconia, we can have occlusal clearance of only .5 millimeters. That’s a gold-like prep.
Axial reduction, how much do we remove from the sides of the teeth and interproximally? .5 millimeters. We could have supragingival margins because of the translucency. This material is stronger than any porcelain we’ve ever placed on a porcelain-fused-to-metal crown. We have conservation of tooth structure, durability, and if we go back to cost, one of the most affordable restorations that we offer here at Keating is our Bruxer, which offers huge benefits for our patients. We look at esthetics, most of our patients at one time maybe they didn’t mind showing a gold crown. Now they’re having gold replaced because they want tooth colored restorations. Now we can place a very durable restoration, whether it be in the front or the back of the mouth, that is affordable, conservative, and esthetic.
One of the hot buzz words in dentistry right now is bioactive. Is this restorative material bioactive. Is this cement bioactive? What bioactive means basically is that it’s a substance that interacts with living tissue. I like to classify bioactive as regenerative, restorative materials where there’s an interaction that will actually regenerate or form healthy tooth structure when it’s associated next to these bioactive or regenerative materials.
Now if we think about when we would use these type of materials, bioactive’s not new in dentistry. We’ve actually been using it for over 25 years, some of the coatings that they used to put on implants to help with osseointegration. We would actually see some of the appetite interact with these coatings of implants, ideally to help them to integrate more efficiently. Now the product I want to talk about today is called TheraCal L C from Bisco Dental Products. I like to say it’s a calcium hydroxide on steroids, because we do have situations where we either have a direct pulp exposure or we have very, very deep dentin where we’re concerned about sensitivity and we want some remineralization in that deep dentin.
Traditionally, we use calcium hydroxide. The advantage of calcium hydroxide is it’s easy to place and had been used in dentistry for many years, so we had some clinical experience, and it did kill bacteria because it had a very alkaline or basic pH, so it killed bacteria. The problem with Dycal is it didn’t bond to the tooth. It didn’t bond to the overlying restorative material. It was very water soluble, and it had very poor compressive strength. We’ve all taken out existing restorations, usually amalgams, and there’s either a void underneath the amalgam or it looks like cottage cheese underneath the amalgam because either we or another dentist in the past, when they had a deep cavity preparation they placed Dycal, and then with the leakage of the amalgam it just washed the Dycal out.
Dycal’s an option, not a great option in my opinion. The next is glass ionomer. We were excited about glass ionomer when they first came out because we had fluoride releasing properties. Now the advantage of glass ionomer over Dycal was it actually was a little bit more durable once it set up. Also, it bond the tooth structure a little bit. The problem is that glass ionomer [is toxic 00:14:47], and you don’t want to put that on a direct pulp exposure. We could put it in deep dentin but, again, we don’t have really high bonds and we don’t have high compressive strength.
The third material, which has great studies, is MTA. MTA is mineral trioxide aggregrate. Endodontists really started to use that when they had perforations in roots or when they were trying to get apexification. There’s great data that we actually do get interaction and new appetite formation when this material is in close proximity or interacts with dentin. The problem with MTA, it has about a three hour set time. That’s not a problem for endodontists. He puts it down a canal and seals it. Certainly a problem for me as a restorative dentist. I’m not going to sit around and wait three hours for this to set up before I can place my restorative, so that’s not a good option for me. Recently, and this is where TheraCal L C comes into play, manufacturers have created what we call resin modified calcium silicate cements, and that’s what TheraCal is.
What this is, it’s actually a resin based material that has chemistry similar to MTA, and it is bioactive. We actually get an interaction between the tooth. We get new appetite formation, when it’s associated next to the TheraCal L C, this regenerative material. Now where we use TheraCal L C is direct pulp caps, awesome for that. Once we control the bleeding, assuming that it’s not necrotic, we go ahead and put a very thin layer of TheraCal. Typically we like to keep our increments to a millimeter or less in thickness. It has a photoinitiator in it, so we actually light cure that, and it sets hard. Then we can move right on to our restorative.
Now what’s different between TheraCal and some of the early silicate cements is TheraCal actually has a hydrophilic monomer that allows interaction with the calcium hydroxide and the calcium in the tooth and the TheraCal, so we do get ionic exchange. Some of the early cements, they were so hydrophobic that water could not allow that ionic exchange, so they weren’t really regenerative or bioactive. I’ll use TheraCal L C direct pulp caps, and then after I place it in light cure I can go right to a total etch or a [select 00:17:18] etch, whatever you like to use with your restorative, and I’ll also use it in areas where I have very, very, very deep dentin exposure, maybe not a pulp cap, but I’m worried about thermal sensitivity or postoperative sensitivity by having that restoration so close to the pulp. I’ll put a very thin layer of TheraCal.
It sets up very quickly, 10 to 15 seconds, and then I can move on with my restorative. Hopefully, you’ll get a chance to look at TheraCal L C. Again, these bioactive materials, these regenerative materials are going to change the way we do dentistry in the future. Imagine if we could have a cement for our crowns or a restorative material that actually interacted and remineralized the tooth as that microscopic roughness between the restoration and the tooth, as that demineralized, we’d have this interaction. These restorations could actually repair themselves.
This is the fastest growing restoration in the history of dentistry. We really have two different materials, or two applications for this. The first one would be what we call the KDZ Bruxer®. Now, this material is the strongest all ceramic material that we have, the flexural strength, and I’ll talk a little bit about flexural strength now. Imagine if we had two little saw horses, we put a bar of ceramic across that, so this would be ceramic, we applied a force, how much force would it take before this ceramic broke?
That’s flexural strength. The flexural strength of the KDZ Bruxer® is about a 1000, to1,200, megapascals. Now to give you a relationship between that and a PFM, the ceramic that we put on ever PFM, everyone you’ve done and I’ve done, has a flexural strength of only one hundred. You can see that our KDZ Bruxer® has a flexural strength and I’m going to relate flexural strength to potential durability of the material because the patient bites down on the functional cusp, functional fossa, let’s a pre-molar as they go through lateral and they hit against that, could be a working or balancing interference. Our KDZ Bruxer® is ten times stronger than a PFM.
Now, the KDZ Bruxer®, the limitation, however, is it’s opaque, so we’re going to limit it to posterior applications. Where I do a KDZ Bruxer® are on molars, especially with limited occlusal clearance. We can actually make the KDZ Bruxer®’s 0.5 mm occlusal reduction, the thinness on the occlusal. The second time that we use this is as a bridge in posterior. Again, we have a flexural strength of a 1000 to 1500 megapascals and so when we’re doing a multi-unit bridge in the posterior, closest to the hinge axis, we want to make sure we that we use the strongest material possible.
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