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Building the Bridge from Dentist to Ceramist: Why Communication Matters Part II

Part 3 - Completion of the anteriors and why contours are so important.

Tom Trinkner, DDS
Matt Roberts, CDT

We may not want to go straight in one into full contour that's going to add about 3 quarters of a millimeter of height and that might be too much translucent so I'm going to feather just a little more dentin in that area especially on this tooth. This tooth is just a little more lingualized than the other one. You have to remember tore-member how natural teeth are formed. You have dentin of your lobes with enamel deposition over the top of them. Most of your color and opacity is deep within the dentin right around the pulp chamber, around the core of the tooth, and your enamel is very prismatic relatively milky clear material over the top which extends all the from the CEJ to the incisal edge so I think many technicians tend to under utilize some of the more opalescent enamels and they're afraid to put them on too thick and some of the older porcelains systems a clear porcelain tends to lower value and gray things out a little bit and especially if you're coming over an opaque PFM to thick of layers of enamel sometimes work against you and you don't like the looks of it. And all ceramic restorations we're getting light interaction with the under lying tooth structure as well as the ceramic itself and the rules are a little-different there. For me at least with my style of building I like thicker enamel layers when I can do it. Porcelain has incredibly strong compressive strength. You can squash it and it won't crush but it has lousy tinsel strength you can snap it like a twig if you load it into a bridge configuration. So with Zirconia they've designed a very high strength ceramic material that has good tinsel strength that acts as a support for the layering ceramic and comes over it that has the aesthetic quality that you want to it and the porcelain shrinks a little bit compressively around the core material whether it's Zirconia or it's PFM substructure and you get some added strength from the compressive forces as well in your porcelain. But different ceramics have different flex of under ural strengths. Typically, and I'm not sure what Lava's layering porcelain has. Most of the porcelains I know of that are going over Zirconia have a flexural strength of under 100 MPa. The leucite reinforced porcelains like Empress or Authentic have flexural strengths in the area of 100-200 MPa depending on whose numbers you read and which system you're talking about. Lithium disilicate porcelains like Empress II or Eris or some of the components of the new emac system have flexural strengths so they of around 400 and those have less than ideal aesthetics so they have to start being layered again too and then your procera copings have a flexural strength, those have luminal cores, those have flexural strengths of around 600 and Zirconia has flexural strength of 900-1200. So Lava copings fall into that range. I'm now just internalizing them. That an internal structure in the tooth and all I'm doing now is just building a nice clear glass layer around all those colors. That will give it some depth and some vitality hopefully if I do everything right. We'll just put the final touches on our shape here. We've got it pretty well worked out now. We might want a little more brightness up here at the incisal third on this patient just because they were kind of oriented that way. I'm going to grab a little bit of the N2 or N3 porcelain and I'm just going to bring the value up a little bit. Remember as much as I like translucent incisals and very dynamic effects, the patients lower teeth didn't exhibit as much as I would have initially layered in there. They had a very bleached out enamel that wasn't super translucent over the top. What we may find is something that that may relapse a tiny bit so I'm shooting for something that has a little bit more effect than the lower teeth do but still has a little bit of internal anatomy and an overall white appearance. I think without trying to Mike you made the point perfectly just a moment ago when you asked me if you had mammalons in your teeth and I couldn't tell you from two feet away without having direct lighting on the tooth and grabbing some loops. You don't want them to stand out and if they're done naturally there's just a little bit there that shows up under very close personal space conditions or under good digital photography. Probably the most frequent condition they are seen in is on a 60 ft wide screen in a dental presentation. That's their natural environment. Contour on the other hand, you can see lousy contour from 30 feet away. So at that stage let's check our stick bite again. Let's see where we are with our stick bite. Let's do it off camera for just a second. I don't want to move everything under the camera at this stage. We're good but I'm seeing one thing here and it's good to change your view every once in a while. I've been looking under the scope quite a bit and it's wonderful for detail but sometimes your overall multi-tooth aesthetic you start to miss and what I just saw looking at it outside the scope that had been staring me in the face and I missed it is this tooth is lingualized. This tooth is out much more into arch form. The mesial of this lateral is tucked in too much so as long as that's still damp I'm going to pick up a little porcelain and bring that out facially just a touch so that we cure that. I think I just under layered the enamel layering on it. Get that deflective zone so that the radius tightens as it comes into that area. Keep the middle lobe a little higher than the mesial lobe. The mesial half of the lateral reflects to the front of the mouth, the distal half starts to turn the corner and so it is a tooth that has the middle lobe the highest point of the tooth and just the opposite where the central is. Central your middle lobe here is the lowest area. There's triangular depressions coming off the mesial lobe and a little bit off the distal lobe but overall in the incisal third your middle lobe is lower than the mesial and distal here it's higher. Let's see if that brought that out. Almost. Not 100%. Again,you'll notice the different angles I'm looking at as I'm evaluating my contour. I'm looking here it looks flat. I look here and suddenly you can see Oh yeah you get kind of a chunky depression going on out there in the middle. OK,I've solved that one so let's slice these apart and fire them and see what we get out of the oven. We've got the anterior restorations are about 90% done. We did the buildup on that yesterday and we have it to where the contacts are close to being adjusted, they're a little bit light still. We have a couple of our areas where our margins need to be filled in but what I want to do now is build Zirconia based lava restorations in the posterior, get everything built back up, I'll take the pieces of wax off and put the Zirconia copings on. If you remember us discussing this earlier the second molar on the right side had a very black prep and a metal build up inside so I'm going to use some opaquing modifier to cover that and that will probably be the only tooth I use opaque on the rest of them I'm just going to use some fluorescing stains to give a little color gradient to the lava copings. We'll do one firing of that and then we'll start our dentin enamel build up and build up some teeth. This is their framework modifying porcelain that's opacified; I'm using it in a bleach shade. I don't use it everywhere because it does block light transmission and has some less than desirable aesthetic implications but I think with most patients a little bright is better than real gray for final results. I find that with our public today that if I'm going to air, air on the white side. We used to think A1 was a bright shade now it's one of the darker shades that we get to use in dentistry. And that's not universally true,there are still many dentists doing good quality dentistry that try to match existing natural dentition. It's just with the advent of bleaching many patients have bleached teeth that are brighter than A1.