Question on translucency measurements on zirconia pucks and finding the correct puck

KingGhidorah

KingGhidorah

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So I’ve noticed different places have different ways of measuring translucency. A lot of zirconia manufacturers will use a percentage system from 44 to 51 percent. Then ivovlar specifically uses a system that goes from 3y to 5y. Is anyone familiar with what percentages the 3y to 5y system translates to? I’m also trying to find a specific puck but I’ve had difficulty finding a manufacturer that makes it. I’m trying to find a pre shaded multi layered zirconia, with an even 49 percent translucency throughout the entire puck. Our multi layered pre shaded puck we have currently only has 48 percent translucency. We like the ease of a pre shaded, but my lab also prefers the slightly more translucent cube-x at 49 percent translucency. Though it’s a definite negative that cube-x is not preshaded. 50 percent translucency seems to be a bit too high, so trying to find that perfect spot for zirc, any suggestions?
 
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richgreen

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So I’ve noticed different places have different ways of measuring translucency. A lot of zirconia manufacturers will use a percentage system from 44 to 51 percent. Then ivovlar specifically uses a system that goes from 3y to 5y. Is anyone familiar with what percentages the 3y to 5y system translates to? I’m also trying to find a specific puck but I’ve had difficulty finding a manufacturer that makes it. I’m trying to find a pre shaded multi layered zirconia, with an even 49 percent translucency throughout the entire puck. Our multi layered pre shaded puck we have currently only has 48 percent translucency. We like the ease of a pre shaded, but my lab also prefers the slightly more translucent cube-x at 49 percent translucency. Though it’s a definite negative that cube-x is not preshaded. 50 percent translucency seems to be a bit too high, so trying to find that perfect spot for zirc, any suggestions?
Your Majesty,
Translucency is a function of grain shape, grain size, and sintering temperature. Manufacturers typically use a specific thickness sample to determine translucency. As I am sure you have observed, thicker crowns may not be as translucent as thinner crowns. So a 50% translucent crown that is say 6mm on buccal surface (implant crown) will not look as translucent as a 50% 1.5mm thick crown. So crown thickness plays a part.
Lets talk about 3y-5y zirconia. The 3y zirconia is a highly tetragonal zirconia. 3 mol percent yttria is used to stabilize the zirconia in its tetragonal phase. Due to the shape of the grains there is a considerable amount of light scattering, resulting in an inherently lower translucency material. 5y zirconia has more cubic zirconia in the formula, which requires more yttria to stabilize it in that phase. Because cubic zirconia refers to the shape of the grain e.g. cubic, its shape allows for more transmission of light and less scattering.
To determine the "perfect" zirconia for your needs you may have to obtain 2-3 sample disks to mill units from and compare the out comes post sinter. Your sintering oven may treat the zirconia in a slightly different fashion from the manufactures oven. Be sure to run any test samples at the manufacturers guidelines. You may still need to adjust but its a good starting point. Rich
 
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Car 54

Car 54

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Nice post Rich, as well as a good job regarding your Lab Day webinars ;) :)
 
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