White ring at sprue

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JDD

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I'm going to try a6 gauge. If the theory of length be less than width then I'm going 6 at 4 mm and make the length 3.5.
Those logs going down the tube will have more room to manouver. It's their theory. We will see tomorrow. I will post the results for you if you would like. I'm trying anything.
 
ps2thtec

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I'm going to try a6 gauge. If the theory of length be less than width then I'm going 6 at 4 mm and make the length 3.5.
Those logs going down the tube will have more room to manouver. It's their theory. We will see tomorrow. I will post the results for you if you would like. I'm trying anything.

Hey JDD, the 6ga at 4mm is overkill. Won't eliminate it. It's something we just live with and "hide" it by sprueing all posteriors on the lingual. You do want to sprue to the thickest , so just beef up a lingual cusp if you have to and contour back after press. Stay with 8ga and 3mm length. Your connection to the crown should be like the top of a funnel, not constricted so the "logs" flow better. And sprue angle is key too.
After stain and glaze the spot appears to disappear, or blend in. Most times I would say it's not an issue.
Now if you want to try anything, we haven't talked about the Super ring for a while.;)
 

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Hey JDD, the 6ga at 4mm is overkill. Won't eliminate it. It's something we just live with and "hide" it by sprueing all posteriors on the lingual. You do want to sprue to the thickest , so just beef up a lingual cusp if you have to and contour back after press. Stay with 8ga and 3mm length. Your connection to the crown should be like the top of a funnel, not constricted so the "logs" flow better. And sprue angle is key too.
After stain and glaze the spot appears to disappear, or blend in. Most times I would say it's not an issue.
Now if you want to try anything, we haven't talked about the Super ring for a while.;)
Let me be sinical for a minute. Emax sucks and we have to sell the product. This is probably why they came up with mill Emax. To avoid what they couldn't fix but make a million off of. Ok I'm done. Back to patchwork quilting on the emax. I hate giving a used car to someone who pays for new.
 
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I'm pretty sure the came up with emax CAD to eliminate all of the time and archaic steps involved in a finished crown and add another product to sell.
 
ps2thtec

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image.jpeg I wouldn't call this a used car. Excuse the crappy iPhone pic. Maybe the milled came out so you can feel that sharp poke in the back side.:eek: These are great restorations. We just seem to be doing less with the surge of the FCZ ....?
 
ps2thtec

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I'm pretty sure the came up with emax CAD to eliminate all of the time and archaic steps involved in a finished crown and add another product to sell.
.....and that too!
 
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If I have to produce a true to life crown that's going in the mouth of someone I love, its going to be e.Max.
 
Sda36

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Does any body know how to get rid of white ring with dark center at sprue area of all presses. I've talked to techs
Etc. tried every thing that I know of. Doesn't matter if it's LT HT or MT. Can't get rid of it. I use a Zubbler press oven.
It's not your pressing, it's the nature of the crystalline structure of the material. Picture a bunch of logs flowing down a river. That's the way the crystals are and flow parallel to the sprue. Gives kind of a fibre optic effect where you may not like it. Try spruing from diso- lingual cusp areas and certainly avoid mesio buccal placements. On anteriors, straight down from incisal and that can lead to some interesting effects, not problems. Hope this helps you. Physics of the material, not your techniques.

Dave

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CatamountRob

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It's not your pressing, it's the nature of the crystalline structure of the material. Picture a bunch of logs flowing down a river. That's the way the crystals are and flow parallel to the sprue. Gives kind of a fibre optic effect where you may not like it. Try spruing from diso- lingual cusp areas and certainly avoid mesio buccal placements. On anteriors, straight down from incisal and that can lead to some interesting effects, not problems. Hope this helps you. Physics of the material, not your techniques.

Dave

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Logs floating down a river you say? Sort of like a municipal waste water system then?
Sorry. It's Friday night and I've been drinking.
 
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Patrick Coon

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It is definitely not the size of the sprue, it is all location and crystal flow.

I have attached a series of slide (in pdf format) that I use in courses to talk about this phenomenon. There are no descriptions, but I think they are self explanatory, especially after reading my previous posts.
 

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I sprue to the same area you indicate and the thickest point on posteriors but still get that ring.
Now what. I've been at this for four years. Same advice. Same results. Frustrated
 
SiKBOY

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Patrick, those sprues in the pdf look quite long. It's a lot longer than what I am doing. Are there any other reasons why we are getting that grey spot at the sprue junction?
 
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Do you have any pictures or how you would sprue a bi or a molar?
 
Patrick Coon

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I sprue to the same area you indicate and the thickest point on posteriors but still get that ring.
Now what. I've been at this for four years. Same advice. Same results. Frustrated

JDD,

I'm sorry for your frustration. Can you take some clear photos of your sprueing and the results. Maybe by seeing exactly what you are doing and the results, I can make some other suggestions. I would love to help you solve this issue.
 
Patrick Coon

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Patrick, those sprues in the pdf look quite long. It's a lot longer than what I am doing. Are there any other reasons why we are getting that grey spot at the sprue junction?
Do you have any pictures or how you would sprue a bi or a molar?

Hi SiKBOY,

All sprues should be at least 3mm and no longer than 8. What I go by for sprue length is how much sprue do I need to get the restoration going into the optimal thermal zone of the ring. To do this I use the Sprue Guide for the appropriate ring size. This is a clear plastic piece that came with your original kit (if you bought the kit). I make my sprues long enough that my patterns touch the outside/top edge of the sprue guide. That will make the sprue longer on small restorations and shorter on large restorations.

Hope this helps!
 

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JDD,

I'm sorry for your frustration. Can you take some clear photos of your sprueing and the results. Maybe by seeing exactly what you are doing and the results, I can make some other suggestions. I would love to help you solve this issue.
I just tried my own technique. Finally no nothing. Turned out amazing. I did it on two cases. Checking to see if it is consistent.
Pardon my ignorance but how you sprue to emax and emax multi press makes your spruing info make no sense. A 8 gauge down to a vertical small attachment on central in a multi is so different than your log theory. The logs cannot be as large as your illustration. Otherwise I would get major problems in my anatomy and my sharp edges. Never get grayness there. Please explain.
 
ps2thtec

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image.jpeg Had this filed away, IVO used to issue these updates.
 
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View attachment 23145 Had this filed away, IVO used to issue these updates.
Should I transition to a 200 ring and slant it out into that zone or is 100 ok. Is the heating area causing my dis colorization.

My new technique was short lived. Whatever. At least one turned out good.
 

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