Emax press voids in anatomy

[killgja]

Have been using microstar HS investment and emax for a years with no problems but recently we are experiencing voids in pressings (mostly molars) in the anatomy. They look like they have had a miniature icecream scoop taken right out of the top with everything else pressing out perfect. Margins, fit...etc perfect! Just these reandom voids. Microstar HS 23min set time from start of mix, strait in hot oven, burnout 1565, ivoclar and zubler pressing ovens, fan cooled, hand devested. Any thoughts?

 

[rlhhds]

We just had two of those today also.

 

[rlhhds]

Is it on a 100g ring? If so the unit could be to close to the center of the ring in the heat zone creating suckback.

 

[killgja]

100g ring. Interesting thought on suckback although most our waxups are sprued with margins out and pushing them as far out as we can from the center of the ring.

rlhhds: Do you often get these voids or is this something that just started happening to you? Are you also using microstar? I ask this because we haven't had this issue until last week with the microstar investemnt. We did however have this exact same problem happen while testing a new (not yet released) investment material last month. Until that point we had never seen this issue despite making 30+ emax a day.

 

[rlhhds]

We have always use Microstar. We have been noticing this on 100g rings only. Looking at them the voids are always toward the center not out at the edges where our margins are. So now I am going to be more aware of my unit placement on the 100g rings and see if that helps.

 

[NicelyMKV]

Sprue positioning. Lithium disilicate is thick in its viscous state. It can overlap itself and cause voids. This is what I was told when i was having this issue. I got really precise with my spruing and it immediately went away and stayed away.

 

[ps2thtec]

I had bubbles (#4 sz) in occlusal and a rather large one once on the side of the sprue. The word I got was its caused from overheating the material too much in the press oven. Filled them with incisal.

It's crazy what we're told, but at least we have the DLN community to hopefully help sort it out.

What shades. I had it in BL4 LT, and B1. But I don't think that's the cause.

 

[Gru]

Fan cooled? rlhhds may be right on suck back. BTW, 23min is longer than recommended, but it seems unlikely it's the investment anyway. We benchset 17 min, remove and scrape the end (button) and let set up to 2 min to release steam. If your calibrations are all correctly done, and you aren't putting ingots into the burnout, then might I suggest checking the press plunger in the press? Occasionally they get some build up on them and stick to the ring plunger. This can draw it back when the cycle is completed and create suction in the pressing. Which Ivo press are you using? This used to happen on the ep600 more often than the others.

 

[killgja]

After testing everything that has been mentioned on here the problems have gone away. Oddly the plungers were clean, burnout and press temps were tested to be correct...etc. Went through that box of investment and now the problem is gone. Seems we had a bad batch of investment material since we didn't change the way we attached the waxups.

 

[killgja]

Per the fan cooled question. Placing rings out of the oven directly to the cooling rack with a fan cools 100g ring in 12 mins to help push more emax through. Haven't ever had a issue with cracking despite what I have read other places.

 

[[email protected]]

I had the same thing a few times, when you put the sprued crown on the base, make sure the intaglio surface ie the fitting surface of the crown faces outwards towards your silicon form, if you look at any of the emax manuals they always sprue like that, have not had any of those voids since. Yaaaaaay!!

 

[twinrivers14]

Use a IVOLCAR PRESS FURNACE AND THEIR INVESTMENT MAY HELP WITH A LOT OF THE PROBLEMS

 

[Pete CCDL]

Sprue positioning. Lithium disilicate is thick in its viscous state. It can overlap itself and cause voids. This is what I was told when i was having this issue. I got really precise with my spruing and it immediately went away and stayed away.

Would like to talk to you about sprue positioning. I have had these voids from the start of using e.max. How can I reach you?

 

[charles007]

Sprue positioning. Lithium disilicate is thick in its viscous state. It can overlap itself and cause voids. This is what I was told when i was having this issue. I got really precise with my spruing and it immediately went away and stayed away.

Jason nailed it ! I had the same sort of problem when I first started pressing emax. Very precise spruing is KEY when spruing emax. The sprue angle, sprue size, length, position, has to all be precise. Look/ read very carefully at the diagrams in your manual on spruing.
The problem I had was " 1 " very small scooped out area just below the buccal cusp on occlusal that lined up at the same angle of the sprue...

 

[Zubler USA]

killgja, Upload a picture for us. I am pretty sure I know what you are seeing, but I would prefer to see it.

 

[McTeeth]

We started getting this "suckback scoop" recently. Same spot (incisal 1/3, below cusp tip)
Microstar HS
Vita Vacumat 6000 MP

I don't recall getting it very much out of the Ep3k or Combi 600 if at all
Vacumat settings??

 

[McTeeth]

I went over my spruing technique in my manuals. I noticed my old Emax instruction manual (2007) showed margins out (facing silicone ring),but in my Multi-ingot instruction manual(2014),the monochromatic spruing shows margins in??

Guess I'll give it a shot

 

[ps2thtec]

I went over my spruing technique in my manuals. I noticed my old Emax instruction manual (2007) showed margins out (facing silicone ring),but in my Multi-ingot instruction manual(2014),the monochromatic spruing shows margins in??

Guess I'll give it a shot

The molar diagram on p38 is still not correct. Yes margins in but a more diagonal position on that molar.
You want to picture the flow going up and out as it presses. Not horizontal and back towards the middle
of the ring. Pay attenti to the 10mm rule also. I also use the Super ring. Great results and
wax positioning.
Why not keep using the ep3000 that was giving great results?

 

[Zubler USA]

We started getting this "suckback scoop" recently. Same spot (incisal 1/3, below cusp tip)
Microstar HS
Vita Vacumat 6000 MP

I don't recall getting it very much out of the Ep3k or Combi 600 if at all
Vacumat settings??

Hi McTeeth, I would love to tell you it is your furnace, but I doubt it is all furnaces get this result. Every time I see this, It has to do with Spruing. Your vacuum isn't the cause and a ring former isn't going to fix it, in fact it could add more issues, especially if it changes the thermal mass of the overall ring. I would look at your sprue angle, sprue guage, bevels on you attachments and sprue placement. all these are important. make sure you consider the flow of the material.

 

[McTeeth]

The molar diagram on p38 is still not correct. Yes margins in but a more diagonal position on that molar.
You want to picture the flow going up and out as it presses. Not horizontal and back towards the middle
of the ring. Pay attenti to the 10mm rule also. I also use the Super ring. Great results and
wax positioning.
Why not keep using the ep3000 that was giving great results?

Thanks for reply
I will take note. We still use the EP3k, Vita is just a 2nd press oven we have...just annoying when its not working "properly" (human error or equipment)