Grey lines on emax crowns after pressing

[Msteffen11]

After deventing our EMAX, we are seeing grey lines in our crowns. Does anyone have any idea what is actually causing this and how we can possibly fix it???

TIA!!

 

[CatamountRob]

Got any pictures? We love pictures. I’ll page our Ivoclar guy for you. He’s awesome if he hasn’t been drinking.
@Patrick Coon

 

[Patrick Coon]

After deventing our EMAX, we are seeing grey lines in our crowns. Does anyone have any idea what is actually causing this and how we can possibly fix it???

TIA!!

Got any pictures? We love pictures. I’ll page our Ivoclar guy for you. He’s awesome if he hasn’t been drinking.
@Patrick Coon

Thanks for the mention CRob!

As for the grey line, this happens where the material flows together from two different directions. We see this usually on bridges where you sprue to the retainers and as the material flows into the pontic and comes together the long crystals will turn and you get more translucency in that area.

It can also happen if you sprue too far down the axial wall on a molar and the material flows around the prep (mesially and distally) instead of over the prep and down the axial walls.

If you have some pictures you can attach, that will allow me to confirm this. If possible, leave the sprues attached and still attached to the button.

 

[dandyfop]

I second sprue position. Basically If you have the sprue coming straight down into the crown without any flairing out, the particles get aligned in a straight direction and allow light to penetrated deeper. This makes that section more translucent and therefore more grey. Making the sprue flair out before hitting the crown allows the particles to disperse more randomly.

 

[SiKBOY]

I second sprue position. Basically If you have the sprue coming straight down into the crown without any flairing out, the particles get aligned in a straight direction and allow light to penetrated deeper. This makes that section more translucent and therefore more grey. Making the sprue flair out before hitting the crown allows the particles to disperse more randomly.

Have any pictures of an example? I always get a grey spot where the sprue is

 

[dandyfop]

Sorry I don't, but this is almost for sure the problem. I struggled with it a while back. It can be particularly pronounced on anteriors. I try to sprue slightly on the lingual, just to be safe, but a wide sprue base, though a pain to cut off, will significantly reduce the effect.

 

[Patrick Coon]

Have any pictures of an example? I always get a grey spot where the sprue is

Traveling today, but when I get settled (tonight or tomorrow) I'll show some pics. There is also a tech tip video on our site (ivoclarvivafent.us) called eliminating the bullseye, where I explain and show some illustrations on the subject.

Sent from my SM-G935V using Tapatalk

 

[2thm8kr]

Traveling today, but when I get settled (tonight or tomorrow) I'll show some pics. There is also a tech tip video on our site (ivoclarvivafent.us) called eliminating the bullseye, where I explain and show some illustrations on the subject.

Sent from my SM-G935V using Tapatalk

Ah, the annual Ivoclar Tropical Midwinter Cruise. Have a few cocktails for us working stiffs.

 

[Patrick Coon]

Ah, the annual Ivoclar Tropical Midwinter Cruise. Have a few cocktails for us working stiffs.

I wish! Left the house in Sarasota, just landed in Buffalo!

Sent from my SM-G935V using Tapatalk

 

[Car 54]

Have any pictures of an example? I always get a grey spot where the sprue is

For me especially with the HTs, but not with the more opaque LTs

Need to check out Patrick's above link suggestion.

 

[Darvoid]

Thanks for the mention CRob!

As for the grey line, this happens where the material flows together from two different directions. We see this usually on bridges where you sprue to the retainers and as the material flows into the pontic and comes together the long crystals will turn and you get more translucency in that area.

It can also happen if you sprue too far down the axial wall on a molar and the material flows around the prep (mesially and distally) instead of over the prep and down the axial walls.

If you have some pictures you can attach, that will allow me to confirm this. If possible, leave the sprues attached and still attached to the button.

What is the solution to avoiding a translucent line on the Pontic? Thank you.

 

[Patrick Coon]

What is the solution to avoiding a translucent line on the Pontic? Thank you.

Due to the nature of the material, I plan on layering a slight amount on the facial of bridges to take care of this.

If I try to change the position of my sprues (or add a sprue to the pontic) it will only change the position of the line, and could cause other issues resulting in a miss-press.