SynOcta miscast help!

[jasperjo]

I hoping to obtain some tips here for casting gold abutments.
Once in a while when casting the Straumann Synocta gold abutments we get gold runing onto the fitting surface and it will vary from a light layer to a rough surface tiny spicules covering a large areas of the surface. We use the same procedure for other systems like Nobel replace and active and never have problems only these synoctas. Is it the design of their gold cylinders that is the prob.

no debubblelizer is ever used
we use Deguvest F investment
Burn out to 1000 C and then lowered to 850C for torch cast and not electric

 

[dmonwaxa]

I use less special liquid when investing, expansion isn't really necessary. Lower your burnout temp, and lower your casting temp. Lastly you can score a line around the cast to componen the just below the wax line, use a bard parker blade. This will help stop the flow of metal when casting.

 

[subrisi]

I use Isoporpyl alcohol and a cotton swab to degrease the metal base. That helped me. The investment "adhered" better and the gold did not run all the way down the base.

 

[JohnWilson]

Troy hit it on the head reduce your investments expansion and use alcohol to clean the non oxidizing interface.

 

[dhdc]

Agree to lowering expansion liquid,but lowering casting and burn out temp would be crazy,you need the heat in the abutment to prevent the metal cooling when casting.I would increase the burn out temp for implants.

 

[dmonwaxa]

Increasing BO temp increases expansion IMHO. 1000 C / 1832 F. You could use less winds on the casting machine, eg. 2 1/2 instead of 3.

Agree to lowering expansion liquid,but lowering casting and burn out temp would be crazy,you need the heat in the abutment to prevent the metal cooling when casting.I would increase the burn out temp for implants.

 

[rkm rdt]

1832 F seems high for burnout. Are you using semi precious? I burnout at 1500 F

 

[dmonwaxa]

1832 F seems high for burnout. Are you using semi precious? I burnout at 1500 F

rkm thats my point exactly. original poster said burnout temp is 1000c then lowered to 850c. at 1000c expansion has taken place and cooling to 850c doesnt quite close the expansion gap made by the original burnout temp...IMHO @ dhdc

 

[rkm rdt]

I just devested a synocta and had the same problem as jasperjo.This is not the first time either.I have done everything from cotton swabing to scoreing the wax and still a problem.I thought it was me but now I'm seeing a pattern here.

2stage overnight burnout at 1500 F

By the way, staumann voids their guarentee if a 3rd party abutment is used on their implants.

 

[dmonwaxa]

I just devested a synocta and had the same problem as jasperjo.This is not the first time either.I have done everything from cotton swabing to scoreing the wax and still a problem.I thought it was me but now I'm seeing a pattern here.

2stage overnight burnout at 1500 F

By the way, staumann voids their guarentee if a 3rd party abutment is used on their implants.

rkm, are you casting t3 or t4. I dont score nor do I use alcohol. Well only for mood changes... Are you using resin such as GC for modelling or are you using wax? I do burn out @ 1355F 2 stage, for T3 and T4 and never have a problem.

Tell me your technique see if we can brainstorm this.

 

[rkm rdt]

Thanks Dmon,

I'm not sure what you mean by T3 or T4

I use Bego modeling wax

sprued with a resevoir sprue with 20 guage vent sprues from near wax/titanium interface

invested 20 ml liquid, 3 ml water

overnight burnout 2 stage 1500 F 1 hour hold

2 winds of broken arm

Argen 54B alloy 53.3 % paladium 37.5% Ag

 

[dmonwaxa]

T3, T4; Type III and Type IV gold alloys. Sorry for the confusion. What is the recommended liq/water ratio from investment manufacturer for the type of alloy you're using? What is the recommended burn out temp for casting the alloy being used? Remember gold can be thinned out to thousandths of an inch thick, think gold foil; so any opening larger will be filled with the melt when casting.
Zoom in on the surface, that more than likely is the problem.

 

[rkm rdt]

I used 20 ml liquid, 3 ml water which is what I use for copings ( silver palladium)

I'm following all of the recommended temps and ratios . From what I am reading here I may have to decrease the expansion so how far should I go?

Would 6ml water/17ml liq...or...10ml water/13 liq be enough ?

I was so spitting mad on the phone with the rep that he's sending me a free ucla.

 

[dmonwaxa]

I used 20 ml liquid, 3 ml water which is what I use for copings ( silver palladium)

I'm following all of the recommended temps and ratios . From what I am reading here I may have to decrease the expansion so how far should I go?

Would 6ml water/17ml liq...or...10ml water/13 liq be enough ?
I was so spitting mad on the phone with the rep that he's sending me a free ucla.

You're on track, I use GC investment and that calls for 12/8 liq/water ratio for regular C&B; I switch the ratios for abutments. So by that reasoning what hilighted above should work. As stated in previous post check out the photos.

 

[rkm rdt]

Thanks Dmon,

I'll give it a try and make sure I brush all the wax flakes off before I take the macro

 

[dmonwaxa]

Thanks Dmon,

I'll give it a try and make sure I brush all the wax flakes off before I take the macro

LOL. let me know how it turns out and what procedure you followed. Good Luck, fingers crossed,,, it'll turn out fine.

 

[dhdc]

your reply Dmon suggests dropping casting and burn out temp,but if that is what he is successfully casting his alloy at,i would not be advising this until you know what the alloy is.Big risk on an expensive abutment

 

[rkm rdt]

I won't be dropping my burnout temp but I will be decreasing the expansion of the investment.

I will keep you posted.

 

[JonB]

I had a similar problem last week with an ID Replant UCLA with alloy spilling over onto the mating surface. Doug Jackson recommended doing the scoring around the area where the alloy meets the titanium to act as a momentum break. So the next one I cast to replace the first one, cast out perfectly.
I didn't change my liquid powder ratio at all from what I normally cast similar alloy - in fact three other crowns were in the ring with it. If expansion doesn't matter - why change it?
I did clean the surface with alcohol.
No debub when investing.
I burn porcelain alloys out to 1500ºF and cast at that temp - no drop. Full gold I drop to 750ºF before casting.

I think the biggest problem with my first casting was that I "pre-invested" the UCLA while it was on the sprue by running investment down into the hole and around the mating surface. Then after setting I invested the ring. Big problem with alloy all over the UCLA mating surface and a trapped bubble inside the screw hole.

Doug's tip of running floss through the hole and just investing the whole thing at once fixed all that, and the scoring around the edge probably contributed to no alloy where it shouldn't be.

Oh yeah - I didn't sprue vent as extensively as the photo above. Not that that has anything to do with the problem - but i used a square yellow Belle de St. Clair sprue gate to a runner bar, with only one small 2mm long vent on the opposite side of the crown from the sprue point about half way down the side of the crown. No porosity at all in the final casting. I do my waxing and finishing under a microscope - so I would have seen porosity if it were there.

 

[dmonwaxa]

your reply Dmon suggests dropping casting and burn out temp,but if that is what he is successfully casting his alloy at,i would not be advising this until you know what the alloy is.Big risk on an expensive abutment

T3, T4; Type III and Type IV gold alloys. Sorry for the confusion. What is the recommended liq/water ratio from investment manufacturer for the type of alloy you're using? What is the recommended burn out temp for casting the alloy being used? Remember gold can be thinned out to thousandths of an inch thick, think gold foil; so any opening larger will be filled with the melt when casting.
Zoom in on the surface, that more than likely is the problem.

dhdc, WADR, for argument sake; does temperature influence expansion? I believe so. That being the case, if an increase in temperature increases expansion then the opposite is true; decrease the temperature, decrease the expansion. High temperatures combined with the investment produces a space just enough to allow molten metal to flow through. I've done too many to not know. I dont score a line around my abutments, but I also dont have that problem. Other things that insures/directly influence cast metal on the mating surface of the abutment is material used in modelling the abutment; ie wax or resin. Resin, because a liqiud is used it can flow onto the surface without you realizing because it appears clean but a very thin tranparent layer may be present. FWIW, just my 2 sense.