Casting plastic implant copings issue

[Pronto]

Anyone else have problems with casting an open coping like the Straumman solid abutment one? I cut them down and seal them with wax but it seems something happens to the wax and it gets rough and pushed down into the coping preventing the coping from seating. I assume the investment is expanding but the plasitc doesn't so it pushes the wax into the coping. It's a nusiance to go in there and relieve that area. Should I seal off the top with Duralay?

 

[Al.]

Anyone else have problems with casting an open coping like the Straumman solid abutment one? I cut them down and seal them with wax but it seems something happens to the wax and it gets rough and pushed down into the coping preventing the coping from seating. I assume the investment is expanding but the plasitc doesn't so it pushes the wax into the coping. It's a nusiance to go in there and relieve that area. Should I seal off the top with Duralay?

What exactly is the Straumman abutment?
I sometimes get an impression with a plastic female in the impression and the Dr sends me a metal abutment analog combo that I snap into the plastic female then do the soft tissue and pour. Is that the same thing your talking about? I never asked the name, and Ive probably done a dozen of these.

 

[Pronto]

Straumann-USA>Products>Prosthetics soft tissue level>Crown & bridge prostheses>RN and WN solid
This is the solid abutment. Figure 2 is the plastic coping to cast. It's open at the top.

 

[TheLabGuy]

Pronto have you ever thought about getting the casted abutments, instead of the plastic ones.

 

[Pronto]

I've used those with other styles of the Straumann implants as well as other companies. They only make the plastic copings for the solid abutments though. Double casting has it's own set of issues too.

 

[Al.]

Ive never heard of anything like that happening. I dont know how wax could get pushed down if there is investment against it. Could it be die lube or debublizer? Could the whole casting be underexpanded and it shows up in the tip? Mabey you could try another cc of liquid? Mabey some undercut wax or spacer on the tip?

The attachment I was refering to is Nobel Biocare's snappy abutment.
In their cat. I think they have a plastic coping I could use, but what I have done a dozen times is remvbe the plastic pickup female from the impression and trim it up and remove the little retention prongs in the plastic and cast that. When I trim it up a hole opens on the occlusal and I fill it in with wax.
I havnt had a fit issue with this.

 

[LGTCDT]

Sounds like you are talking about a waxing sleeve w/gold base or what Nobel Biocare calls its GoldAdapt. Never had your problem however, if you try pattern resin instead
of wax it may correct the problem.

 

[SteveT]

I would use a pattern resin to seal the hole such as Pi Ku PLast from Bredent. But burn it out slowly ie not a rapid heat investment and take the furnace from room temp. Also cover as much of the plastic as possible with your normal inlay wax

SteveT

 

[zena]

Anyone else have problems with casting an open coping like the Straumman solid abutment one? I cut them down and seal them with wax but it seems something happens to the wax and it gets rough and pushed down into the coping preventing the coping from seating. I assume the investment is expanding but the plasitc doesn't so it pushes the wax into the coping. It's a nusiance to go in there and relieve that area. Should I seal off the top with Duralay?

Where are you mostly do your grinding? You need a reamer instrument to get rid of the lip you get once it's casted. The coping should snap on the abutment. Anyways we dont use wax on our abutments or copings for implants we use duralay and we do a slow burnout. Check out this link http://www.straumann.com/com_index/.../pc_15x_254_crown_and_bridge_restorations.pdf

 

[Pronto]

The very tip of the plastic coping is open. The coping fits 2 length abutments so it has extra length to it. When I take it down to the right size the hole at the top has to be filled in. Also if I have to adjust the abutment down for clearance the plastic coping has to also be reduced. Either way when the coping is sealed with wax I often get roughness inside the tip of the cast coping as if the investment pushed the wax down into the coping. Maybe the plastic is not expanding and the investment pushed down on the heat softened wax causing the investment to crumble. Once that area is relieved the coping fits fine even after removing that lip. I have no problem with casting other styles of plastic copings.
Double casting is something that is hit or miss for me as well. Many times it seems like the gold base acts like a heat sink and the casting is incomplete. I use a longer burnout and higher temp too.

 

[JohnWilson]

The very tip of the plastic coping is open. The coping fits 2 length abutments so it has extra length to it. When I take it down to the right size the hole at the top has to be filled in. Also if I have to adjust the abutment down for clearance the plastic coping has to also be reduced. Either way when the coping is sealed with wax I often get roughness inside the tip of the cast coping as if the investment pushed the wax down into the coping. Maybe the plastic is not expanding and the investment pushed down on the heat softened wax causing the investment to crumble. Once that area is relieved the coping fits fine even after removing that lip. I have no problem with casting other styles of plastic copings.
Double casting is something that is hit or miss for me as well. Many times it seems like the gold base acts like a heat sink and the casting is incomplete. I use a longer burnout and higher temp too.

I have literally done 100's of Straumann solid abutments cases. Like any casting error there are tons of reasons why you could be experiencing what you are seeing. As you know the lab analogs are over sized to the real abutment thus allowing the room for cement, so sealing it straight to the top of the analog leaves room inside if you didn't know.

When you modify the tip of the plastic coping and seal it over are you waxing down the outside of the coping? Are you just sealing the top and spruing to it? Do you burn out your plastic parts slower ( slow down the rate of climb) and hold the final temp longer? If you have a 2 stage burnout furnace stage it and hold the 1st temp longer.

Don't forget to use the reamer to eliminate the retention lip from the casting as well.

If you have any specific questions fire away I will try and help you out.

 

[Pronto]

I too have done quite few. I just seal off the top, don't let the wax run down inside. I have a program set for slower burnout, longer hold on for plastic copings as well. I'll try slowing down the first stage more, see what happens. I hate that reamer, kills your fingers. I just mill it off under the microscope then use the reamer just to clean up the flange.

 

[JohnWilson]

I too have done quite few. I just seal off the top, don't let the wax run down inside. I have a program set for slower burnout, longer hold on for plastic copings as well. I'll try slowing down the first stage more, see what happens. I hate that reamer, kills your fingers. I just mill it off under the microscope then use the reamer just to clean up the flange.

I will have to take a picture of mine. I modified mine to use it with a hand piece. It works perfect. Truthfully you can just rubber wheel the lip off and get similar results. The reamer doesn't stay sharp forever, I have bought 3 or 4 over the last 7 years.

I have often wondered if anyone has a way to sharpen these. I normally wonder then just place the order, I bet there are a ton of these all over the country that need sharpening.

 

[john]

I will have to take a picture of mine. I modified mine to use it with a hand piece. It works perfect. Truthfully you can just rubber wheel the lip off and get similar results. The reamer doesn't stay sharp forever, I have bought 3 or 4 over the last 7 years.

I have often wondered if anyone has a way to sharpen these. I normally wonder then just place the order, I bet there are a ton of these all over the country that need sharpening.

I also have issues casting the solid abutment copings. The tip of what Straumann calls the frustrum, always breaks off.
I use a staged burnout, 9C rise, 50 min. hold for first stage. The patten is verified clean at time of investment and completely covered in wax, even
beyond the 0.3 min as stated by Straumann, at cervical area as well. It seems to me that the plastic expands and cracks the investment at the tip,
ruining the fit and leaving significant inclusions as well. I'm really at a loss.
I use a high quality phosphate bonded investment, Weber soft 3, and as I said, staged burnout. I regularly cast copings for needle like preps with no difficulty, which leads me to believe its not a casting error, it's happening at burn out. Why are these things so sensitive? The plastic coping is driving me crazy. I currently make my pattern completely in wax. Would it help to make it in pi ku plast?
Thanks for any advice.

 

[JohnWilson]

I also have issues casting the solid abutment copings. The tip of what Straumann calls the frustrum, always breaks off.
I use a staged burnout, 9C rise, 50 min. hold for first stage. The patten is verified clean at time of investment and completely covered in wax, even
beyond the 0.3 min as stated by Straumann, at cervical area as well. It seems to me that the plastic expands and cracks the investment at the tip,
ruining the fit and leaving significant inclusions as well. I'm really at a loss.
I use a high quality phosphate bonded investment, Weber soft 3, and as I said, staged burnout. I regularly cast copings for needle like preps with no difficulty, which leads me to believe its not a casting error, it's happening at burn out. Why are these things so sensitive? The plastic coping is driving me crazy. I currently make my pattern completely in wax. Would it help to make it in pi ku plast?
Thanks for any advice.

Do you have most of the problems with these plastic patterns on small bicuspids or big molars? The plastic is supposed to collapse in on itself rather than expand in the mold and crack the investment. Staging it just allows for the ring to not be put under any undue stress and allows for the material to burn out cleanly.

Are you using a debubleizer or any surfactant to aid you in investing that may be causing internal issues?

The plastic pattern is supposed to be a time saver but it looks like your doing everything right but still having issues, are the plastic patterns you are using real straumann parts? I know of 3rd party that use delron and lexan that react much differently than other patterns. I love the bredent resin you mentioned but it would suck to have to make a pattern when there is something available stock.

 

[john]

Do you have most of the problems with these plastic patterns on small bicuspids or big molars? The plastic is supposed to collapse in on itself rather than expand in the mold and crack the investment. Staging it just allows for the ring to not be put under any undue stress and allows for the material to burn out cleanly.

Are you using a debubleizer or any surfactant to aid you in investing that may be causing internal issues?

The plastic pattern is supposed to be a time saver but it looks like your doing everything right but still having issues, are the plastic patterns you are using real straumann parts? I know of 3rd party that use delron and lexan that react much differently than other patterns. I love the bredent resin you mentioned but it would suck to have to make a pattern when there is something available stock.

Thank you for your reply.
I am using only genuine Straumann parts, no debubbleizer, and have been following Straumann instructions to the letter... Pi-Ku-Plast is an excellent material, agreed.
The case I'm having trouble with at the moment is a maxillary, posterior, two unit splint (#'s 2, 3),so it's fairly massive, approx. 9.0 g. alloy. My final thought regarding these failures is that possibly there has been incomplete sealing of the coping at the top, perhaps such a micro-gap could allow a small portion of investment to flow over the top of the pre-manufactured part of the pattern, which then pushes directly on the investment upon expansion, cracking it at the tip. If that's the case, I would feel foolish but relieved. It's humbling to have such problems after 25 years of experience. Though admittedly, Straumann has never been my favorite system. Thanks again!

 

[JohnWilson]

Maybe the next try use the plastic pattern but use the resin to seal over the top. Sounds like you are doing everything top shelf and I see no reason why your having issues. How are you casting ie broken arm winder, induction?? Do you ever have issues with big bridges that are just waxed with no resin? If you ever have investment breakdown on other restoration perhaps the force of the alloy hitting the pattern is too much ie too many winds in the casting machine.???

Just spit balling here....

 

[john]

Maybe the next try use the plastic pattern but use the resin to seal over the top. Sounds like you are doing everything top shelf and I see no reason why your having issues. How are you casting ie broken arm winder, induction?? Do you ever have issues with big bridges that are just waxed with no resin? If you ever have investment breakdown on other restoration perhaps the force of the alloy hitting the pattern is too much ie too many winds in the casting machine.???

Just spit balling here....

I use resin extensively in fabricating frameworks, and cast using a torch and the Bego, Fundor t casting machine at relatively low torque. I never have investment breakdown in any other castings. Do you know of a way to fabricate copings for Straumann solid abutments without using the pre-manufactured parts? Just an idea. The thing is, this case is a splint and the analogs have a flat area.

 

[rkm rdt]

I scan them and cad cast.

 

[AdamCDT]

I just had the same exact problem on two straumann WN 5.5 solid implants. I used the straumann burnout coping to make my framework. I sealed the top of the coping with wax, which I've concluded is the problem. I actually have waxed the case up 3 times with the exact same result. The tip of the investment kept breaking off, which is leaving a very high fit and unacceptable casting. I at first thought that it was during the casting procedure that the problem occurred; thinking that the sprue was directing the metal straight at the tip of the investment causing it to break off. After spruing the pattern so that the metal would flow a different way, I had the same problem. I'm thinking the problem is happening during the burnout; Although, I am using a very slow burnout. I'm going to try using Duralay to seal the top and hopefully that fixes the problem. I'm using whipmix ceragold investment (which I'm not that fond of)... Any other suggestions on what could be happening?