A technical question

subrisi

subrisi

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I am working on a full lower arch srew retained bridge.(6 implants) The case was cast in sections and welded in five places ( request from the Dentist) It fit very good. After opaqueing the bridge already rocks badly and I don't even have porcelain on it. I sent it back for welding and am planing to make a refractory model with lab analogs placed in it. I was planing to screw the bridge to this model and fire it securely screwed in place. Does anyone has experience in this? Strauman verified that the abutments and screws are made of titanium and will be fire proof. I hope I can avoid warpage with that method. Please give me some input here, this is a large srew retained case and the way the implants are spaced, there is no way to make the bridge in two pieces. The upper is in two pieces and fired fine so far.
Angelika
 
kcdt

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Why not fire it in sections and then laser weld or post solder after? I've seen articles about firing on analogues, but it seems to me that they were custom fabricated out of steel with a special tray to contain the investment. If you've never done it before it sounds like a great opportunity to really screw the pooch.
I'd stick to something more achievable.
Besides if its in one piece how are you gonna deal with flexure of the mandible? Almost anyone I've heard restoring a full arch lower sections at the midline because of this.
I hope that doesn't open a can of worms for you...
 
JeffT

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Hi Angelika, is bridge in NP or gold?

jeff
 
subrisi

subrisi

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Hi Angelika, is bridge in NP or gold?

jeff


It is made from semi precious metal = 52% palladium
 
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subrisi

subrisi

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Besides if its in one piece how are you gonna deal with flexure of the mandible? Almost anyone I've heard restoring a full arch lower sections at the midline because of this

The Dentist does not like post solder and I think it weakens the structure since it is soldered with gold.
The bridge can't be sectioned in the midline, because the four anterior teeth are pontics.
The implants are positioned at the two canines, the second premolars and the second molars.
 
Al.

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Mabey the joints are too small ?
How was it on the tray ? Mabey it slumped from the weight of the bridge on the tray or not being supported enough during firing.

Did you check it after degassing? That is probably where it happened from the high temp. What temp does the solder start to slump vs your degassing temp.

I would for sure keep the solder joints on the thick side and watch that high degassing temp and give even support for every abuttment.

Also do multiple bakes for the porc so it dosent stress the bridge during shrinkage.

I cast connections on large bridges in the middle of the pontics and never had one of those move or break.
Mostly for NP because I trust that more than soldering to NP. Ive probably done that 2 dozen times. Never tired it on precious metal.
I cut the pontic in half then cut deep mechanical retention on both pontics then wax and cast a connection.
 
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kcdt

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Besides if its in one piece how are you gonna deal with flexure of the mandible? Almost anyone I've heard restoring a full arch lower sections at the midline because of this

The Dentist does not like post solder and I think it weakens the structure since it is soldered with gold.
The bridge can't be sectioned in the midline, because the four anterior teeth are pontics.
The implants are positioned at the two canines, the second premolars and the second molars.

So you can't have it laser welded post ceramic production with parent metal?
All I'm saying is trying to fire this in one piece doesn't seem to be working, so why keep doing it?
Its also been my experience that when the Drs start imposing limitations on the technical aspects of sound construction, it usually leads to problems....
 
Kreyer

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I am working on a full lower arch srew retained bridge.(6 implants) The case was cast in sections and welded in five places ( request from the Dentist) It fit very good. After opaqueing the bridge already rocks badly and I don't even have porcelain on it. I sent it back for welding and am planing to make a refractory model with lab analogs placed in it. I was planing to screw the bridge to this model and fire it securely screwed in place. Does anyone has experience in this? Strauman verified that the abutments and screws are made of titanium and will be fire proof. I hope I can avoid warpage with that method. Please give me some input here, this is a large srew retained case and the way the implants are spaced, there is no way to make the bridge in two pieces. The upper is in two pieces and fired fine so far.
Angelika

Just curious why you are building this up in porcelain and not composite?
There are great techniques using opaques, dentins, enamels and gingival
composites from Micerium Hri Tender or Shofu Ceramage..

Rob Kreyer
 
kcdt

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Just curious why you are building this up in porcelain and not composite?
There are great techniques using opaques, dentins, enamels and gingival
composites from Micerium Hri Tender or Shofu Ceramage..

Rob Kreyer

You are so right Robert! I also wondered why not a hybrid?
 
TheLabGuy

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Just curious why you are building this up in porcelain and not composite?
There are great techniques using opaques, dentins, enamels and gingival
composites from Micerium Hri Tender or Shofu Ceramage..

Rob Kreyer

Exactly right, I wouldn't even attempt something like this in pink porcelain. I throw in the towel with anything that consists of 6-8 units or more by using GC Gradia with some metal primer, it'll take no time at all, easily added too, and looks wonderful.
 
CRWNMKR

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composite discolors,We do alot of implant supported "ceramic dentures" usually in 2 to 3 sections, but sometimes it is not possible and we will make it in 1, the key is strong joints and laser welding . and also to keep the porcelain firings at a minimum
 
TheLabGuy

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composite discolors,We do alot of implant supported "ceramic dentures" usually in 2 to 3 sections, but sometimes it is not possible and we will make it in 1, the key is strong joints and laser welding . and also to keep the porcelain firings at a minimum

Composite will degrade over time, but that's years.........and even if it does, it's easily removed and more added, especially if you have a recessed area. Composite pink beats a ton of porcelain any day. When the dentist removes it to clean it, then add a little composite if needed. You won't have that luxury or ease with porcelain.
 
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Try to heat treat your frame work before degasing.
 
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Im sure this isnt of the immediate being sought, but... I couldnt imagine working for a doctor who was going to 'tell me how its going to be made'; thats my speciality. The guys who suggested hybrid were right, but I wouldnt have used composits, and NO WAY Id use a precious(or semi) alloy for the frame. (or abutments). I dont like to make 'batteries' in the mouth and possibly allow a galvanic reaction around the implants- not good for longevity. Id have done a YZ frame, e.max individual crowns that saddle on and are cemented, then wax-up my tissue and have my buddy in the denture lab process it. Slam dunk.
 
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We are in the process of bringing in a new system from Bredent called Visiolign which is comprised of PMMA veneers, posterior shells and a comprehensive composite system with stains and gingival shades. The PMMA veneers possess all of the properties of a SOLID, PMMA denture tooth and maintain a true shade at a thickness of approx. 1mm. This makes them perfectly suitable for a myriad of designs for hybrid overdentures.

To see a detailed fabrication sequence of the Visiolign technique follow this link, it should take right to the sequence, if not, click on the tab that says "CASE PICTURES"
http://www.xpdent.com/catalogs/bredent/attachments/security-lock-attachment.aspx?sm=b_i

For more information on the PMMA veneers go here visio.lign

You may also request a free Visiolign DVD by contacting our office at 877-328-3965
 
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crivasCDT

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Sorry for the double post guys, something weird occured when i submitted it and it ended up repeating it.

To see a detailed fabrication sequence of the Visiolign technique follow this link, it should take right to the sequence, if not, click on the tab that says "CASE PICTURES"
XPdent - Security Lock

For more information on the PMMA veneers go here visio.lign

You may also request a free Visiolign DVD by contacting our office at 877-328-3965
 
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subrisi

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I used to work for this dentist before I had my own lab. He is a prosthodontist who is used to his way of doing things. This part is very important for him and he always finds a lab that works with him. I am contemplating if he is a keeper or not. He does great sales numbers and I am willing to roll out the red carpet to a certain degree. I just have not learned yet where too much is too much. The bridge is solid and quite heavy. Since the case is screw retained, it did not sit on any pin. It sits secure on the bases of the abutments.
NO WAY Id use a precious(or semi) alloy for the frame. (or abutments). I dont like to make 'batteries' in the mouth and possibly allow a galvanic reaction around the implants- not good for longevity.
Why would you create "batteries" the abutments are "cast to" and therefore precious metal. So you would create more galvanic reactions when you cast non precios metal to it. Also most implant cases are made of titanium and crowns placed over it. Those crowns are mostly precious. I do not see a problem here. The only place where a galvanic reaction could happen is at the junction from the implant to the high platinum content of the abutment base. So it would not matter what metat the bridge is cast in.
 
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After 10:00 pm, the veiws or opinions expressed by2thBob, are not necessarily those of Bob, his affiliates or sponsors.
 
JeffT

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like Bob said, except screw retained (if Doc wants) zirc bridge, then wax and Zirpress gingiva and customize if desired. Then build up as per normal with Ceram.

Does anyone know if the teeth can then be waxed and pressed after this without effecting the gingiva press? (gingiva obviously not customized prior to this)

cheers , jeff
 
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