Straumann milled cocr

tehnik

tehnik

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Hi,

My question is, is it necessary to make oxide firing to the metal or can I sandblast it (I use 250 sand@ 2 bar) and apply bonder?

Regards.
 
Gru

Gru

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On the rare occasions I choose $traumann I simply sand blast and opaque. No oxide firing, no bonder. This is particularly true if I intend to polish any area since I wish to keep it easy.
 
tehnik

tehnik

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On the rare occasions I choose $traumann I simply sand blast and opaque. No oxide firing, no bonder. This is particularly true if I intend to polish any area since I wish to keep it easy.

Ok, but are there any official recommendations from the straumann what should be done?
 
Gru

Gru

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If you care, check their website. Otherwise follow your ceramic dfu. $traumann says an oxide firing is not needed due to an absence of manufacturing flaws.
 
tehnik

tehnik

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I have searched from straumann homepage, but do not find any info on that, thatswhy I asked here. If you could give me a link (if you have found it on the homepage),I would be grateful.
 
PDC

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BASIC INFORMATION ON STRAUMANN® CARES® TOOTH-BORNE PROSTHETIC PROCEDURES

Finishing
coron® Frameworks delivered by Straumann may need to be ground for finishing and adjusting. For successful results the following rules shall be observed:
ppCoarse and fine, sharp, tungsten carbide cutters shall be used for surfaces to be layered.
ppThe surface should always be processed in the same direction to avoid overlaps of the material. The finished framework surface shall be sandblasted with a one-way sandblast abrasive Al2O3 with a medium grain size of 125 μm at a maximum pressure of 2 to 3 bar.
ppThe framework shall be cleaned with a hot steam or with distilled water in an ultrasound bath. Do not immerse coron® Frameworks into a pickling bath.
 
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Malcolm Graham

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From what I have read on using cocr you don't need to do a oxide fire but they do give you an oxide fire instructions to do so if you wish.
I have gone away from using the steam cleaner after sandblasting copings and gone back to the ultrasonic. There still seemed to be an accumulation of scale in the steam cleaner even though I only have used distilled water since it was new.
 
rkm rdt

rkm rdt

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If you care, check their website. Otherwise follow your ceramic dfu. $traumann says an oxide firing is not needed due to an absence of manufacturing flaws.

Are you serious? They said that? What complete and utter bs.

I haven't done any separate oxide firing on any alloy in over 20 years.

absence of manufacturing flaws......What a loaded statement. I have no respect for that company.
 
Gru

Gru

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Yes, that's what they said. See pdf page 30 column 1 under processing/b)layering
ddl.straumann.com/content/dam/internet/xy/resources/brochurecatalogue/brochures/en/152.821_low.pdf

BTW, I never do an oxide firing on CrCo, even torch cast. It creates excess oxide, a evergreen tint that's hard to hide, and doesn't seem to enhance the bond in any way. My 2cents.
 
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tehnik

tehnik

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So a colleague of mine is doing an oxide firing and then puts directly on the oxide layer a bonder or opaque paste. Is that correct or unnecessary or false?
 
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Mohammad Khair

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finish the cr-co as you wish, sandblast it with al2o3 with any size any pressure any direction(keep the nose of the sandblaster at least 5 cm away from the framework),wash it with tap water, dry it with the lower corner of your lab coat or use a tissue(if you don't feel comfortable with this, use distilled water or a steam cleaner),apply the opaque in a proper manner.

take extra care of following:
1- the air bubbles underneath the sprue( always properly solder it).
2- oil with compressed air.
3- the use of used metal.
4- thin metal areas( less than 0.4 mm is not good).
5- malfunction vacuum system of the porcelain furnace.
6- over-firing any layer.
7- sharp corners, whether its positive sharp or negative sharp( a groove like).

there are so many other mistreats of the metal but mostly they are well known.

to check the opaque bonding make a trial crown or bridge finish it glaze it, then hammer it on the occlusal side on a piece of soft wood, now look to the framework if its still have a thin layer of opaque or ceramic, then your metal treatment is good, if the metal or the oxide exposed totally after hammering thin you most likely have a problem in treatment of the metal.

to check for air bubbles occurring during firing because of the metal oxide, fire a trial crown with porcelain for ten full cycles, each cycle reduce the temp 3-4 degrees with no hold at final temp, don't remove the glazed layer as removing it will allow the gas/air to escape easy with no problem, now if you have air bubbles after those ten cycles open the air bubble and look if the metal or the oxide is totally exposed, if its exposed then you have a problem with the metal oxidation or opaque firing(many times the compressor oil will cause such a problems).

to check the greenish problem , fire the opaque, then warp the cold opaqued object with a white paper tissue, dip it in water, remove it, leave it for ten minutes, open the tissue, if you find any yellow or green spots on the tissue it is most likely because of a problem with vacuum of the furnace.

if you take care of all those issues you can grant your porcelain to metal bonding for lifetime in 99.99% of the cases.

best wishes
 
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adamb4321

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So a colleague of mine is doing an oxide firing and then puts directly on the oxide layer a bonder or opaque paste. Is that correct or unnecessary or false?

It depends on the alloy. Most precious alloy manufacturers recommend an oxide firing, some specify that you leave the oxide on, some specify that you blast it off. Most non precious alloys don't need an oxidation firing, it doesn't seem to harm it if you do one though, and most NP alloys require blasting after oxidation.

So, the conclusion is... read the instructions, it's up to you if you follow them or not
 
Gru

Gru

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One additional comment: Excess oxide layer weakens the bond to the opaque and will possibly result in failure at some point, hence the post-oxidation blasting. As mentioned above, follow the alloy manufacturer's instructions.
 
rkm rdt

rkm rdt

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So what is the point of oxidizing in the first place?
 
Gru

Gru

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As I understand it...
Some alloys need the extra oxide to improve the mechanical bond. This tends to be true for noble/ high noble alloys. Alloys that produce heavy oxide (like most base alloys) will create a lower amount of oxide during a opaque wash firing negating the need for a separate oxide firing.
If someone is a metal expert, feel free to correct me if I'm wrong.
 
rkm rdt

rkm rdt

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Just to add to the confusion , some call it degassing .
 
Gru

Gru

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Yes, in the dark ages of casting, the casting gases would get trapped in the metal. Not so much anymore.
 
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