charles hallam cdt
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Both parties are informed. Mentioned that earlier
Experimenting on things not going into an unwilling uninformed patient's mouth would be a place to start.
That doesn't make it a success. Just keep your eyes on this one.View attachment 18561 Porcelain fired nice no signs of cracking.
Agree success might not b rite word. Give it a few years than maybe success. But don't wort pts name on my bench liteThat doesn't make it a success. Just keep your eyes on this one.
glad I could helpfirst off, I don't understand why you would want to cast directly to Ti anyway... just because you can, doesn't mean you should.
ok, you cut retention grooves, but I can guarantee there will be micro movement. also, as mentioned, there will be an oxide layer that will be eroded out with the patients morning orange juice, further opening a gap, and further movement..
from a time and materials standpoint this makes absolutely NO sense whatsoever.. it took longer to cut the retention, polish the tibase after firing, than it would to bond a correctly fabricated restoration... I just simply don't understand why this would be done form a "cost" prospective.
when I do things on restorations in the Lab that i'm not comfortable with, it's because it's one of those cases where there are no other options, and I am certain I have done everything I can before it goes out the door.
ethically, our goal is to restore and preserve a patients oral health.. that's primary. I too loose sight of that sometimes, but it's times like "now" that center me again
Both parties are informed. Mentioned that earlier
look, i'm not judging you. i'm simply stating some facts. the bottom line, is there is an easier, more cost effective and better way to do this.glad I could help
It's not a matter of opinion Charles, there is a very good reason that UCLA abutments are not made of titanium. Not everything is a conspiracy by big manufacturers to force you to pay more.I am not saying this is the way I plan on fabricating all my screw retained crowns. I respect all opinions here. But they are just that opinions. We all have our educated theories of which we base our conclusions on. We all try to follow manufactures protocol and a lot of times find ourselves tweekn there directions because there is a better way to do it. I've been in the business long enough to know that not everything is set in stone. Ha ha get it. Set in stone.
Charles, what burnout temp ave you used for overcasting this Ti base? What alloy have you used and what porcelain have you baked to it?I am not saying this is the way I plan on fabricating all my screw retained crowns. I respect all opinions here. But they are just that opinions. We all have our educated theories of which we base our conclusions on. We all try to follow manufactures protocol and a lot of times find ourselves tweekn there directions because there is a better way to do it. I've been in the business long enough to know that not everything is set in stone. Ha ha get it. Set in stone.
1675f burnout. Penceram 06 alloy. Synspar porc.Charles, what burnout temp ave you used for overcasting this Ti base? What alloy have you used and what porcelain have you baked to it?
May I ask what the good reason is.i would then ask why they make engaging and non engaging. Mechanical retention maybe.It's not a matter of opinion Charles, there is a very good reason that UCLA abutments are not made of titanium. Not everything is a conspiracy by big manufacturers to force you to pay more.
May I ask what the good reason is.i would then ask why they make engaging and non engaging. Mechanical retention maybe.[/QUOTE
hi Charles so you have burnout above 882, oxide and porcelain firing above that temp as well. You have changed the mechanical properties of Ti . No one would bond to Ti if cast/ press was ok.1675f burnout. Penceram 06 alloy. Synspar porc.
BTW have you ever made a bridge with engaging components? Probably not or you would not ask that question.
yes I understand which is why I'm not relying on the chemical bond as there is none. That's why I put mechanical retention inDo you ever read the physical properties charts of any of your materials?
Do you know what the CTE is of the grade of titanium you are using?
Does it match your alloy?
Zero gave you a great explanation of what happens to the surface of titanium when brining it to burnout temperature.
Andrew gave a great example of how it could be affected in the patients mouth.
UCLA abutments do not have a titanium interface. The interface is gold and platinum alloy. Why is that you ask? Because platinum does not form an oxide layer at these temperatures and when you cast to it you get a chemical bond.
Of course the physical properties change any time you heat alloy, that is why the manufacturers add trace elements to the alloy. These burn out with each casting, hence adding new alloy to every casting. If you don't add alloy and keep casting the same button you will run into CTE problems.