Does everyone trim back their zirconia margins manually?

D

Denture Dude

Active Member
Full Member
Messages
166
Reaction score
16
.
 
Last edited:
JMN

JMN

Christian Member
Staff member
Full Member
Messages
12,058
Reaction score
1,884
Hey everyone. I'm a doctor in a big group practice with an internal lab, and I'm the liaison between the doctors and the lab. I was hoping you could help me out with this. Our lab mills zirconia crowns, the after they're sintered, they trim back the margins manually. Whenever there's a margin issue, my doctors say that the error is caused by the manual trimming, and that other labs don't do that. Our lab says that of course everyone does that - that's the only way it can be done. So who's right? Does everyone trim back their margins manually, and does that tend to be a big source of margin error?

You people are the best. You definitely answered my question, and I didn't even mind the sarcasm and rants :)
If you can put up with our acerbic humor, you come on back now y'hear?
 
F

FullPartial

Active Member
Full Member
Messages
100
Reaction score
16
. That's where the real talent comes into play. Blending in the margin, maintaining at least 2 mm of blend of contour with emergence profile of underlying preparation. "Ring around the collar" (Tanaka) impressions give you that Really required anatomic reference to blend with.

can you link the article/publication you’re referring to with Tanaka and the ring around the collar?
 
Sda36

Sda36

Active Member
Full Member
Messages
843
Reaction score
93
can you link the article/publication you’re referring to with Tanaka and the ring around the collar?
Simply a term he uses for a succesful full margin capture impression. Also picks up anatomy of the tooth structure below the margin to assist in guiding emergence profile of the restoration to proper form. Good tissue management is essential to achieve this result.
 
JKraver

JKraver

Well-Known Member
Full Member
Messages
2,866
Reaction score
451
About techniques used... not sure how the rest of you approach it but here’s what I do.
Follow pics.
First shows the White margin I see that needs finishing. I go at it with wheel spinning in reverse looking inside crown so I can see whats happening.
Second I do a light smoothing finish in reverse from buccal , wheel spinning away from margin.
Third shows buccal margin is finished.
that’s the way I skin this cat.
View attachment 38523 View attachment 38524 View attachment 38525
You use a homogenous rubber wheel in reverse? why? There is no direction in the cutting surface...
 
ps2thtec

ps2thtec

Well-Known Member
Donator
Full Member
Messages
2,231
Reaction score
620
You use a homogenous rubber wheel in reverse? why? There is no direction in the cutting surface...
🤔…. did you see pics in post #20? I like to see the White edge margin as I’m finishing it back. For you being lefty, then run your handpiece in forward. Whatever works !
 
JKraver

JKraver

Well-Known Member
Full Member
Messages
2,866
Reaction score
451
I bet that sucks to have to buy a mounted finishing wheel every time instead of mandrel based. I guess you could buy left handed mandrels.
 
sidesh0wb0b

sidesh0wb0b

Well-Known Member
Full Member
Messages
4,842
Reaction score
649
I bet that sucks to have to buy a mounted finishing wheel every time instead of mandrel based. I guess you could buy left handed mandrels.
i buy left handed mandrels. with the exception of carbides and diamonds i want that mess flying away from my face!
 
Davor RDT

Davor RDT

Member
Full Member
Messages
21
Reaction score
0
Hey everyone. I'm a doctor in a big group practice with an internal lab, and I'm the liaison between the doctors and the lab. I was hoping you could help me out with this. Our lab mills zirconia crowns, the after they're sintered, they trim back the margins manually. Whenever there's a margin issue, my doctors say that the error is caused by the manual trimming, and that other labs don't do that. Our lab says that of course everyone does that - that's the only way it can be done. So who's right? Does everyone trim back their margins manually, and does that tend to be a big source of margin error?
All margins have to be finished manually post sinter and I mean ALL of them from all machines and cam and cad softwares . So this was either over polishing or under finishing . Explorer picks it up from crown side it is over polished . Explorer picks it up from margin side it is under polished . No comment on model less crowns due to sheer lack of them where I work . As much as I know there is always offset at margin to be able to just mill it without chipping , now even if its thinned out to max there is still finishing needed after sinter .
The Techs are doing it properly but mistakes can happen . Impression? Modelwork? Crown too loose and when it moves one side is shy while other is overextended .
 
Last edited:

Similar threads

Top Bottom