Making abutments non-engaging

npdynamite

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I believe I know this answer already, and I have seen other threads that touch on it so I think I know what the general opinions about it are, but I wanted to start a thread on this specifically so I can gain an understanding of what is opinion and fact and what is a good idea for ass covering vs. what is legal.

The question is as as the thread says, modifying abutments to make them non engaging. In my years in the lab I have seen this topic come up and based on how the FDA regulates custom abutments it would seem to me that it is not legal to remove the interface from an abutment and make it non-engaging. That said I can see why it might not seem like a big deal when you are working on something like a NobelActive where the conical part of the interface can remain intact and create some sort engagement so that there is more than a screw holding the restoration in place ( have seen a Nobel Trilobe interface removed for this purpose before and that seemed like an a terrible idea, legal or not).

The one situation I see where being able to do this would be a great advantage is when there is a screw retained bridge that you also want angle changing abutments on. Not all companies are making ASC non engaging abutments and some of the companies that are making them are making the interface for the crown so short that the strength of the case would be compromised. In these situations getting an engaging part and removing the engaging aspect could create a better restoration, but it if it puts the lab in legal trouble that doesn't really help. I would like to know how bad of an idea this may be if it were to come up again.

So what do ya'll say? Is this straight up illegal, something to avoid for just in case/CYA reasons, or more of a "if the doctor is aware and ok with it" type of thing?
 
HonestAbe

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I don't know anything about the specific legalities, but don't we make stuff and it's the doctor that has to put their stamp of approval on it? Like part of their credentials is to say "okay this is still in line with FDA guidelines, I'm going to use it." As far as I understand that's not on the lab. Like if you hand them a bridge you made out of woodchips you glued together and whittled down, it's on them if they use it.

Ethics wise is a whole other situation. If a lab lied about it (by omission too maybe?) and the doctor used it and it failed and they got sued and the modification discovered? If the doctor instructed the lab to modify things and there was some sort of record of them doing so then I can't imagine the lab would be liable.
 
CatamountRob

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Somewhere in the dusty DLN archives there is a thread where John W talks about this, I don’t remember which company it was but there are, or at least were at that time, cases where here isn’t a non-engaging option. If you want one, you have to alter an engaging abutment.
 
rkm rdt

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Custom abutments are all engaging just like CRob
 
npdynamite

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Why not get the non-engaging abutment?
I'm thinking of when the non-engaging part isn't available or would cause other compromises, like if you need an angled screw channel, I don't believe thatStraumann offers a non-engaging ASC base, or sometimes on tall posterior implant bridge if the only non-engaging part only has a 3.5mm tall interface or something along those lines
 
npdynamite

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Somewhere in the dusty DLN archives there is a thread where John W talks about this, I don’t remember which company it was but there are, or at least were at that time, cases where here isn’t a non-engaging option. If you want one, you have to alter an engaging abutment.
I will try to find it, but I'm not sure I'm familiar with John W, am I too new around here?
 
npdynamite

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Custom abutments are all engaging just like CRob
Personally, I'd rather just do custom abutments and cement retained bridges, but doctors don't seem to like playing with cement anymore
 
rkm rdt

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Personally, I'd rather just do custom abutments and cement retained bridges, but doctors don't seem to like playing with cement anymore
I do screw retained .
 
HonestAbe

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Right after reading this thread, a bridge case hit my desk (I'm just learning how to order custom abutments etc). Bossman considered the possibility of modifying the hexes (in the past, the doc has asked for that) but in this case we're going to do custom abutments. According to him (a 40 year vet of the industry) it is indeed on the doc. Can't hurt to CYOA though and keep records of stuff.
 
Darren S

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Right after reading this thread, a bridge case hit my desk (I'm just learning how to order custom abutments etc). Bossman considered the possibility of modifying the hexes (in the past, the doc has asked for that) but in this case we're going to do custom abutments. According to him (a 40 year vet of the industry) it is indeed on the doc. Can't hurt to CYOA though and keep records of stuff.
DESS makes non-engaging Ti bases and with ASC if needed. Zahn is now a distributor of those components. I've used them extensively in the past. You can get the .dme files for their products no problem. I've lectured in the past wit docs promoting screw retained restorations. A lot of upsides to it.
 
npdynamite

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Right after reading this thread, a bridge case hit my desk (I'm just learning how to order custom abutments etc). Bossman considered the possibility of modifying the hexes (in the past, the doc has asked for that) but in this case we're going to do custom abutments. According to him (a 40 year vet of the industry) it is indeed on the doc. Can't hurt to CYOA though and keep records of stuff.
In most labs this is the impression I've gotten, it's just with the amount of changes in regulation regarding custom Ti abutments and what it takes for a lab to be able to mill an interface, it just seems like this should fall into the same type of regulation.

At the same time I've had recent conversations with a Dr. who has suggested that because he is a doctor that he doesn't need the FDA clearance to mill an interface that a lab would need. It doesn't make any sense to me that a doctor should be able to circumvent a regulation to control the quality of manufacturing medical parts because the matter at hand has absolutely nothing to do with a doctors education, it has to do with engineering and manufacturing. Why would a doctor be more qualified to say if a custom milled/modified part is "good enough"? That's getting into a slightly different subject but still along the same lines.

The other question all this brings up is, why does the FDA even matter to labs if we can supposedly circumvent their regulation as long as the doctor is in the loop and ok with it? Because if this modification is ok with a doctors permission but not ok without, isn't that what is implied? So say for example if a lab worked up their entire own implant library and bought Ti pucks and started milling their own custom abutments and various interfaces but didn't get any of this approved through the FDA. If they went to their doctors they could just explain what they were doing and if the doctor was cool with it they could just proceed? This seems highly unlikely to me.
 
npdynamite

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DESS makes non-engaging Ti bases and with ASC if needed. Zahn is now a distributor of those components. I've used them extensively in the past. You can get the .dme files for their products no problem. I've lectured in the past wit docs promoting screw retained restorations. A lot of upsides to it.
I'm aware of DESS's parts, but they are extremely short. If you get say a 4 unit posterior bridge that will need to be milled out of a 20mm puck and that the patient will be functioning on you are going to want a taller part than that. In this case I would say custom Ti abutments and a cement retained bridge, this is going to be the better situation.

I have attended my share of lectures on the subject and I realize that there are upsides to it. My observation is that the people lecturing on screw retained do a really good job of getting doctors scared of cement clean up so instead of learning to be great at their job, they lean on products that allow them to not perfect their craft. Then when the lab calls and says that a screw retained case isn't ideal and we need to do custom abutments and cement retained they would rather do a restoration with compromises that the patient is going to be the one who has to deal with. Sorry, I'm slightly bitter about the screw retained trend, but that's because I believe that it is more rooted in lazy dentistry than people care to admit. Probably an unpopular opinion.
 
Andrew Priddy

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TRU has non-engaging bases as well.. good stuff. great angled solution as well
 
Contraluz

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I believe I know this answer already, and I have seen other threads that touch on it so I think I know what the general opinions about it are, but I wanted to start a thread on this specifically so I can gain an understanding of what is opinion and fact and what is a good idea for ass covering vs. what is legal.

The question is as as the thread says, modifying abutments to make them non engaging. In my years in the lab I have seen this topic come up and based on how the FDA regulates custom abutments it would seem to me that it is not legal to remove the interface from an abutment and make it non-engaging. That said I can see why it might not seem like a big deal when you are working on something like a NobelActive where the conical part of the interface can remain intact and create some sort engagement so that there is more than a screw holding the restoration in place ( have seen a Nobel Trilobe interface removed for this purpose before and that seemed like an a terrible idea, legal or not).

The one situation I see where being able to do this would be a great advantage is when there is a screw retained bridge that you also want angle changing abutments on. Not all companies are making ASC non engaging abutments and some of the companies that are making them are making the interface for the crown so short that the strength of the case would be compromised. In these situations getting an engaging part and removing the engaging aspect could create a better restoration, but it if it puts the lab in legal trouble that doesn't really help. I would like to know how bad of an idea this may be if it were to come up again.

So what do ya'll say? Is this straight up illegal, something to avoid for just in case/CYA reasons, or more of a "if the doctor is aware and ok with it" type of thing?
There are a couple interfaces where it is possible to convert them to non-engaging. For example Nobel active, MegaGen and Straumann, where it is possible to cut away or modify carefully the engaging part, without loosing the contact surface of the taper (Not sure I make sense here...).

On Zimmer abutments, and all its copy cats, it is almost impossible to modify the anti-rotational part without messing up the hole interface.

Edit: spelling
 

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