Making abutments non-engaging

Contraluz

Contraluz

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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
Try TruAbutment. Non-engaging ASC abutments are possible.
 
Andrew Priddy

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TRU should be "first" one for material download imo. IMG_0714.jpeg

IMG_0794.jpeg
2 Non-engaging at TRU with Panthera Angled
(temp case)

this was "before" TRU had angled solutions
 
JohnWilson

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So Rob you have a good memory :) Not sure this will answer any questions but let me chime in anyhow.

Back in the day any multiple unit splinted restoration was restored at the abutment level not the fixture level. A trans-mucosal abutment was the only way and is what today we call a multi unit abutment. Literally there were no definitive parts for straumann fixtures for a bunch of years because 1, the lit all said things needed to be done a certain way, and 2, it sold more parts :) Yeah my opinion

Fast forward lots of years, back in the day NT trading didn't even have non eng ti bases, they had a really horrid MUA path called Two connect and it followed the old lit about only restoring to the abutment level. Heck probably had FDA crap to get around too???

All of the prefab parts that FDA was cracking down on even to this day is regulated and I am sure Keith from Dess USA will chime in if he is still on this site essentially was some of the first in the states that had a clean path to restore splinted restorations.

Today the milling centers are still playing fast and loose with fixtures, many may be milling more interfaces than they should and thats not for me to spill the beans on.

One of the first milling center to offer a NON ENG custom abutments to my knowledge was TRU Abutment and I can attest they are great. Are they compliant, again thats for you to ask them.

Remember anything touching a fixture that you buy that has compliance will always have compliance as long as you run a clean biz have good GMP's in place and track your lots. For years we would take abutments put them on a mini lathe and round over or cut off parts in a very clean precise way, The vast majority of internal hex fixtures will still have a projection ( I call it a chimney) in contact with the morse or tapered wall of the fixture. I have many many cases done this way it works plain and simple.

Regulations, piggybacking off of others 510k is essentially what us labs do daily, its still on your to keep good records but in todays market where you can get a bitchen custom abutment from an approved milling center for less than 100 bucks makes it seem so silly to even consider milling in house.

Even premils which we do mill in my lab are ONLY done when someone in my lab screws up or we need to rush out a special favor case.
 
npdynamite

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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
I agree that if this is something ok to do, that those are the platforms that work for it because the conical aspect of the interface can remain intact so that the parts will still seat together correctly
 
npdynamite

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I was aware of TRU abutments but my exposure was limited. In a previous lab we had received a scan with their scan body so I got there digital model analogs, which I hated because the were triangular at the interface. I never looked deeper into their lineup after that. The parts ya'll are referencing do look like great solutions so I will have to check out their products further.
 
npdynamite

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Remember anything touching a fixture that you buy that has compliance will always have compliance as long as you run a clean biz have good GMP's in place and track your lots.
Thanks for your input John! I was slightly confused by this line though, would you mind clarifying what you mean by "anything touching a fixture that you buy that has compliance will always have compliance? Thank you!
 
Darren S

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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.
Look into Open Implants as well. They have Ti bases that are 10mm high and can be cut down in 2mm sections. Also come in different gingival heights and in non-engaging. I did a case study with them an a patient a few years back Than consulted with them when designing the different gingival heights.
 
keith goldstein

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I'm aware of DESS's parts, but they are extremely short. Are you referring to the collar height or the chimney.
 
keith goldstein

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Look into Open Implants as well. They have Ti bases that are 10mm high and can be cut down in 2mm sections. Also come in different gingival heights and in non-engaging. I did a case study with them an a patient a few years back Than consulted with them when designing the different gingival heights.
the issue with ALL tapered wall tibases is a weaker bond retention. This is mechanical engineering 101. All you need is a 5 degree tapered wall and you decrease the bond retention by 68%. This is a test we did- following the same protocals for ISO 14801 stress and fatigue testing which is required for all tibases.
 
npdynamite

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I'm aware of DESS's parts, but they are extremely short. Are you referring to the collar height or the chimney.
The chimney and I should have specified that I was referring to the angled screw channel parts, not the C-bases
 
npdynamite

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the issue with ALL tapered wall tibases is a weaker bond retention. This is mechanical engineering 101. All you need is a 5 degree tapered wall and you decrease the bond retention by 68%. This is a test we did- following the same protocals for ISO 14801 stress and fatigue testing which is required for all tibases.

I can understand the advantage of the parallel walls as shown here, but my point of concern for the angle changing base is restoration breaking rather than becoming de-cemented. The situation where I have seen this the most is narrow anteriors that are tall and also need to function. While the material thickness around the part may be adequate per the manufacturer specifications, if the tooth is too tall in relation to the base used they will still break right around the top of the base. So that is why the shortness is a concern to me.
 
keith goldstein

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I can understand the advantage of the parallel walls as shown here, but my point of concern for the angle changing base is restoration breaking rather than becoming de-cemented. The situation where I have seen this the most is narrow anteriors that are tall and also need to function. While the material thickness around the part may be adequate per the manufacturer specifications, if the tooth is too tall in relation to the base used they will still break right around the top of the base. So that is why the shortness is a concern to me.
Here is the testing done for stress and fatigue- 11mm tall by 5mm wide zirconia placed at 30 degree angled and pushed 5 million times at 300ncm - The perception and marketing hype is taller chimney = greater bond retention and stronger and the tooth will not break right around the top of the base is not true. This is why you want to ensure that the tibase you are using is FDA approved and stated in the 510K since if it does not go through these stress and fatigue test (which many have not) is why there is the problem you experienced. Here is the testing done on this part.
 

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Darren S

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I am with Keith on this. You really don't need more than the 4mm that has always been the norm. I have done many screw retained cases on 4mm high chimneys with great success. The bond is what you do not want to fail. That is what will cause fractures. Done some restorations as tall as 14mm in e.Max to multi-unit and the Ti bases from Neoss and many more. Prepping the surfaces, using bonding agents and a dual cure resin cement. It really boiled down to technique. Thought I had some pics, but they are on my 3Tb hard drive at home that has all my lecture material. I will post some if I remember to.;)
 
npdynamite

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Here is the testing done for stress and fatigue- 11mm tall by 5mm wide zirconia placed at 30 degree angled and pushed 5 million times at 300ncm - The perception and marketing hype is taller chimney = greater bond retention and stronger and the tooth will not break right around the top of the base is not true. This is why you want to ensure that the tibase you are using is FDA approved and stated in the 510K since if it does not go through these stress and fatigue test (which many have not) is why there is the problem you experienced. Here is the testing done on this part.
Thank you for sharing that, that is interesting and good information. I'm certainly not saying that this is a bad part or that it doesn't have application. I intend to use these a good deal.

That said it does have it's limitations and any lab that does a lot of screw retained cases is going to have several, if not a lot of cases that these will not be ideal for on a yearly bases. to what @Darren S mentioned, not needing more than 4mm has never been the norm, a required minimum of 4mm is the norm. There is a big difference between can't be shorter than and doesn't need to be longer than. ;

Yes technique is a big deal here, you can have double the chimney height and still have failures regardless of wall taper if the work is done wrong. That said a perfectly prepared test of a product does prove that it works but it doesn't necessarily give you a real world feel for how a part would hold up. For example, the zirconia restoration will never have the perfect even thickness walls of the restoration used in DESS's test. Also 11mm is a short restoration, I'm referring to restorations in closer to the 20mm range. Especially situations where you have a tall tooth and an implant that is placed deep so the material has to remain narrow for the entire emergence out of the tissue, which could be twice the height of these bases already.

Once again, I'm not trying to attack the Dess part, I think it's a great part. But it is absolutely limited in application by its height
 
npdynamite

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Here is the testing done for stress and fatigue- 11mm tall by 5mm wide zirconia placed at 30 degree angled and pushed 5 million times at 300ncm - The perception and marketing hype is taller chimney = greater bond retention and stronger and the tooth will not break right around the top of the base is not true. This is why you want to ensure that the tibase you are using is FDA approved and stated in the 510K since if it does not go through these stress and fatigue test (which many have not) is why there is the problem you experienced. Here is the testing done on this part.
I just realized the test never lists the wall thickness of the zirconia coping, do you know what that thickness was?

Edit: Also the zirconia type/stength?
 
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