Wiggly crowns on abutments

rkm rdt

rkm rdt

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A few factors come to mind. How much spray is applied to the abutment during the scanning of the abutment itself. Any anti rotation on the abutment? And cement gap.

I had the same issue until I completely dialed in my settings and design.

Here is a pic of what I try to put in all my custom abutments if the walls are thick enough and allow me to place it in the design. I made a custom attachment with a flat wall and 90 degree edge and on the other side is a flat wall and a 45 degree edge.

View attachment 22289 View attachment 22290

Then in 3Shape I have the margin gap @ 0.01 and the extra cement gap @ 0.025. Then on my VHF CAM I have the cavity set to -0.010mm All my Ti and Zr abutment crown have near zero wiggle. I also find the issue even with these setting to be the scan spray, quick check and Tinactin come on very thick as were my Scan spray from talladium is much thinner. You only need a slight layer to stop the anti glare so the camera and catch the data.

This is how I got rid of my wiggly crowns on abutments.

It might be a good idea to lightly sandblast the abutment prior to scanning.
 
2thm8kr

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I have a similar design to Sevan with a chamfer at the bottom (apical) of the flat edge.
 
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I had the same problem when you have abutments shaped like that. So parallel and no retention is the culprit.
Using Exocad I lowered my cement space gap as low as it will go....02 or .01 this barely helps !
This helps a lot !
Rise the Start of Cement Gap, but below the slot,,, this will help tighten up the crown to any degree you desire.
If your Start of cement gap has a default setting of 1 and the Start could be raised to 3 and still just below
the slot, try increasing Start to 2 as an example.. or maybe 1.5 ?
Using Exocad !, my normal X/Y is set at .02 Scanning titanium abutment I lowered to 0. If I were to use .01 or
.02 X/Y my abutment crowns would spin like a top on titanium...
May want to mill several crowns using higher start points to learn where the ideal Start of cement works best if
you have never made this change of setting.
fyi: If you start the cement gap above the Slot where there is a change of contour of the prep, the milled crown my not seat.

fyi when I design very short crowns with little to no retention on gold, FCZ, DPM, I raise the Start of cement gap to achieve tighter fitting crowns.
If you have never moved the Start, a little goes a long way for tighter fitting crowns...
 
CoolHandLuke

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i trust Riley already knows how to get tight fit crowns on abutments - the issue here i'd bet is a dentist that has some problem with his work, or is mostly nitpicky over nothing of importance.
 
CatamountRob

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i trust Riley already knows how to get tight fit crowns on abutments - the issue here i'd bet is a dentist that has some problem with his work, or is mostly nitpicky over nothing of importance.
Really?
You trust Riley?
Do I have to go retrieve the vibrator thread?
 
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charles007

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Your right Luke, and Riley knows a lot more than me, but other techs reading this post may learn a few tips... :)
 
RileyS

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Lots of good stuff to work on. Thanks everyone except CRob!!
I like the attachment idea seven. I'll figure out what exactly to look for on measuring for drill comp ( care to elaborate JDub?) And I'll make small changes to spacers.
 
Jenners

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I'm so glad this thread was started. I've been arguing with zi copings on ITI Solid Abutments. Zi fits great on our custom abutments but rotate a little on the solid abutments. I took away all the spacer. I'm using DWOS and Sum3D. I'll take the mill compensation off next time I have a solid abutment but if there are any other DWOS users with tips, it would much appreciated.
 
Sevan P

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I'm so glad this thread was started. I've been arguing with zi copings on ITI Solid Abutments. Zi fits great on our custom abutments but rotate a little on the solid abutments. I took away all the spacer. I'm using DWOS and Sum3D. I'll take the mill compensation off next time I have a solid abutment but if there are any other DWOS users with tips, it would much appreciated.

My trick to those is on my 3shape I scanned a slightly worn edges analog in as a die then took that file and put it in a folder on the desktop. Now while im scanning i have the option to import a scan then i import that scan as the die so im not always spraying and scanning it every time. Plus I took it even further to make sure the fit was perfect before I made it the final scan file. The slightly worn edges on the top cap makes for a even better fit on the sharp clean abutment on the model and in the Mouth. Working on getting nobels easy abutments in as well.

Watch out on how much spray you put on if you do, otherwise try a lite sandblast like RKM stated.
 
Jenners

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My trick to those is on my 3shape I scanned a slightly worn edges analog in as a die then took that file and put it in a folder on the desktop. Now while im scanning i have the option to import a scan then i import that scan as the die so im not always spraying and scanning it every time. Plus I took it even further to make sure the fit was perfect before I made it the final scan file. The slightly worn edges on the top cap makes for a even better fit on the sharp clean abutment on the model and in the Mouth. Working on getting nobels easy abutments in as well.

Watch out on how much spray you put on if you do, otherwise try a lite sandblast like RKM stated.

Smart, didn't even think of saving and importing files for these. I'll have to dig into that further. I know how to do the basics on this system. I'm not nearly as well versed as the good folks on this forum.
 
KentPWalton

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Riley,

The design of the top cap and the radius you design will dictate the tightness because of how the drill compensation and cement spacer parameters are effected by this design


Riley...this is important! You need to contact Argen and ask them what is the radius of the

end mill they're using around the margins....then you can set your drill radius properly for a

better fit.


After you have the proper radius, you can then tweak the cement gap, extra cement

gap, distance to margin line, smooth distance, drill radius, drill comp offset. These are the settings

that will help tighten/loosen up the crown. Go to the control panel, click on cement gap, and look

at where that setting is affecting your fit. Once you understand completely what effects what and

where, then you can fine tune it. I do split file cases every day with a great fit, but we did do a lot

of R&D to figure out which setting we were happy with. I suggest you get a duplicate abutment from

Argen and scan it in, play with the settings on a coping to see what you're getting until you're happy.

Like @JohnWilson said, do a 2d cross section to see the effects of the changes as well.
 
KentPWalton

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It might be a good idea to lightly sandblast the abutment prior to scanning.

You're going to make the abutment darker if you do that and if you anodize it

afterwards, it will be a completely different shade.
 
KentPWalton

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Riley,

Do you have problems with other Dr.'s complaining about "loose" fits of your

crowns on top of your abutments? You may just need to separate the chafe from

the wheat!!
 
rkm rdt

rkm rdt

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You're going to make the abutment darker if you do that and if you anodize it

afterwards, it will be a completely different shade.

Drs can use an opacious cement or you can use a brass bristle brush to renew the colour.

images
 
KentPWalton

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Drs can use an opacious cement or you can use a brass bristle brush to renew the colour.

images

Why do an extra step when it's not needed? If you sandblast it...you're going to make it more loose!
 
Sevan P

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Why do an extra step when it's not needed? If you sandblast it...you're going to make it more loose!
Kent, he meant sandblast it before scanning, that way the surface of the abutment us not shinny.

Sent from my SM-G920V using Tapatalk
 
sidesh0wb0b

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I don't section my implant cases. I do try to make contacts extra broad but he's checking the crown to the abutment off the model i presume.




I'm designing cust abutments on 3shape, milled by Argen. FZC crowns on top that I scan after receiving the new abutment.
i always have anti-rotational grooves (1 or 2) on every abutment that permits it. well worth it IMHO
 
KentPWalton

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Kent, he meant sandblast it before scanning, that way the surface of the abutment us not shinny.

Sent from my SM-G920V using Tapatalk

Sevan,

What I meant is that when you sandblast the Ti abutment, it makes it darker and harder to mask

out behind Emax, etc. Not all Dr.'s use shaded cement and we know that. That's all I was saying,

that it just makes it that much harder on tougher cases sometimes.
 
rkm rdt

rkm rdt

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I get the tougher cases and I know what cement my drs are using.
I also want a good surface area to adhere to and light sandblasting provides that.

I can change the colour of an abutment by using a brass bristle brush if I want to go there but rarely do when I have opacious cements.

If you think anodization solves all shading issues with an all ceramic crown then you haven't been a ceramist for very long.
 

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