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    Cracking

    Discussion in 'Zirconium' started by sndmn2, Jun 12, 2018.

    1. sndmn2

      sndmn2 Well-Known Member Full Member

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      I tried milling out this case twice. Same results each time. Cracked. Its AG Zolid Fx. Multi. Its the first time its happened. Design issues , crown to thick? Anatomy to deep? I cooled as I normally do.
       

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      Last edited: Jun 12, 2018
    2. Elías

      Elías Member Full Member

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      I had the same problem with all zirconium between 600 and 700 Mpa. In all my crowns with channel access. We solved the problem using 900 Mpa zirconium.


      Enviado desde mi iPhone utilizando Tapatalk
       
    3. user name
      Question

      user name Well-Known Member Donator Full Member

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      Could be your tool is bumping the side for the screw channel. I always smooth the edge of the occlusal entrance to the channel.
       
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    4. Contraluz

      Contraluz Well-Known Member Full Member

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      You seem to have a bit bad luck with your Zirconia... You may want to check your singeing furnace...
      I tend to agree.
       
    5. DanM

      DanM Member Full Member

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      I use Fx often and works great regardless of thickness. I think like username said, the only time I've seen it when I had funny access and was trying to mill with 5x. I suspected the bur cracked it. That situation I turned off 5x and it turned out fine.
       
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    6. DanM

      DanM Member Full Member

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      Are you marking depth limit and insertion directions from top and bottom in CAM?
       
    7. Car 54
      No Mood

      Car 54 Well-Known Member Donator Full Member

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      In 3Shape you can create an occlusal bevel to help with any corner that the bur may bump into, as Bob suggested.
       
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    8. sndmn2

      sndmn2 Well-Known Member Full Member

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      How would I bevel the screw hole ?
       
    9. Car 54
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      Car 54 Well-Known Member Donator Full Member

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      When you add the hole in 3Shape there is a setting I was shown by support to create the bevel, but since I only do cementable implant crowns (as of now) I didn't write it down.
      Call Core3d and they'll gladly show you like they did me, unless Sevan or someone else stops by.

      The other nice thing about that occlusal bevel is that it helps create a smooth "edge" compared to a sharp corner that could chip?
       
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    10. user name
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      user name Well-Known Member Donator Full Member

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      ...and it makes it much nicer for the Dr to fill with composite and not have to blend into a sharp edge.
       
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    11. Car 54
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      Car 54 Well-Known Member Donator Full Member

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      Good point, hadn't thought of that one.
       
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    12. rkm rdt

      rkm rdt Well-Known Member Donator Full Member

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      Drs will use a low viscosity composite to fill the hole.
      There will be erosion.
       
    13. Car 54
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      Car 54 Well-Known Member Donator Full Member

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      Unless they pack amalgam in it :D:D
       
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    14. sndmn2

      sndmn2 Well-Known Member Full Member

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      Support couldnt find it. Ill have to do more looking.
       
    15. Car 54
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      Car 54 Well-Known Member Donator Full Member

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      It may depend on who answers the phone. I don't have an implant case in the lab, and I can't modify and old case to try to find that for you.
       
    16. KIM

      KIM Well-Known Member Full Member

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      Wish my tool bumped the screw channel....Anywho......
       
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    17. DanM

      DanM Member Full Member

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      Hmm is it hole filet? I thought I remembered bevel during assembly but I don't see it now. Went through 4 libraries, on version 2017. Maybe it changed?
       
    18. Car 54
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      Car 54 Well-Known Member Donator Full Member

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      I believe I was on 17.2 when they showed me, maybe 16? But it was there, somewhere.
       
    19. Contraluz

      Contraluz Well-Known Member Full Member

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      Very true and very, but very annoying!!! There is more inconsistency in 3shape tech support (doesn't matter whom you call) than in a politician, keeping his/her promises.
       
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    20. Car 54
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      Car 54 Well-Known Member Donator Full Member

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      Funny, sad but true.
       
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