Fractured ankylos abutment: feedback?

I placed an Ankylos 5.5 X 11 implant in #14 (UL6) position, and six months later restored it using an indexed stock straight abutment, and a cemented zirconia crown. There is a functional tooth distal to the implant/crown. The patient has a strong bite, but no para-functional excursions. The implant axis is angled slightly toward the facial with the long axis coming out within the occulsal table, but closer to the facial cusps.

The abutment fractured at the platform level after 10 months of function. I was able to retrieve the broken abutment and the threads which had separated from the screw shank. I am considering replacing the indexed abutment with a solid stock abutment. Intuitively it would seem to me to be stronger than the hollow indexed abutment. Dentsply has offered to replace the stock abutment with an Atlantis abutment, but I have a gut feeling that this would not be as strong as the solid stock abutment. I would appreciate any feed-back from any one who has had a similar problem.

5.5 X 11 Ankylos implant with fractured abutment and screw threads
5.5 X 11 Ankylos implant with fractured abutment and screw threads
fractured abutment at implant platform
fractured abutment at implant platform
crown with seperated threads and recovered abutment
crown with seperated threads and recovered abutment

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17 thoughts on “Fractured ankylos abutment: feedback?

  1. it is called metal fatigue.
    I use minimum of 7 mm implant diameter to replace molars with 5.7 mm platform.
    I had never any fracture of such implants, or abutments.
    If you keep the same implant make sure pt uses a NG.

  2. Please could you let me know how you removed the broken abutment and the screw threads which had separated from the screw shank?

    I have had the exact thing happen this morning when a patient presented with the implant crown/fractured abutment in his hand! Ankylos implant C11 (5.5mm x 11mm).

    On closer inspection, it seems the screw threads have separated from the shank.
    How did you remove??

    Ron

    1. I had the same issue with the abutment breaking at implant level, then the screw thread separating from the screw thread. I first tried to engage the remains of the abutment using a large hedstrom file (#110) then tapping with a crown remover. Didn’t work!
      Went to Plan ll. I used a coarse flame diamond, 4000 rpm with electric hand piece, lots of water, and cut a grove inside the full
      length of the abutment–Very careful not to touch too much the inside of the implant. It spun right out with about 5 minutes of touch and wait drilling,
      The screw thread was easy. I first I tried using the tool the is in my surgical kit. It is a tapered HP shank with a reverse thread on it. Its used to remove stripped cover screws on their implants. It didn’t work!
      So I went back to the #110 Hedstrom file, engaged the thread and it came right out. The whole process didn’t take more than 15 minuets. I have Photos I can send if it would help.

  3. Take the offer of the Atlantis abutment.
    The Atlantis abutment has several advantages over the stock abutment that make it very appealing.
    It is a Cad/Cam fabricated abutment, which means that you can work closely with the design technician to optimize the shape of the abutment such as adequate reduction and clearance for porcelain, perfect margins and corrections of axial inclination according to opposing occlusal table.
    This is ideal in your situation since you are replacing a molar and you can create the emergence profile with the shape needed for a molar, which you could not do with a stock abutment.
    You can design the margins .5 mm subgingivally in order to easily remove any cement that could cause a problem.
    And finally you have the ability to request a “duplicate” abutment and crown with just a phone call if the abutment ever fails again since they keep the digital file from which the abutment is made.
    The stock abutment is not stronger than the Atlantis abutment.
    It’s a no-brainer.
    Good luck!

      1. Thank you all for the comments. At this point I believe I will go with the Atlantis Abutment, I like the design control, but still have my reservations as to whether it is as strong as a solid stock abutment.

        One other last possibility if this abutment fails, would to hollow out the internals of the implant into an ovoid shape and proceed with a cast/cemented post/abutment. Has any one had experience doing something like this?

  4. Actually, Dr. Healy has a good point. Ankylos is a great system but the good news/bad news is that they only have one abutment neck size. That’s handy for us restorative docs that only need one impression coping for any sized implant but not the best design when placing a small necked abutment into a high stress area, even if it’s on a 5.5mm implant. An Atlantis abutment is titanium, the same as the stock abutment and will be a hollow necked design just like the stock abutment and will be skinny, just like the original. Therefore, from a strength perspective, they will be nearly identical. Dr. Healy is asking about using a solid abutment that does not index into the Ankylos implant and therefore is solid and hot a hollow tube. Yes Dr. Healy, this makes the most sense from a strength standpoint. From a restorative standpoint it will be more challenging to restore and to clean the cement from the finish line. However, this would be the option of choice to increase strength. In the future, as good as the ankylos system is, you may want to explore a stronger implant system for posterior restorations.

  5. Hi All,

    mwjohnson dds is exactly correct, I place Ankylos almost exclusively and am currently enrolled in the MOI programme which is predominantly taught but Prof Nentwig (the inventor of Ankylos). In the course it is advocated that you need not go larger then 4.5mm diameter for this exact reason. The platform is identical for all diameters and it was discussed that this creates high stress at the implant -abutment junction just as the abutment emerges from the implant. We were also taught that this issue can only be rectified by keeping the current platform for 3.5 & 4.5 diameter and increasing the platform width for the 5.5 & 7.
    Atlantis abutments are magnificent but without managing the bite better ie shimstock clearance at minimum, this will happen again (be glad you were able to remove the remaining abutment this time) best of luck.

  6. We have seen this happen over 11 times with Ankylos in the posterior areas of the mouth. Never seen this with any another brand. We have abandoned the Ankylos system 4 years ago and still have to replace broken abutments or trefine 2-4 times a year. It is clearly not strong enough for posterior teeth.

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