Loose abutment screw will not tighten or back out: recommendations?

I have a patient with a cement retained implant bridge #6-11.  The implant used was not appropriate for this application, and the abutment screws in #6 and 11 have apparently been loosening and causing problems for years.  On both 6 and 11, the cement is holding, but the abutment screws are now loose again.  I have accessed the abutment screws through the labial and can securely engage the hex.  But, I cannot back out the screw or screw it down to tighten.  I was trying to avoid cutting off the bridge.  Do you have any recommendations? Thank you.

22 thoughts on “Loose abutment screw will not tighten or back out: recommendations?

  1. JR says:

    Try pulling on the bridge while you try removing the screw. There are occasions when the access hole that is made allows engagement of the screw hex, but not removing the screw.

  2. ken says:

    -any x-rays to check for screw fracture?
    -is there any resin blocking the exit path or the screw?
    -after covering the airway, blow a puff of air down the hole & see if the screw pops out
    good luck

  3. Paul says:

    From personal experience:
    – double check that the screwdriver is not slipping in the screw head. Sometimes the screwdriver has been stripped or the screw has been stripped.
    – last resort eliminate the screw head to lift the restoration and the rest can perhaps be removed with a fine hemostat.

    No matter what it is easier to deal with the screw when the abutment is off.
    As told by a rep in the case of Implant Direct and Nobel the screws are not interchangeable and therefore there can be an issue of cross threading.

  4. Sam says:

    Try widening the access, or gentle with a high speed handpiece clean any debris/metal/resin around the access/orifice which could be blocking the screw from coming out.

  5. Brandt says:

    If the hex is engaging and rotating but it won’t go up or down, the screw could be broken. This is Especially likely if it has happened before in the same screw was used to type back down.

  6. LCM says:

    More likely than not, the screw is not broken but bent enough after all that time
    when it was loose and still in function. Good luck.

  7. Barrow Marks says:

    This is a good example of why I do not like to permanently cement my crowns. Implants and abutments do not decay.why is it necessary to place a bridge that is not retrievable. In this case if temporary cement was used The bridge could easily be retrieved and the screw head would be more accessible to either screw down or back out. In any event, if the screw is bent and no longer properly engages the screw threads you could drill off the abutment and access the screw and save the implant. At that point as long as the implant is salvaged you could even retrofit the bridge with a PEEK abutment which you could adapt to the original bridge. In addition, this also gives you the option to periodically retrieve the bridge every few years to check all of the parts and easily perform any necessary scaling and debridement.

    I would be very interested to hear what my colleagues say about my approach to crown cementation.

    • Ed Dergosits D.D.S. says:

      The same problem exists even when temporary cement is used if the abutments have minimal taper. I used to see screw loosening problems with implant systems that had an internal hex and a flat I/A interface. I thought I was prepared for this event by using Temp Bond. Unfortunately many years ago I discovered that almost all cases of screw loosening required access through the crown to get to the screw head even when Temp Bond was used. . Screws generally do not loosen with systems that have internal conical connections and an anti rotation element. The most common situation where a screw will loosen is a single tooth replacement. Implant restorations that are splinted are way less prone to screw loosening. Using PEEK temporary abutments to retrofit an existing implant supported bridge is something I would only do as a temporary treatment.

  8. Raul R Mena says:

    Marks,
    I have no problems with screws, I don’t use screws the systems that I have used for many years are True Morse engagement 1.5 degrees, and I cement all my crowns and bridges with permanent cement.
    Trouble free and I can sleep at night without having to worry about screws coming loss.

  9. Jerome says:

    The most frequent cause of abutment screw loosening is OCCLUSION. Check the occlusion in lateral, protrusive, CO and MI. You will find once the premature contacts, working and non-working interferences are eliminated from the implant crown( you need to use the 12 micron thick mylar articulating tape or shim stock) the loose screw will be eliminated. Also make a nocturnal occlusal guard to protect the implant from parafunctional habits. I do believe not permanently cementing the implant crowns are better than having to cut them off!

  10. Raul R Mena says:

    Jerome,
    The reasons that you mentioned are important factors in screws becoming loos.
    The main factor is thread and screw design including the base of the screw head and the internal portion of the abutments.
    We don’t here that the screws in the car tires become loose, even thought they suffer from a lot of forces in the road. The main reason is that those screws are properly designed.
    In implant dentistry any Micky Mouse idea is applied to the screws. Give you one example, there is a company I reserve the name, that was having problems with screws becoming loss. Instead of fixing the screw design what they did is they made the screw out of gold so they could distort and stay in place. What they created was a nightmare, since now the screws started to fracture and the doctors had a hard time removing them. Wao but then they had a new source of income, ” Screw Removing Instrument” .
    See the mistake keeps propagating, but Company income increases since they sale more instruments and more parts.
    Good Luck with loss screws.

  11. Charles D LLano, DDS says:

    Maxillary Anterior restoration success is occlusion dependent. Deep lower bites and lower anterior movement will stress maxillary restorations. This will not be the first concern of the restoring dentist and it is definitely not a believable fact for the patient to accept. LOOK AT BITE STABILITY AND GUIDENCE AND CONSIDER THAT LOWER ANTERIORS ARE NOT GOING TO STAY FIXED.

  12. Daniel Stragier says:

    Some abutments have “captured” screws (Ankylos?) that are retained in the abutment and can’t be screwed back out of the abutment. The screw comes out with the abutment. You must pull up on the abutment while unscrewing. Sounds like the threads have stripped though.

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