Loose Crown or Abutment Screw: Treatment Plan?

Anon. asks:

One of my dental implant patients returned with a loose cemented crown. I cannot be sure if the crown is loose or if the abutment is loose. Is there any reliable way to determine this?

If the crown is loose should I attempt to tap it off? Or would this be too dangerous? If the abutment screw is loose I am assuming the only way to deal with this is to cut thru the crown access to the abutment screw or to cut the crown off. One of my colleagues uses only temporary cement and claims that in a situation like this, if the crown is loose he can remove it without damaging it or the abutment. Any suggestions? Please help.

8 thoughts on “Loose Crown or Abutment Screw: Treatment Plan?

  1. The screw is probably loose. If the crown was cemented and you detect movement of the restoration and cannot pull the crown in the long axis of the implant without the crown coming off it is the screw. If it where a cement failure, the crown would come off fairly easily. This senario is similar to conventional post and buil-up loose or is the crown loose. If it is appreciably loose but you cannot remove the crown, the build-up and post are loose but cannot be removed because the post although loose has an undercut therefore not easily removed. The analogy is rough, but the screw loosens and the remaining threads prevent removal. One attempt at saving the existing restoration would be to make an assessment of where the abutment access hole is, drill with a diamond through the porcelain, then through the metal with a carbide. Gain access and unscrew the abutment. Inspect the integrity, place a new screw, cover the access with a restoration and now you are not committed to a do over unless you and the patient agree differently. I did this for a new patient last week, and I saved them from a do over. Hope this helps

  2. I am not a dentist, I am a technician (MDT and CDT}. I have found this to be an all too often occurrence, some respected authorities advocate screw retention to prevent this kind of an issue. Another suggestion is to be sure that the abutment is prepared with a retentive, parallel walls making sure the casting has a retentive fit to the abutment. These crowns will only need to be cemented with provisional cement making them much easier to remove if necessary.

  3. I would agree with Dr. Shaw. It most probably is the screw between the implant fixture and the abutment that is loose. You may want the sacrafice the crown if you are having difficulty in removing it rather then risking fracturing a weakened screw within the fixture. If you can create an access hole, I would still replace with a new screw at the proper torque setting and then check the occlusion. Good Luck

  4. Add to my pervious post:
    In order to accomplish this it is neccessary need to lift the crown higher than the non rotational element so it is diengaged, ie; a hex etc, while completing the rotations.

  5. some related thoughts:
    1. sacrifice the crown and start over if it was restored within the last year or so. A repaired crown may diminish the pt’s impression of your skill and professionalism

    2. For some unknown reason patients can accept and comprehend the concept of natural teeth and restorations on them failing. However, they seem to have different and often unrealistic expectations for implants. We need to educate them well and CHARGE APPROPRIATE FEES! The time and education invested in learning implant skills is considerable. Charge fairly and adequately so that the occasional remake or replacement can be absorbed by you and not the pt. Their investment is also considerable. That said,I also believe we need to educate the patient better regarding any possible future treatment needed due to biologic or parafunctional changes in their general and oral health. Dentists need to learn more from orthopeadic docs. They don’t have “failures” they do “revisions” and charge for them. Of course we should always be setting our standards higher and providing the very best treatment plans and care.

  6. Andy, well said. I just removed a crown from a patient who had 2 implants placed in the posterior. One was all the way in the non KT tissue area and in crossbite, the posterior one. It failed rapidly. The other next to the premolar is experiencing distal bone loss. They are both 3.7s in the molar region almost 13 mm apart. Another dentist had placed them. I finally got fed up with poor placements and difficult restorative situations. One thing I have learned is that placemtn CAN be difficult and it takes a few to humble yourself. BUT, planning ahead will avoid that completely.Ive got to repair the defect on the anterior one but the posterior one is history. I am fortunate for such a good patient in my case. This was certainly a poor surgical case and restorative “teaching” experience for me. Looking back, I should have never accepted that case back for restoration but I did and it was a poor clinical choice to proceed further. Bill

  7. It is believed that my abutment screw is loose. It has been 10 years since my implant and my dentist is suggesting to drill into the implant to uncover the screw and tighten it. Is this the best course of action? What are the risks of proceeding in this manner?

  8. i have a similar case and i would like to do an access hole and re tight the screw .i think if we use a torque wrench and give 35 newton then it wont be a problem .if iam wrong please correct me

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