Dealing with loose implant crownHave you ever had to deal with a loose implant crown? implants are being used more and more in dentistry and if you have not dealt with this yet, chances are you will sooner or later. When it comes to loose implant crowns, I personally think the most difficult to deal with are cement-retained implants with a loosened abutment screw.

Even though implant design has improved greatly over the years and the incidence of screw loosening has decreased greatly, the simple fact is that screws still come loose occasionally. Not to mention, there are still a lot of older implants out there that are more prone to screw loosening.

The first step in dealing with any implant restoration is to determine the exact implant you are dealing with to ensure you have the right components ready and available. While this should be easy if the implant was placed while the patient was under your care, you may experience difficulty obtaining records if the implant was placed by another dentist prior to the patient being under your care. If you can’t find records that document the exact implant that you are dealing with, your job will be harder since there will be a risk of misidentifying the implant. On the bright side, many implant manufacturers have technical departments that are skilled in identifying implants based upon radiographs. The few times I have done this, they have accurately identified the implant.

loose screwWhile you could try to tap the crown off the abutment, you are faced with two potential problems – breaking the abutment screw and damaging the internal threads of the implant. Due to this risk, I prefer to access the abutment screw though the crown leaving an access hole similar to an endodontic access. It’s worth noting if the crown is rotating on the implant, it can help you determine the location of the screw since it should be in the center of the point of rotation. It is important to remember that while you may place material such as cotton, wax or Teflon over the abutment screws, a previous dentist may not have used those materials.

When it comes to trying to find the screw my best advice is to make sure you aren’t pushing it too far. You do not want to damage the screw; this could complicate removing the screw, or worse, you could damage the implant itself. While you and your patient will be disappointed if you cannot save the crown, it will be much worse if you damage the implant and possibly lose the implant itself.

Even if you can’t safely locate the screw, you still have to get the restoration off, so the question now becomes "What now?" In cases like this, I like to cut the mesial and distal of the crown off to create a diastema on both sides that is large enough to allow you to rotate the crown to remove it. Of course the downside to this approach is the fact that the restoration is now ruined and the patient will need a new one. While we prefer to avoid this, it is far better than compromising the implant itself.

While I hope you don’t have a patient with a loose implant crown, I hope this will give you some ideas that will help you if you come across a patient with this problem.

John R. Carson, DDS, PC, Spear Visiting Faculty and Contributing Author [ www.johncarsondds.com ]


Comments

Commenter's Profile Image Debi Doron
June 13th, 2014
Great idea , I've come to use the same technique - being afraid of breaking the screw by trying to remove the crown, so I've opened up the crown to access the screw, usually then replacing it with a new screw , to prevent future failure at the screw level. Unfortunately I've seen worse ....I've seen implants broken at the screw level , retentaining part of the screw in the implant. Not a nice scenario, ended up replacing the implant. As a result I highly recommend the use of a night guard to patients who are implanted especially with more than one implant , as a preventative measure against implant failure, and proper occlusal contacts to limit stresses on implant
Commenter's Profile Image Carlos Boudet, DDS DICOI
June 17th, 2014
I am glad to see Dr. Carson shares my philosophy for dealing with a loose abutment screw. I strongly believe that all dentists, even those that choose not to be involved in the surgical placement of implants should familiarize themselves with these types of problems. External hex implants placed many years ago were prone to screw loosening and we are likely to see one walk in our office asking for our help.
Commenter's Profile Image Manjitsingh Bhalla
October 20th, 2014
Loosened implant crowns with much more damage (getting banged with bacteria invasion) will not be a surprise! At this point, do you think an importance of non-fixable implant crowns over a fixable one? An accurate identification of implants is how much significance will then be understood once we get caught with such problems; else, not an issue; will be fixed by a good dentist! Screw removal with great care not affecting an original implant itself is also an expertise – yes, so far as we take an implant life in considerations. Nice info!
Commenter's Profile Image John Carson
October 21st, 2014
Manjitsingh, are you asking my thoughts on screw retained vs cemented implant restorations? If so yes I do give consideration to these and make my choice on a case by case basis. I will also say that nearly every implant I restore now is an Astra as with their connection I have seen zero loosening.
Commenter's Profile Image Gerard Cuomo
December 13th, 2014
I also agree with the general philosophy shared by the group. I have been helping dentists with loose and fractured abutment screw cases for several years. I must mention that microscope use takes the guess work out of the equation. This month I offered a 3 hour hands-on course to local clinicians in the South Florida area. Both GPs and specialists had to use tooled instruments to remove two fractured abutment screws located in "dummy fixtures" placed in a typodont model. One fragment was located above the first thread of the fixture and the other was located below. Each participant demonstrated simple hand instrument fragment removal techniques, as well as drilling a pilot hole, slotting the screw head, and using flat driver to remove the broken screw. I've been video documenting each case and uploading them onto YouTube for educational purposes.
Commenter's Profile Image Deacon Hanson
January 9th, 2015
In situations where you have had to remove the abutment screw by first drilling through the crown, have you ever encountered a situation where you are able to fully loosen the abutment screw but cannot pull it out of the implant? I am currently in this situation. I was experiencing a feeling of "softness" in my implant so my dentist drilled through the crown, loosened the abutment screw, and proceeded to pull out the abutment screw from the implant. Although it was completely loose, it would not pull free. He tried several times with substantial force, and even brought out a special hammering instrument with the apparent objective of possibly knocking on the right path. We finally tightened it back up and put a temporary plug in. I supposed to see him in a week. He is very experienced and has indicated that in 25 years of practice he has never run into this type of situation. I would like to avoid loosing the implant, so if any of you have experienced a similar situation, please let me know. I will pass any helpful tips on to my dentist.
Commenter's Profile Image John Carson
January 11th, 2015
Deacon, I am sorry to hear you are having trouble. I have not ever encountered the problem you describe It is hard to say what is going on for sure without more information. Typically, as your dentist as indicated, if you get the screw fully loosened you can then remove the implant restoration. Really about the best advice I can offer would be to see if your dentist would be open to posting more details (including any x-rays and photos he has) about what is going on in Spear Educations Spear Talk which is online discussion profession discussion forum. The members there are great about offering whatever constructive help they can. I hope this helps and that things go smoothly moving forward, Dr. Carson
Commenter's Profile Image Frank B. Dal Santo MD, DDS
April 13th, 2015
I have seen this problem several times before with tapered internal connection "platform switching" implants. The internal connection of these systems forms such a tight "cold weld" that even when the screw is removed the crown will sometimes remain tightly adherent. Some implant systems (Nobel) make special parts for their systems that help with this removal problem. With other systems a combination of rubber tipped crown removal forceps/ abrasive dust and crown removal "juju-bees" has worked well. hope this helps!
Commenter's Profile Image Brien Harvey
April 13th, 2015
I am not sure I am understanding Deacon's question. If "softness" of the implant equates with mobility of the crown/abutment complex, then backing the screw out far enough should allow removal of the crown and abutment together as one "unit". If the crown is not loose and the dentist has backed the abutment screw out and just cannot remove it, I would suspect that the access opening is not aligned precisely with the path of access for the screw. If the crown remains rigid, assess the alignment of the access opening and adjust it as necessary to allow complete removal of the retaining screw. In a situation where the screw is loosened and the abutment/crown remains rigidly fixed - as Dr. Dal Santo mentioned above, being most commonly encountered with an internal conus interface between the abutment and the implant - I frequently find it helpful to gently tap or rattle the side of the hex while it is engaged with the retaining screw against the internal aspect of the abutment and crown, attempting to jar the abutment loose. I have had less luck using vertical forces.
Commenter's Profile Image Theresa M.
January 11th, 2016
from Theresa E. Madden, DDS, MS, PhD, FACD (Olympia, WA) Thank you for presenting this article. As a periodontist I have regularly been referred such cases. A few times the screw was fractured. As posted by Dr. Cuomo, it is possible to remove the apical part of the fractured screw. First I try with an sharp explorer to back out the screw fragment. If this doesn't work, I CAREFULLY cut a slot in the top of the screw, allowing better engagement of the explorer or narrow chisel. Once, the internal aspect of the implant screw threads was damanged. However, I was able to successfully salvage the implant be rethreading the internal threads. This was a Straumann Tissue Level fixture. My Straumann rep provided me with a loaner kit for this purpose. It was like tapping the internal threads to the correct pitch. Of course, this is a last resort. But a new screw was used by the restorative dentist and this abutment and crown have not become loose again in the past 4 years.
Commenter's Profile Image John C.
January 11th, 2016
Thanks for sharing Theresa! Glad I don't see these regularly since as you know they are no fun! Out of curiosity how often do you see things like this?
Commenter's Profile Image Andrew S.
January 11th, 2016
I have dealt with this scenario a few times myself. Yes, implants are getting better, and more recently I was introduced to the reasons why implants like Astra are better at this. What are the opinions of others on how a flat abutment interface design can cause fractures of the implant and bacterial integration into the screw of the implant. Versus a conical designed one where there is no micro gap, like the Astra? Here is a video on the subject matter. https://www.youtube.com/watch?v=AhsjiYjmTLE
Commenter's Profile Image Bryan B.
January 12th, 2016
Far better than contacting reps to find out an unknown implant is using the website http://whatimplantisthat.com/ This post reminded me that I have wanted to tell my lab to make a small brown or yellow dot at the access point built into the crown.
Commenter's Profile Image John C.
January 12th, 2016
Andrew, I too like engagement in the to the implant like you get with Astra and Straumann.
Commenter's Profile Image John C.
January 12th, 2016
Bryan, that site can be helpful for sure however IMO a good rep is also invaluable, that being said I have also been burned by reps that were less than good, however I am currently blessed to have access to several stellar reps!