How I Deal With Broken Screws

In my practice, I get some referrals for handling broken screws.  And if you have worked with dental implants long enough, you may run into a situation in dealing with broken screws you caused or someone else has caused.

I don’t claim to be an expert in dealing with broken screws but the nature of my practice has forced me to develop a strategy in dealing with them.  And I have to admit, of all the broken screw cases I see, I was not able to retrieve all of them.  I would say I am successful in about 60-70% of the cases.

When I see patients with broken screws, I usually prepare them that I will start with the most conservative methods in removing broken screws.  Depending on how deep and how accessible the screw is, the worst case scenario is that there is internal damage and may render the implant non-restorable requiring implant removal.  I also will explain to the patient that it may take time to try different techniques and that time is often reflected in the fees for managing broken screws.

Once I have managed my patients’ expectation, my initial evaluation involves whether the fragment is above the implant body or below implant body.  The most favorable scenario (which does not happen often) is when the fragment is totally exposed without the attached abutment and above the implant body.  The next thing I will see if the screw head is still intact or whether it is stripped.  If it is not stripped, I will try to see if I can loosen up using an explorer or an ultrasonic thin scaler by wedging it between the screw and the internal wall of implant in an anti-clockwise direction.  If there has been no movement and the screw head is stripped, I will try to reshape the screw head to a slot shape configuration by using a ¼ size round bur or something similar.   Then using a slot driver I will try to engage the screw and loosen up the broken screw in reverse direction.  Sometimes the act of vibrations applied to the screw head with your hand piece when trying to cut a slot may loosen it up a bit for you.  If not, the slot screw driver will allow you to engage the newly redefined slot to loosen it.  You may find yourself having to modify your slot screw driver to fit into the screw depending on the size of your slot and the diameter of the access hole.  Alternatively, you can buy a mini screw driver in a hardware store to perform the same task or purchase a separate slot driver reserved strictly for these clinical situations.

In another scenario where the screw is hidden inside the overlying abutment/crown but above the implant body, I would try the same methods as described above.  Sometimes, if I can sacrifice the abutment and the crown,I will simply reduce the vertical height of the abutment/crown until I can see the screw.  Or sometimes I will have to section and remove part or all of the crown/abutment.  This is just to facilitate access.  Yes you do destroy the abutment/crown but it makes the screw more accessible for you.  Sometimes, the screw head is so stripped that it is very difficult to make a slot over it, my bur would be skidding over the surface.  In this case, I would also reduce the screw head here to create a flat surface first, and then redefine it with a slot over it with a ¼ round bur or something similar and using a slot driver to engage the screw that way.  In the past, I also noticed there is often so much binding between the internal walls of the abutment and the screw, I find myself that I have to create a ring of space to facilitate loosening up of the screw.  This approach is similar to trephining the bone around the implant to facilitate implant removal.  Here you are trephining the metal to facilitate screw removal.  This approach is possible only if binding is above the implant body. Otherwise, you are essentially damaging the internal walls of the implant body.

In the last scenario, the screw is broken with no overlying abutment but the screw fragment is below and inside the implant body.  In my opinion, this is the most difficult scenario and runs a high risk of internal damage.  If the broken fragment is not so deep, you can use the techniques as described above.  If not, there are screw retrieval kits and screw removal kits from implant companies for these clinical situations.  The screw retrieval kit allows you to cut in reverse and attempt to rotate it out.  It does require purchase of the kit which can be quite pricey but I have tried the implant screw removal kit from Nobelbiocare where it came with a drill to essentially “drill out” the broken screw.  It comes with a guide sleeve to assist positioning the drill along the correct angulation to minimize the risk of internal thread damage.  Then it comes with re-tapping tool to redefine the internal threads.  The one case I have used it I was able to remove about 80% of the broken screw.  I was able to re-tap the internal threads of the implant with copious amount of irrigation to remove all the metal bits and I was able to put a new screw into it.  However, in my opinion, it was a very time consuming procedure and I can’t imagine doing this procedure in less accessible sites like posterior area with limited mouth opening or on very off angled implants.  All the above procedures can be facilitated with the use of a microscope for visualization.

In the worst case scenario, if there is internal damage than a new screw can no longer engage the internal threads of the implants.   Prior to considering an explantation option, I have heard colleagues treating the internal implant like a canal space and restoring it as a one piece cast post and crown and cementing it with the strongest cement on the market.  I have never tried this technique myself but thought it can be explored if patient really does not want to remove the implant.

So these have been my techniques in dealing with broken screws.  I hope you will find this material useful.  What have been your tricks and techniques in dealing with broken screws?  Feel free to share that with me at drleung@drbeatriceleung.ca.  I would love to hear from you.

 

Clinical Scenarios Possible Solutions
  ·       Implant screw fragment visible with no associated abutment/crown

·       Part of the fragment is above implant body

·       Screw head visible

·       Assess mobility of fragment and if the screw head is stripped

·       Use explorer/thin ultrasonic tips to move in counter clockwise direction;

·       If no movement is noted, use an appropriate screw driver to unscrew the fragment

·       If screw is stripped, create a slot on the screw head and use a  mini screwdriver that can fit into the slot to unscrew it out

·       If the screw head is so damaged, try to flatten the screw head first before recreating a slot configuration

  ·       Implant screw is inside an abutment and or a crown

·       Screw head may or may not be visible depending on access

·       Try the above possible solutions

·       Consider screw retrieval system from implant company

·       Consider removing/sectioning the crown and abutment to improve access to the screw

·       Create a ring of space around the screw and the abutment (like trephining the screw) to facilitate removal

  ·       Implant fragment below the implant body ·       Try all above possible solutions

·       Consider screw retrieval system

·       Consider screw removal system

·       Consider explantation