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Dr. L. asks:
I am a recent grad and have been placing dental implants for 3 years. Recently, I completed a case where I forgot to torque down the abutment screw completely. Now it is loose! The crown is still cemented tightly to the abutment.
I always had an implant rep help me in the beginning. How do I retrieve this screw and tighten it? Can I approach it like an endo access? I placed Memosil in the top of the abutment just in case I needed access. Will I need a special bur to cut through through the crown? How do I avoid damaging the abutment and even worse, the abutment screw head?
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18 Responses to “ Loose Abutment Screw ”
Dear mL: Yes you can do it as an endo access opening. I have had to do this on occvasion and it does work. Rich
use sharp carbide to cut thru metal part of crown and stop as soon as u see your sealer.you won’t damage screw.
Only thing you should worry is damaging threads of abutment screw,because of the movement of abutment during drilling. Make sure to hold crown tightly with hemostat to minimise movement.
If that dose not work, just sacrifice crown and remake new crown after tightening the screw.
Here’s a suggestion whether you can retrieve the crown or have to made a new one. After torquing in the screw for the abutment, cement the crown “provisionally”. I usually lubricate the crown casting interior and the abutment with a light coating, then cement with ImProv cement for a road test of about two weeks. Then I retrieve the crown with the Richwil Crown and Bridge Remover if there is no interproximal debris accumulation and no occlusal problems, then cement “definitively” with RelyX or similar. The road test helps trouble shoot problems while the crown is still retrievable. You also get another chance to torque the screw at the final cementation appointment.
As a laboratory technician who has witnessed this several times,I often indicate the point of access with a small spot of coloured porcelain, or a slight depression in the case of gold.
This is also helpfull if there is a need for removal to repair damaged ceramic.
The crown can then be seperated from the abutment by placing in the furnace at standby temp. for a few minutes to break down the cement
All the posts have provided you with the two options you have, to cut the endo access and with a little luck access the screw and either torque the abutment-crown or remove the same, separate the abutment from the crown and replace each ideally. The other option of course is to sacrafice the crown while saving the abutment.
However, what wasn’t mention in prior posts is that if you used an external hex implant that the loose abutment can be damaging the hex which is a more difficult problem to deal with. So, take action ASAP.
That is a problem. We have all been there. There is a learning curve. I suggest to use an implant that does not require a torque procedure. Also, be careful on the road test idea, crowns will come off which can be another problem. A good lab person can help. Do as Dr Burk says take action ASAP.
Dr L: Cut your losses. Take a VPS triple tray of the new crown (hopefully this does not involve a bridge. Cut the crown off doing the least amount of danmage to the abutment. Torque down the screw and recover. Re-impress and temporize. The new crown should be back in two weeks and you patient will be fine with the temp. Patient now has a perefctly intact crown without a hole in the porcelain….it is no fun finding the screw access hole through a permanently cemented porcelain crown…its takes a while and its stressful. and after this patient has paid you alot of $, they now have damaged goods…your cost should be $130.00 + time. good luck.
Be careful using the temporary cement. This would not be done in conventional dentistry. We don’t use temporary cement in regular crown & bridge dentistry. This causes yet another problem if the temporary cement dissolves underneath the crown. Now you have two micro-gaps! This is exactly what we don’t want! I believe we have seen enough research on micro-gaps at the implant-abutment junction to know that creating additional micro-gaps can only be detrimental to the patient. Please be careful with the temporary cement!
MB,DDS
VERY GOOD POINT!!!
What do you (the readers) think of retightening a loose screw on an implant in function. My past ( fortunatly limited) experience is that once a screw loosens, retightening it does not last long. I have made it a point to replace any loose screw in my implants and this has stoppped the loosening issue. I seem to remember that loaded screw threads “stretch abit and can never be tightened sufficently to hold under lateral forece again. Just interested in your thoughts .
I agree with Dr. Frost. When we (docs) drop the ball, it is our duty to make it right. Cut the crown off and start over. The patient desrves no less. It is a lab fee for the new crown and your time to make it right. Good luck.
I wholeheartdely agree with Larry S. Once a screw has loosened (whether or not it was torqued to start with) I replace the screw. There is no sense to risk that this screw could loosen again (stretching is a real phenomenon)and fracture. I have had to access multiple loosened implant crowns (I had one patient with 8 implant crowns placed in Mexico and every one loosened). Not a situation to redo the crowns. Really study a Bite wing and determine the mesial-distal position of the implant under the crown. As an aside, if I have an off angled screw hole I take an intra-oral photo of the abutment on the implant and attach it to the digital record.
While redoing the crown is the ideal, if you plan to save the crown, cut through the porcelain with a diamond bur. Then cut through the metal with a GW 2 from great white. These cut through metal in seconds. You will shortly fall into the memosil you placed then immediately go laterally to open the access and you should perceive the internal of the abutment as increased resistance through the handpiece. Do not go too deep and muck up the head of the screw, life will then be very difficult. It is much better to notch up the internal of the abutment than hit the screw. the second you fall into the internal of the abutment, stop and just go horizontally. We all learn by experience…you’ll never forget to torque again. good luck.
Use of Technolock can further reduce the rare incidence of loosening..
Call your rep!
I have tried to find the answer, but no luck, so here goes. Why does an implant become loose? I have had to have my crown removed by my dentist and will see the Oral Surgeon that performed the original implant to retighten the abutment. At the time it is tightened, the tooth in front of that implant will be extracted, infection and tooth can not be saved, but again, why did the abutment become loose?
Any help would be appriciated.
Screw loosening is primarily attributed to improper occlusion set up (and not torquing in the first place!)
Absolutely replace crown and screw
I certainly would not accept a hole my crown
Re microgap and temp cement I have to DISagree with previous posts of not using temp cement Microgap issues are at the junction of the implant and connection to abutment
Crown margins are not at bone level ..or should not be so
I do use temp cement and fairly often it keeps options open and allows the patient to get accustomed to the prosthesis
In larger cases even with passive fit (as is essential)metal to metal is very retentive .
What if your 8 unit anterior implant bridge case comes back and says she wants more OJ or OB or shade alteration?
Done too many of these to risk resin cement right away (there are also non soluble temp cements)
I’m a patient. Screws in two adjacent implants had to be tightened 8 years after insertion. Have had no problems with half a dozen or so other implants, older and newer. Question is why? Loosening due to vibration or heat/cold expansion and contraction seems unlikely. However, could it be the result of repeated x-rays at frequencies that cause harmonic resonance in the metal (which are crystaline in formation)? I may also be a grinder. Could that do it?
Martin - Ever ride a Harley? Screws come loose from vibration almost daily! Eight years without retorqueing seems pretty good to me. If you are a grinder, just count your blessings! I can’t imagine any way an x-ray could cause a harmonic resonance. x-rays are just photons with a different frequency than visible light.
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