Dental Implants and Abutment Screws

When torquing the second time have you found additional movement in the screw? If you did then there has been some settling of the abutment and torquing a second time would be a good idea. If you have found no additional movement of the screw then I would use that 10 minutes somewhere else.

In 15 years we have problems with the first cases when we solve our Occlusal schema with screws. I have never beleived in the advantages of gold screws, personally the word gold means expensive and hard to get it. Nobel biocare came out with torque-tite (which is not of its own idea) and you really feel comfortable with this product.We use titanium abutments and soon we will experience titanium fastening screws coated with NiTi and the pre-load and load concepts will be the same as the previous parameters. Ideal occlusal forces is the key, not the screws.

Externally hexed implants is the consecuence of the industry request from Prof. Branemark to place implants...he realize that the prosthetic components joint by a screw was a very unstable junction. Internally hexed, morse tappered,6-lobe-3-lobe implants will not have that problems.The problem today is that implants produce money and everyone want a part of the cake. Recent new- merge-companies-appear with "best technology" in less than three years, it is amazing how doctors place new products with just one case report and a catalog. Today Prof, Baranemark lives outside sweden without being part of his amazing scientific work with dental implants what could happen?

I have had ONE case in many hundreds, over 15+ years, where the abutment screw came loose. This was an oddly aligned upper central (a 3i 4mm standard hex, with a "GoldTite" square-drive screw, tightened to 35 NCm ... historically, my standard approach). Maybe I even forgot to tighten to 35? (I finger-tighten, fit the crown, then have the assistant take a seating-verification x-ray while I finish the crown for cementation. I final-torque just before I cement. Could I forget? Unlikely ... but possible.) I think the newer internal-connection type implants (Nobel-Replace/Replace-Select & 3i Certain & the like) which depend more on engineering & less on a heavy-duty, highly-torqued screw, will prove to be the wave of the future.

The recommendation with implant screws of waiting ten minutes and torquing again is based on the theory of embedment relaxation. There is little doubt from the literature that some degree of permanent deformation occurs on the screw threads when components are joined. This effectly causes friction in the tightening process which impedes the applied torque and thus achieving optimal preload. Allowing the bolted joint to "relax" for a few minutes, backing off and retorquing may help to abate this frictional hindrance. Also the type of torque wrench and ramp time of applied torque should be considered. A "clutch driven" wrench which cuts out suddenly would likely be more suseptable to embedded friction than a slowly held spring driven wrench.

Any suggestions on how to remove Osi implant screws, where the heads have been sheared off, as the bridge broke off completely, shearing the heads on three implants. Cut a slot and try to use a small screw driver? Does Osi make and "easy-out" for this problem. Drill out and re-tap? Does anyone have experience along these lines or suggestions.