Implants placed in grafted sites for a implant support bridge 11- x - 13
pt had declined sinus lift procedure therefore did not place implant in the 14 position as well.
76 yr old woman with atrophic maxilla
otherwise healthy
after 6 months begin restorative phase
implants integrated with torque test
screw retained bridge had ASC at the 11 site and conventional hex screw at 13
prosthetic fit was good however when torquing the ASC screw at 11 the ASC driver would disengage above around 20 ncm . The screw channel was widened but this did not help.
Ultimately a new impression ( digital scan) was taken and sent back to the lab . Either the driver was binding in the screw channel or there was some distortion of fit ? Has anyone had this type of issue with ASC before ?
I have run into this and I think it is going to become a more common problem in the near future due to the obsession with screw retained restorations. This ASC concept is great but I think we go too far trying to screw everything down when cement retained fixed bridges have been successfully replacing teeth for decades. My solution is to use conventional custom abutments with cement retained final rather than poorly engineered Phillips screw head type components… Not to mention that it could be poorly manufactured aftermarket parts on copycat budget friendly hardware which is a bad combination regardless of the project being restored. There is something comforting about a hex driver fully engaging the retaining screw that I haven’t found when using a rounded ASC driver, designed to be sloppy, partially gripping fragments of the special retaining screw.
I have had this issue- with straumann and dynamic abutments. It’s usually residual lab dust preventing the driver from fully seating, or zirconia at the top or further below the screw channel increasing the angle of engagement. Sometimes it finger tightens okay, but slips when attempting to torque, like in this case. In the interest of increasing zirconia bulk, the technician is probably increasing the angle more than they should.
Not sure that going back to cemented prosthesis is the answer.
these 2 implants so straight. you can do cementable bridge.
place abutment. torque. cement the zirconia bridge. remove the bridge. remove excess cement. then replace the bridge and torque final.
real good labs will give you 2 abutment screws. lab screw and final screw.
usually bridge i like to do custom abutment. Im still analog guy.
