Implant-abutment screw joint preload of 7 hex-top abutment systems

This study measured the screw joint preload of the implant-abutment interfa ce for 7 common hex-top abutment systems. Increasingly, prosthetic designs are utilizing a direct prosthetic connection to the implant, placing the im plant-abutment screw joint under direct functional loads and moments. Suffi ciently high screw joint preloads are required to maintain screw joint inte grity and confer clinical longevity to implant prosthetic components to pre vent such complications as abutment screw loosening and screw fracture. Str ain-gauged abutment load cells were calibrated to measure screw joint prelo ad at the implant-abutment interface. Torque delivery by electronic torque controller was varied at low- and high-speed settings. At manufacturer's re commended torques, the overall mean preload measured was 181.6 +/- 60.0 N f or the Nobel Biocare Standard abutment, 291.3 +/- 41.2 N for the Nobel Bioc are EsthetiCone abutment, 456.5 +/- 44.0 N for the Nobel Biocare MirusCone abutment, 369.7 +/- 32.9 N for the 3i Titanium Abutment post, 643.4 +/- 143 .1 N for the Nobel Biocare CeraOne abutment, 536.3 +/- 68.6 N for the Nobel Biocare "Gold Cylinder to Fixture" abutment, and 556.9 +/- 145.6 N for the Nobel Biocare TiAdapt abutment. Analysis of variance revealed significant differences between abutment systems (P <.001) and between torque driver sp eed settings (P <.001). Implant-abutment screw joint preload of external-he x implants is dependent on abutment design, screw diameter, material, tight ening torque, and torque controller speed.