Introduction: In contrast to the high success rates of osseointegration (95% to 97%), mechanical complications are still common in implant dentistry (reported to be as high as 44.9%) Mechanical complications such as screw loosening, screw fracture, and framework fracture. Objectives: Evaluate the wear of the implant-abutments interface after a torsional fatigue test that simulates a loose abutment situation. Materials and Methods: 5 external hexagonal implants were embedded with acrylic resin and divided into 3 groups: - Control group: non engaging titanium abutment - Group A: two engaging titanium abutments - Group B: two engaging zirconia abutment Rotational freedom for each pair was access before and after testing. Each pair was torque to 35Ncm and placed on an Instron 8874 machine and loaded on a rotational test: +/3,3° 4Hz, with a compressive force of 100N for 250.000 cycles. Results: The screws in all groups were loose after testing. In group A and B there was an increase in the rotational freedom with wear of the hexagon but not on the control. There was evidence of adhesive wear and abrasion in group A and in group B there was adhesive wear, abrasion and 3 body abrasion. Conclusions: The loose screw in an implant prosthesis may lead to the wear of the hexagon on both parts. The wear is sufficient to compromise the implant-abutment connection beyond repair Clinical Implication When a patient presents a loose screw restoration, it should be removed and inspected Disclosure: MIS Implants Technologies Ltd; FCT IDMEC, LAETA, UID/EMS/50022/2013 Schlagwörter: Wear, implants, abutments