The aim of this study is to evaluate the preload maintenance of different retention screws of UCLA abutments used to fabricate single crowns attached to external hexagon implants submitted to mechanical cycling. Twelve metallic crowns obtained with UCLA abutments cast in Co-Cr alloy will be used. The crowns will be attached to the external hexagon implants with different retention screws according to the groups (n=12): Group A - titanium retention screw, Group B - gold retention screw with gold coating, Group C - titanium retention screw with diamond like carbon coating, and Group D - titanium retention screw with aluminum titanium nitride coating. Three intial detorque measurements will be obtained after torque insertion by an analogic torque gauge, totalizing 36 intial measurements for each group. The replicas will be submitted to mechanical cycling during 1000000 cycles at 2Hz. After cycling, the final detorque value will be measured for each group. Data will be submitted to statistical analysis.
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