Patent ID: 8123524

Claim:
Implant ( 1 ) and piece ( 11 ) unit, wherein said unit comprises an implant ( 1 ) provided with a first anti-rotational area ( 6 ) and disposed along a longitudinal axis ( 5 ), and a piece ( 11 ) provided with a second anti-rotational area ( 16 ), wherein the first anti-rotational area ( 6 ) cooperates with the second anti-rotational area ( 16 ) to prevent the piece ( 11 ) from rotating with respect to the implant ( 1 ), wherein the implant ( 1 ) and the piece ( 11 ) can be assembled together to form an assembly, with said assembly comprising an area of connection between said first and second anti-rotational areas ( 6 , 16 ), wherein the area of connection comprises clearances ( 29 ) between the implant and the piece and areas of contact ( 30 ) between the implant and the piece, wherein a plane perpendicular to the longitudinal axis of the implant and piece unit extends through both the clearances and the areas of contact, wherein said implant is formed along the longitudinal axis ( 5 ) and finished on its top part by a top surface ( 7 ), and said implant ( 1 ) further comprising: a blind hole ( 3 ) that opens from the top surface ( 7 ), wherein said blind hole ( 3 ) comprises the first anti-rotational area ( 6 ), and a first non anti-rotational area ( 8 ) and a threaded area ( 9 ), wherein the first anti-rotational area ( 6 ) comprises a series of first anti-rotational components ( 20 ), wherein each first anti-rotational component ( 20 ) comprises a series of first arcs ( 21 , 22 , 23 , 24 , 25 ) tangent to each other and determined by respective radii (R 1 , R 2 , R 3 ), wherein the closest point ( 26 ) of each of the first anti-rotational components ( 20 ) to the longitudinal axis ( 5 ) determines the smallest diameter (d) of the respective each one of the first anti-rotational components ( 20 ) and of the first anti-rotational area ( 6 ), the first anti-rotational area ( 6 ) consists only of four first anti-rotational components ( 20 ), the first anti-rotational components ( 20 ) being identical and the series of first arcs comprising four first arcs ( 21 , 22 , 24 , and 25 ) which are convex with respect to the longitudinal axis ( 5 ).