The present invention relates to a screw for an implant and, more particularly, to a screw for an implant capable of preventing unfastening of the screw, which keeps fastening a fixture and an abutment, thereby maintaining a stable fastening state. A screw for an implant according to the present invention comprises a screw portion and a head portion. The head portion has a plurality of troughs formed on the outer peripheral surface, which is inserted into an abutment and contacts the abutment, along the circumferential direction, thereby coupling the abutment arranged on the upper end of a fixture. And the head portion is formed to have a diameter decreasing from the upper portion thereof towards the lower portion thereof. According to the present invention, troughs are formed on the outer peripheral surface along the circumferential direction such that, during screw coupling, the lower surface of the screw, which is coupled to an abutment, is deformed towards the troughs. The deformed lower surface then applies a force to the abutment such that screw coupling between the screw and the fixture does not become unfastened. And, since the diameter decreases from the upper portion towards the lower portion, and at least a plurality of troughs are formed, a side surface contact at each trough portion causes deformation, thereby increasing the strength of screw coupling between the screw and the fixture. In addition, according to the present invention, the outer side of the lower surface of the head portion is formed to protrude more than the inner side thereof such that deformation of the head portion is larger at the portion of contact with the abutment, thereby preventing unfastening of the screw coupling of the screw and the fixture.La présente invention concerne une vis pour un implant et, plus particulièrement, une vis pour un implant pouvant empêcher que la vis ne se dévisse, qui maintient la fixation dun élément de fixation et dune butée, maintenant ainsi un état
