FREITAS, Renato de; DORIA, Máx Costa; OLIVEIRA-NETO, Luiz Alves    LORENZONI, Fabio Cesar. Failure of mini angled conical abutment cone morse transfixing screw: case report. Innov. Implant. J., Biomater. Esthet. (Online) []. 2010, 5, 2, pp. 65-69. ISSN 1984-5960.

Dental implants failures may occur by biological and mechanical factors. The main technical complications of implant components are fixture fracture and screw loosening or fracture. Internal tapered connections were developed to improve biomechanical properties and to reduce mechanical problems found in other implant connection systems, however the transfixing screws of the two piece abutments presents some problems. This clinical report describes a angled conical mini-pilar abutment with transfixing screw failure and the procedure used for removal the threaded portion of screw remaining inside cone morse implant. The main causes of screw loosening or fracture are inadequate tightening, misfi t in implant components, adverse occlusal forces, lack of basic antirotational characteristics of implant-abutment interface and fatigue character and yielding strength of the screw material. Internal tapered connections improve mechanical properties, but, in two piece abutments, there is a reduction of resistance due to the laserwelded between the threaded portion and screw shaft. Implant abutment screw failures can be a serious problem, as some fragment remaining inside the implant may prevent the implant appropriate function. To overcome it, this article presents a technique to safely remove the fractured screw and restore the tooth without sacrificing the implant. After removal the threaded portion of transfixing screw, new abutment was used, and fi xture could be done again. In conclusion, authors recommend extreme caution in the use of angled conical abutments with transfixing screw due to the weld type used in this two piece abutments. Placement of cone morse implants should be indicated only when it's possible a correct position and inclination in relation to adjacent teeth.

: Dental implants; Dental prosthesis; Dental prosthesis; implant-supported.