An In Vitro Evaluation of Titanium, Zirconia, and Alumina Procera Abutments with Hexagonal Connection

Purpose: The purpose of this study was to assess the precision at the implant interface of titanium, zirconia, and alumina Procera abutments with a hexagonal connection for single-tooth restorations. Materials and Methods: Twenty Procera abutments were produced with commercially pure titanium, 20 with zirconia, and 20 with alumina using computer-assisted design and manufacture (CAD/CAM). The rotational freedom of the abutments was assessed to detect the precision of fit of each abutment on the top of the implant hexagon. Results: Significant differences relative to rotational freedom were found between groups: the titanium group and the zirconia group did not differ significantly, but both demonstrated significantly smaller mean rotational freedoms than the alumina group (P .05). Rotational freedom was less than 3 degrees for all abutments. Conclusions: The hexagonal misfit of the Procera abutment on the implant hexagon may be implicated in screw joint loosening. In the present study, all types of CAD/CAM Procera abutments consistently showed less than 3 degrees of rotational freedom in a situation where the abutment was connected to an implant by a hexagonal external connection. Keywords: abutments, hexagonal connections, single-implant restorations