Evaluation of the precision of fit between the Procera custom abutment and various implant systems

It has been suggested that the CAD/CAM Procera custom abutment may be universally applied with multiple implant systems. An acceptable fit between the internal hexagon of an abutment and the external hexagon of various implant systems, along with true interchangeability of the Procera abutment screw, would support this concept. This study determined the precision of fit of the CAD/CAM-produced Procera abutment onto the external hexagon and bearing surfaces of implants from 6 implant manufacturers and the interchangeability of the Procera abutment screw with these systems.

This investigation consisted of 3 parts: (1) direct measurement of the internal hexagon and bearing surface of each Procera abutment and the external hexagon and the bearing surface of 6 implants from 6 different systems, (2) radiographic examination of 30 Procera abutment-implant junctions following tightening to 32 Ncm to determine the precision of fit between the bearing surfaces and the top of the external hexagon of the implant with the superior surface of the internal hexagon of the abutment, and (3) examination of 3 abutment screws and 3 implants from the various manufacturers for interchangeability based on American National Standards.

The mean flat-to-flat external hexagons of the implants measured between 2.67 and 2.69 mm. The Procera abutment's flat-to-flat internal hexagon measured 2.73 mm. The height of the various implant systems' external hexagon ranged from 0.69 to 0.81 mm. The height of the Procera abutment blanks was 0.90 mm. Radiographic examination demonstrated that not all of the manufacturers' screws fit appropriately within the internal screw bore of the Procera abutment. The internal bore of all implant systems studied had a metric thread designation of M2 x 0.4 - 6H. The metric thread designation of all abutment screws examined was M2 x 0.4 - 6g. The greatest variations in the dimensions of the abutment screws measured were seen in the diameter of the screw head, which ranged from 2.12 to 2.69 mm.

The Procera abutment's internal hexagon fit the external hexagon of all implant systems evaluated. The Procera abutment screw fit the internal screw bore of the implant systems tested.

The Procera abutment with its screw can be universally applied to the implant systems studied. This fact, plus the CAD/CAM feature of this system, would thus provide a dynamic approach to satisfying the design and spatial needs of implant placements observed clinically.