[Investigation of the micromorphological differences of the implant-abutment junction]

The aim of this pilot study was to investigate the morphological micro-features of 3 commercially available implant-abutment joints, using compatible and original prosthetic components and to explore the correlation between the micromorphology and potential functional complications.

Three abutments (one original and two compatibles) were torqued on original Straumann RN implants, according to the manufacturer's instructions. The implant-abutment units were sliced in the microtome and photographed under different magnifications through a scanning electron microscope. Calibration measurements were conducted under magnification corresponding to the area under assessment.

Major dimensional differences were identified between all studied contact areas of the three units. The tight contact in the implant shoulder was similar in all three units, but engagement of the internal connection and, in particular, the anti-rotation elements were seriously compromised in the compatible abutments. One compatible abutment demonstrated compromised engagement of the abutment screw as well.

Compatible abutments can present critical morphological differences from the original ones. The differences in the cross-sectional geometry result in large differences in the overall contact areas, both in terms of quality and quantity which could have serious implications from the long-term stability of the prosthesis.