Investigating the micromorphological differences of the implant–abutment junction and their clinical implications: a pilot study

Purpose The aim of this pilot study was to investigate the morphological micro-features of three commercially available implant–abutment joints, using compatible and original prosthetic components. Furthermore, possible correlations between the micromorphology and potential functional complications were investigated with the use of finite element analysis. Material and methods Three abutments (one original and two compatibles) were torqued on original Straumann RN implants, as according to each of the manufacturer's instructions. The implant–abutment units were sliced in the microtome and photographed under different magnifications (10×–500×) through a scanning electron microscope. Finite element analysis models were reconstructed for each of the implant–abutment units using the precise measurements from the SEM. Differences in stress, strain and deformation for the three different abutments were then calculated using ANSYS Workbench v13. Results 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 was seriously compromised in the compatible abutments. One compatible abutment demonstrated compromised engagement of the abutment screw as well. Equivalent stress and strain in the FEA were much higher for the compatible abutments. An evaluation of the sequence of preload application revealed differences in the pattern of deformation between the original and compatible abutments, which can have serious clinical implications. Conclusion 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 for the long-term stability of the prosthesis.