title: Investigating the micromorphological differences of the implant-abutment junction and their clinical implications: a pilot study.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China. nikos@mattheos.net.
authors.forename: Nikos
authors.initials: N
authors.lastname: Mattheos
authors.affiliation: Dalian Stomatological Hospital, Dalian, China.
authors.forename: Xiaona
authors.initials: X
authors.lastname: Li
authors.affiliation: Specialist Clinic for Endodontics and Periodontology, Public Dental Service, Värmland, Sweden.
authors.forename: Antonios
authors.initials: A
authors.lastname: Zampelis
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ma
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.|Specialist Clinic for Prosthodontics, Public Dental Service, Lund, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Janda
mesh_terms: D059605:Dental Implant-Abutment Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010865:Pilot Projects; D019415:Torque
keywords: biomechanics; finite elemente analysis; morphometric analysis; prosthodontics