title: Micromorphological differences of the implant-abutment junction and in vitro load testing for three different titanium abutments on Straumann tissue level implants.
abstract: BACKGROUND
  The aim of this study was to investigate the micromorphological differences among three commercially available titanium abutments on Straumann implants. Furthermore, the possible impact of functional loading on the micromorphology and potential complications was investigated with the use of in vitro testing.
  
  
  METHODS
  Three groups of Titanium abutments (A: Straumann Variobase n = 5, B: EBI best Duo n = 5, and C: Implant Direct n = 5) were torqued on Straumann RN implants, as according to each of the manufacturer's instructions. The implant-abutment units were scanned with Micro-CT. Three units of each group were directly sliced in the microtome and photographed under different magnifications (10×-500×) through a Scanning Electron Microscope. Six units (two from each group) were restored with cement-retained crowns, subjected to 2000,000 load cycles with loads between 30 and 300 N at 2 Hz, examined through Micro-CT and finally sliced and photographed as described above. The micromorphology of each unit was studied, and the total length of tight contact (<3 μm) was calculated between the implant, abutment and screw contact areas.
  
  
  RESULTS
  Major morphological differences were identified between the three units, as well as differences in the extent of tight contact in all areas examined. Despite the morphological differences, the 2M cycles of loading via in vitro test did not result in any noticeable complications although some changes in the micromorphology were observed.
  
  
  CONCLUSIONS
  The examined implant-abutment units presented with major morphological differences. Two million cycles of in vitro loading did not appear to affect the stability of the units despite the micromorphological changes. These results need to be interpreted however under the limitations of the small sample size and the specific set-up of the in vitro testing.
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
authors.forename: N
authors.identifier: http://orcid.org/0000-0001-7358-7496
authors.initials: N
authors.lastname: Mattheos
authors.affiliation: Faculty of Odontology, Malmo University, Malmo, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Larsson
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
authors.forename: L
authors.initials: L
authors.lastname: Ma
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.
authors.forename: G
authors.identifier: http://orcid.org/0000-0002-4880-0125
authors.initials: G
authors.lastname: Fokas
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.|Faculty of Dentistry, University of Athens, Athens, Greece.
authors.forename: V
authors.initials: V
authors.lastname: Chronopoulos
authors.affiliation: Faculty of Dentistry, The University of Hong Kong, Hong Kong, China.|Specialist Clinic for Prosthodontics, Public Dental Service, Lund, Region Skåne AB, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Janda
mesh_terms: D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D014025:Titanium; D055114:X-Ray Microtomography
chemical_list: D014025:Titanium
keywords: imaging; material sciences; prosthodontics; radiology