title: Histological and biomechanical analysis of porous additive manufactured implants made by direct metal laser sintering: a pilot study in sheep.
abstract: OBJECTIVE
  It was the aim of this study to analyze osseointegrative properties of porous additive manufactured titanium implants made by direct metal laser sintering in a sheep model after an implantation period of 2 and 8 weeks.
  
  
  METHODS
  Three different types of implants were placed in the pelvis of six sheep. In each sheep were placed three standard machined (M), three sandblasted and etched (SE), and three porous additive manufactured (AM) implants. Of these three implants (one per type) were examined histologically and six implants were tested biomechanically. Additionally a semiquantitative histomorphometrical and qualitative fluorescent microscopic analysis were performed.
  
  
  RESULTS
  After 2 and 8 weeks bone-to-implant-contact (BIC) values of the AM surface (2w: 20.49% ± 5.18%; 8w: 43.91% ± 9.69%) revealed no statistical significant differences in comparison to the M (2w: 20.33% ± 11.50%; 8w: 25.33% ± 4.61%) and SE (2w: 43.67 ± 12.22%; 8w: 53.33 ± 8.96%) surfaces. AM surface showed the highest increase of the BIC between the two observation time points. Considering the same implantation period histomorphometry and fluorescent labelling disclosed no significant differences in the bone surrounding the three implants groups. In contrast Removal-torque-test showed a significant improve in fixation strength (P ≤ 0.001) for the AM (1891.82 ± 308, 44 Nmm) surface after eight weeks in comparison to the M (198.93±88,04 Nmm) and SE (730.08 ± 151,89 Nmm) surfaces.
  
  
  CONCLUSIONS
  All three surfaces (M, SE, and AM) showed sound osseointegration. AM implants may offer a possible treatment option in clinics for patients with compromised bone situations.
authors.affiliation: Musculoskeletal Research Unit, Equine Hospital, Vetsuisse Faculty ZH, University of Zurich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland; Center for Applied Biotechnology and Molecular Medicine (CABMM), Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Stübinger
authors.forename: Isabel
authors.initials: I
authors.lastname: Mosch
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Robotti
authors.forename: Michéle
authors.initials: M
authors.lastname: Sidler
authors.forename: Karina
authors.initials: K
authors.lastname: Klein
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Ferguson
authors.forename: Brigitte
authors.initials: B
authors.lastname: von Rechenberg
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000494:pharmacology*; D007834:Lasers; D008422:Materials Testing; D016348:Osseointegration / Q000187:drug effects*; D010865:Pilot Projects; D016062:Porosity; D019736:Prostheses and Implants; D012756:Sheep; D014025:Titanium / Q000494:pharmacology*
chemical_list: D018786:Bone Substitutes; D014025:Titanium
keywords: bone remodelling; bone-to-implant contact; dental implants; laser sintering; osseointegration; removal torque test; sheep