title: In vitro reaction of human osteoblasts on alumina-toughened zirconia.
abstract: OBJECTIVE
  Alumina toughening enhances the mechanical properties of zirconia ceramics but the biocompatibility of this material has rarely been addressed. In this study, we examined the osteoblast response to alumina-toughened zirconia (ATZ) with different surface topographies.
  
  
  METHODS
  Human osteoblasts isolated from maxillary biopsies of four patients were cultured and seeded onto disks of the following substrates: ATZ with a machined surface, airborne-particle abraded ATZ, airborne-particle abraded and acid etched ATZ. Airborne-particle abraded and acid etched titanium (SLA) and polystyrene disks served as a reference control. The surface topography of the various substrates was characterized by profilometry (R(a), R(p-v)) and scanning electron microscopy (SEM). Cell proliferation, cell-covered surface area, alkaline phophatase (ALP) and osteocalcin production were determined. The cell morphology was analyzed on SEM images.
  
  
  RESULTS
  The surface roughness of ATZ was increased by airborne-particle abrasion, but with the R(a) and R(p-v) values showing significantly lower values compared with SLA titanium (Mann-Whitney U-test P<0.05). The proliferation assay revealed no statistically significant differences between the ATZ substrates, SLA titanium and polystyrene (Kruskal-Wallis test, P>0.05). All substrates were densely covered by osteoblasts. ALP and osteocalcin production was similar on the examined surfaces. Cell morphology analysis revealed flat-spread osteoblasts with cellular extensions on all substrates.
  
  
  CONCLUSIONS
  These results indicate that ATZ may be a viable substrate for the growth and differentiation of human osteoblasts. Surface modification of ATZ by airborne-particle abrasion alone or in combination with acid etching seems not to interfere with the growth and differentiation of the osteoblasts.
authors.affiliation: Department of Prosthodontics, School of Dentistry, University Hospital Freiburg, Freiburg, Germany.
authors.forename: Ralf J
authors.initials: RJ
authors.lastname: Kohal
authors.forename: Maria
authors.initials: M
authors.lastname: Baechle
authors.forename: Jung S
authors.initials: JS
authors.lastname: Han
authors.forename: Dennis
authors.initials: D
authors.lastname: Hueren
authors.forename: Ute
authors.initials: U
authors.lastname: Huebner
authors.forename: Frank
authors.initials: F
authors.lastname: Butz
mesh_terms: D000537:Aluminum Oxide / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003722:Dental Alloys / Q000494:pharmacology*; D003776:Dental Porcelain / Q000494:pharmacology; D006801:Humans; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D019736:Prostheses and Implants; D018709:Statistics, Nonparametric; D013499:Surface Properties; D015040:Zirconium / Q000494:pharmacology*
chemical_list: D003722:Dental Alloys; D003776:Dental Porcelain; D015040:Zirconium; D000537:Aluminum Oxide