In vitro reaction of human osteoblasts on alumina-toughened zirconia.
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.
Kohal
Ralf J
RJ
Department of Prosthodontics, School of Dentistry, University Hospital Freiburg, Freiburg, Germany.
Baechle
Maria
M
Han
Jung S
JS
Hueren
Dennis
D
Huebner
Ute
U
Butz
Frank
F
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*
D003722:Dental Alloys; D003776:Dental Porcelain; D015040:Zirconium; D000537:Aluminum Oxide