Accelerated Osteogenic Differentiation and Bone Formation on Zirconia with Surface Grooves Created with Fiber Laser Irradiation.

Background: Modification of the surface topography of biomaterials is a critical factor for the proliferation and differentiation of osteoblasts. Elucidating the biological response to surface roughening is necessary for clinical application of zirconia implants.

Purpose: To investigate the effects of fiber laser-induced zirconia surface roughening on cultured osteoblast-like cell morphology, proliferation, differentiation, and calcification, and on in vivo bone formation.

Materials And Methods: Sixty-six machine-surfaced yttria-tetragonal zirconia polycrystal plates (S-Zr) and 16 machine-surfaced implants were used as controls. We prepared 66 rough plates (R-Zr) and 16 rough implants by surface treatment using a fiber laser.

Results: MC3T3-E1 cells spread well in all directions on S-Zr, whereas elongated cells with poorly organized actin stress fibers were observed on R-Zr. Cell proliferation was significantly greater on R-Zr than on S-Zr. The Runx2 mRNA level increased time dependently in osteogenic culture condition. Alkaline phosphatase activity and osteocalcin mRNA levels were higher on R-Zr compared with S-Zr. Alizarin red S staining revealed greater calcification on R-Zr than on S-Zr. Laser treatment of zirconia implant bodies placed in rat tibiae increased the bone-implant contact ratio and removal torque considerably.

Conclusions: Our results suggest that fiber laser irradiation produces adequate surface roughening of zirconia ceramics to support osseointegration.