Biological and osseointegration capabilities of hierarchically (meso-/micro-/nano-scale) roughened zirconia

Abstract

PurposeZirconia is a potential alternative to titanium for dental and orthopedic implants. Here we report the biological and bone integration capabilities of a new zirconia surface with distinct morphology at the meso-, micro-, and nano-scales.MethodsMachine-smooth and roughened zirconia disks were prepared from yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), with rough zirconia created by solid-state laser sculpting. Morphology of the surfaces was analyzed by three-dimensional imaging and profiling. Rat femur-derived bone marrow cells were cultured on zirconia disks. Zirconia implants were placed in rat femurs and the strength of osseointegration was evaluated by biomechanical push-in test.ResultsThe rough zirconia surface was characterized by meso-scale (50 µm wide, 6–8 µm deep) grooves, micro-scale (1–10 µm wide, 0.1–3 µm deep) valleys, and nano-scale (10–400 nm wide, 10–300 nm high) nodules, whereas the machined surface was flat and uniform. The average roughness (Ra) of rough zirconia was five times greater than that of machined zirconia. The expression of bone-related genes such as collagen I, osteopontin, osteocalcin, and BMP-2 was 7–25 times upregulated in osteoblasts on rough zirconia at the early stage of culture. The number of attached cells and rate of proliferation were similar between machined and rough zirconia. The strength of osseointegration for rough zirconia was twice that of machined zirconia at weeks two and four of healing, with evidence of mineralized tissue persisting around rough zirconia implants as visualized by electron microscopy and elemental analysis.ConclusionThis unique meso-/micro-/nano-scale rough zirconia showed a remarkable increase in osseointegration compared to machine-smooth zirconia associated with accelerated differentiation of osteoblasts. Cell attachment and proliferation were not compromised on rough zirconia unlike on rough titanium. This is the first report introducing a rough zirconia surface with distinct hierarchical morphology and providing an effective strategy to improve and develop zirconia implants.

UV-Photofunctionalization of Titanium Promotes Mechanical Anchorage in A Rat Osteoporosis Model

“…As previously described [50], the amount of formazan product was measured with a multi-detection microplate reader, Synergy TM HT (BioTek Instruments, Winooski, VT, USA), at a wavelength of 450 nm. Additionally, the proliferative activity of the cells was measured by BrdU incorporation during DNA synthesis on day 5 of culture [51]. Absorbance at 370 nm was measured with a Synergy TM HT.…”

“…Implants were placed only in the left femurs. A 1-mm diameter × 2-mm length implant site was prepared at 9 mm from the distal edge of the femur by drilling with a 0.8-mm round burr and was enlarged using reamers (#ISO 090 and 100) as described previously [49,51,55]. The total number of animals used was 32 (each group n = 8, implants n = 8), distributed among the sham-untreated, sham-UV, OVX-untreated, and OVX-UV implant groups (healing time 2 weeks).…”

Surface properties of dental zirconia ceramics affected by ultrasonic scaling and low-temperature degradation

“…The surface properties (e.g. surface roughness, surface free energy, and chemical conditions of the topmost surface) of zirconia play an important role in achieving appropriate biocompatibility and in reducing bacterial adhesion [ 10 , 11 ]. Ultrasonic scaling may mechanically alter the surface properties.…”

Heat treatment dependent cytotoxicity of silicalite-1 films deposited on Ti-6Al-4V alloy evaluated by bone-derived cells

“…Likewise, a study comparing a flat zirconia surface with a hierarchically-structured surface (i.e., a combination of nano-, micro-, meso-morphology) did not show any improvement in the adhesion or in the proliferation of osteoblasts; however, the expression of osteogenic markers was higher in cells grown on the surface with the hierarchical morphology. Moreover, the hierarchically-organized roughness also promoted better osseointegration and greater biomechanical strength in vivo 45 . Thus, slower cell adhesion and proliferation observed in vitro do not necessary mean poor and slow osseointegration in vivo.…”