Cell attachment and proliferation of bone marrow-derived osteoblast on zirconia of various surface treatment

PURPOSE: This study was performed to characterize the effects of zirconia coated with calcium phosphate and hydroxyapatite compared to smooth zirconia after bone marrow-derived osteoblast culture. MATERIALS AND METHODS: Bone marrow-derived osteoblasts were cultured on (1) smooth zirconia, (2) zirconia coated with calcium phosphate (CaP), and (3) zirconia coated with hydroxyapatite (HA). The tetrazolium-based colorimetric assay (MTT test) was used for cell proliferation evaluation. Scanning electron microscopy (SEM) and alkaline phosphatase (ALP) activity was measured to evaluate the cellular morphology and differentiation rate. X-ray photoelectron spectroscopy (XPS) was employed for the analysis of surface chemistry. The genetic expression of the osteoblasts and dissolution behavior of the coatings were observed. Assessment of the significance level of the differences between the groups was done with analysis of variance (ANOVA). RESULTS: From the MTT assay, no significant difference between smooth and surface coated zirconia was found (P>.05). From the SEM image, cells on all three groups of discs were sporadically triangular or spread out in shape with formation of filopodia. From the ALP activity assay, the optical density of osteoblasts on smooth zirconia discs was higher than that on surface treated zirconia discs (P>.05). Most of the genes related to cell adhesion showed similar expression level between smooth and surface treated zirconia. The dissolution rate was higher with CaP than HA coating. CONCLUSION: The attachment and growth behavior of bone-marrow-derived osteoblasts cultured on smooth surface coated zirconia showed comparable results. However, the HA coating showed more time-dependent stability compared to the CaP coating.

Numerical simulation of aerosol deposition in human upper respiratory tract / 医用生物力学

Objective To study the rule of aerosol deposition in human upper respiratory tract and analyze the impact of respiratory pattern on aerosol deposition. Methods A computer model of human upper respiratory tract was established first. CFD (computational fluid dynamics) method was then used to numerically simulate the aerosol deposition within the human upper respiratory tract and the rule of aerosol deposition was analyzed. Results The efficiency of aerosol deposition in human upper respiratory tract was improved with the increase of inertial parameter. The breathing intensity and aerosol property had little impact on the pattern of aerosol deposition, which was at most in larynx due to the inertial impact and turbulent dispersion. Under the mode of cyclic inhalation, the aerosol deposition efficiency was higher at unsteady respiratory than that at steady respiratory, at cyclic inhalation than at cyclic exhalation. Conclusions Inertial impact is the main key deposition mechanism for micro aerosol, while turbulent dispersion, secondary flow and recirculation flow have an equally important impact on aerosol deposition in human respiratory tract.