Improving the stability and bioactivity of micro-arc oxidized calcium phosphate/titania porous coatings by high energy shot peening pretreatment

Abstract Micro-arc oxidation (MAO) is one of the conventional methods for surface modification of titanium (Ti)-based dental materials. However, in the process of MAO, the surface porous titania (TiO2) coating is prone to micro-crack, which affects the stability of coating and the long-term service life of the implant. In this work, high-energy shot peening (HESP) pretreatment would be used to improve the stability and bioactivity of the MAO coatings and increase the effective doping of calcium and phosphorus (Ca & P) elements in surfaces. We verified that the MAO specimens pretreated by HESP (S-MAO) had larger pore size (∼ 4.0 μm), coating thickness (∼ 8.5 μm) and critical load (∼ 11.1 N) than the samples without pretreatment (MAO, ∼ 3.1 μm, 6.2 μm & 6.2 N); and the content of Ca and P in S-MAO group (Ca: ∼ 6.3 wt%; P: ∼ 9.4 wt%) was higher than that of MAO group (Ca: ∼ 5.8 wt%; P: ∼ 6.7 wt%. Meanwhile, it was also proved that compared with Ti and MAO groups, MC3T3-E1 cells on S-MAO substrates had better spreading, viability, ALP activity, and osteogenic gene expression. All the above results indicate that the HESP pretreatment has excellent potential to improve the coating stability and bioactivity of MAO-treated substrates.