Atomic layer deposition SiO₂ films over dental ZrO₂ towards strong adhesive to resin

Atomic layer deposition (ALD) is a self-limiting nanoscale film deposition technology with the advantages of good stability, consistency and conformability. In this study, we proposed to deposit silica (SiO2) films over dental zirconium-oxide (ZrO2) by ALD for better SiO2 films and higher bond strength between ZrO2 and resin. To investigate the superiority of film deposited by ALD, other surface modification methods such as sol-gel, vapor phase hydrolysis and electrostatic self-assembly were compared in terms of the short-term and long-term bond strength between ZrO2 and resin, measured by universal testing machine. Meanwhile, the surface morphology and chemical elemental analysis were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR). Results showed that the SiO2 films deposited by ALD or electrostatic self-assembly were uniform and consistent while sol-gel and vapor phase hydrolysis formed SiO2 films with cracks or pores, changing the morphology of ZrO2.ALD had the best results among all methods and increased the bond strength to 16.49 +/- 1.60 MPa and 13.44 +/- 1.63 MPa before and after aging respectively, which is expected to improve the long-term success rate of clinical dental ZrO2 prostheses.