Infiltrating fluorapatite glass-ceramics on the surface of dental 3 % yttria-stabilized zirconia to enhance bond strength

Abstract

Zirconia is a material commonly used for denture repair due to its excellent mechanical properties. However, the low bond strength between zirconia dentures and natural teeth may cause the prosthesis to fall off, which is a major obstacle to its clinical success. Improving the bonding strength between dental zirconia and teeth and resisting the adhesive failure of zirconia prosthesis have been difficult problems in recent years. Thus, this study aims to infiltrate synthesized fluorapatite (Ca5(PO4)3F, FAp) glass-ceramics on an unsintered zirconia surface. The microstructure, phase characterization, surface morphology, mechanical properties, and bonding strength were comprehensively evaluated in this study. Scanning electron microscopy images of the cross-section of infiltrated zirconia revealed a residual FAp glass-ceramics coating on the surface, under which is the graded layer, demonstrating that the FAp glass-ceramics infiltrated the loose porous zirconia embryo to form a mechanical chimera. Energy dispersive spectroscopy results showed that silicon, which is the principal element of the FAp glass-ceramics, penetrated the zirconia to a depth of nearly 150 μm. These results verified the mechanical stability of the FAp glass-ceramics coating. Meanwhile, the shear strength test between the infiltrated zirconia and teeth showed that the bonding strength increased by approximately 3-fold, while the bond durability and flexural strength of the infiltrated zirconia also increased. As a new material for infiltrating zirconia, the application of the synthesized FAp glass-ceramics on the surface of unsintered zirconia with an appropriate coating time can ensure a high penetration depth and prevent stripping. Meanwhile, the bond strength and durability of the infiltrated zirconia can be significantly enhanced without reducing its mechanical properties.