To elucidate the mechanism of adhesion of soft and hard tissues to yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP), Y-TZP and titanium disks were immersed in ultrapure water and in Hanks' solution, and the changes in the surface compositions and chemical states were characterized using X-ray photoelectron spectroscopy. After immersion in ultrapure water for 60 days, the concentration of hydroxyl groups on the Y-TZP surface increased. In addition, only phosphate ions were incorporated into the surface during immersion in Hanks' solution, while other ions did not react. On the other hand, the surface of Ti was also hydrated in ultrapure water; however, calcium phosphate formed on it during immersion in Hanks' solution. Therefore, the reactivity of Y-TZP with electrolytes was lower than that of Ti. We conclude that the formation of the phosphate on the Y-TZP surface in physiological conditions possibly enhances the adhesion of soft and hard tissues to Y-TZP.
Keywords: Chemical state; Dental implants; Titanium; XPS; Yttria-stabilized tetragonal zirconia polycrystalline.