To investigate the Ag release characteristics of our samples, they were immersed in 10 mL of phosphate-buffered saline (PBS) at 37 ͦ C . After 24 h stored in the dark, the solution was taken out for analysis and fresh 10 mL PBS was transferred back to the release medium, the release from the samples was monitored for 10 days. This was done to mimic the physiological conditions inside the human body. The amount of the released ions was determined using inductively coupled plasma mass spectrometry (ICP-MS) on a model iCap Qc ICP-Q-MS (Thermo Fisher Scientific, Bremen, Germany). The Qtegra ISDS software (2.10.3324.131, Thermo Fisher Scientific) was used to control the instrument. Sample introduction was achieved with a model ESI SC-2 DX autosampler (ESI Elemental Service & Instruments GmbH, Mainz, Germany), a MicroFlow PFA-ST nebulizer (Thermo Fisher Scientific) with a sample flow rate of ca. 470 µL min -1 , and a Peltier-cooled cyclonic quartz spray chamber (cooled to 3 °C). The plasma torch inner diameter was 1 mm and the sampling position was set to 5 mm. The high-sensitivity skimmer cone insert "2.8" (Glass Expansion, Melbourne, Australia) for the nickel skimmer cone was used to increase the sensitivity of the instrument. The radio frequency (RF) generator power was set to 1400 W and extraction lens 1 and 2 voltages were 0 V and -220 V, respectively. The interface pressure was 1.7 mbar. Argon (5.0, Messer Industriegase GmbH, Siegen, Germany) was used as a nebulizer, plasma, and cooling gas with flow rates of 0.51, 0.8, and 14 L min -1 , respectively. All dilutions were prepared in deionized, bi-distilled water. For ICP-MS determination of the silver and zirconium content in the immersion liquid of each zirconia substrate, 2 mL of the immersion liquid was added to 8 mL of 2% nitric acid (diluted from 70% nitric acid, Fisher Scientific, Loughborough, UK), respectively, and spiked with indium solution (Inorganic Ventures, Christiansburg, VA, USA) to obtain a concentration of 10 µg L -1 In as internal standard. For analysis, ion signal intensities from 90 Zr + , 91 Zr + , 107 Ag + , 109 Ag + , and In + were acquired in triplicate for each sample. Since the AgNP adhered to zirconia substrates, it was assumed that the zirconium concentration in the immersion liquid was high enough to cause significant signal interferences on the silver ion traces during ICP-MS analysis. Therefore, two separate dilution series of silver and zirconium stock solutions (Inorganic Ventures, Christiansburg, VA, USA), respectively, were prepared for silver concentration calibration and mathematical correction of the polyatomic interferences of 91 Zr 16 O + on 107 Ag + and 92 Zr O 1 H + on 109 Ag + .