In Vitro Bioactivity Assessment of Implant Materials

The bioactivity assay was performed following “Implants for surgery—In vitro evaluation for apatite-forming ability of implant materials” (ISO 23317:2014) and as stablished by Kokubo et al. [39 (link)]. Pellets with 7 mm of diameter were immersed in simulated body fluid (SBF), an ionic solution with composition similar to the human plasma (Table 3), for 12 h, 24 h, 48 h, 96 h, 336 h and 672 h. The volume of SBF ( $V_s)$ , in mm³, placed in contact with the pellets considering their apparent surface area as indicated in the following equation: $$V_s=100· S_a$$
where $S_a$ is the superficial area of the sample. All pellets after immersion were washed with ultrapure water. The sample’s surface was analyzed before and after immersion times with SEM-EDS from TESCAN VEGA 3 (TESCAN, Brno, Czech Republic). A semi-quantitative study of the atomic elements percentage on the surface’s samples was made using the Bruker EDS system coupled to the microscope. In addition, the pH of the SBF medium for the all samples was measured at the end of the immersion times, as previously described [40 (link)]. The assay was performed in duplicate.