Replacement of damaged or missing bone tissue is a serious problem in orthopedic surgery. Although various artificial materials are available, none of them fulfil the requirements completely. In this study, new bone substitute materials, silica aerogel-based β-tricalcium phosphate, and hydroxyapatite composite ceramics, along with a control sample were synthesized and tested. Porosities and pore size distribution curves were determined by nitrogen gas adsorption/desorption porosimetry, and surface morphology changes were studied by scanning electron microscopy. Bioactivities were tested in vitro by soaking the samples in simulated body fluids (SBF). Three new advanced SBFs containing eight essential amino acids and bovine serum albumin were developed, extending the complexity of the original simulated body fluid in order to approximate the human blood plasma’s composition more accurately. Each sample was treated with SBF1–SBF4 for two weeks. According to our results, it seems to be necessary to re-evaluate hydroxyapatite deposition as proof of bioactivity of artificial bone substitutes when synthetic body fluids analogous in their composition to human blood plasma are used in studies.