This article, published in the journal *Biomaterials* by Elsevier, discusses the use of simulated body fluid (SBF) to test the bioactivity of materials, particularly in the context of bone bonding. The authors, Marc Bohner and Jacques Lemaitre, argue that there is insufficient scientific evidence to support the widespread acceptance of SBF as an effective method for predicting in vivo bone bioactivity. They highlight several issues with the current practice, including the arbitrary nature of SBF compositions, the lack of control over carbonate content, and the complexity of the preparation process. The article also presents theoretical arguments and experimental facts to support these claims and suggests improvements to the bioactivity test, such as simplifying the SBF composition and improving the preparation method. The authors conclude that in vitro bioactivity tests in SBF solutions cannot reliably predict the in vivo bone bonding ability of materials and recommend further research to refine the method.This article, published in the journal *Biomaterials* by Elsevier, discusses the use of simulated body fluid (SBF) to test the bioactivity of materials, particularly in the context of bone bonding. The authors, Marc Bohner and Jacques Lemaitre, argue that there is insufficient scientific evidence to support the widespread acceptance of SBF as an effective method for predicting in vivo bone bioactivity. They highlight several issues with the current practice, including the arbitrary nature of SBF compositions, the lack of control over carbonate content, and the complexity of the preparation process. The article also presents theoretical arguments and experimental facts to support these claims and suggests improvements to the bioactivity test, such as simplifying the SBF composition and improving the preparation method. The authors conclude that in vitro bioactivity tests in SBF solutions cannot reliably predict the in vivo bone bonding ability of materials and recommend further research to refine the method.