In the framework of producing new composite biomaterials, this study investigated the interfacial interactions between molten brand new biocompatible glasses with model formulations and Ti, hydroxyapatite, zirconia and a CrNi-steel. Analysis, by grouping the results of each particular substrate, indicates that Ti reduces the molten glass-oxides, HA tends to diffuse with them, zirconia grain-boundaries are vulnerable towards them, and Cr-Ni-steel very poorly adhere to them. Analysis, by grouping the results of each particular glass, indicates that the matching of their expansion coefficient with that of substrate and crystallization affect the formation of continuous or cracked interface. Viscosity and surface tension of glasses determine wettability. Wettability is not however determinative index of evaluating the quality and the strength of the resulting interfaces.