While the reciprocity between bioceramics and living cells is complex, it is principally governed by the implant’s surface chemistry. Consequently, a deeper understanding of the chemical interactions of bioceramics with living tissue could ultimately lead to new therapeutic strategies. However, the physical and chemical principles that govern these interactions remain unclear. The intricacies of this biological synergy are explored within this paper by examining the peculiar surface chemistry of a relatively new bioceramic, silicon nitride (Si₃N₄). Building upon prior research, this paper aims at obtaining new insights into the biological interactions between Si₃N₄ and living cells, as a consequence of the off-stoichiometric chemical nature of its surface at the nanometer scale. We show here yet unveiled details of surface chemistry and, based on these new data, formulate a model on how, ultimately, Si₃N₄ influences cellular signal transduction functions and differentiation mechanisms. In other words, we interpret its reciprocity with living cells in chemical terms. These new findings suggest that Si₃N₄ might provide unique new medicinal therapies and effective remedies for various bone or joint maladies and diseases.