We synthetized a series of strontium-substituted submicron bioactive glasses spheres (Sr-SBG, SiO2-P2O5-CaO-SrO) in which strontium was substituted for calcium on a mole percentage basis, then investigated the effect of strontium-substituted amount on morphologies, physicochemical properties, apatite-forming bioactivity of SBG and evaluated the proliferation, differentiation and mineralization of Sr-SBG with different strontium substitution amounts by co-cultured with human dental pulp cells (HDPCs). Results showed that Sr-SBG with different strontium substitution amounts were successfully fabricated and substituting different strontium amounts did not affect the morphology and particle size of SBG. All the Sr-SBG possessed good apatite-forming ability, but substituting a certain amount of strontium for calcium would weaken the apatite-forming ability of SBG. Additionally, all the Sr-SBG extractions promoted proliferation, early odontogenic differentiation and mineralization of HDPCs, however, the cell proliferation, differentiation and mineralization abilities would be reduced when the substituted amount of strontium was excess (15 mol%). This study suggests that Sr-SBG with moderate strontium substitution amounts can be used as a more promising biomaterial for dental repair. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.