Introduction Nanoparticles are gaining more interest in dentistry for their antimicrobial, physical as well as properties. This study aimed to evaluate the effects of adding two types of nanoparticles (NPs) on calcium silicate hydraulic cements (CSHC) unique bioactivity and antibacterial properties Materials and methods Biotitania/AgCl NPs were synthetized and characterized for its morphology, types of formed functional groups and crystalline AgCl using field emission scanning electron microscope equipped with energy-dispersive X-ray spectroscopy, X-ray diffractomer, Fourier transformation infrared spectroscopy and thermo-gravimetric analysis. The former NPs and commercial titania (TiO2) NPs were added (0.5, 1.5 and 3-wieght %) to commercial (CSHC) powder. 140 disk-shaped specimens (10 mm X 1mm) were prepared ( seven groups per each test in addition to the eighth cell control group) to evaluate cell viability and alkaline phosphatase activity (ALP) after 3 and 12 days, respectively. All were incubated with mesenchymal stem cells. Antibacterial efficacy against streptococcus mutans (S. mutans) was evaluated through the bacterial growth curve slopes while being in direct contact with the tested material groups for 18 hours. One-way analysis of variance (ANOVA) and post hoc Tukey tests were used to analyze the obtained data. Results: Addition of all NPs percentages had no significant effect on cell viability in comparison to positive control CSHC. Commercial TiO2 NPs (0.5 weight %) had significant lower values for bacterial growth curve slope. However, addition of all NPs percentages had significantly improves the ALP activity of CSHC with the most prominent effect to 3-weight% biotitania\AgCl NPs. Conclusions: Based on this in vitro study results, addition of biotitania\AgCl NPs up to 3-weight% significantly improved the bioactivity of CSHC without having significant negative impact on its antibacterial efficacy. However, addition of commercial TiO2 only with small amounts can significantly improve CSHC antibacterial efficacy.