Improvement of bioactivity and investigating antibacterial properties of dicalcium silicate in an artificial saliva medium

In recent years, there has been a growing interest in using bioceramics for dental restorations. These materials have shown promising results in terms of their ability to promote bioactivity and enhance adhesion between tooth tissues and restorative materials.the main aim of this study is to synthesize dicalcium silicate (13-Ca2SiO4, 13-C2S) - Hardystonite (Ca2ZnSi2O7) phases as a new bioceramics restoration with good antibacterial ability and bioactivity. This type of material could be used as a denture base material, helping to preserve oral health by preventing the demineralization of the residual dentition through the release of appropriate ions that serve as substrates for hydroxyapatite formation. The hardystonite and the dicalcium silicate phases were synthesized by reaction in the solid state and addition of 5% proportion of Zinc nitrate (Zn (NO3)2). Moreover, the in vitro test was performed by immersing C2S-Hardystonite powder in artificial saliva for different times ranging from 1 h to 5 h to analyze the growth of hydroxyapatite (HA) on the surface of this powder. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR), Thermogravimetric analysis (TGA), differential thermal analysis (DTA) was utilized to analyze the samples for mineralogical and microstructural properties. The characterization of powder shows a mixture of C2S-Hardystonite phases with hydroxyapatite (Ca5(PO)4)3(OH)) and Tetracalcium phosphate (Ca4 (PO4)2O) phases precipitated on the surface of this powder within 1 h after soaking in artificial saliva. The micrographs obtained by SEM show fine particles of spherical agglomerates morphology attributed to hydroxyapatite phase. The antibacterial activity was tested by the Agar well diffusion method against two different strains. Staphylococcus aureus, Microbacterium resistant, Bacillus subtilis belong to the Gram-positive bacteria studied, and Escherchoa coli, Klebsiella pneumoniae and Pseudomonas chloritidismutans belong to the Gram-negative bacteria. Furthermore, the powder exhibited a shortened setting time and good injectability, along with an outstanding level of anti-washout performance. Finally, the results obtained suggest that dicalcium silicate-Hardystonite ceramics are promising candidates for dental restorations.