Synthesis of strontium orthosilicate (Sr2SiO4) by sol-gel method for the use in endodontic cements to enhance bioactivity and radio-contrast

Strontium orthosilicate (Sr2SiO4) is identified as a potential biomedical material because of its bioactivity, and the radio-contrast ability of strontium ions. This work demonstrates a viable sol-gel based method to synthesize strontium orthosilicate. At the optimized gelation conditions and calcination temperature (650 °C), a crystalline material with an average particle size of 3 m was obtained. The phase analysis using XRD and FTIR showed the product to be strontium orthosilicate. The x-ray radio-contrast was found to be nearly 10 times the equivalent thickness of aluminum. The minimum weight percentage of the material required to impart the clinically relevant radio-opacity to an endodontic cement formulation was found to be 30%. The low size of the particles can impart efficient occlusion of the dentinal tubules. The in vitro bioactivity tests showed apatite deposition on the material surface when soaked in SBF, indicating it to be bioactive. In cell culture studies, mouse fibroblast cells were found to attach and grow over the surface. The powder has been observed to be non-toxic in lower ionic concentrations of the extract. The low particle size, high radio-contrast, bioactivity and cell compatibility warrants the use of this sol-gel derived strontium orthosilicate (Sr2SiO4) in silicate-based endodontic cement formulations.