The 100% phase pure calcium silicate nanoparticles (CSNPs) of the alpha-wollastonite phase by hydrothermal synthesis is achieved first. Next this work reports the first-ever microwave-assisted low temperature synthesis of calcium silicate-cellulose nanograss composites. The characterization by FESEM studies confirm that calcium silicate-cellulose composites possess the nanograss like morphology spread over the matrix of calcium silicate. The structural information of the calcium silicate-cellulose composites are derived by both theoretical and experimental techniques. Low-energy ground state geometrical structures of the cellulose on the triclinic wollastonite surfaces and their interactions have been primarily determined by Density Functional Theory. Accordingly, the short-range structural information is confirmed by Pair Distribution Function analysis. Structural information along with binding interactions are also confirmed from X-ray photoelectron spectroscopy. The implications of these detailed analysis of structures in tuning the properties of such ceramic polymeric hybrid composites for futuristic endodontic application is discussed.