Characterisation Of Biodentine And Its Behaviour In Stimulated Oral Environment

Objectives: Biodentine is used as a dentine replacement restorative material. The aim of this study was to characterise the structure, setting behaviour and mechanical properties of Biodentine, as a detailed understanding of the structure-property relationship allows us to improve the clinical performance. Methods: Crystal phases in Biodentine powder were characterised by X-ray diffraction (XRD). An Instron universal testing machine was used to determine the compressive strength at 2 weeks (n=8). 29Si magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy was used to characterise the silicate structure of Biodentine powder and set material (after 2 weeks). Results: XRD showed tricalcium silicate (71.7 %), calcium carbonate (22.2 %), zirconium oxide (6.1 %) with some traces of dicalcium silicate. 29Si MAS NMR spectrum of the untreated powder showed tricalcium silicate peaks at 65.5, 68.0 and 70.0ppm, corresponding to a Q0 structure. The set material at two weeks showed a shift in the peaks seen at 66.7, 68.3, and 70.2ppm, a new peak at 69.2ppm and formation of Q2 silicate species at 75.2 and 79.0ppm, which is consistent with the formation of calcium silicate hydrate. The mean compressive strength was 73.8MPa (SD=0.9MPa). Conclusion: The results suggest that setting of Biodentine is at least partially due to polymerization of the silicate phase to a Q2 chain-like structure, similar to that present in Portland cement.