Bio-coating Formation on Bio-active Endodontic Materials Derived from Portland Cement

Objectives: The aim of this study was to assess the in vitro ability of experimental materials, derived from Portland cement and designed as endodontic sealers and root-end filling materials, to produce apatite on their surface in presence of phosphate solution. Materials and methods: Calcium chloride, calcium sulphate and a phyllosilicate were added to a thermally treated white Portland cement to prepare the experimental wTC1% and wTC1%-TCP cements. Both materials were mixed with deionized water. Cement disks were prepared, immersed and stored in phosphate solution (DPBS) at 37°C. ATR-FTIR, micro-Raman and SEM-EDX analyses were carried out at different storage times on both superficial/outer and internal/fractured surfaces of the discs. Results: SEM-EDX of cements surface showed high peaks of Ca, the disappearance of Si and the absence of P at the early stages (1-7 days) of storage. Detectable amount of P and the formation of a coating layer P-containing on surface were revealed after 14 days. After 21 and 28 days a thick coating layer high in P was observed on cements surface. Higher peaks of P were always displayed by wTC1%-TCP. The ATR-FTIR and micro-Raman spectra of the samples stored for 1 day revealed the presence of a poorly crystalline calcium phosphate deposit on the surface of both cements. The deposit resulted thicker and more homogeneous on wTC1%-TCP than on wTC1%. The samples stored in DPBS for 7 and 14 days displayed the same bands with a better-defined profile. The samples stored for 21 and 28 days showed the bands typical of a more crystalline carbonate-apatite layer. The deposit resulted more crystalline on the wTC1%-TCP. Conclusions: The experimental cements resulted able to form apatite on their surface (bio-coating layer) in presence of environmental phosphate ions and represent innovative bio-active materials for endodontics and bone application and healing.