Investigating the effect of bicarbonate ion on the structure and strength of calcium silicate-based dental restorative material-Biodentine.

OBJECTIVES

Investigating the effect of carbonation on the strength and structure of calcium silicate-based cement (Biodentine™) in the presence of bicarbonate ion.

MATERIALS AND METHODS

Cylindrical samples of Biodentine (N = 120) were prepared and cured in deionised water (DW) or bicarbonate solution (BC) for 1 and 2 days and 1, 2 and 4 weeks. After storage, the compressive strength of cured samples was tested using a universal testing machine, and carbonate was quantified on the surface or within the structure of samples using Raman and Fourier transform infrared spectroscopy, respectively. Levels of calcium and silicon ions and pH were measured after each storage duration, and 4-week-old samples were imaged using scanning electron microscopy.

RESULTS

Cement's compressive strength was significantly higher after curing in BC for 2 days. This was associated with significantly higher levels of carbonate on the surface of the cement but not within its structure. Levels of calcium and silicon ions and pH in BC dropped significantly after 1 day and remained at a steady lower level. The pH and calcium ion levels dropped gradually over 4 weeks in DW, unlike the silicon ion level that maintained a steady higher level than in BC.

CONCLUSIONS

Our results indicate that Biodentine exhibited higher strength in the presence of bicarbonate, which can be explained by the carbonation process that encouraged the formation of calcium carbonate on the cement's surface.

CLINICAL RELEVANCE

Carbonation should be of more consideration when studying calcium silicate-based cements, with curing and testing conditions closer to the intraoral conditions.