How effectively do hydraulic calcium-silicate cements re-mineralize demineralized dentin.

OBJECTIVE: To characterize the chemical interplay and to quantify the re-mineralization potential of hydraulic calcium-silicate cements (hCSCs) at demineralized dentin.

METHODS: Pairs of class-I cavities were prepared in non-carious human third molars. One dentin cavity was demineralized with 10% formic acid (5h); the other served as control. The cavities were filled with two resin-free hCSCs (Biodentine, Septodont; ProRoot MTA, Dentsply Sirona) or one resin-based hCSC (TheraCal LC, Bisco). After 1-week, 1-, 3-, and 6-month storage in simulated body fluid (SBF), polished specimen cross-sections were chemically characterized using Field-emission-gun Electron Probe Micro-Analysis (Feg-EPMA) and micro-Raman spectroscopy (μRaman).

RESULTS: Feg-EPMA line-scans and elemental mappings confirmed early re-mineralization induced by all three hCSCs at 1week. The relative depth and intensity of re-mineralization were for the resin-free hCSCs in the range of 50.5%-84.8% and 68.1%-89.2%, respectively. Re-mineralization did not significantly differ for the storage periods (p>0.05). Significantly less re-mineralization was achieved by the resin-based hCSC TheraCal LC that reached only at 6months a re-mineralization level that was no longer significantly different from that achieved by the resin-free hCSCs at 1week (p>0.05). Re-mineralization of intertubular dentin, including tubular occlusion, was observed; Si was occasionally detected to have infiltrated the dentin tubules. Dentin re-mineralization by hCSCs was confirmed using μRaman that revealed an increased phosphate peak at 960cm-1 .

SIGNIFICANCE: hCSCs do re-mineralize demineralized dentin. The resin-free cements induced re-mineralization at a higher speed/intensity than the resin-based hCSC. However, re-mineralization was incomplete for all hCSCs tested, this even at 6months.