Novel calcium encapsulated mesocellular siliceous foams for crystal growth in dentinal tubules

Objectives: The aim of this study was to investigate the novel mesocellular siliceous foams (MCF) containing CaCO ₃ nanoparticles (denoted as CMCF) combined with phosphoric acid could occlude dentinal tubules through the formation of biomimetic crystal barrier. Methods: Ultrastructures of MCF and CMCF were examined by transmission electron microscopy (TEM). Elemental components were analyzed with energy dispersive X-ray spectrometry (EDX). CMCF was mixed with distilled water, 10%, 20% and 30% phosphoric acid then applied on dentine discs. Crystals were characterized by X-ray powder diffractometry (XRD). The sealing efficacy of the dentinal tubules was examined by scanning electron microscopy. Results: TEM images showed MCF presented a pore size of approximately 30.0 nm and CMCF contained abundant nano-CaCO ₃ . Sealing efficacy showed that CMCF, when reacted with 30% phosphoric acid, would form crystals in the dentinal tubules to a depth of 83.2 ± 17.6 μm at an occlusion percentage of 75.6 ± 12.8% on average; both occlusion percentage and depth were higher than those obtained with 10% or 20% phosphoric acid (p < 0.05). The results of XRD and EDS indicated that the crystal growth in the dentinal tubules could be transformed into the biomimetic crystals. Conclusion: This study showed that the CMCF with 30% phosphoric acid could effectively occlude the dentinal tubules through the formation of biomimetic crystal barrier. Clinical significance: The novel CMCF combined with phosphoric acid may have potential for the treatment of dentine hypersensitivity.