An ion extract obtained from mineral trioxide aggregate induced dentin remineralization and dentin tubule occlusion in artificially demineralized bovine dentin.

PURPOSE: To investigate the ability of a mineral trioxide aggregate (MTA) extract mixed with a phosphate buffered saline (PBS) system to induce remineralization and dentin tubule occlusion in artificially demineralized bovine dentin.

METHODS: The MTA extract solution was prepared by mixing white ProRoot MTA with distilled water (1:2) for 48 hours, before subjecting it to centrifugation. The elemental composition of the MTA extract solution was analyzed with inductively coupled plasma atomic emission spectrometry. The deposits produced by the MTA extract-PBS mixture were chemically analyzed using electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The effects of the two-step application of the mixture (MTA extract solution followed by PBS) to bovine dentin samples that had been artificially demineralized with phosphoric acid (10%, 10 seconds) were investigated with scanning electron microscopy and EPMA after the specimens had been stored in PBS for 1 or 7 days.

RESULTS: The MTA extract solution contained calcium, silicone, and aluminum (Ca>Si>Al), and the deposits produced by the MTA extract-PBS mixture contained calcium, phosphorous, sodium, silicone, and aluminum (Ca>P>Na>Si>Al) as major mineral elements. XRD also revealed that the deposits contained hydroxyapatite. The two-step application process resulted in the formation of a 2-3 microm-thick "mineral infiltration layer", together with mineral tag-like structures in the dentin tubules. The MTA extract-treated specimens exhibited a significantly higher dentin tubule occlusion rate than the untreated specimens (P < 0.05).