Evaluation of calcium-releasing and apatite-forming abilities of fast-setting calcium silicate-based endodontic...

To evaluate two fast-setting calcium silicate-based endodontic materials (Endocem mineral trioxide aggregate (MTA) and Endocem Zr) with regard to their ability to release calcium ions (Ca(2+)) and produce apatite-like precipitates after immersion in phosphate-buffered saline (PBS).

Endocem MTA, Endocem Zr and white ProRoot MTA (WMTA) were used. Chemical composition of the powder of each material was analysed with a wavelength-dispersive X-ray spectroscopy electron probe microanalyser with image observation function (SEM-EPMA). The amount of Ca(2+) released from water-immersed set cements was measured with an EDTA titration method. Morphology and chemical composition of surface precipitates formed on the surface of PBS-immersed cements were analysed with the SEM-EPMA. Data obtained were analysed using one-way analysis of variance and Tukey's honestly significant difference test with a significance level of 5%.

Endocem MTA and WMTA contained calcium (Ca), silicon (Si) and bismuth as the major elemental constituents, whereas Endocem Zr contained zirconium as the most abundant element, followed by Ca and Si. The amount of Ca(2+) release was WMTA >Endocem MTA ≥Endocem Zr. After immersion in PBS for 14 days, the three materials produced Ca- and phosphorus (P)-containing apatite-like surface precipitates. WMTA showed higher Ca/P ratio of the precipitates compared with the other cements, with statistical significance between WMTA and Endocem Zr (P < 0.05).

Compared with WMTA, Endocem MTA and Endocem Zr were associated with significantly less Ca ions release and, when immersed in PBS, produced apatite-like crystalline precipitates of significantly lower Ca/P ratios.