Chemical and physical surface and bulk material characterization of white ProRoot MTA and two Portland cements.

OBJECTIVES

The chemical and physical properties of white ProRoot MTA were analyzed in the bulk and at the surface and compared with two common Portland cements types CEM1 and CEM2.

METHODS

The main components were analyzed by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray analysis (EDX), and the minor constituents were identified with inductively coupled plasma optical emission spectroscopy (ICP-OES). Moreover, the setting of the different cements was studied: the chemical composition of the surface of both powder and bound cement was investigated by XPS and the morphological changes were examined by scanning electron microscopy (SEM).

RESULTS

In ProRoot MTA, the amount of gypsum is approximately half of that of the Portland cements. ProRoot MTA consists of less toxic heavy metals (Cu, Mn, Sr), less chromophores (Fe3+), and less Al-species, but contains about 2 at % Bi. In contrast to Portland cements, ProRoot MTA contains about 2 at.% Bi. In all three products, the amount of sulfur at the surface in the bound cements was 3 times higher than in the powder, indicating that in terms of the kinetics of the hardening reaction, a sulfate action mechanism prolongs the setting time. The Portland cements are composed of particles with a wide range of size, whereas ProRoot MTA showed a uniform and smaller particle size.

SIGNIFICANCE

With regard to chemical and physical surface and bulk properties, ProRoot MTA cannot simply be substituted by the cheaper Portland cement. Both products are similar but not equal and exhibit marked differences.