A qualitative X-ray analysis of white and grey mineral trioxide aggregate using compositional imaging

Mineral trioxide aggregate (MTA) is used in endodontics as a filling and sealant material. An earlier commercial formulation Grey MTA (GMTA) was liable to became progressively discoloured, and a whiter version (WMTA) has been introduced for cosmetic reasons. This study compares the composition and particle size distribution of the two formulations using energy dispersive X-ray analysis in a scanning electron microscope. Particle size is smaller in WMTA. X-ray analysis reveals similar major peaks (calcium, silicon and bismuth) but those of the minor elements aluminium, magnesium and particularly iron are considerably less in WMTA, which may account for the colour difference. Neither contains phosphorus, a major constituent of the original formulation.