Heavy metal analysis of ortho MTA and ProRoot MTA

Recently, several kinds of mineral trioxide aggregate (MTA)-based products have been introduced in endodontics. Ortho MTA (BioMTA, Seoul, Republic of Korea) is one of those products, which was developed for retrograde filling, perforation repair, orthograde root canal obturation, and direct pulp capping. The inclusion of heavy metals in MTA-based materials is of concern because they come into direct contact with hard and soft tissues. The aim of this study was to investigate and compare the levels of arsenic (As), chromium (Cr), hexavalent chromium (Cr(6+)), and lead (Pb) in Ortho MTA and ProRoot MTA.

One gram of each MTA was digested using a mixture of hydrochloric and nitric acids and filtered. The As, Cr, and Pb in the resulting filtrates were analyzed by inductively coupled plasma-optical emission spectrometry. The level of Cr(6+) was measured by the methods suggested in the Korean Standard L 5221. The results were statistically analyzed using the Mann-Whitney U test.

The concentration of As in ProRoot MTA was 1.16 ppm, but As was not detected in Ortho MTA. Cr(6+) and Pb were not detected in either MTA. Ortho MTA contained significantly less Cr than ProRoot MTA (P < .05).

Ortho MTA and ProRoot MTA meet the ISO specification 9917-1 regarding the safety limits of As and Pb and are safe biomaterials when the purity of As, Cr(6+), and Pb is considered.