Chemical Modification of ProRoot MTA to Improve Handling Characteristics and Decrease Setting Time

Mineral trioxide aggregate (MTA) fulfills many of the ideal properties of a root-end filling material. However, the composition of this material often makes MTA difficult to use, a direct result of its granular consistency, slow setting time, and initial looseness. Additives used by the Portland cement (PC) industry to increase PC’s plasticity and decrease its setting time were added first to PC and then to gray MTA in an attempt to improve MTA’s handling characteristics, with the combination providing the best handling characteristics tested for its effect on compressive strength (for changes in the original material’s properties) and decrease in setting time. An admix of 1% methylcellulose and 2% calcium chloride resulted in a mix of chemically modified MTA that, when compared with unmodified MTA, (1) handled similarly to a reinforced zinc oxide–eugenol cement, (2) gave an approximately equal compressive strength, and (3) set one third faster (57 ± 3 minutes).