Effect of selected accelerants on the physical properties of mineral trioxide aggregate and Portland cement

To decrease setting time by a clinically significant amount, classic Portland cement accelerators (calcium chloride, calcium nitrite/nitrate, and calcium formate) were added to gray and white mineral trioxide aggregate (MTA) (GMTA, WMTA) as well as to Portland cement (PC). Time to initially set was measured, as well as dimensional stability, temperature during set, and pH. The data were analyzed by one-way analysis of variance and Bonferroni multiple comparison test. It was found that all 3 accelerators significantly accelerated the set of GMTA and PC; only calcium chloride and calcium formate significantly accelerated WMTA. Dimensional stability was not significantly different between control and experimental groups. A statistically significant increase in temperature was observed in one group, but it was considered insignificant clinically (less than 3 degrees C). There were seemingly minor but statistically significant differences in pH between groups set with calcium nitrite/nitrate and calcium formate. The results indicate that GMTA, WMTA, and PC mixed with these accelerators merit further study including evaluation of biocompatibility and sealing ability.