Comparision of Setting time compressive strength of white MTA with or without adding Na2Hpo4 in dafferent liquid to powder ratio

Abstract

MTA has been used in various endodontic procedures since its introduction, including pulp capping, perforation repair, and as a root-end filling material. However, the initial reaction of inflammatory cells to MTA and its setting time are not favorable. Studies have shown that Na2HPO4, as an MTA accelerator, decreases its setting time but does not change its pH. In this study the effect of various liquid-to-powder ratios on the setting time of WMTA and mixture of MTA and Na2HPO4 (NAMTA) was evaluated. Materials and methods: A total of 60 samples were placed in round plastic molds measuring 10 mm in diameter and 4 mm in depth to measure setting time. In 30 samples WMTA and in 30 samples a 2.5-wt% mixture of Na2HPO4 and MTA were placed. The setting time of the samples were measured at different liquid-to-powder ratios of 0.50, 0.60, and 0.70 at different intervals using Vicat machine. Two-way ANOVA was used to evaluate inter-group differences. If there were differences, appropriate post hoc tests or non-parametric Kruskal-Wallis and Wilcoxon-Wallis tests were used. Statistical significance was defined at P<0.05. Results: The type of the material (WMTA and NAMTA) had a significant effect on setting time (P<0.001, Z=6.416). Kruskal-Wallis test showed no significant differences in setting time between the three different material ratios (chi-squared=5.901, Df=2, P=0.052). Conclusion: The setting time of NAMTA at 0.50 and 0.60 liquid-to-powder ratios is less than that of MTA.