The Effect of Using Propylene Glycol as a Vehicle on Microhardness of Mineral Trioxide Aggregate

Abstract

Mixing mineral trioxide aggregate (MTA) with different proportions of propylene glycol (PG) improves its handling property. The aim of this study was to evaluate the effect of PG on microhardness of MTA as a criterion for the setting quality. Materials and Methods: MTA was mixed with different proportions of distilled water (DW)/PG to prepare 5 groups of 30 samples each. The DW/PG used in groups 1 to 5 were 100%DW, 80%DW/20%PG, 50%DW/50%PG, 20%DW/80%PG, and 100%PG, respectively. Mixed MTA was condensed into acrylic moulds. Microhardness of half the samples in each group was evaluated after 4 days and the remainder at 28 days. The data were statistically analyzed using Robust test of Welch, Games-Howell post hoc test, and paired samples t-test. . Results: In group 5, 100%PG prevented setting so that this group was excluded. The microhardness in group 1 was significantly higher than other groups (p<0.001)., and there was a corresponding significant decrease in microhardness with increase in PG/DW (p<0.05). The microhardness at 28 days was significantly higher than 4 days in groups 1 and 2 (p<0.05). In contrast, the microhardness in group 4 was significantly lower at 28 days compared with 4 days (p<0.05). In group 3, there was no difference in microhardness between 4 and 28 days (p>0.05) Conclusions: PG reduces the microhardness of MTA and is likely to have an adverse effect on its setting process. A proportion of 20% of PG with DW is recommended to improve MTAEs handling without significant interference with setting