Mixing with propylene glycol enhances the bond strength of mineral trioxide aggregate to dentin

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 MTA-dentin push-out bond strength.

Seventy-five 2-mm-thick midroot sections were prepared from single-rooted human extracted teeth. The lumen of each slice was enlarged with Gates-Glidden burs. The slices were randomly divided into 3 groups (n = 25). In each group, 0.3 mL of the liquid was mixed with 1 g MTA (Angelus, Londrina, Brazil). The liquid vehicles used in groups 1-3 were 100% distilled water (DW), 20% PG-80% DW, and 100% PG, respectively. After incubation, the push-out strength of the samples was measured using a universal testing machine. The samples were then cut in halves and examined under a stereomicroscope to determine the failure pattern. One-way analysis of variance followed by the Tukey post hoc test was used to compare the push-out strength among groups.

There were statistically significant differences between groups (P < .001). The push-out strength in group 1 (DW) was significantly lower than groups 2 and 3 (P < .001 and P = .022, respectively). However, there was no significant difference between groups 2 (DW-PG) and 3 (PG).

Mixing MTA with PG increased its push-out bond strength to dentin. In the present study, the most suitable ratio was 80% DW-20% PG.