Introduction: Mineral trioxide aggregate (MTA) has numerous applications in dentistry due to various advantages. However, its long setting time has still remained a problem. The current study was conducted to investigate the effect of temperature (ambient and distilled water temperature) on the setting time of mineral trioxide aggregate (MTA).

Materials and methods: This experimental study comprised of two parts. In the first part, MTA and distilled water samples were kept at ambient temperature for 24 hours (before mixing: effect of distilled water temperature on the setting time of MTA and after mixing: effect of distilled water and ambient temperature on the setting time of MTA), and analyzed and divided into three groups: group 1 (4°C), group 2 (37°C) and group 3 (90°C). The mixed samples were placed in the glass cylinders with an internal diameter of 8 mm and a height of 10 mm, and kept at 37°C temperature and 100% humidity. In the second part, the samples were prepared the same as those of the first part and divided into three groups according to the terms of maintenance: group 1 (4°C), group 2 (37°C) and group 3 (75°C). The mixed samples were then put in glass cylinders with an internal diameter of 8 mm and a height of 10 mm and the samples of groups 1, 2 and 3 were kept at 4, 37 and 75 °C, respectively. At the end of each part, the primary and final setting times were measured by Gilmore needle. Data were analyzed by SPSS using Kruskal-Wallis test (p<0.05).

Results: The findings of this study showed a significant reduction of the primary and final setting time of MTA for the samples of both parts of the study with an increase in ambient temperature (p<0.05).

Conclusion: This study indicated that increased ambient temperature caused a reduction in the setting time of MTA.