In vitro comparison of the setting of dry ProRoot MTA by moisture absorbed through the root

This study explored the potential of dry ProRoot mineral trioxide aggregate (MTA) (Dentsply Tulsa Dental, Tulsa, OK) powder to set solely by moisture absorbed through the root. Thirty-three single-rooted extracted teeth were decoronated and instrumented. The canal was packed with dry powder, and the coronal and apical 4 to 5 mm was sealed with nail varnish. Teeth were grouped and submerged in physiologic saline as follows: group A, 12 hours; group B, 36 hours; and group C, 72 hours. After submersion, the teeth were sectioned, and a 5-lb pound weight was placed on the Proroot MTA for 1 minute. The surface was evaluated for any evidence of penetration or fracture at 15x magnification. Nine of 10 samples were set at 72 hours versus 4 of 10 at 36 hours and 1 of 10 at 12 hours. Statistical analysis using a McNemar test with a significance of p < 0.05 found the number of roots in which dry MTA powder set at 72 hours versus 12 hours was statistically significantly different (p = 0.0133).