Tehran University of Medical Sciences
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Mohammad Hossein Nekoofar

The effect of various mixing techniques on the surface microhardness of mineral trioxide aggregate

Authors: Nekoofar, M. H. - Aseeley, Z. - Dummer, P. M. -
Keywords: *Aluminum Compounds/chemical synthesis/chemistry , *Calcium Compounds/chemical synthesis/chemistry , Dental Stress Analysis , Drug Combinations , Drug Compounding/*methods , Hardness , Materials Testing , *Oxides/chemical synthesis/chemistry , Pressure , *Root Canal Filling Materials/chemical synthesis/chemistry , *Silicates/chemical synthesis/chemistry , Surface Properties , Ultrasonics , Vibration ,
Int Endod J, Vol.43, No.4, 2010,Page:312-20
AIM: To evaluate the influence of various mixing procedures including ultrasonic vibration, trituration of customized encapsulated mineral trioxide aggregate (MTA) and condensation on the Vickers surface microhardness of MTA. METHODOLOGY: ProRoot MTA Original, ProRoot MTA (white), MTA-Angelus (grey) and MTA White Angelus (white) were prepared using several mixing techniques including ultrasonic vibration, trituration of customized encapsulated MTA and conventional condensation. Twelve experimental groups (four materials: three techniques) were evaluated, each with 35 samples. All samples were incubated after preparation and subjected to Vickers surface microhardness testing after 4 and 28 days. Data was were subjected to a two-way anova. RESULT: At 28 days, the surface microhardness value was significantly greater for all experimental groups compared to 4 days after mixing (P < 0.00001). The application of ultrasonic energy to MTA produced significantly higher surface microhardness values compared to the other mixing techniques at both 4 and 28 days (P < 0.0001). However, no significant difference existed between condensation and trituration techniques at both time intervals. Regardless of the mixing technique employed, a significant difference (P < 0.0001) was observed in surface microhardness value between all types of MTA apart from between Angelus grey and ProRoot white at both 4 and 28 days, both of which produced the highest values. CONCLUSION: Compared to trituration and condensation techniques, the application of ultrasonic energy to MTA produced a significantly higher surface microhardness value at both 4 and 28 days. Irrespective of mixing technique, ProRoot white and Angelus grey had the highest surface microhardness values. Trituration of encapsulated, premeasured MTA and water provides a standardiszed method of mixing that produces MTA slurries with more controllable handling characteristics.