Effect of particle size on physical and chemical properties of experimental mineral trioxide aggregate
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Mineral Trioxide Aggregate has gained popularity among clinicians, in respect to other endodontic materials, due to the superiority of its biological and physical properties. However, the main disadvantage of MTA is its prolonged setting time. MTA may gain wider acceptance in endodontic applications if its setting time could be shortened to a single appointment time frame. The purpose of this study was to investigate the effects of particle size on control; group, 50-75 microns,75-90 microns and [greater than]150 microns setting time, strength, microleakage, and pH of an experimental version of Mineral Trioxide Aggregate (EMTA). Setting time was determined by measurement of penetration depths at fixed time intervals using a dial indicator microgauge. Biaxial flexural strength was determined with an Instron universal testing machine after 1, 7 and 21 days of setting. A fluid filtration method was used for quantitative evaluation of apical microleakage. The quality of seal of each specimen was measured after 1, 7, 14, 21, days. The pH of storage solutions of each specimen in 20 ml of deionized water was measured after 6 hours, 1, 2, 7 and 21 days. The data were statistically analyzed with both one-Way ANOVA and Tukey’s HSD test methods. The results showed that the setting time and rate of EMTA were significantly decreased when the particle size was 50 microns. Results also showed that particle size did not have any effect on the strength of the EMTA. The microleakage was compared between different particle sizes of control group, 50-75 microns, 75-90 microns and [greater than]150 microns. The control group was the one that had the most leakage compared to all other powders. Under the conditions in which this study was conducted the setting time was greatly affected as the particle size got smaller without affecting other properties.
Thesis (D.Sc.D)--Boston University Goldman School of Dental Medicine, 2009 (Department of Endodontics).Includes bibliographical references (leaves 93-95).
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