The effects of additives and particle size on the strength and setting time of experimental mineral trioxide aggregate
Paczesny, Diana E.
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The use of Mineral Trioxide Aggregate (MTA)in various endodontic procedures has proven to be successful and it has many properties that are superior to previously used materials. MTA is antibacterial, can induce cementogenesis, and it has less leakage than amalgam all of which make it an excellent material for apical surgery. However, a common concern is its long setting time. The purpose of this study was to compare the effects of varying particle size and additives on the strength and setting time of Experimental MTA (EMTA). EMTA was prepared by separating type III Portland Cement[TM] into four groups based on particle size (Group A control, Group B [more than] 38um, Group C = 25-38um, Group D [less than] 25um) and then adding bismuth oxide and gypsum in ratios identical to MTA. The additives tested were 3% CaC1, 6% CaC1, and 10% Bioactive Inorganic Element (BIE). Biaxial flexural strength was determined using an Instron universal testing machine at time intervals of 1 day, 7 days and 21 days. Setting time was determined using a Mitutoyo[TM] dial indicator by measuring the degree of dial indicator microgauge penetration until the material was set. Data was analyzed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison for significant difference (p [less than]0.05). The results showed that decreasing particle size will increase initial biaxial flexural strength. The addition of 3% CaC1 does not significantly affect strength after twenty-one days, however the addition of 6% CaC1 significantly decreases strength in EMTA with particles over 25 microns. The addition of 10% BIE does not affect the initial strength and decreased strength after 21 days. Setting time is significantly decreased by decreasing particle size and adding 3% or 6% CaC1. The addition of 10% BIE decreases the setting time for EMTA with particles over 38 microns but not for EMTA with particles under 38 microns. Further studies are needed to compare microleakage, PH, and shrinkage as well as the long term effects on strength.
PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact firstname.lastname@example.org.Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2010 (Department of Restorative Science and Biomaterials).Includes bibliographic references: leaves 77-80.
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