The effect of alumina zirconia and alcen alumina whiskers on flexural strength of a pressable ceramic
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Objectives: This study was done to determine the flexural strength of pressable ceramic after the addition of different materials such as alumina, Zirconia and Alcen alumina whiskers. Materials and Methods: The control group was alpha ceramic (Vita, Bad Sackingen, Germany). The test materials were calcined alumina (Light High Technology, China), Tosoh Zirconia (Tosoh Corporation, Grove City, Ohio) and Alcen alumina whiskers (RATH Perfomance Fibers, Inc, Wilmington, Delaware). These materials were mixed with alpha in different concentrations. The experimental groups each consisted of fifteen bars of alpha ceramic, alpha with 1% calcined alumina, alpha with 5% calcined alumina, alpha with 10% calcined alumina, alpha with 1% Tosoh zirconia, alpha with 5% Tosoh zirconia, alpha with 10% Tosoh zirconia and alpha with 1% Alcen alumina whiskers. Also, five bars of alpha with 5% Alcen alumina whiskers, alpha with 10% Alcen alumina whiskers and alpha with 20% Alcen alumina whiskers were fabricated. Alumina and alpha powders were added together in a 500 ml polypropylene jar, which was placed in a paint mixer machine (Gyro Mixer, Miller) and mixed for a total of 30 minutes. The same process was used to mix zirconia with alpha powder. Mixing alpha with whiskers was done by a colloidal process. After the bars were polished, measurements of the length, width and thickness of each bar were taken with a caliper. Bars were then subjected to a three-point bend test on an Instron machine (Mode1 4202, Instron Corporation). Results: The flexural strength of alpha did not change after alumina was added. All alumina concentrations, 1%, 5% and 10% had similar flexural strength, which were about 114[plus or minus]6 MPa. Adding 1% and 5% zirconia to alpha showed an increase in flexural strength, which was about 117[plus or minus]5 MPa, but it was not statistically significant. However, there was a significant difference in the flexural strength of alpha with 10% zirconia, about 121 MPa. The alpha with whiskers groups did not show any increase in flexural strength and remained between 77-113 MPa. Conclusions: The groups of this study showed that the addition of calcines alumina and Alcen alumina whiskers in any concentration had no effect on flecural strength of pressable alpha. Alpha with 10% zirconia did affect the flexural strength; however, the lower concentrations of zirconia did not. Porosity decreases the flexural strength of the material.
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 Goldman School of Dental Medicine, 2006.Includes bibliographic references : leaves 46-48.
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