TY - JOUR
T1 - Degree of conversion and mechanical properties of a BisGMA:TEGDMA composite as a function of the applied radiant exposure
AU - Calheiros, Fernanda C.
AU - Daronch, Márcia
AU - Rueggeberg, Frederick A.
AU - Braga, Roberto R.
PY - 2008/2
Y1 - 2008/2
N2 - Objective: Verify the influence of radiant exposure (H) on composite degree of conversion (DC) and mechanical properties. Methods: Composite was photoactivated with 3, 6, 12, 24, or 48 J/cm2. Properties were measured after 48-h dry storage at room temperature. DC was determined on the flat surfaces of 6 mm x 2 mm disk-shaped specimens using FTIR. Flexural strength (FS) and modulus (FM) were accessed by three-point bending. Knoop microhardness number (KHN) was measured on fragments of FS specimens. Data were analyzed by one-way ANOVA/Tukey test, Student's t-test, and regression analysis. Results: DC/top between 6 and 12 J/cm2 and between 24 and 48 J/cm2 were not statistically different. No differences between DC/top and bottom were detected. DC/bottom, FM, and KHN/top showed significant differences among all H levels. FS did not vary between 12 and 24 J/cm2 and between 24 and 48 J/cm2. KHN/bottom at 3 and 6 J/cm2 was similar. KHN between top and bottom was different up to 12 J/cm2. Regression analyses having H as independent variable showed a plateau region above 24 J/cm2. KHN increased exponentially (top) or linearly (bottom) with DC. FS and FM increased almost linearly with DC/bottom up to 55% conversion. Conclusions: DC and mechanical properties increased with radiant exposure. Variables leveled off at high H levels.
AB - Objective: Verify the influence of radiant exposure (H) on composite degree of conversion (DC) and mechanical properties. Methods: Composite was photoactivated with 3, 6, 12, 24, or 48 J/cm2. Properties were measured after 48-h dry storage at room temperature. DC was determined on the flat surfaces of 6 mm x 2 mm disk-shaped specimens using FTIR. Flexural strength (FS) and modulus (FM) were accessed by three-point bending. Knoop microhardness number (KHN) was measured on fragments of FS specimens. Data were analyzed by one-way ANOVA/Tukey test, Student's t-test, and regression analysis. Results: DC/top between 6 and 12 J/cm2 and between 24 and 48 J/cm2 were not statistically different. No differences between DC/top and bottom were detected. DC/bottom, FM, and KHN/top showed significant differences among all H levels. FS did not vary between 12 and 24 J/cm2 and between 24 and 48 J/cm2. KHN/bottom at 3 and 6 J/cm2 was similar. KHN between top and bottom was different up to 12 J/cm2. Regression analyses having H as independent variable showed a plateau region above 24 J/cm2. KHN increased exponentially (top) or linearly (bottom) with DC. FS and FM increased almost linearly with DC/bottom up to 55% conversion. Conclusions: DC and mechanical properties increased with radiant exposure. Variables leveled off at high H levels.
KW - Composite
KW - Degree of conversion
KW - Mechanical properties
KW - Radiant exposure
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U2 - 10.1002/jbm.b.30897
DO - 10.1002/jbm.b.30897
M3 - Article
C2 - 17635039
AN - SCOPUS:38349175690
SN - 1552-4973
VL - 84
SP - 503
EP - 509
JO - Journal of Biomedical Materials Research - Part B Applied Biomaterials
JF - Journal of Biomedical Materials Research - Part B Applied Biomaterials
IS - 2
ER -