Relación de la energía de polimerización y Degradación por UV, sobre el grado de conversión en composites
Fecha
2011-01Autor
Zamarripa Calderón, Juan Eliezer
Ancona Meza, Adriana Leticia
Metadatos
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The degree of conversion (DC) is directly related with the physical and mechanical properties that allow a successful
restorative treatment. The aim of this study was to evaluate the influence of the energy density, on the DC in composites,
as a function of the subjected time to accelerated aging by UV. Two hundred and forty resin composite specimens were
made, using a stainless steel mold of 6mm - diameter x 2mm - depth; the energy output was applied, only, over the top
area of the samples. The materials used were: Filtek Z-250 - Filtek Supreme / 3M ESPE and Tetric Ceram - Tetric
EvoCeram / Ivoclar Vivadent. The specimens were divided in three groups (according the energy output): A (3.75 J/cm2
),
B (9 J/cm2
) and C (24 J/cm2
), and each one of them, subdivided in: 1(no aging), 2 (500 hours of aging), 3 (1000 hours of
aging) and 4 (1500 hours of aging). The results were analyzed by means of ANOVA and Tukey tests (p<0.05) to determine
the effect of the factors. Correlation and lineal regression were performed to determine the possible relationship among the
variables. The energy density determined the DC in specimens without aging; however, it is not a decisive factor after 500
h under accelerated aging by UV. The DC increases significantly, while the time of aging increases: 0 h (53.9%), 500 h
(62.7%), 1000 h (77.5%), but after 1500 h, the material presents a significant decrease of DC (61.4%).
The organic matrix degradation and the generation of double bonds, after 1500 h under accelerated aging is, probably, the
cause for the decrease of DC. The clinician, should keep this behavior in mind, to check the composite restorations
frequently.