Abstract
This study evaluated the influence of different levels of power density on resin polymerization in the staining of composite resins. Thirty-six specimens were made with composite resin (Z350 3M ESPE) with cylindrical Teflon matrix (8 mm X 1 mm). The light curing was performed with different degrees of power density for each group (n=12): 300mW/cm², 700mW/cm² e 1000mW/cm². Afterwards, the specimens had their color checked, with the help of a spectrophotometer and immersed in coffee solution during 7 days. After, a new measuring was done (CIEL*a*b* color system). Results showed, for Δa, only G1000 group obtained a significantly lower value, and the same result was found in the evaluation of Δb. For ΔE and ΔL, no significant differences were found between groups. It is concluded that, low and medium power density entails more reddish and bluish composite resin, while the specimens submitted to high power density and then immersed in coffee did not present color change in a short term.
Highlights
The use of composite resins has increased significantly over the last years and currently is the major dental material for direct restorations [1], which is due to the optimization of physical and mechanical properties [13]
This study evaluated the influence of different levels of power density on resin polymerization in the staining of composite resins
The light curing was performed with different degrees of power density for each group (n=12): 300mW/cm2, 700mW/cm2 e 1000mW/cm2
Summary
The use of composite resins has increased significantly over the last years and currently is the major dental material for direct restorations [1], which is due to the optimization of physical and mechanical properties [13]. A satisfactory polymerization provides resins with good biocompatibility, hardness, physicochemical properties and resistance to masticatory forces to which they are subjected [11, 13]. It provides greater aesthetic stability, because an insufficient cure induces higher water absorption and incorporation of substances [3, 12, 14]. There are no studies in the scientific literature assessing the influence of different power densities on the staining of composite resins. It is appropriate to assess the direct influence of different power densities and the consequent degree of conversion on composite resins subjected to staining after immersion in dye beverages
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