Influence of light curing and sample thickness on microhardness of a composite resin
Influence of light curing and sample thickness on microhardness of a composite resin
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DOI：
10.2147/ccide.s4863
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发表时间：
2009-01-01
影响因子：
1.8
通讯作者：
Lovadino, Jose R.
中科院分区：
文献类型：
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作者：
Aguiar, Flvio H. B.;Andrade, Kelly R. M.;Lovadino, Jose R.
本体外研究的目的是评估光固化单元和不同样品厚度对复合树脂显微硬度的影响。随机制备复合树脂试件，并将其分为9个实验组（n = 5）：考虑3个光固化单元（常规石英卤钨[QTH]：550 mW/cm（2）- 20 s;高辐照度QTH：1160 mW/cm（2）- 10 s;和发光二极管[LED]：360 mW/cm（2）- 40 s）和三种样品厚度（0.5 mm、1 mm和2 mm）。所有样品均在距样品8 mm处使用光尖端聚合。然后在每个样品的顶部和底部表面上测量努普显微硬度。除了一些例外，顶部表面几乎相似;然而，相对于底部表面，发现固化单元和厚度之间存在统计学差异。在所有实验组中，0.5 mm厚的增量显示显微硬度值在统计学上高于1 mm和2 mm增量所观察到的值。传统和LED装置显示出更高的硬度平均值，并且与高辐照度装置存在统计学差异。在所有的实验组中，显微硬度的平均值获得的顶面高于观察到的底面。总之，更高水平的辐照度或更薄的增量将有助于改善混杂复合树脂聚合。
The aim of this in vitro study was to evaluate the influence of light-curing units and different sample thicknesses on the microhardness of a composite resin. Composite resin specimens were randomly prepared and assigned to nine experimental groups (n = 5): considering three light-curing units (conventional quartz tungsten halogen [QTH]: 550 mW/cm(2) - 20 s; high irradiance QTH: 1160 mW/cm(2) - 10 s; and light- emitting diode [LED]: 360 mW/cm(2) - 40 s) and three sample thicknesses (0.5 mm, 1 mm, and 2 mm). All samples were polymerized with the light tip 8 mm away from the specimen. Knoop microhardness was then measured on the top and bottom surfaces of each sample. The top surfaces, with some exceptions, were almost similar; however, in relation to the bottom surfaces, statistical differences were found between curing units and thicknesses. In all experimental groups, the 0.5-mm-thick increments showed microhardness values statistically higher than those observed for 1-and - 2-mm increments. The conventional and LED units showed higher hardness mean values and were statistically different from the high irradiance unit. In all experimental groups, microhardness mean values obtained for the top surface were higher than those observed for the bottom surface. In conclusion, higher levels of irradiance or thinner increments would help improve hybrid composite resin polymerization.