Briso André Luiz Fraga, Fedel Tânia Maria, Pereira Sibéria de Morais, Mauro Sílvio José, Sundfeld Renato Herman, Sundefeld Maria Lúcia Marçal Mazza
Department of Restorative Dentistry of Araçatuba Dental School - State University of São Paulo Paulo-UNESP - Araçatuba, São Paulo, Brazil.
J Appl Oral Sci. 2006 Jan;14(1):10-5. doi: 10.1590/s1678-77572006000100003.
The evolution of light curing units can be noticed by the different systems recently introduced. The technology of LED units promises longer lifetime, without heating and with production of specific light for activation of camphorquinone. However, further studies are still required to check the real curing effectiveness of these units.
This study evaluated the microhardness of 4 shades (B-0.5, B-1, B-2 and B-3) of composite resin Filtek Z-250 (3M ESPE) after light curing with 4 light sources, being one halogen (Ultralux - Dabi Atlante) and three LED (Ultraled - Dabi Atlante, Ultrablue - DMC and Elipar Freelight - 3M ESPE).
192 specimens were distributed into 16 groups, and materials were inserted in a single increment in cylindrical templates measuring 4mm x 4mm and light cured as recommended by the manufacturer. Then, they were submitted to microhardness test on the top and bottom aspects of the cylinders.
The hardness values achieved were submitted to analysis of variance and to Tukey test at 5% confidence level. It was observed that microhardness of specimens varied according to the shade of the material and light sources employed. The LED appliance emitting greater light intensity provided the highest hardness values with shade B-0.5, allowing the best curing. On the other hand, appliances with low light intensity were the least effective. It was also observed that the bottom of specimens was more sensitive to changes in shade.
Light intensity of LED light curing units is fundamental for their good functioning, especially when applied in resins with darker shades.
光固化机的发展可以从最近推出的不同系统中看出。LED光固化机技术有望延长使用寿命，无发热现象，并能产生用于激活樟脑醌的特定光。然而，仍需要进一步研究来检验这些光固化机的实际固化效果。
本研究评估了复合树脂Filtek Z - 250（3M ESPE）的4种色号（B - 0.5、B - 1、B - 2和B - 3）在用4种光源进行光固化后的显微硬度，其中一种是卤素灯（Ultralux - Dabi Atlante），三种是LED灯（Ultraled - Dabi Atlante、Ultrablue - DMC和Elipar Freelight - 3M ESPE）。
192个样本被分为16组，材料以单次增量填入尺寸为4mm×4mm的圆柱形模板中，并按照制造商的建议进行光固化。然后，对圆柱体的顶部和底部进行显微硬度测试。
所获得的硬度值进行方差分析，并在5%置信水平下进行Tukey检验。观察到样本的显微硬度根据材料的色号和所使用的光源而变化。发射更高光强度的LED设备在B - 0.5色号下提供了最高的硬度值，实现了最佳固化效果。另一方面，光强度低的设备效果最差。还观察到样本底部对色号变化更敏感。
LED光固化机的光强度对其良好运行至关重要，特别是当应用于深色树脂时。
