J Korean Acad Conserv Dent.  2003 Jul;28(4):354-359. 10.5395/JKACD.2003.28.4.354.

The amounts and speed of polymerization shrinkage and microhardness in LED cured composites

Affiliations
  • 1Department of Conservative Dentistry, Yonsei University, Korea. sunghopark@yumc.yonsei.ac.kr
  • 2College of Dentistry, Yonsei University, Korea.

Abstract

This study evaluated the effectiveness of the light emitting diode(LED) units for composite curing. To compare its effectiveness with conventional quartz tungsten halogen (QTH) light curing unit, the microhardness of 2mm composite, Z250, which had been light cured by the LEDs (Ultralume LED2, FreeLight, Developing product D1) or QTH (XL 3000) were compared on the upper and lower surface. One way ANOVA with Tukey and Paired t-test was used at 95% levels of confidence. In addition, the amount of linear polymerization shrinkage was compared between composites which were light cured by QTH or LEDs using a custom-made linometer in 10s and 60s of light curing, and the amount of linear polymerization shrinkage was compared by one way ANOVA with Tukey. The amount of polymerization shrinkage at 10s was XL3000 > Ultralume 2, 40, 60> FreeLight, D1 (P<0.05) The amount of polymerization shrinkage at 60s was XL3000 > Ultralume 2, 60> Ultralume 2,40> FreeLight, D1 (P<0.05) It was concluded that the LEDs produced lower polymerization shrinkage in 10s and 60s compared with QTH unit. In addition, the microhardness of samples which had been cured with LEDs was lower on the lower surfaces than the upper surfaces whereas there was no difference in QTH cured samples.

Keyword

LED; Microhardenss; Polymerization shrinkage; Composites; QTH

MeSH Terms

Polymerization*
Polymers*
Quartz
Tungsten
Polymers
Quartz
Tungsten
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