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

Sung-Ho Park; Su-Sun Kim; Yong-Sik Cho; Soon-Young Lee; Do-Hyun Kim; Yong-Joo Jang; Hyun-Sung Mun; Jung-Won Seo; Byung-Duk Noh

doi:10.5395/JKACD.2003.28.4.354

Journal List > J Korean Acad Conserv Dent > v.28(4) > 1056068

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Park, Kim, Cho, Lee, Kim, Jang, Mun, Seo, and Noh: The amounts and speed of polymerization shrinkage and microhardness in LED cured composites

Original Article

Journal of Korean Academy of Conservative Dentistry

Journal of Korean Academy of Conservative Dentistry 2003; 28(4): 354-359.

Published online: 31 July 2003

DOI: https://doi.org/10.5395/JKACD.2003.28.4.354

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

Sung-Ho Park, Su-Sun Kim, Yong-Sik Cho, Soon-Young Lee, Do-Hyun Kim^#, Yong-Joo Jang^#, Hyun-Sung Mun^#, Jung-Won Seo^#, Byung-Duk Noh

Department of Conservative Dentistry, Yonsei University, Korea.

^#College of Dentistry, Yonsei University, Korea.

Corresponding author (sunghopark@yumc.yonsei.ac.kr)

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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)

The microhardness on the upper and lower surface was as follows;

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.

Keywords: LED, Microhardenss, Polymerization shrinkage, Composites, QTH

Figures and Tables

Fig. 1

Schematic diagram of custome made linometer with sample in place.

Fig. 2

Change in the amount of linear polymerization shrinkage versus time in Z250 that was light cured with LEDs or QTH

Table 1

Curing light used in the present study

Table 2

Amount of linear polymerization shrinkage at 10s and 60s of light curing (um)

Table 3

Microhardnesses of upper & lower surfaces of samples

^*indicates different microhardness between upper and lower surface in the paired- t test at 95% levels of confidence Different letters indicate different microhardness on the upper or lower surface at the 95% levels of confidence

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