Restorative Dentistry & Endodontics

Power density of light curing units through resin inlays fabricated with direct and indirect composites: Hoon-Sang Chang, Young-Jun Lim, Jeong-Mi Kim, Sung-Ok Hong; J Korean Acad Conserv Dent 2010;35(5):353-358. Published online September 30, 2010; DOI: https://doi.org/10.5395/JKACD.2010.35.5.353

Abstract PDF PubReader ePub: Objectives
The purpose of this study was to measure the power density of light curing units transmitted through resin inlays fabricated with direct composite (Filtek Z350, Filtek Supreme XT) and indirect composite (Sinfony).
Materials and Methods
A3 shade of Z350, A3B and A3E shades of Supreme XT, and A3, E3, and T1 shades of Sinfony were used to fabricate the resin inlays in 1.5 mm thickness. The power density of a halogen light curing unit (Optilux 360) and an LED light curing unit (Elipar S10) through the fabricated resin inlays was measured with a hand held dental radiometer (Cure Rite). To investigate the effect of each composite layer consisting the resin inlays on light transmission, resin specimens of each shade were fabricated in 0.5 mm thickness and power density was measured through the resin specimens.
Results
The power density through the resin inlays was lowest with the Z350 A3, followed by Supreme XT A3B and A3E. The power density was highest with Sinfony A3, E3, and T1 (p < 0.05). The power density through 0.5 mm thick resin specimens was lowest with dentin shades, Sinfony A3, Z350 A3, Supreme XT A3B, followed by enamel shades, Supreme XT A3E and Sinfony E3. The power density was highest with translucent shade, Sinfony T1 (p < 0.05).
Conclusions
Using indirect lab composites with dentin, enamel, and translucent shades rather than direct composites with one or two shades could be advantageous in transmitting curing lights through resin inlays.

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Dentin bond strength of bonding agents cured with Light Emitting Diode: Sun-Young Kim, In-Bog Lee, Byeong-Hoon Cho, Ho-Hyun Son, Mi-Ja Kim, Chang-In Seok, Chung-Moon Um; J Korean Acad Conserv Dent 2004;29(6):504-514. Published online January 14, 2004; DOI: https://doi.org/10.5395/JKACD.2004.29.6.504

ABSTRACT

This study compared the dentin shear bond strengths of currently used dentin bonding agents that were irradiated with an LED (Elipar FreeLight, 3M-ESPE) and a halogen light (VIP, BISCO). The optical characteristics of two light curing units were evaluated. Extracted human third molars were prepared to expose the occlusal dentin and the bonding procedures were performed under the irradiation with each light curing unit. The dentin bonding agents used in this study were Scotchbond Multipurpose (3M ESPE), Single Bond (3M ESPE), One-Step (Bisco), Clearfil SE bond (Kuraray), and Adper Prompt (3M ESPE). The shear test was performed by employing the design of a chisel-on-iris supported with a Teflon wall. The fractured dentin surface was observed with SEM to determine the failure mode.

The spectral appearance of the LED light curing unit was different from that of the halogen light curing unit in terms of maximum peak and distribution. The LED LCU (maximum peak in 465 ㎚) shows a narrower spectral distribution than the halogen LCU (maximum peak in 487 ㎚). With the exception of the Clearfil SE bond (P < 0.05), each 4 dentin bonding agents showed no significant difference between the halogen light-cured group and the LED light-cured group in the mean shear bond strength (P > 0.05).

The results can be explained by the strong correlation between the absorption spectrum of cam-phoroquinone and the narrow emission spectrum of LED.

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Polymerization ability of several light curing sources on composite resin: Hye-Jin Shin, Jin-Woo Kim, Kyung-Mo Cho; J Korean Acad Conserv Dent 2003;28(2):156-161. Published online March 31, 2003; DOI: https://doi.org/10.5395/JKACD.2003.28.2.156

Abstract PDF PubReader ePub

The purpose of this study is to evaluate the polymerization ability of three different light sources by microhardness test. Stainless steel molds of 1, 2, 3, 4 and 5 mm in thickness of 7 mm in diameter were prepared. The hybrid composite Z100 was packed into the hole of the mold and curing light was activated for designated time. Three different light sources, conventional halogen, light emitting diode, and plasma arc, were used for curing of composite. Two different curing times applied; one is to follow the manufacturer's recommendation and the other is to extend the curing time of LED and plasma arc for balancing the light energy with halogen. Immediately after curing, the Vickers hardness was measured at the bottom of specimen.

The results were as follows.

The composite cured with LED showed equal to higher microhardnesss than halogen.

The composite was cured with plasma arc by manufacturer's recommendation showed lowest microhardness at all thickness. However, when curing time was extended, microhardness was higher than the others.

In conclusion, this study suggested that plasma arc needs properly extended curing time.

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