Hardness evaluation of a dental composite polymerized with experimental LED-based devices

Kurachi, Cristina; Tuboy, A M; Magalhães, Daniel Varela; Bagnato, Vanderlei Salvador

doi:10.1016/s0109-5641(00)00088-9

Cited by 165 publications

(166 citation statements)

References 9 publications

Supporting

Mentioning

126

Contrasting

Unclassified

Order By: Relevance

“…Other technologies, such as lightemitting-diodes (LEDs) are also available. LED is formed by junctions of doped semiconductors (p-n junctions) to generate light and, hence, require no filters to produce blue light with narrower spectral (440-490 nm) falls within the camphoroquinone absorption spectrum (468 nm) (14).…”

Section: Introductionmentioning

confidence: 99%

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness

et al. 2009

View full text Add to dashboard Cite

The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm 2 , respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (a=0.05). The QTH LCU provided significantly higher (p<0.05) KHN values than the LED LCU. When the post-cure times were compared for the same shade, QTH and LED at 24 h provided significantly higher (p<0.05) KHN values than at 15 min. It may be concluded that the Knoop hardness was generally dependent on the LCU and post-cure time. The opaque shade of the resin cement showed lower Knoop hardness than the other shades for both LCUs and post-cure times.

show abstract

Section: Introductionmentioning

confidence: 99%

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness

et al. 2009

View full text Add to dashboard Cite

show abstract

“…However, this type of equipment still emits a considerable amount of other wavelengths. The spectral impurities of the conventional LCUs deliver several wavelengths that are highly absorbed by dental materials, inducing heating to tooth and resin during the curing process 2 . Moreover, halogen bulbs (whose effective lifetime is limited from about 40 to 100 hours), reflectors and filters degrade over time due to high operating temperatures and to the intense heat produced during curing cycles 3 .…”

Section: Introductionmentioning

confidence: 99%

“…Their relatively low power consumption makes them suitable for portable use. The narrower spectral output of these blue LEDs of 440 to 490 nm falls within the camphoroquinone (CQ) absorption spectrum 2 . Long curing time is inconvenient for the patient, impractical with children, uncomfortable for the dentist, and makes the treatment more expensive because of extra time in the dentist's chair.…”

Section: Introductionmentioning

confidence: 99%

Effect of exposure time vs. irradiance on knoop hardness of dental composites

et al. 2006

View full text Add to dashboard Cite

A comparison was made of the hardness of Z250 and Esthet-X composites light cured with different light sources. Cavities (3 mm diameter x 6 mm deep) were prepared in 240 bovine incisors. The composite was bulk inserted and light-cured using halogen light, LED or xenon plasma arc (PAC) with different irradiances and exposure times, maintaining the same energy density. The specimens were stored in an incubator at 37 °C for 24 hours prior to sectioning for hardness measurements. Three measurements were taken at each depth: surface, 1, 2, 3, 4 and 5 mm. The data were analyzed by ANOVA and Tukey's test (p < 0.05). No statistically significant differences were found for LED up to 2 mm, for PAC up to 3 mm, and for halogen light up to 5 mm. Photoactivation with intermediate power density and exposure time resulted in the highest Knoop hardness values.

show abstract

“…The specificity of the light emitted by LED is advantageous for polymerizing composites activated by the amine/camphoroquinone system. The use of filter to limit the width of the wavelength is not mandatory for LED, although they induce lower heating to tooth during light-curing (2). Current LED units promote considerable heating during the light activations of materials (3).…”

Section: Introductionmentioning

confidence: 99%

Effect of the increase of energy density on knoop hardness of dental composites light-cured by conventional QTH, LED and xenon plasma arc

et al. 2005

View full text Add to dashboard Cite

The aim of this study was to evaluate the effect of the increase of energy density on Knoop hardness of Z250 and Esthet-X composite resins. Cylindrical cavities (3 mm in diameter X 3 mm in depth) were prepared on the buccal surface of 144 bovine incisors. The composite resins were bulk-inserted and polymerized using different light-curing units and times: conventional QTH (quartz-tungstenhalogen; 700 mW/cm 2 ; 20 s, 30 s and 40 s); LED (light-emitting diode; 440 mW/cm 2 ; 20 s, 30 s and 40 s); PAC (xenon plasma arc; 1700 mW/cm 2 ; 3 s, 4.5 s and 6 s). The specimens were stored at 37°C for 24 h prior to sectioning for Knoop hardness assessment. Three measurements were obtained for each depth: top surface, 1 mm and 2 mm. Data were analyzed statistically by ANOVA and Tukey's test (p<0.05). Regardless of the light source or energy density, Knoop hardness of Z250 was statistically significant higher than that of Esthet-X (p<0.05). Specimens cured with PAC had lower hardness than those cured with QTH and LED (p<0.05). Higher Knoop hardness was obtained when the energy density was increased for LED and PAC (p<0.05). No statistically significant differences (p>0.05) were found for QTH. Knoop hardness values decreased with the increase of depth. The increase of energy density produced composites with higher Knoop hardness means using LED and PAC.

show abstract

Hardness evaluation of a dental composite polymerized with experimental LED-based devices

Cited by 165 publications

References 9 publications

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness

Effect of exposure time vs. irradiance on knoop hardness of dental composites

Effect of the increase of energy density on knoop hardness of dental composites light-cured by conventional QTH, LED and xenon plasma arc

Contact Info

Product

Resources

About