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

Correr, Américo Bortolazzo; Sinhoreti, Mário Alexandre Coelho; Sobrinho, Lourenço Correr; Tango, Rubens Nisie; Schneider, Luís Felipe Jochims; Consani, Símonídes

doi:10.1590/s0103-64402005000300009

Cited by 57 publications

(45 citation statements)

References 17 publications

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“…Bonded all-ceramic restorations are popular with clinicians and patients because of their superior esthetics: notably the diffuse transmission combined with diffuse and spectral reflectance of light that mimics the depth of translucency and color of natural teeth (15). However, clinical success with these restorations requires that they are bonded to teeth with high-strength, low solubility, and thin-film adhesives commonly light polymerized resin luting agents (8).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2009

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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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2009

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“…Failures with light-cured composite resins have been attributed to moisture contamination or incomplete polymerization when considering the light exposure time or limited depth polymerization (4), which varies with the light penetration into the material (5). This reduction in polymerization has been called depth of cure and has significant influence on physical (5) and biological properties of composite resins.…”

Section: Introductionmentioning

confidence: 99%

Effect of Activation Mode on Shear Bond Strength of Metallic Brackets

Correr

Costa

Lucato³

et al. 2013

Braz. Dent. J.

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The aim of this study was to evaluate the shear bond strength (SBS) of metallic orthodontic brackets bonded to bovine teeth using light-activated or chemically activated composite resins. One hundred and twenty bovine mandibular incisors were divided into 6 groups (n=20), according to the bonding materials: Transbond XT (T); Enforce Dual (ED); Enforce chemical (EC); Enforce Light-activated (EL); Concise Orthodontic (C); and RelyX Unicem Capsule (UN). Metallic brackets were positioned and firmly bonded to the teeth. Lightactivation for T, ED, EL and UN was carried out with four exposures on each side of the bracket with 20 s total exposure times using XL2500 (3M ESPE). EC and C were chemically cured. Next, all specimens were stored in deionized water at 37 °C for 24 h. The shear bond strength was carried out at a crosshead speed of 1.0 mm/min. Data were subjected to one-way ANOVA and Tukey's test (α=0.05). The adhesive remnant index (ARI) was evaluated at 8× magnification. C (17.72±4.45) presented significantly higher SBS means (in MPa) than the other groups (p<0.05), followed by EC (11.97±5.77) and ED (10.57±1.32). EL (5.39±1.06) and UN (4.32±1.98) showed the lowest SBS means, while T (9.09±2.56) showed intermediate values. For ARI, there was a predominance of score 0 for EC, C and UN, and score 3 for T, ED and EL. In conclusion, the activation mode influenced the SBS.

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“…Photo-activated resin agents are usually used for this purpose (6,7). Several lightcuring units (LCUs) presenting varied light sources are available for photo-activation (8)(9)(10)(11)(12)(13)(14). In addition to the traditional quartz-tungsten-halogen (QTH) LCUs and the increasingly popular light-emitting diodes (LEDs), plasma arc (PAC) and laser units have been introduced to reduce the curing time.…”

Section: Introductionmentioning

confidence: 99%

Effect of etching time and light source on the bond strength of metallic brackets to ceramic

et al. 2011

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This study evaluated the bond strength of brackets to ceramic testing different etching times and light sources for photo-activation of the bonding agent. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. After application of silane on the ceramic surface, metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek). The specimens for each etching time were assigned to 4 groups (n=15), according to the light source: XL2500 halogen light, UltraLume 5 LED, AccuCure 3000 argon laser, and Apollo 95E plasma arc. Light-activation was carried out with total exposure times of 40, 40, 20 and 12 s, respectively. Shear strength testing was carried out after 24 h. The adhesive remnant index (ARI) was evaluated under magnification. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Specimens etched for 20 s presented significantly lower bond strength (p<0.05) compared with those etched for 60 s. No significant differences (p>0.05) were detected among the light sources. The ARI showed a predominance of scores 0 in all groups, with an increase in scores 1, 2 and 3 for the 60 s time. In conclusion, only the etching time had significant influence on the bond strength of brackets to ceramic.

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

Cited by 57 publications

References 17 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 Activation Mode on Shear Bond Strength of Metallic Brackets

Effect of etching time and light source on the bond strength of metallic brackets to ceramic

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