• Tribology and Lubricants
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• v.21 no.6
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• pp.268-271
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• 2005

In this study, the wear characteristics of five different dental composite resins cured by conventional halogen light and LED light sources were investigated. Five different dental composite resins of Surefil, Z100, Dyract AP, Fuji II LC and Compoglass were worn against a zirconia ceramic ball using a pin-on-disk type wear tester with 15N contact force in a reciprocal sliding motion of sliding distance of 10mm/cycle at 1Hz under the room temperature dry condition. The wear variations of dental composite resins were linearly increased as the number of cycles increased. It was observed that the wear resistances of these specimens were in the order of Dyract AP > Surefil > Compoglass > Z100 > Fuji II LC. On the morphological observations by SEM, the large crack formation on the sliding track of Fuji II LC specimen was the greatest among all resin composites. Dyract AP showed less wear with few surface damage. There is no significant difference in wear performance between conventional halogen light curing and light emitting diodes curing sources. It indicates that a light emitting diodes (LED) source can replace a halogen light source as curing unit for composite resin restorations.

• Proceedings of the KACD Conference
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• 2003.11a
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• pp.565-566
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• 2003

The clinical performance of light polymerized composite resins is greatly influenced by the quality of the light curing unit used. Commonly used halogen light curing units(LCUs) have some specific drawbacks such as decreasing light output with time. To overcome this, the blue LED LCUs are newly developed and introduced. The purpose of this study was to observe the reaction kinetics and the degree of polymerization of composite resins when cured by different light sources and to evaluate the effectiveness of the blue LED LCUs compared with conventional halogen LCUs.(omitted)

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.604-610
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• 2005

This study was to evaluate the effects of several light curing units on the microleakage of composite resin restorations in primary teeth. The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Filpo) low heat plasma arc light(Aurys) and high intensity LED(Freelight 2). After preparing cavities on sound primary teeth, cavities were filled with composite resin(Z100) using the same resin bond agent(Scotchbond Multi-Purpose) and were cured with each curing light system. After storing each specimen in sterile water for 24 hours, thermal circulation was done 1,000 times followed by pigmentation using 2% methylene blue solution. Each specimen was sliced and the degree of pigmentation was graded. When microleakage is graded, the average of Aurys was 0.95 which was the lowest and Freelight 2(1.05), Filpo(1.25), Optilux 360(1.30) followed. But values were not shown statistically significant difference (P>0.05). The results suggest that the newly developed curing units which has advantage in children by decreasing discomfort and procedure time can increase the microleakage of the composite resin.

• Restorative Dentistry and Endodontics
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• v.29 no.4
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• pp.386-398
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• 2004

Objectives: The purpose of this study was to observe the reaction kinetics and the degree of polymerization of composite resins when cured by different light sources and to evaluate the effectiveness of the blue Light Emitting Diode Light Curing Units (LED LCUs) compared with conventional halogen LCUs. Materials and Methods: First, thermal analysis was performed by a differential scanning calorimeter (DSC). The LED LCU (Elipar Freelight, $320{\;}mW/\textrm{cm}^2$) and the conventional halogen LCU (XL3000, $400{\;}mV/\textrm{cm}^2$) were used in this study for curing three composite resins (SureFil, Z-250 and AEliteFLO). Second. the degree of conversion was obtained in the composite resins cured according to the above curing mode with a FTIR. Third, the measurements of depth of cure were carried out in accordance with ISO 4049 standards. Statistical analysis was performed by two-way ANOVA test at 95% levels of confidence and Duncan's procedure for multiple comparisons. Results: The heat of cure was not statistically different among the LCUs (p > 0.05). The composites cured by the LED (Exp) LCUs were statistically more slowly polymerized than by the halogen LCU and the LED (Std) LCU (p < 0.05). The composite resin groups cured by the LED (Exp) LCUs had significantly greater degree of conversion value than by the halogen LCU and the LED (Std) LCU (p =0.0002). The composite resin groups cured by the LED (Std) LCUs showed significantly greater depth of cure value than by the halogen LCU and the LED (Exp) LCU (p < 0.05).

• Restorative Dentistry and Endodontics
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• v.39 no.3
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• pp.155-163
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• 2014

Objectives: Light-curing of resin-based materials (RBMs) increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs) of three different RBMs using quartz tungsten halogen (QTH) and light-emitting diode (LED) units (LCUs). Materials and Methods: Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12) during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey), a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE), and a giomer (Beautifil II, Shofu GmbH), was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. Results: The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p < 0.05). Filtek P90 induced higher temperature rise during polymerization than Ceram.X and Beautifil II under demineralized dentin (p < 0.05). The temperature rise under demineralized dentin during Filtek P90 polymerization exceeded the threshold value ($5.5^{\circ}C$), with no significant differences between the DCs of the test materials (p > 0.05). Conclusions: Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

• Restorative Dentistry and Endodontics
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• v.28 no.4
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• pp.354-359
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• 2003

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 Dl) 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 ; (equation omitted) 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.

• Restorative Dentistry and Endodontics
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• v.29 no.6
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• pp.504-514
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• 2004

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 nm) shows a narrower spectral distribution than the halogen LCU (maximum peak in 487 nm). 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 camphoroquinone and the narrow emission spectrum of LED.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.391-399
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• 2004

The purpose of this study was to compare curing efficiency of newly developed curing units to traditional halogen curing unit by measuring thermal change and surface microhardness according to curing light system. Materials and mathods : The types of curing units were traditional low intensity halogen light(Optilux 360), plasma arc light(Flipo), low heat plasma arc light(Aurys), low intensity LED(Starlight), and high intensity LED(Freelight2). Temperature at the tip of light guide was measured by a digital thermometer using K-type thermocouple. And after resin was filled to 2, 3, 4mm teflon mold, bottom temperature measured during curing. After 24 hours, microhardness of top surface and bottom surface of each resin specimen were measured. Results : The result of this study can be summarized as follows, 1. As measuring temperature of curing unit tips, Flipo is the highest as $52.4^{\circ}C,\;Freelight2(37.86^{\circ}C),\;Optilux360(32.68^{\circ}C),\;Aurys(32.34^{\circ}C),\;and\;Starlight(26.14^{\circ}C)$ were followed. 2. Flipo and Freelight2 were the highest similarly and Optilux360 and Aurys were similarly next and Starlight was lowest in temperature of bottom surface of resin mold. 3. Microhardness of top surface were generally similar, and Aurys was relatively low. 4. Optilux 360 and Freelight2 were the highest, and Flipo, Starlight, and Aurys were followed in microhardness of bottom surface. Conclusions : The results suggest that careful use of Flipo and Freelight2 might be able to cure greater depth of resin composite and do not cause thermal problems than other curing units.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.2
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• pp.152-156
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• 2014

The purpose of this study is to compare efficiency of broad spectrum LEDs ($VALO^{(R)}$, Ultradent, USA) with conventional LED curing lights ($Elipar^{TM}$ Freelight 2, 3M ESPE, USA) using a microhardness test. The light curing units used were $VALO^{(R)}$ in three different modes and $Elipar^{TM}$ Freelight 2. The exposure time was used according to the manufacturer's instructions. After cured resin specimens were stored in physiological saline at $37^{\circ}C$ for 24 hours, microhardness was measured using Vickers microhardness tester. The microhardness of upper and lower sides of the specimens were analyzed separately by the ANOVA method (Analysis of Variance) with a significance level set at 5%. At upper side of resin specimens, an increased microhardness was observed in the broad spectrum LED curing light unit with a high power mode for 4 seconds and plasma emulation mode for 20 seconds (p < 0.05). However, at the lower side of resin specimens, there were no significant differences in microhardness between broad spectrum LED curing light unit and conventional LED curing light unit.

• The Journal of Advanced Prosthodontics
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• v.3 no.3
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• pp.126-131
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• 2011

PURPOSE. The aim of this in vitro study was to examine the curing efficiency of various resin-based materials polymerized through ceramic restorations with 3 different thicknesses. Curing efficiency was evaluated by determining the surface microhardness (VHN) of the resin specimens. MATERIALS AND METHODS. Four kinds of resin materials were used. Z350 (3M ESPE $Filtek^{TM}$ Z350: A2 Shade), Z250 (3M ESPE $Filtek^{TM}$ Z250: A2 Shade) and $Variolink^{(R)}$ II (VL: Ivoclar vivadent, base: transparent) either with or without a self-curing catalyst (VLC: Ivoclar vivadent, catalyst: low viscosity/transparent) were filled into the silicone mold (10 mm diameter, 1 mm thick). They were cured through ceramic discs (IPS e.max Press MO-0 ingot ivoclar vivadent, 10 mm diameter, 0.5, 1 and 2 mm thicknesses) by LED light-curing units for 20 and 40 seconds. Vicker's microhardness numbers (VHNs) were measured on the bottom surfaces by a microhardness tester. Data were analyzed using a 3-way analysis of variance (ANOVA) at a significance level of 0.05. RESULTS. The thickness of ceramic disc increased, the VHNs of all four resin types were decreased (P<.05). The mean VHN values of the resins light cured for 40 seconds were significantly higher than that of LED for 20 seconds in all four resin materials (P<.05). VLC showed significantly higher VHN values than VL regardless of other conditions (P<.05). Z350 and Z250 showed higher values than VL or VLC (P<.01). CONCLUSION. Thinner ceramic disc with increased curing time resulted higher VHN values of all resin materials. The use of a catalyst produced a greater hardness with all polymerization methods. Restorative resin materials (Z350, Z250) showed higher VHN values than resin cement materials (VL, VLC).