Effect Of Preheating On Surface Roughness And Microhardness Of A Nanohybrid Composite Resin - An In Vitro Study

Introduction: The success of dental composites in restorative dentistry stems from their good aesthetic properties andadequate durability. The clinical performance of composite resins is directly related to the degree of monomer conversion afterphoto polymerization. Placing composites at an elevated temperature reduce their viscosity and increase the efficiency ofpolymerization. Heating the composite prior to placement in the cavity increases monomer conversion rate and therefore theduration of the irradiation period may be reduced.Purpose of Study: Evaluate and compare effect of pre-heating on surface roughness and microhardness of nanohybrid compositeresin subjected to two different temperatures and two different durations using light emitting diode curing unit (LED LCU).Methods: Nanohybrid composite resin was tested at two temperatures (37°C and 55°C) and pre-heating of composite wasdone using incubator at two durations (10 and 20 minutes) respectively. Samples were injected into cylindrical Teflon molds andthe top surface of the specimens were polymerized using LED LCU for 40 s. After preservation for 24 h, specimens checkedfor surface roughness and Vickers hardness measurements. Statistical analysis were performed using one-way analysis ofvariance and Tukey post hoc test at a level of significance of P < 0.05 for both surface roughness and microhardness.Results: Pre-heating of composite affect on microhardness and did not influence on surface roughness.Conclusion: Pre-heating of resin composite increases microhardness and no significant effect on roughness.

An Evaluation of the Light Output from 22 Contemporary Light Curing Units

Abstract This study measured the radiant power (mW), irradiance (mW/cm2) and emission spectra (mW/cm2/nm) of 22 new, or almost new, light curing units (LCUs): - Alt Lux II, BioLux Standard, Bluephase G2, Curing Light XL 3000, Demetron LC, DX Turbo LED 1200, EC450, EC500, Emitter C, Emitter D, KON-LUX, LED 3M ESPE, Led Lux II, Optilight Color, Optilight Max, Optilux 501, Poly Wireless, Radii cal, Radii plus, TL-01, VALO Cordless. These LCUs were either monowave or multiple peak light emitting diode (LED) units or quartz-tungsten-halogen LCUs used in anterior and posterior teeth. The radiant power emitted by the LCUs was measured by a laboratory grade laser power meter. The tip area (cm²) of the LCUs was measured and used to calculate the irradiance from the measured radiant power source. The MARC-Patient Simulator (MARC-PS) with a laboratory grade spectrometer (USB4000, Ocean Optics) was used to measure the irradiance and emission spectrum from each LCU three times at the sensor located on the facial of the maxillary central incisors and then separately at the occlusal of a maxillary second molar. The minimum acceptable irradiance level was set as 500 mW/cm2. Irradiance data was analyzed using two-way ANOVA and the radiant power data was analyzed by one-way ANOVA followed by Tukey test (a=0.05). In general, the irradiance was reduced at the molar tooth for most LCUs. Only the Valo, Bluephase G2 and Radii Plus delivered an irradiance similar to the anterior and posterior sensors greater than 500 mW/cm2. KON-LUX, Altlux II, Biolux Standard, TL-01, Optilux 501, DX Turbo LED 1200 LCUs delivered lower irradiance values than the recommended one used in molar region, KON-LUX and Altlux II LCUs used at the maxillary incisors. Bluephase G2 and Optilight Max delivered the highest radiant power and KON-LUX, Altlux II and Biolux Standard delivered the lowest power. The emission spectrum from the various monowave LED LCUs varied greatly. The multi-peak LCUs delivered similar emission spectra to both sensors.

Resumo Este estudo mediu a potência (mW), irradiância (mW/cm2) e espectro da luz (mW/cm2/nm) emitida por 22 fontes de luz (Alt Lux II, BioLux Standard, Bluephase G2, Curing Light XL 3000, Demetron LC, DX Turbo LED 1200, EC450, EC500, Emitter C, Emitter D, KON-LUX, LED 3M ESPE, Led Lux II, Optilight Color, Optilight Max, Optilux 501, Poly Wireless, Radii cal, Radii plus, TL-01, VALO Cordless) disponíveis comercialmente. A potência emitida pelas fontes de luz foi medida usando um medidor laboratorial de potencia com grade a laser. A área (cm²) da ponta ativa efetiva das fontes de luz foi medida com paquímetro digital e utilizada para calcular a irradiância emitida. O simulador de paciente-MARC (MARC - PS) com espectrómetro (USB4000, Ocean Optics) foi usado para medir a irradiância e o espectro de luz emitida por cada fonte de luz na região anterior e posterior. Esta medição foi repetida por três vezes em dois sensores localizados na região anterior e posterior da arcada dentária. Os dados de irradiância foram analisados utilizando análise de variância em dois fatores, e os dados de potência foram analisados com análise de variância em fator único seguido pelo teste de Tukey (a=0,05). As fontes de luz Valo, Bluephase G2, Radii Plus emitiram irradiância semelhante tanto na região anterior como posterior com valores superiores ao mínimo de 500 mW/cm2. Seis fontes de luz emitiram irradiância menor que o recomendado (500 mW/cm2) quando usadas na região posterior: Kon-lux, Altlux II, Biolux Standard TL-01, Optilux 501, DX Turbo LED 1200 e duas quando usadas na região anterior: Kon-lux e Altlux II LCUs. As fontes Bluephase G2, Optilight Max emitiram os maiores valores de potência e as fontes de luz Altlux II e Biolux Standard emitiram os menores valores de potência. O espectro de luz das fontes LED de espectro único variou de forma evidente entre as fontes. As fontes LED multi pico de espectro emitiram espectros de luz similar para ambos os sensores. A fotoativação na região posterior tende a reduzir substancialmente a irradiância da maioria das fontes de luzes testadas.

Evaluation of Eye Protection Filters Used with Broad-Spectrum and Conventional LED Curing Lights

Abstract The high irradiance and the different emission spectra from contemporary light curing units (LCU) may cause ocular damage. This study evaluated the ability of 15 eye protection filters: 2 glasses, 1 paddle design, and 12 dedicated filters to block out harmful light from a monowave (HP-3M ESPE) and a broad-spectrum (Valo, Ultradent) LED LCU. Using the anterior sensor in the MARC-Patient Simulator (BlueLight Analytics) the irradiance that was delivered through different eye protection filters was measured three times. The LCUs delivered a similar irradiance to the top of the filter. The mean values of the light that passed through the filters as percent of the original irradiance were analyzed using two-way ANOVA followed by Tukey test (a= 0.05). The emission spectra from the LCUs and through the filters were also obtained. Two-way ANOVA showed that the interaction between protective filters and LCUs significantly influenced the amount of light transmitted (p< 0.001). Tukey test showed that the amount of light transmitted through the protective filters when using the HP-3M-ESPE was significantly greater compared to when using the Valo, irrespective of the protective filter tested. When using the HP-3M-ESPE, the Glasses filter allowed significantly more light through, followed by XL 3000, ORTUS, Google Professional, Gnatus filters. The Valo filter was the most effective at blocking out the harmful light. Some protective filters were less effective at blocking the lower wavelengths of light (<420 nm). However, even in the worst scenario, the filters were able to block at least 97% of the irradiance.

Resumo A alta irradiância e diferentes espectros de luz emitidos por aparelhos fotopolimerizadores (Fp) podem causar danos oculares. Este estudo avaliou a capacidade de 15 filtros de proteção ocular em bloquear a luz prejudicial de um Fp convencional (HP-3M ESPE) e outro de largo espectro (Valo, Ultradent). Utilizando sensor anterior do equioamento MARC-Patient Simulator (BlueLight Analytics inc.) a irradiância que passou através dos diferentes filtros protetores foi mensuradas três vezes. Os valores médios da irradiância que passaram pelos filtros foram analisados usando Análise de variância fatorial e pelo teste de Tukey (a= 0.05). O espetro emitido dos Fps através dos filtros também foi obtido. A análise de variância mostrou que a interação entre os filtros protetores e Fps influenciou significantemente a quantidade de luz transmitida (p<0,001). O teste de Tukey mostrou que a quantidade que luz transmitida através dos protetores oculares quando usado o HP-3M ESPE foi significantemente maior quando comparado aos valores para o Valo, independentemente do filtro testado. Quando foi utilizado a fonte de luz HP-3M ESPE, o filtro de proteção ocular permitiu significativamente maior passagem de luz, seguido por XL 3000, ORTUS, Google Professional, e pelo filtro Gnatus. O filtro do Valo foi o mais eficiente ao bloquear a luz prejudicial. Alguns filtros foram menos eficazes ao bloquear menores comprimentos de onde (<420 nm). No entanto, mesmo no pior cenário dos resultados deste estudo, os filtros foram capazes de bloquear ao menos 97% da irradiância emitida pelas fontes de luz testadas.

Aumento de la temperatura en la superficie dental durante la foto-polimerización

Se sabe que durante el fotocurado de los materiales dentales se libera calor, ya sea por parte de la fuente emisora de luz o por la reacción de polimerización del compuesto utilizado. Este aumento de temperatura se transmite a los tejidos, el cual puede repercutir en ellos. Debido a esto, se realiza un estudio comparativo de la temperatura alcanzada durante la obturación y reconstrucción de piezas dentales in vitro, utilizando lámparas de fotocurado de tipo cuarzo-tungsteno-halógeno (QTH) , LED y lámparas conformadas por 4 LED, y se analiza sus programaciones: modo rampa, modo intermitente y normal; y se proponen pautas clínicas para reducir los riesgos térmicos potenciales a la pulpa y tejidos de soporte.

It is known that the heat is realeased during light-curing of dental materials, either by the light emitting source or by the polymerization reaction of the compound used. This temperature increase is transmitted to tissues, which may have an effect on them. Due to this, a comparative study of the temperature reached during the sealing and reconstruction of teeth In vitro was performed, using light-curing lamps from the type quartztungsten- halogen (QTH), LED and lamps formed by 4 LEDs, analyzing their programming: Ramp Mode, Intermittent Mode, and normal: and clinical guidelines are proposed in order to reduce potential thermal risks to the pulp and supporting tissues

Comparison of the bonding strengths of second- and third-generation light-emitting diode light-curing units / 대한치과교정학회지

OBJECTIVE: With the introduction of third-generation light-emitting diodes (LEDs) in dental practice, it is necessary to compare their bracket-bonding effects, safety, and efficacy with those of the second-generation units. METHODS: In this study, 80 extracted human premolars were randomly divided into eight groups of 10 samples each. Metal or polycrystalline ceramic brackets were bonded on the teeth using second- or third-generation LED light-curing units (LCUs), according to the manufacturers’ instructions. The shear bond strengths were measured using the universal testing machine, and the adhesive remnant index (ARI) was scored by assessing the residual resin on the surfaces of debonded teeth using a scanning electron microscope. In addition, curing times were also measured. RESULTS: The shear bond strengths in all experimental groups were higher than the acceptable clinical shear bond strengths, regardless of the curing unit used. In both LED LCU groups, all ceramic bracket groups showed significantly higher shear bond strengths than did the metal bracket groups except the plasma emulation group which showed no significant difference. When comparing units within the same bracket type, no differences in shear bond strength were observed between the second- and third-generation unit groups. Additionally, no significant differences were observed among the groups for the ARI. CONCLUSIONS: The bracket-bonding effects and ARIs of second- and third-generation LED LCUs showed few differences, and most were without statistical significance; however, the curing time was shorter for the second-generation unit.

Effects of radiant exposure and wavelength spectrum of light-curing units on chemical and physical properties of resin cements

OBJECTIVES: In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs) on the degree of conversion (DC) and the mechanical properties of resin cements. MATERIALS AND METHODS: Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG), according to the different radiant exposures (5, 10, and 20 J/cm²) and two LCUs (single-peak and polywave). The specimens were made (7 mm in length × 2 mm in width × 1 mm in height) using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E) by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA) and post hoc Tukey's test were performed. RESULTS: No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. CONCLUSIONS: On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.

Temperature changes under demineralized dentin during polymerization of three resin-based restorative materials using QTH and LED units

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). 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.

A survey on light intensity outputs of QTH, cabled and cordless LED light curing units

Light intensity output is one of the determinants for adequate curing of visible light-cured materials. The aim of this survey was to evaluate the light intensity outputs (LIOs) of light curing units (LCUs) in dental clinics of Hospital Universiti Sains Malaysia (HUSM) and School of Dental Sciences, Universiti Sains Malaysia (USM). The respective LIOs of all functioning Quartz Tungsten Halogen (QTH) and Light Emitting Diode (LED) LCUs were tested using two light radiometers. For cordless LED LCUs, the testing procedure was done in situ and after being fully charged. Statistical analysis using Kruskal Wallis and Wilcoxon signed ranks tests were performed to compare the LIOs between groups and between the LIOs of in situ and post-charged cordless LED LCUs, respectively. The level of significance was set at 0.05 (p<0.05). The results revealed that 72.72%, 42.47% and 92% of QTH, cabled LED and cordless LED LCUs exhibited acceptable LIOs, respectively. Data analysis using Kruskal Wallis test showed a statistically significant difference between groups (p<0.05). The intergroup comparisons using multiple Mann Whitney test with Bonferroni correction revealed a significant difference between the LIOs of cordless LED and both QTH and cabled LED (p<0.017). The difference between the LIOs of in situ and post charged cordless LED LCUs was also significant (p<0.05). In conclusion, both QTH and cordless LED LCUs performed better in term of LIOs than cabled LED LCUs. Periodic testing of LCUs is essential to ensure optimal performance.

Comparison of light transmittance in different thicknesses of zirconia under various light curing units

PURPOSE: The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. MATERIALS AND METHODS: A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical significance was determined using two-way ANOVA (alpha=.05). RESULTS: ANOVA revealed that thickness of zirconia and light curing unit had significant effects on light transmittance (P<.001). CONCLUSION: Greater thickness of zirconia results in lower light transmittance. Light-emitting diodes light-curing units might be considered as effective as Plasma arc light-curing units or more effective than Quartz-tungsten-halogen light-curing units for polymerization of the resin-based materials.

Power density of light curing units through resin inlays fabricated with direct and indirect composites / 대한치과보존학회지

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.

Effect of light curing units and storage time on the degree of conversion of fissure sealants / Efeito das unidades fotopolimerizadoras e do tempo de armazenamento no grau de conversão dos selantes de fissuras

OBJECTIVE: To investigate the effect of light curing units and storage time on the degree of conversion of fissure sealants. MATERIAL AND METHOD: Three different fissure sealants were used: a resin-based pit and fissure sealant (Clinpro SealantTM), a polyacid modified resin composite (Dyract SealTM), and a resin modified glass ionomer cement (VitremerTM). Each fissure sealant was polymerized with a halogen, high intensity quartz tungsten halogen, LED. Half of the specimens were tested to assess the degree of conversion immediately after polymerization and the others after one month’s storage in artificial saliva. The degree of conversion was measured by FTIR. The data were analyzed using two way ANOVA. RESULTS: Statistical analysis of Dyract SealTM showed significant differences between the DC values of samples tested immediately and again after one month’s storage (p < 0.05). The DC values of ClinproTM increased after the storage period (p < 0.05). The DC of VitremerTM showed no change after storage (p > 0.05). Results of the curing units testing showed no significant differences among the DC of samples polymerized with LED, HQTH, OTH tested immediately and again after one month for Dyract SealTM, VitremerTM and Clinpro SealantTM (p > 0.05). CONCLUSION: Light curing units had no effect on the degree of conversion of the fissure sealants. But storage after initial light activation and polymerization for one month in artificial saliva can affects on DC of fissure sealants.

OBJETIVO: Investigar o efeito de unidades de polimerização por luz no grau de conversão dos selantes de fissuras. MATERIAL E MÉTODO: Três diferentes selantes foram utilizados: um selante resinoso de fissuras (Clinpro SealantTM, uma resina composta poliácida modificada (DyractSealTM) cimento de ionômero de vidro modificado (VitremerTM). Cada selante de fissura foi polimerizado por LED halógeno de quartzo/tungstênio. Metade dos espécimes foi testada para assegurar o grau de conversão imediatamente após polimerização e outros após um mês de armazenamento em saliva artificial. O grau de conversão foi medido por FTIR. Os resultados foram analisados por meio do ANOVA. RESULTADOS: A análise estatística do Dyract SealTMdemonstrou diferenças estatisticamente significantes entre os valores DC dos espécimes testados imediatamente e novamente após um mês de armazenamento (p < 0,05). Os valores do ClimproTM aumentaram após o período de armazenamento (p < 0.05). O DC do VitremerTM não demonstraram alterações após o armazenamento (p > 0.05). Os resultados das unidades de fotopolimerização não mostraram diferenças significantes ente DC de amostras polimerizadas com LED, HQTH, O TH testados imediatamente e novamente após um mês para o Diract SealTM, VitremerTM e Climpro SealantTM. CONCLUSÃO: Unidades de fotopolimerização não tiveram efeito no grau de conversão dos selantes de fissuras. Porém, armazenamento após ativação inicial e polimerização por um mês em saliva artificial pode afetar o DC dos selantes de fissuras.

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

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/cm2, 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.

Este estudo avaliou a dureza Knoop após 15 min e 24 h de diferentes cores do cimento resinoso dual após fotoativação indireta com 2 fontes de luz. O cimento resinoso Variolink II (Ivoclar Vivadent) nas cores XL, A2, A3 e opaco foram misturados com a pasta catalisadora e inseridos dentro de um molde de teflon preto com (5 mm de diâmetro x 1 mm de espessura). A tira de poliéster transparente foi inserida sobre o molde e um disco da cerâmica (Duceram Plus, cor A3) foi posicionada sobre o cimento resinoso. A fotoativação foi realizada sobre o disco de cerâmica por 40 s usando a lâmpada de luz halógena (XL 2500, 3M ESPE) ou luz emitida por diodo (LED) com intensidade de luz de 615 e 610 mW/cm2. A dureza Knoop foi medida usando o microdurômetro HMV 2 (Shimadzu) com carga de 50 g por 15 s, após 15 min e 24 h. Quatro indentações foram feitas em cada amostra. Os dados foram submetidos à Análise de Variância e ao teste de Tukey (a=5 por cento). A fonte de luz halógena promoveu valores de dureza significantemente maiores (p<0,05) que o LED. Quando os tempos pós-polimerização foram comparados para a mesma cor, a luz halógena e o LED promoveram valores de dureza significantemente maiores (p<0,05) em 24 h do que aos 15 min. Pode-se concluir que, de maneira geral, a dureza Knoop foi dependente da fonte de luz e do tempo pós-polimerização. A cor opaca do cimento resinoso mostrou menores valores de dureza Knoop que as outras cores para ambas as fontes de luz e tempos pós-polimerização.

Efeito da polimerização por LED na microinfiltração marginal das restaurações classe II de resina composta / Effect of LED curing on microleakage of class II composite resin restorations

A proposta do trabalho foi avaliar o grau de microinfiltração marginal do sistema adesivo Single Bond (3M ESPE) por meio de dois diferentes tipos de fotopolimerizadores. Foram utilizados dez pré-molares humanos e confeccionadas cavidades do tipo classe II, sendo uma ocluso-mesial e outra ocluso-distal, com término oclusal em esmalte e término cervical localizado em cemento, em seguida, restauradas com Single Bond (3M ESPE) e resina composta Filtek Z250 (3M ESPE) cor A2. Os dentes foram divididos em dois grupos: Grupo 1 û fotopolimerizado com o aparelho de luz halógena Optilight (Gnatus); Grupo 2 û fotopolimerizado com o aparelho sem fio LED Radii (SDI). Os dentes e os forames apicais foram isolados, deixando exposta à margem de 1,0 mm ao redor da restauração, sendo em seguida termociclados 250 vezes (±5°C e ±55°C). Após, os corpos-de-prova foram mergulhados em solução de fucsina básica a 0,5 porcento por 48 horas para posterior avaliação obedecendo aos escores: grau 0 û ausência de infiltração; grau 1 û infiltração até 1/3 da parede; grau 2 û infiltração entre 1/3 a 2/3 da parede e grau 3 û infiltração mais do que 2/3 da parede. Os escores para dentina foram: G1: 0 = 100 porcento; G2: 0 = 70 porcento; 1 = 10 porcento; 2 = 20 porcento. Para esmalte: G1: 0 = 90 porcento; 1 = 10 porcento; G2: 0 = 50 porcento; 2 = 20 porcento; G3 = 30 porcento. Os resultados foram submetidos à análise estatística de Mann-Whitney (p < 0,05), demonstrando não haver diferença estatisticamente significante entre os grupos. Concluiu-se que a microinfiltração marginal não foi influenciada negativamente quando foi empregada a unidade fotopolimerizadora LED

The purpose of this study was to evaluate the microleakage of the bonding system Single Bond (3M ESPE) when used 2 differents light-curing units. Class II cavities were prepared in 10 human premolars. After, the cavities prepared were treated with the bonding agent Single Bond (3M ESPE) and filled with Filtek Z250 (3M ESPE) composite resin, color A2. The teeth were divided into 2 groups: G1 ­ the restorations were light-cured with a conventional halogen-based light-curing unit (Gnatus); G2 ­ the restorations were cured with a LED cordless light-curing unit Radii (SDI). The specimes were thermo-cycled 250 cycles (± 5 °C and ± 55 °C) prior to immersion in 0.5% basic fuchsin for 48 hours for posterior evaluation. The scores in dentin were: G1: 0 = 100%; G2: 0 = 70%; 1 = 10%; 2 = 20%. In the enamel: G1: 0 = 90%; 1 = 10%; G2: 0 = 50%;­ 2 = 20%; G3 = 30%. The data were subjected to statistical analysis using Mann-Whitney test (p < 0.05) and showed no significant statistical difference between the groups. In conclusion the LED light source no influenced the microleakage