OBJECTIVE:This study aimed at evaluating the degree of conversion (DC) of four composite resins, being one nanofilled and 3 microhybrid resins, photo-activated with second- and third-generation light-emitting diodes (LEDs). MATERIAL AND METHODS: Filtek TM Z350 nanofilled composite resins and Amelogen® Plus, Vit-l-escenceTM and Opallis microhybrid resins were photo-activated with two second-generation LEDs (Radii-cal and Elipar Free LightTM 2) and one third-generation LED (Ultra-Lume LED 5) by continuous light mode, and a quartz halogen-tungsten bulb (QHT, control). After 24 h of storage, the samples were pulverized into fine powder and 5 mg of each material were mixed with 100 mg of potassium bromide (KBr). After homogenization, they were pressed, which resulted in a pellet that was evaluated using an infrared spectromer (Nexus 470, Thermo Nicolet) equipped with TGS detector using diffuse reflectance (32 scans, resolution of 4 cm-1) coupled to a computer. The percentage of unreacted carbon-carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1637 cm-1) against internal standard before and after curing of the specimen: aromatic C-C (peak at 1610 cm-1). RESULTS: The ANOVA showed a significant effect on the interaction between the light-curing units (LCUs) and the composite resins (p<0.001). The Tukey’s test showed that the nanofilled resin (FiltekTM Z350) and Opallis when photo-activated by the halogen lamp (QTH) had the lowest DC compared with the other microhybrid composite resins. The DC of the nanofilled resin (FiltekTM Z350) was also lower using LEDs. The highest degrees of conversion were obtained using the third-generation LED and one of second-generation LEDs (Elipar Free LightTM 2). CONCLUSIONS: The nanofilled resin showed the lowest DC, and the Vit-l-escenceTM microhybrid composite resin showed the highest DC. Among the LCUs, it was not possible to establish an order, even though the second-generation LED Radii-cal provided the lowest DC.

OBJETIVO: o uso de diferentes fontes de luz como auxiliar no clareamento de consultório tem sido descrita na literatura.Assim, o objetivo deste estudo foi avaliar as alterações da cor dos dentes após a aplicação de técnicas de clareamento com diferentes produtos, com e sem ativação por um sistema de LED-laser. METODOLOGIA: Vinte-quatro superfícies de dentes bovinos foram submetidas a três técnicas de clareamento com dois agentes clareadores disponíveis comercialmente à base de peróxido de carbamida a 35% (n=8). Os espécimes foram inicialmente imersos em vinho tinto por 48 ha 37°C, e submetidos às técnicas de clareamento. As alterações de cor foram mensuradas antes e após o manchamento, bem como imediatamente e 24 hs após as técnicas de clareamento, por meio de dois diferentes métodos de avaliação da cor: software ScanWhite V1.1 e espectrofotômetro intra-oral Vita Easyshade. Os dados foram analisados pelos testes de ANOVA e Kruskal-Wallis. RESULTADOS: A análise estatística não apontou diferenças significantes entre os diferentes grupos testados, independentemente do período de avaliação, método de avaliação ou uso do sistema LED-laser. CONCLUSÃO: Os resultados sugeriram que o uso da luz não influenciou nas mudanças de cor.

PURPOSE: The use of different light sources as an adjunct to in-office bleaching has been questioned. Thus, the aim of this study was to evaluate the color changes of teeth after application of bleaching techniques with different products, with and without activation by a LED-laser system. METHODS: Twenty-four bovine teeth surfaces were submitted to three bleaching techniques with two commercially available 35% hydrogen peroxide bleaching agents (n=8). The specimens were immersed in red wine for 48 h at 37°C and submitted to the bleaching techniques. Color changes were measured before and after staining as well as immediately after and 24 h after the bleaching treatments, with two different methods of color evaluation, software ScanWhite V1.1 and intra-oral spectrophotometer (Vita Easyshade). Data were analyzed by ANOVA and Kruskal-Wallis test. RESULTS: The statistical analysis showed that there was no statistically significant difference at 5% of significance level between the different groups, independently of the evaluation time, evaluation methods or the use of LED-laser systems. CONCLUSION: The results suggested that the use of light in the bleaching techniques did not influence the color changes.