Molar extinction coefficients and the photon absorption efficiency of dental photoinitiators and light curing units

Neumann, Miguel G.; Miranda, Walter Gomes; Cavalheiro, Carla Cristina Schmitt; Rueggeberg, Frederick A.; Correa, Ivo Carlos

doi:10.1016/j.jdent.2004.11.013

Cited by 207 publications

(163 citation statements)

References 17 publications

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“…BAPO has an increased efficiency in free radicals generation, higher than TPO and CQ. Following the light energy absorption, this molecule undergoes an α-cleavage in the excited triplet state of the C-P bond, which may occur twice, with the ability to generate four free radicals per molecule (16), while TPO can generate two and CQ only one (17). Furthermore, BAPO and TPO have higher molar absorption coefficients than CQ, which means that those compounds absorb more light than CQ at the corresponding maximum absorption peak (18).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the temperature rises, which may cause colored peroxides formation and a significant yellow discoloration (23). TPO has lower yellow degree relatively to BAPO, which is probably due to the higher TPO molar absorption coefficient, which leads to more TPO molecules consumption during the polymerization reaction (17). Furthermore, before curing BAPO provides more yellowing than TPO (22).…”

Section: Discussionmentioning

confidence: 99%

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Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites

et al. 2017

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The aim of this study was to determine the influence of photoinitiator systems on physical-chemical properties of flowable composites. Conventional (CFC), composed by bisphenol-glycidyl dimethacrylate (BisGMA)+triethyleneglycol dimethacrylate (TEGDMA), and self-adhesive (SAFC), composed by BisGMA+TEDGMA+bis[2-(methacryloyloxy) ethyl] phosphate (2MP), flowable composites were developed. Five photoinitiator systems were tested: camphorquinone (CQ), ethyl-4-dimethylaminobenzoate (EDMAB), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), phenylbis (2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), CQ+EDMAB+TPO and CQ+EDMAB+BAPO. A two-peak LED was used; degree of conversion (DC) and the maximum polymerization rate (RP max ) were determined by nearinfrared spectroscopy. For the yellowing degree a spectrophotometer was used. Water sorption (Wsp) was obtained after 30 days of water storage (n=5). Data were submitted to two-way analysis of variance and Tukey's test (α=0.05). BAPO presented the highest DC and RP max values for both series. SAFCs presented lower DC and RP max for CQ+EDMAB-based materials. Greater yellowing was observed for SAFCs compared with CFCs, except for BAPO. Greater Wsp was observed for SAFCs compared with CFCs. The photoinitiator did not influence Wsp for CFCs, but TPO and BAPO presented the highest Wsp in SAFCs. The photoinitiator system affected differently the physical-chemical properties of CFCs and SAFCs.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites

et al. 2017

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“…Em relação aos resultados de grau de conversão monomérica total após 300 segundos, (UHL et al, 2003;NEUMANN et al, 2005;OGUNYINKA et al, 2007). Alguns autores acreditam que essa menor eficiência não se deve somente a característica de absorção de luz desse fotoiniciador, mas também, a características fotoquímicas sendo este menos reativo (SCHROEDER et al, 2007, SCHNEIDER et al, 2009b.…”

Section: Determinação Dos Monômeros Residuais Nas Amostras Reaisunclassified

“…Estes fotoiniciadores que apresentam cor mais clara absorvem luz com comprimento de onda inferior à canforoquinona, mais próximos ao ultravioleta (NEUMANN et al, 2005).…”

Section: Introductionunclassified

“…Isso faz com que as resinas contendo esses diferentes fotoiniciadores não sejam adequadamente polimerizadas por estes aparelhos, podendo apresentar baixo grau de conversão e baixas propriedades mecânicas (UHL et al, 2003;NEUMANN et al, 2005). Mas, a associação dos dois fotoiniciadores (CQ e PPD) apresenta um pico máximo de absorção em torno de 452nm (SCHNEIDER et al, 2008), possibilitando perfeitamente sua ativação por aparelhos dentro da faixa azul do espectro eletromagnético.…”

Section: Introductionunclassified

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Avaliação do grau de conversão monomérica, parâmetros de cinética de polimerização e determinação de monômeros residuais em resinas experimentais

Amaral¹

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This study aimed to investigate multiple aspects of composite resin polymerization as the degree of monomer conversion (DC), the kinetic parameters of polymerization and the determination of residual monomers TEGDMA and BisGMA, and evaluate the performance of light curing units. The experimental composites were manipulated by varying the photoinitiators R1-) camphorquinone/amine, R2-) PPD/amine, R3-) PPD + camphorquinone/ amine) and two devices were used for the polymerization I-) halogen lamp (Demetron LC / SDS Kerr, USA) and II-) LED (Poly 600/Kavo-Brasil) both with 600 mW cm -2 for 40 s. DC after 300 s and the kinetic parameters such as maximum rate of polymerization conversion (Rp max ), time of occurrence of the maximum rate of polymerisation (t max ) and the conversion occurred when Rp max were determined by infrared absorption spectroscopy in real time (RT-FTIR), the infrared spectrum was collected from the specimen (n=5) in order kinetics for 305 s, between 1680 and 1550 cm -1 . The first 5 scans were used to provide the collected absorption spectrum of the uncured resin (calculated DC). In the sixth scan, the curing unit was connected (by 40 seconds) while the spectrum continued to be collected up to 300 s after activation of the light. The presence of residual monomers (TEGDMA and BisGMA) was assessed by high performance liquid chromatography (HPLC), and the specimens (n=6) were immersed in acetonitrile (5 mL-24 h) with mechanical stirring, the method developed used: HPLC, C18 column, mobile phase A: water with triethylamine (0,05%) acidified with acetic acid (pH 4) and phase B: acetonitrile, gradient elution mode (40-85% -17 min/55 o C), flow 1 mL/min, UV detector at 210 nm, injection of 20 μL. Regarding the results of DC after 300s were the highest values for both R1 resin polymerized with LED (65.90% ±1.81) and with a halogen lamp (64.40% ±0.83), and lower values when the resin was found that R2 was polymerized by LED (35.64% ±1.73) and the only resin that showed significant differences in the sources of light was the R2. The values of the resins decreased Rp max who had PPD photoinitiator. The time of occurrence of the maximum rate of conversion (t max ) occurred more rapidly for the resin with CQ. And all resins showed values similar degree of conversion in t max . For HPLC results, the amount of monomer extracted (M/M%) ranged from 1.98% ±0.16 to 3.34% ±0.07 for the monomers of TEGDMA and 3.57% ±0.30 to 7.57% ±0.40 for the monomers BisGMA. Resin R2 showed the highest amount of residual monomers as polymerized with both sources, especially when polymerized with LED. Resins R1 and R3 had similar behavior for both curing units. In conclusion, the resin R3 can be a good choice, as compared with the resin obtained R1 advantages as reduction in Rp max as well as the time it occurred (t max ), and be suitably photoactivated with LED devices.

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Processes, Machines and Materials

2017

From Additive Manufacturing to 3d/4d Printing 1

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Molar extinction coefficients and the photon absorption efficiency of dental photoinitiators and light curing units

Cited by 207 publications

References 17 publications

Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites

Influence of Photoinitiator System on Physical-Chemical Properties of Experimental Self-Adhesive Composites

Avaliação do grau de conversão monomérica, parâmetros de cinética de polimerização e determinação de monômeros residuais em resinas experimentais

Processes, Machines and Materials

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