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This study aimed to analyze the kinetic parameters of two monomers using attenuated total reflectance Fourier transform infrared (ATR-FTIR): 2,2-bis-[4-(2-hydroxy-3-methacryloxypropyl-1-oxy)-phenyl] propane (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA). The following were calculated to evaluate the kinetic parameters: maximum conversion rate (Rp max ), time at the maximum polymerization rate ( max ), conversion at Rp max , and total conversion recorded at the maximum conversion point after 300 s. Camphorquinone (CQ) and phenyl propanedione (PPD) were used in this study as photoinitiators, whereas N,Ndimethyl-p-toluidine (DMPT) amine was used as a coinitiator. LED apparatus and halogen lamp were used in turn to evaluate the effect that light source had on the monomer kinetics. The mass concentration ratio for the three resin preparations was 0.7 : 0.3 for Bis-GMA and TEGDMA: R1 (CQ + DMPT), R2 (PPD + DMPT), and R3 (PPD + CQ + DMPT). The PPD association with the CQ photoinitiator altered the polymerization kinetics compared to a resin containing only the CQ photoinitiator. The light sources exhibited no significant differences for max of R1 and R3. Resins containing only the PPD initiator exhibited a higher max than those containing only CQ. However, the Rp max decreased for resins containing the PPD photoinitiator.

The goal of this study was to evaluate the in vitro cellular toxicity and biological behavior of new bone graft composites after subcutaneous implantation during remodeling and wound-healing processes. We developed composites based on hydroxyapatite (obtained by deproteinizing bovine bone), collagen (obtained from bovine tendon) and chitosan (obtained from gladii of the squid species Loligo), that were characterized by different techniques (X-ray, FT-IR, Thermogravimetry, DSC and SEM). Three biomaterials were evaluated here: B1 (collagen/chitosan/hydroxyapatite), B2 (collagen/hydroxyapatite) B3 (collagen/hydroxyapatite). For in vitro cytotoxicity tests, two cell lines were used: HEp human larynx tumor cells (ATCC-CCL-23) and VERO cells from African green monkey (Cercopithecus aethiops). These toxicity tests demonstrated that the evaluated composites are not toxic. In biocompatibility tests, the results of a histological analysis showed that all three biomaterials present a low inflammatory tissue reaction. The tissue response was most favorable for sample B3, followed by B2 and B1, in that order. Based on these results, we conclude that all three biomaterials show good biocompatibility and no evidence of cytotoxicity; thus, these materials represent good candidates for tissue and graft engineering for use in bone regeneration.

The effect of different propionaldehyde ratios on the properties of bis-GMA-based comonomers and copolymers diluted with propoxylated bis-GMA (CH 3 bis-GMA) was evaluated. Five experimental comonomers were prepared combining bis-GMA with CH 3 bis-GMA and propionaldehyde at 0, 2, 8, 16, 24 mol%. Light polymerization was effected with the use of 0.2 wt. (%) each of camphorquinone and N,N-dimethyl-p-toluidine. Resin degrees of conversion (%DC) were evaluated by FT-IR spectrophotometry and T g by Differential Scanning Calorimeter. Complex viscosity (η*), the effect of temperature on η*, and Microhardness (H) for dry and wet samples were also determined. Data were analyzed by Student's t-test, one-way ANOVA and Tukey-Kramer test (α = 0.05). The group with 24 mol% additive had a significant increase in %DC and H, and the lowest comonomer T g and η*. No remarkable variation was noted in copolymers T g s. All resins presented Newtonian behavior of viscosity, which linearly decreased with increased temperature. The η* decreased sigmoidally as the additive ratio increased.

This paper evaluates the photopolymerization kinetics and degree of conversion of different com mercial dental composites when photoactivated by a LED curing unit using two different modes (standard and soft start mode). The investigation was performed on with RelyX ARC (dual cured), Filtek Z 350 (Nanocomposite), Filtek Z 250 (Hybrid), and Filtek Z 350flow (Flowable) resin composites. The analysis used was attenuated total reflection with a Fourier transform infrared (ATR FTIR). The RelyX ARC resin demonstrated the highest degree of conversion with both LED photoactivation modes. For this resin a 28% decrease in maximum rate was observed and the time to reach its highest rate was almost 2.3 times higher than when the soft start photoactivation light curing was used. Z 350flow resin recorder a higher maximum rate using the soft start mode rather than the standard mode. In contrast, the Z 250 showed a higher value using the standard mode. Although Z 250 and Z 350 showed a higher total degree of conversion effectiveness using the soft start mode, RelyX and Z 350flow achieved a higher value using the standard mode.

ABSTRACT. This paper evaluates the effects of different light sources on the monomer conversion (DC%) and Vickers microhardness number (VHN) of a nanocomposite resin. Three different depths were measured in this study (1, 2 and 3 mm), and photoactivation methods including a halogen lamp, a LED and an argon ion laser were used. In contrast to other studies, the conditions for each photoactivation source such as the exposure time and the same power density were considered and kept the same. It was also shown that increasing the depth lowered the VHN. At each of the depths, it was observed that the three light sources behaved similarly. The correlation between the VHN and DC% is shown. However, only a weak correlation was observed, which implies that a higher DC% value does not necessarily indicate a higher VHN.Keywords: photopolymerization, mechanical properties, infrared spectroscopy, composite resin.O efeito de diferentes fontes de fotoativação em uma resina de nanopartículas: aplicação de LED, halógeneo e laser de argônio RESUMO. Este artigo avalia os efeitos das diferentes fontes de luz no grau de conversão monomérica (DC%) e microdureza Vickers (VHN) de uma nanoresina composta. Três profundidades diferentes foram medidas neste estudo (1, 2 e 3 mm), enquanto que foram utilizadas três diferentes fontes de luz: uma lâmpada halógena, uma LED e um laser de argônio. Em contraste com outros estudos, foram mantidas as mesmas condições para cada fonte de fotoativação, o mesmo tempo de exposição, assim como a mesma densidade de potência de cada fonte de luz. Com o aumento da profundidade há diminuição dos valores de VHN, e para as diferentes fontes de luz foram observados valores similares de DC% para cada profundidade. Analisando a correlação entre os valores VHN e DC% o que se observa é apenas uma fraca correlação entre ambos os valores, o que implica que altos valores de DC% não é necessariamente um indicativo de altos valores de VHN.Palavras-chaves: polimerização, propriedades mecânicas, espectroscopia de infravermelho, resinas compostas.

A Deus, por me abençoar e estar sempre presente em minha vida me dando força, coragem, determinação, paciência e vontade de vencer. A meus pais Geraldo e Ivone, que sempre acreditaram em meus sonhos e sempre me incentivaram em todos os momentos de minha vida, sendo para mim um exemplo a ser seguido pela humildade, perseverança e honestidade. A meus irmãos, Eduardo e Anali, e minha cunhada Gisele, pelo companheirismo e incentivo, sempre me apoiando com muito carinho. A minha sobrinha e afilhada Isabella, pela felicidade e alegria que ela proporciona em minha vida. E finalmente a meu marido Mauricio, meu grande amor, companheiro, paciente, dedicado e que esteve comigo, lado a lado, nessa jornada de nossas vidas e que com muito amor e carinho, me apoiou e ajudou, em todos os momentos, na realização desse trabalho. Agradecimentos especiais Agradecimentos Especiais AGRADECIMENTOS ESPECIAIS A minha orientadora Profa. Ana Plepis, que é um exemplo de humildade, honestidade, transparência e que, com a sua calma e paciência, me orientou durante o mestrado, agradeço os ensinamentos e a confiança depositada em mim. A meus sogros Joaquim e Vera, que me acolheram em sua casa e me trataram como uma filha, não medindo esforços para me ajudar, gostaria de expressar meu eterno respeito e gratidão à vocês. A Profa. Alessandra Rastelli, que se mostrou uma verdadeira amiga me orientando em muitos momentos e sendo um exemplo de determinação e humildade a ser seguido, conquistando meu respeito e admiração. Agradecimentos Resumo se mostraram aptas a polimerização da resina composta até 2 mm de profundidade de acordo com os parâmetros utilizados nessa pesquisa. Palavras chave: materiais dentários, resinas compostas, espectroscopia infravermelho transformada de Fourier (FTIR), dureza, profundidade de polimerização.

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