Effect of different surface penetrating sealants on the roughness of a nanofiller composite resin

This study evaluated the effectiveness of different sealants applied to a nanofiller composite resin. Forty specimens of Filtek Z-350 were obtained after inserting the material in a 6x3 mm stainless steel mold followed by light activation for 20 s. The groups were divided (n=10) according to the surface treatment applied: Control group (no surface treatment), Fortify, Fortify Plus and Biscover LV. The specimens were subjected to simulated toothbrushing using a 200 g load and 250 strokes/min to simulate 1 week, 1, 3 and 6 months and 1 and 3 years in the mouth, considering 10,000 cycles equivalent to 1 year of toothbrushing. Oral-B soft-bristle-tip toothbrush heads and Colgate Total dentifrice at a 1:2 water-dilution were used. After each simulated time, surface roughness was assessed in random triplicate readings. The data were submitted to two-way ANOVA and Tukey's test at a 95% confidence level. The specimens were observed under scanning electron microscopy (SEM) after each toothbrushing cycle. The control group was not significantly different (p>0.05) from the other groups, except for Fortify Plus (p<0.05), which was rougher. No significant differences (p>0.05) were observed at the 1-month assessment between the experimental and control groups. Fortify and Fortify Plus presented a rougher surface over time, differing from the baseline (p<0.05). Biscover LV did not differ (p>0.05) from the baseline at any time. None of the experimental groups showed a significantly better performance (p>0.05) than the control group at any time. SEM confirmed the differences found during the roughness testing. Surface penetrating sealants did not improve the roughness of nanofiller composite resin.

Este estudo avaliou a efetividade de diferentes selantes aplicados a uma resina nanoparticulada. Quarenta espécimes de Filtek Z-350 foram obtidos depois da inserção do material em um molde de aço inoxidável seguido por fotoativação por 20 s. Os grupos foram divididos (n=10) de acordo com o tratamento superficial aplicado: Grupo controle (sem tratamento superficial), Fortify, Fortify Plus ou Biscover LV. Os espécimes foram submetidos a escovação simulada usando uma carga de 200 g e 250 ciclos/min para simular 1 semana, 1, 3 e 6 meses e 1 e 3 anos, considerando que 10.000 ciclos equivalem a um ano de escovação. Escovas Oral-B de cabeça macia e dentifrício Colgate Total diluído a 1:2 em água foram utilizados. Depois de cada período de simulação, a rugosidade superficial foi medida em triplicata. Os dados foram submetidos à ANOVA de dois fatores e ao teste de Tukey com nível de 95% de confiança. Os espécimes foram observados em microscopia eletrônica de varredura (MEV) depois de cada ciclo de escovação. O grupo controle não foi diferente (p>0,05) que os outros grupos, exceto pelo Fortify Plus (p<0,05), que foi mais rugoso. Nenhuma diferença (p>0,05) foi observada em 1 mês de simulação entre os grupos experimentais e o controle. Fortify e Fortify Plus apresentaram rugosidade regular com o tempo, diferindo da inicial em todos os tempos. Nenhum dos grupos selados mostrou melhor desempenho (p>0,05) que o grupo controle em qualquer um dos tempos. MEV ressaltou as diferenças encontradas durante o teste de rugosidade. Selantes de penetração de superfície não melhoram a rugosidade da resina nanoparticulada.

Preparation, characterization and release of verapamil hydrochloride from polycaprolactone/ acrylic acid [PCL/AA] hydrogels

In this study pH sensitive, biocompatible and controlled released hydrgels were prepared and their localized drug delivery effect was analyzed. Polycaprolactone and acrylic acid [PCL/AA] were reacted by free radical polymerization and developed inter penetrating polymeric network [IPN] hydrogels. Benzylperoxide was used as initiator and N, N methylenebisacrylamide [NNMBisAm] was employed as a cross-linking agent. Different concentrations of monomer, polymer and cross-linking agent were used and the reaction parameters were optimized. The obtained PCL/AA hydrogels were fully characterized by Fourier transform infrared spectroscopy [FT-IR], scanning electron microscopy [SEM], and thermogravimetric analysis [TGA] that determined the polymer structure, its morphology and strength respectively. Verapamil, a calcium channel blocker was loaded by incubation of polymerization method. Controlled release Verapamil hydrogel was developed due to its low solubility; low permeability and having very short half life of 1.2-2 h. The dynamic swelling, equilibrium swelling and drug release were carried out in a buffer solution of pH 1.2, 4.5 and 6.8. Concentration of Acrylic acid showed direct, while Polycaprolactone inverse relation to swelling and drug release due to their hydrophilic and hydrophobic nature respectively. Cross-linking agent also had the contrary effect on swelling. Diffusion coefficient [D] of hydrogels was determined by using Flory-Rehner theory. Drug release and swelling data were analyzed by different kinetic models, like Zero order, First order, Higuchi, Korsmeyer's and Peppas. The release and diffusion was best described by the first order kinetics where n value was <0.5 for all the formulations indicating Fickian drug release mechanism

Influence of pressure application before light-curing on the bond strength of adhesive systems to dentin

This study evaluated the influence of defined pressure application before light-curing on the tensile bond strength (TBS) of two adhesive systems to wet and perfused dentin. Bonding sites were analyzed by scanning electron microscopy (SEM) to assess morphological changes. Dentin discs from 120 human third molars were prepared in such a way to allow simulation of intrapulpal pressure. The specimens were randomly assigned to 6 groups (n=20) according to different experimental conditions. The adhesive systems (ScotchbondTM Multi-Purpose and Syntac®) were applied either to wet or perfused dentin. In the latter, compression was applied before adhesive light-curing . TBS was recorded using an universal testing machine. Qualitative examination of the bonding sites was performed by SEM after dissolving the dentin with 50 percent nitric acid. Pressure application prior to light-curing resulted in a remarkable decrease of TBS for Syntac®, while no significant change was observed for ScotchbondTM MP. SEM analysis showed no considerable lengthening of the resin tags after pressure application. These findings suggest that application of adhesive systems to dentin under pressure before light-curing had no positive effect on TBS.

Este estudo avaliou a influência da aplicação de uma pressão definida antes da polimerização sobre a resistência à tração de dois sistemas adesivos à dentina molhada e perfundida. Os sítios de adesão foram analisados em microscopia eletrônica de varredura (MEV) a fim de determinar a ocorrência de alterações morfológicas. Discos de dentina de 120 terceiros molares humanos foram preparados de tal forma a simular a pressão intrapulpar. Os espécimes foram alocados aleatoriamente em 6 grupos (n=20), de acordo com as diferentes condições experimentais propostas. Os sistemas adesivos (Syntac® e ScotchbondTM Multi-Purpose) foram aplicados sobre a dentina molhada ou perfundida. Nesta última, compressão (7 N) foi aplicada antes da polimerização do sistema adesivo. A resistência à tração foi registrada em máquina universal de ensaios. A análise qualitativa dos sítios de adesão foi realizada em MEV após dissolução da dentina em 50 por cento de ácido nítrico. A aplicação da pressão antes da polimerização do sistema adesivo resultou em diminuição significativa da resistência à tração do Syntac®, ao passo que para o ScotchbondTM MP nenhuma alteração significativa foi observada. A análise em MEV não mostrou aumento considerável do tamanho dos tags de resina após a aplicação da pressão. Esses achados sugerem que a aplicação de sistemas adesivos à dentina sob pressão previamente à polimerização não teve efeito positivo sobre a resistência à tração.

Cementado y adhesión en ortodoncia / Cementation and bonding in orthodontics

Hemos desarrollado extensamente lo referido a los ionómeros vítreos porque pensamos que, en su forma tradicional o en las de más reciente desarrollo, es un excelente material que ha mejorado la performance clínica de los antiguos cementos utilizados para el cementado de bandas de ortodoncia

Hydrazidoyl halides in heterocyclic synthesis.III+: synthesis of several new pyrazole pyrrolino [3,4-c] pyrazoles and pyrazolo [3,4-d] pyridazine, derivatives via dipolar cycloaddition reactions

A variety of new pyrazole, pyrrolinopyrazole and pyrazolopyridazine derivatives were synthesised via the dipolar cycloaddition reactions of acrylonitrile, ethyl acrylate and N-arylmaleimides with the nitrile imine regenerated from 2-bromo-1- benzofurylglyoxal-2-[3-phenylpyrazol-5-yl]-hydrazone. Structure of the newly synthesized derivatives were established on the basis of elemental analysis and spectral data