Shear bond strength of self-etch and total-etch bonding systems at different dentin depths

The purpose of this study was to evaluate the dentin shear bond strength of four adhesive systems (Adper Single Bond 2, Adper Prompt L-Pop, Magic Bond DE and Self Etch Bond) in regards to buccal and lingual surfaces and dentin depth. Forty extracted third molars had roots removed and crowns bisected in the mesiodistal direction. The buccal and lingual surfaces were fixed in a PVC/acrylic resin ring and were divided into buccal and lingual groups assigned to each selected adhesive. The same specimens prepared for the evaluation of superficial dentin shear resistance were used to evaluate the different depths of dentin. The specimens were identified and abraded at depths of 0.5, 1.0, 1.5 and 2.0 mm. Each depth was evaluated by ISO TR 11405 using an EMIC-2000 machine regulated at 0.5 mm/min with a 200 Kgf load cell. We performed statistical analyses on the results (ANOVA, Tukey and Scheffé tests). Data revealed statistical differences (p < 0.01) in the adhesive and depth variation as well as adhesive/depth interactions. The Adper Single Bond 2 demonstrated the highest mean values of shear bond strength. The Prompt L-Pop product, a self-etching adhesive, revealed higher mean values compared with Magic Bond DE and Self Etch Bond adhesives, a total and self-etching adhesive respectively. It may be concluded that the shear bond strength of dentin is dependent on material (adhesive system), substrate depth and adhesive/depth interaction.

Microtensile bond strength of adhesive systems to dentin with or without application of an intermediate flowable resin layer

This study evaluated the effect of flowable composite resin application on the microtensile bond strength (muTBS) of adhesive systems to dentin. Occlusal surfaces of human third molars were ground to obtain flat dentin surfaces. The crown of each tooth was sectioned occluso-gingivally into four quarters with a water-cooled diamond saw. One of the following adhesive systems was applied to dentin surface in each quarter of the same tooth, following manufacturers' instructions: Scotchbond Multipurpose, Single Bond Adper Prompt and Clearfil SE Bond. Experimental and control groups received the same treatment, except for the fact that a layer of flowable composite (Filtek Flow) was placed and light-cured on top of the adhesive layer in the specimens of the experimental groups. Resin composite (Filtek Z250) crown buildups were then made on the bonded surfaces and incrementally light-cured for 20 s. The restored teeth were stored in water at 37ºC for 24 h. Each tooth quarter was serially cut in a longitudinal direction in order to obtain several bonded sticks (0.9-mm² in cross-section). Maximal microtensile stress (in MPa) at failure was recorded using a universal testing machine. Data were analyzed by two-way ANOVA and Tukey's test at 5 percent significance level. Placement of a low-viscosity resin to the hybridized dentin increased the muTBS for all tested adhesive systems. However, such increase was significant only for Clearfil SE Bond (p<0.05). When the restorations were placed without low-viscosity resin, Clearfil SE Bond presented higher muTBS than Adper Prompt (p<0.05). For the groups treated with flowable composite, Clearfil SE Bond produced the highest muTBS means to dentin. In conclusion, the effect of the addition of an intermediate flowable composite layer on muTBS to dentin was material-dependent and resulted in an increased adhesion for all tested materials, though with significance only for Clearfil SE Bond.

Este estudo avaliou o efeito da aplicação de uma resina flow na resistência de união (RU) (microtração) de sistemas adesivos à dentina. Superfícies oclusais de terceiros molares humanos foram abrasionadas para formar superfícies dentinárias planificadas. As coroas foram seccionadas no sentido ocluso-gengival em quatro partes de tamanhos similares com disco diamantado sob refrigeração. Os sistemas adesivos (Scotchbond Multipurpose; Single Bond; Adper Prompt e Clearfil SE Bond) foram aplicados nas superfícies dentinárias, de acordo com as instruções dos fabricantes, sendo cada um deles em uma das quatro partes de um mesmo dente. Os grupos experimentais e controle receberam o mesmo tratamento, porém a resina flow (Filtek Flow) foi aplicada e fotoativada sobre os sistemas adesivos nos espécimes dos grupos experimentais. Um bloco de compósito (Filtek Z250) foi confeccionado em incrementos sobre as superfícies tratadas com o sistema adesivo e fotoativado por 20 s. Os dentes restaurados foram armazenados em água a 37ºC por 24 h e seccionados longitudinalmente para obtenção de espécimes com formato de paralelepípedo, com 0,9 mm² na área de união. O ensaio de tração foi realizado em máquina universal de ensaios e os valores de RU foram expressos em MPa. Os dados foram analisados pela ANOVA (dois fatores) e teste de Tukey (5 por cento). A aplicação da resina flow na dentina previamente hibridizada aumentou a RU para todos os sistemas adesivos, entretanto, foi estatisticamente significativa somente para o adesivo Clearfil SE Bond (p<0,05). Quando as restaurações foram confeccionadas sem a resina de baixa viscosidade, o Clearfil SE Bond obteve maior valor de RU que o adesivo Adper Prompt (p<0,05). Para os grupos com a resina flow, o Clearfil SE Bond resultou no maior valor médio de RU à dentina. Conclui-se que o efeito da aplicação da resina flow foi depende do sistema adesivo utilizado e indicou um aumento na RU para todos os sistemas adesivos...

Influence of water storage time on the bond strength of etch-and-rinse and self-etching adhesive systems

The purpose of this study was to evaluate comparatively the shear bond strength (SBS) of etch-and-rinse (Adper Scotch Bond Multi Purpose - ASBMP and Adper Single Bond 2 - ASB2) and self-etching (AdheSe -AD and Adper Prompt - AP) adhesive systems after short- and long-term water storage. Eighty bovine teeth were randomly assigned to 4 groups (n=20, 10 teeth for 24 h and 10 for 6 months). After surface treatment, composite resin cylinders were made with Tetric Ceram using a bisected metallic matrix. The specimens were stored in distilled water at 37°C for either 24 h or 6 months. After these periods, shear strength was assessed in a universal testing machine (0.5 mm/min). Data were submitted to ANOVA and F test at 5 percent significance level. Mean SBSs (MPa) for ASBMP (10.03 ± 3.78) and ASB2 (6.10 ± 2.67) showed no statistically significant differences (p>0.05) between times. The self-etching systems did not differ significantly from each other within the 24-h period, but significant difference was found for AD (1.37 ± 0.64) after 6 months of water storage. In conclusion, the tested etch-and-rinse systems had a better performance in terms of bond durability over time than the self-etching systems.

O objetivo deste estudo foi avaliar, in vitro, a influência do armazenamento em meio degradante a curto e longo prazo sobre os sistemas adesivos: Adper Scotch Bond Multi Purpose (ASBMP); Adper Single Bond 2 (ASB2); AdheSe (AD) e Adper Prompt (AP). Oitenta dentes bovinos foram selecionados e aleatoriamente divididos em 8 grupos (n=10). Após o tratamento da superfície, cilindros de resina composta Tetric Ceram foram confeccionados utilizando uma matriz metálica bipartida. Os espécimes foram armazenados em água destilada a 37°C por 24 h ou 6 meses. Após estes períodos, o teste de cisalhamento foi realizado em uma máquina de ensaio universal (0,5 mm/min). Os resultados em MPa foram submetidos à ANOVA e ao teste F em nível de significância de 5 por cento. O ASBMP (10,03 ± 3,78) e ASB2 (6,10 ± 2,67) não apresentaram diferenças estatisticamente significativas entre os tempos de armazenamento. Os autocondicionantes não diferiram estatisticamente no período de 24 h, mas houve diferença para o AD (1,37 ± 0,64), quando armazenado por 6 meses. Esses adesivos obtiveram valores inferiores nos períodos de avaliação em relação aos convencionais. Os adesivos convencionais mostraram melhor desempenho laboratorial que os autocondicionantes em termos de durabilidade da adesão ao longo do tempo.

Electrochemical investigation of the effect of some organic phosphates on haemoglobin.

The effects of DPG,IHP,GTP,GDP and GMP on the structure and stability of haemoglobin were electrochemically investigated with an iodide-modified silver electrode in 0.01 M KNO 3 at pH 7.0.Anodic and cathodic peaks of haemoglobin were observed at 250 mV and 12 mV with a formal potential value of 133 mV vs.Ag/AgCl.The effects of different concentrations of DPG,IHP,GTP,GDP and GMP on the anaerobic redox reaction were determined. The results showed that DPG and IHP can lead to a positive shift in the reduction peak of haemoglobin,indicating that the oxidation peak shift of haemoglobin was small as a result of stabilization of the reduced state and destabilization of the R-like state of haemoglobin.GTP elicited a more positive shift in the cathodic and anodic peaks of haemoglobin at a higher concentration,signifying that it has a low-affinity binding site on haemoglobin.The positive shift of the cathodic and anodic peaks revealed a slight variation in the structure and indicated the unfolding of haemoglobin in the presence of high concentrations of GTP.Our study also showed that GDP and GMP did not cause significant shift the cathodic and anodic peaks of haemoglobin even at high concentrations,refuting the existence of specific GDP-and GMP-binding sites on the protein.Moreover,the iodide-modified silver electrode method proved to be easy and useful in investigating the effects of ligands or other effectors on haemoglobin in solution.

Textile anionic dyes recovery using tri-n-butyl phosphate as carrier through supported liquid membrane.

The recovery of anionic dyes Acid Red10 B (CI Acid Violet 54) and Acid Pink BE (CI Acid Red 183) in flat type supported liquid membrane (SLM) using tri-n-butyl phosphate as carrier was studied. The parameters studied were the effect of feed phase pH, stripping reagent concentration, string speed and initial dye concentration on permeability of dyes. The influence of salt concentration such as sodium chloride and sodium sulphate on the dye recovery was examined. The reusability of membrane and kinetics of transport were also studied. The optimum conditions of transport are feed phase pH 1 +/- 0.1, 0.1 M sodium hydroxide as stripping phase, stirring speed at 500 rpm. The maximum recovery under optimum conditions was observed as 94.2 % for Acid Red10 B and 85.7 % for Acid Pink BE. The maximum permeability was 11.0 x 10(-6) m/s for Acid Red10 B and 7.7 x 10(-6) m/s for Acid Pink BE.

Effect of enamel preparations on fracture resistance of composite resin buildup of fractures involving dentine in anterior bovine teeth: an in vitro study.

Sixty bovine teeth with simulated mesio-incisal angle fracture were randomly and equally divided in one untreated (control) group and three experimental groups (Bevel, Chamfer and newly introduced Stair-step Chamfer preparation group) to evaluate the effect of enamel preparations on the fracture resistance of composite resin. Post restoration, fracture mechanics approach was used to quantify the failure of composite resins in testing the samples in Instron testing machine. Mean peak failure load (Newton) of composite amongst experimental groups was observed in the order; Chamfer (326.09 +/- 72.73), Stair-step chamfer (315.21 +/- 81.77) and Bevel (253.83 +/- 67.38). Results of the One-Way ANOVA revealed significant difference in the mean peak failure load values of the four different groups. (P<0.001) Scheffe's Post-Hoc comparison test (Subset for alpha = 0.05) revealed that there was no significant difference in the mean peak failure load values of the bevel, stair-step chamfer and chamfer preparation when considered together, but the mean peak values of control group (605.22 +/- 48.96) were observed significantly higher. Failure mode evaluation revealed, majority of failures occurred as cohesive and mixed type for all the experimental groups. Adhesive type failure was observed maximum (33%) in the bevel group. Stair-step chamfer preparation showed greatest potential for application and use as it no only demonstrated comparable values to Chamfer preparation ['t' value (0.39) (P > 0.05)] but also involved sacrificing less amount of tooth structure adjacent to fractured edge.