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Context:Early observations of enamel surfaces prepared by erbium lasers motivated clinicians to use laser as an alternative to chemical etching.Aims:Evaluate shear bond strength (SBS) values of different dental adhesives on Erbium:Yttrium Aluminum Garnet (Er:YAG) laser prepared enamel and to evaluate possible etching patterns correlations between dental adhesives and SBS values.Subjects and Methods:One hundred bovine incisors were randomly assigned to SBS tests on enamel (n = 15) and to enamel morphology analysis (n = 5) after Er:YAG laser preparation as follows: Group I – 37% phosphoric acid (PA)+ ExciTE®; Group II – ExciTE®; Group III – AdheSE® self-etching; Group IV – FuturaBond® no-rinse. NR; Group V – Xeno® V. Teeth were treated with the adhesive systems and subjected to thermal cycling. SBS were performed in a universal testing machine at 5 mm/min.Statistical Analysis Used:One-way ANOVA and post-hoc tests (P < 0.05). For the morphology evaluation, specimens were immersed in Ethylenediamine tetraacetic acid (EDTA) and the etching pattern analyzed under Scanning Electron Microscope (SEM).Results:Mean bond strengths were Group I – 47.17 ± 1.61 MPa (type I etching pattern); Group II – 32.56 ± 1.64 MPa, Group III – 29.10 ± 1.34 MPa, Group IV – 23.32 ± 1.53 MPa (type III etching pattern); Group V – 24.43 MPa ± 1.55 (type II etching pattern).Conclusions:Different adhesive systems yielded significantly different SBSs. Acid etching significantly increased the adhesion in laser treated enamel. No differences in SBS values were obtained between AdheSE® and ExciTE® without condition with PA. FuturaBond® NR and Xeno® V showed similar SBS, which was lower in comparison to the others adhesives. No correlation between enamel surface morphology and SBS values was observed, except when PA was used.

Palladium nanoparticles supported on carbon Vulcan XC72 (Pd/C) and biocarbon (Pd/BC) synthesized by sodium borohydride process were used as catalysts for ethanol electro-oxidation in alkaline media. The biocarbon (BC) from coconut shell with mesoporous and high surface area (792 m 2 g −1) was obtained by carbonization at 900 °C and the hydrothermal treatment in a microwave oven. The D-band and G-band intensity ratio (I D /I G) from Raman analysis showed high disorder of the biocarbon, while X-ray photoelectron spectroscopy (XPS) suggests higher percentage of oxygen groups on the surface of biocarbon than of Vulcan XC72. From X-ray diffraction (XRD), it was observed peaks in 2θ degree related to the face centered cubic (fcc) structure of palladium and the mean crystallite sizes calculated based on the diffraction peak of Pd (220) were 5.6 nm for Pd/C and 5.3 nm for Pd/BC. Using Transmission Electron Microscope (TEM), it was observed particles well dispersed on both carbons support materials. The electrocatalytic activity of the materials was investigated by cyclic voltammetry (CV) and chronoamperometry (CA) experiments. The peak current density (on CV experiments) from ethanol electro-oxidation on Pd/BC was 50% higher than on Pd/C, while the current density measured at 15 min of CA experiments was 80% higher on Pd/BC than on Pd/C. The higher catalytic activity of Pd/BC might be related to the large surface area of the biocarbon (792 m 2 g −1) vs (239 m 2 g −1) of Vulcan carbon, the defects of the biocarbon structure and higher amount of oxygen on the surface than Carbon Vulcan XC 72.

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Ozone is an important disinfecting agent, however its influence on enamel adhesion has not yet been clarified.Objective:Evaluate the influence of ozone pretreatment on the shear strength of an etch-and-rinse and a self-etch system to enamel and analyze the respective failure modes.Material and Methods:Sixty sound bovine incisors were used. Specimens were randomly assigned to four experimental groups (n=15): Group G1 (Excite® with ozone) and group G3 (AdheSE® with ozone) were prepared with ozone gas from the HealOzone unit (Kavo®) for 20 s prior to adhesion, and groups G2 (Excite®) and G4 (AdheSE®) were used as control. Teeth were bisected and polished to simulate a smear layer just before the application of the adhesive systems. The adhesives were applied according to the manufacturer's instructions to a standardized 3 mm diameter surface, and a composite (Synergy D6, Coltene Whaledent) cylinder with 2 mm increments was build. Specimens were stored in 100% humidity for 24 h at 37º C and then subjected to a thermal cycling regimen of 500 cycles. Shear bond tests were performed with a Watanabe device in a universal testing machine at 5 mm/min. The failure mode was analyzed under scanning electron microscope. Means and standard deviation of shear bond strength (SBS) were calculated and difference between the groups was analyzed using ANOVA, Kolmogorov-Smirnov, Levene and Bonferroni. Chi-squared statistical tests were used to evaluate the failure modes. Results:Mean bond strength values and failure modes were as follows: G1- 26.85±6.18 MPa (33.3% of adhesive cohesive failure); G2 - 27.95±5.58 MPa (53.8% of adhesive failures between enamel and adhesive); G3 - 15.0±3.84 MPa (77.8% of adhesive failures between enamel and adhesive) and G4 - 13.1±3.68 MPa (36.4% of adhesive failures between enamel and adhesive).Conclusions:Shear bond strength values of both adhesives tested on enamel were not influenced by the previous application of ozone gas.

Recebido em 20/8/07; aceito em 4/11/08; publicado na web em 25/3/09 TOYS CONTAMINED BY TOXIC SUBSTANCES. The main goal of the present study is the analysis of toxic elements in plastic toys commercialized in Brazil. Metals like cadmium, lead, chromium, zinc, and aluminum, along with organic substances, such as phthalates, were identified in different toys by quantitative analytical techniques. Traces of thorium were detected in one of the studied samples. Although the measured radioactive dose was rather low, the presence of such a radioactive contaminant is against to the International Agency of Atomic Energy regulations. Similar toys manufactured in Brazil were analyzed and found to observe the standards defined by the National Institute of Metrology (Inmetro). introduÇÃo Neste trabalho faz-se um alerta de que brinquedos de plásticos, provenientes de países asiáticos e utilizados normalmente por crian-ças, contêm quantidades de substâncias perigosas à saúde as quais, segundo trabalho prévio, 1 se encontram acima do limite permitido pelo Inmetro. 2 Além de metais como cádmio, chumbo, cromo, mercúrio, alumínio, cobre e tório, foram detectados altos teores de ftalatos, substâncias adicionadas ao plástico para fornecer flexibilidade a este material. Há algum tempo pesquisadores estudam os danos que podem ser causados pelo uso prolongado de utensílios plásticos que contenham ftalatos em suas composições, como copos, pratos, garrafões para água mineral e mamadeiras, que podem causar sérios danos à saúde, afetando principalmente a fertilidade e a capacidade reprodutiva. 3,4 Elementos tóxicos como arsênico, cádmio, cromo, níquel e anti-mônio assim como elementos não tóxicos como bário, cálcio, cobalto, ferro, escândio, selênio e zinco já foram encontrados em amostras de embalagens plásticas metalizadas. 5 Os autores deste trabalho, em estudos anteriores, identificaram elementos tóxicos em amostras de bonecas de PVC e látex, como chumbo, cromo e cádmio, em teores significativos. 1 Com relação a estes elementos pode-se citar que a ingestão de chumbo pode levar a distúrbios de comportamento, dificuldade de concentração e de aprendizado e, em casos graves, contamina o sistema nervoso, a medula óssea e os rins. O risco é maior para crianças e para gestantes, pois o chumbo interfere nos processos genéticos ou cromossômicos e produz alterações na estabilidade da cromatina, como comprovado em cobaias, inibindo reparo de DNA e agindo como agente cancerígeno. 5 Os compostos de cromo, por sua vez, produzem reações cutâneas, nasais, bronco-pulmonares, renais, gastrointestinais e carcinogênicas. As cutâneas são caracterizadas por irritação no dorso das mãos e dos dedos, podendo transformar-se em úlceras. As lesões nasais iniciam-se com um quadro irritativo inflama-tório, supuração e formação crostosa. Em níveis bronco-pulmonares e gastrointestinais, produzem irritação bronquial, alteração da função respiratória e úlceras gastroduodenais. 1 Já o cádmio, mesmo em doses mínimas, provoca envenenamento grave e prolongado ocasionando, t...