The purpose of this study was to evaluate the transmittance of seven different composite resins. Ten specimens were prepared (10 mm diameter, 2 mm thickness) for each experimental group, as follows: G1- Charisma® A2 (Heraeus-Kulzer); G2- FiltekTM Supreme A2E (3M/ESPE); G3- FiltekTM Supreme A2B (3M/ESPE); G4-FiltekTM Supreme YT (3M/ESPE); G5- Esthet-X® A2 (Dentsply); G6- Esthet-X® YE (Dentsply); G7- Durafill® A2 (Heraeus-Kulzer) and G8- FiltekTM Z-100 A2 (3M/ESPE). The transmittance mode was measured using a UV-visible spectrophotometer (Cary Instruments) at 400-760 nm. The specimens were evaluated at three different times: zero hour (initial), 24 hours and 10 days after immersion in artificial saliva. The differences in transmittance were determined by two-way analysis of variance (ANOVA) and Tukey's test. The various composite resins showed significant differences in the wavelength dependence of transmittance. The mean values of transmittance increased significantly, with wavelengths increasing from 400 to 760 nm. The performance of the experimental groups was similar in terms of immersion time, considering that at time zero and after 10 days, all the groups showed similar results, which were statistically higher than the values obtained after 24 hours of immersion. The FiltekTM Supreme YT composite resin presented the highest mean transmittance values along the wavelengths at the three measured times. Esthet-X® YE and Durafill® yielded similar mean transmittance values, which were higher than those of the other groups. This study shows that the transmittance values of composite resins are directly related with the type, size and amount of inorganic filler particles.
The aim of the present work was to carry out experimental comparison between humic substances (HS) and representative alpha-amino acids (methionine, methionine sulfoxide and cysteine hydrochloride) in relation to the complexation of biologically active trace elements (Al, Cu, Pb, Mn, Zn, Cd and Ni). A mobile time-controlled tangential-flow UF technique was applied to differentiate between HS-metal and alpha-aminoacids-metal complexes. Metal determinations were conventionally carried out using a ICP-OES. The results showed that HS may be considered as a selective complexing agents with higher metal bonding capability in relation to Al, Cu and Pb, the fact that may be clinically important.
O objetivo deste trabalho foi comparar a complexação de substâncias húmicas (SH) e alfa-aminoacidos (metionina, metionina sulfoxido e cloridrato de cisteína) por elementos traço de interesse biológico (Al, Cu, Pb, Mn, Zn, Cd e Ni). Sistema de ultrafiltração tangencial foi utilizado para diferenciação entre os complexos SH-metal e alfa-aminoácidos-metal. As determinações de metal foram feitas utilizando ICP-OES. Os resultados mostraram que as SH podem ser consideradas agentes complexantes seletivos com alta capacidade de complexação a Al, Cu e Pb, podendo ser clinicamente importante.