Recebido em 27/1/04; aceito em 2/8/04; publicado na web em 12/11/04Two high performance liquid chromatography (HPLC) methods for the quantitative determination of indinavir sulfate were tested, validated and statistically compared. Assays were carried out using as mobile phases mixtures of dibutylammonium phosphate buffer pH 6.5 and acetonitrile (55:45) at 1 mL/min or citrate buffer pH 5 and acetonitrile (60:40) at 1 mL/min, an octylsilane column (RP-8) and a UV spectrophotometric detector at 260 nm. Both methods showed good sensitivity, linearity, precision and accuracy. The statistical analysis using the t-student test for the determination of indinavir sulfate raw material and capsules indicated no statistically significant difference between the two methods.
This study investigated the effects of oxygen inhibition and finishing/polishing procedures on the composite resin properties. One bulk-fill and two conventional composite resins (nanoparticle and microhybrid) were evaluated. Specimens were prepared using 4 surface treatments: control, no treatment; Gly, oxygen inhibition with glycerin; FP, finishing and polishing; Gly + FP, glycerin followed by finishing and polishing. The degree of conversion (DC) was measured using Fourier Transformed Infrared Spectroscopy (FTIR) immediately and after 15 days (n=5). Color stability (ΔEab, and ΔE00) and opacity were evaluated using a spectrophotometer after 15 days of immersion in coffee, using the CIELAB system (n=5). Data were analyzed by two-way ANOVA and Tukey tests (α=0.05) and opacity by two-way repeated-measures ANOVA. Glycerin usage increased significantly the DC however had no influence on the ΔEab, ΔE00 and, opacity values. Finishing and polishing reduced ΔEab and ΔE00 values, regardless of composite resins. Microhybrid showed higher opacity, followed by the nanoparticle and bulk fill, regardless of surface treatment. Post-polymerization polishing procedures resulted in lower conversion than using an oxygen inhibitor agent (Gly condition), but similar staining caused by coffee.
This study evaluated the influence of the previous application of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) on the bond strength of two restorative systems to dentin. Self-etching adhesive systems Clearfil SE Bond (Kuraray) and FiltekTM LS System Adhesive (3M ESPE) were used in combination with two micro-hybrid composites FiltekTM Z250 (3M ESPE) and FiltekTM LS (3M ESPE), respectively. Twenty-eight sound human third molars had the occlusal surface worn until the total exposure of dentin and were randomly divided into 4 groups (n = 7): G1 (Clearfil + Z250), G2 (CPP-ACP + Clearfil + Z250), G3 (LS system) and G4 (CPP-ACP + LS system). The application of the paste containing CPP-ACP was held in the dentin of G2 and G4 prior to adhesive protocol, which followed the manufacturer's recommendations. Two cylinders of a single increment of resin composite were built on each dentin surface using tygon`s matrix with 1.26 mm of diameter x 1 mm high and light-cured with LED Bluephase 16i (Vivadent) apparatus. Microshear bond strength test was conducted in a universal testing machine (EZ Test, Shimadzu) with a speed of 0.5 mm/min. The data were subjected to two-way ANOVA test with a significance of 5%. There was no significant difference on bond strength between restorative systems with or without the previous use of a CPP-ACP paste. It was concluded that the application of CPP-ACP in the dentin prior to adhesive protocol did not influence the bond strength of the restorative systems tested.
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