Degree of conversion of Z250 composite determined by fourier transform infrared spectroscopy: comparison of techniques, storage periods and photo-activation methods

The purpose of this study was to evaluate the degree of conversion (DC) of the Z250 composite, using six photo-activation methods, two storage periods and two preparation techniques of the FTIR specimens (n = 3). For the KBr pellet technique, the composite was placed into a metallic mold and photo-activated as follows: continuous light, exponential light, intermittent light, stepped light, PAC and LED. The measurements were made after 24 h and 20 days. For the resin film technique, approximately 0.07 g of the composite was pressed between two polyester strips, photo-activated as above described and analyzed. The DC was calculated by the standard technique and submitted to ANOVA and Tukey's test (alpha = 5%). Independently of the storage period and specimen preparation technique, there were no significant differences among photo-activation methods. No statistical difference was observed between the time periods used. The specimens analyzed under the KBr pellet technique presented higher DC values than those analyzed by the resin film technique

Influence of different light-curing units on the surface roughness of restorative materials: in situ study

The aim of this study was to evaluate the influence of different light sources (LED and Halogen lamp) on the roughness (superficial) of composite resin (Filtek Z250, Filtek P60, Charisma and Durafill) varying post-irradiation times, in an in situ experiment. For this purpose, 80 specimens were made in polyurethane moulds. Ten volunteers without medicament use and good oral condition were selected and from them study moulds were obtained. A palatal intra-oral acrylic resin appliance was made for each of the subjects of the experiment. In each appliance, two specimens of each material were fixed (LED/Halogen lamp - control group). Roughness tests were performed immediately and 30 days after initial light-curing. Statistical analysis was performed using ANOVA. Statistically significant difference was observed only between post-irradiation times, where the 30th day showed the highest roughness values. It be concluded that roughness was influenced only by post-irradiation times, presenting the 30- days period inferior behavior