فهرست مطالب a. mahmoudi nahavandi

Fluorescence of natural teeth and its alterations due to environmental factors should also be taken into account in restorations. This study aims to assess fluorescence changes of three types of dental ceramics. 36 Ceramics of Feldspathic, Emax, and Enamic in 10 mm diameter and the thicknesses of 0.5 and 1mm with glaze and polish finishes were studied. Fluorescence was measured before and after aging and were analyzed using Anova test. The results showed that ceramics became opaque as the result of aging. This was more noticeable for Enamic ceramic  with the lightness increase of 4.10 and 4.86 for the UV excited and non-excited measurements, respectively. Moreover, Enamic ceramic experienced significant changes in its fluorescence due to aging (Average Fluoresence ChangeEnamic=-10.2) while Emax (Average Fluoresence ChangeEmax=-3.6) and feldspathic (Average Fluoresence ChangeFeldspathic=-0.4) ceramics were superior to Enamic in this respect. In Feldspathic ceramic, due to the presence of feldspar phase, high resistance to aging process was observed. While, severe shifts in fluorescence due to aging were observed in Enamic ceramic. Several factors affect color and fluorescence change of ceramics due to aging. Preparations stresses, adhesion of glazes and the formation of micro cracks on the ceramic surfaces are among the factors can influence on this behavior. In case on Enamic ceramic caveat should be taken as it can change its appearance due to fluorescence hue shift probably as a result of surface scattering of UV light. According to the findings of this study Feldspathic, Emax and Enamic are respectively preferable in terms of fluorescence stability during aging process.

In this study, the response surface method (RSM) of the central composite design model was used to optimize the extraction of dyes in madder plant root by a shaker-incubator. The optimum conditions for the assessed parameters including pH, time and temperature was 6.57, 63.88 min and 47.46 °C, respectively. Each experiment’s response was determined by assessing light absorption intensity at 413 nm. Experiments to obtain optimum condition out of the chosen model show that there is a very insignificant difference between the model’s absorption and our experimental method. To prepare powder of the extracted dye material, we extracted the dye through four steps. The resulted solution was condensed by a rotary machine in vacuity. Then it was added to a formulation that encompasses filling materials and superficial active materials agents. The results imply that the prepared powder can dye wool thread which in turn showed stable properties involved wash fastness of 4-5, light fastness of 4-5 and rubbing fastness of 3-5.