Effect of two fluorescent dyes on color of restorative materials

The objective of these two studies was to determine whether the use of dyes in vitro would affect the shade of tooth-colored restorative materials.

Two separate studies were performed. In Study 1, four groups (N = 36) of restorative materials; (1) resin composite (RSN), (2) resin-modified glass ionomer (RMGI), (3) conventional glass ionomer (CGI), and (4) porcelain (PCN), were subjected to a rinse in either tap water (control) or Pyrromethene 556 dye at a concentration of 0.01M for 30 seconds or 0.0015 M for 60 seconds. They were then rinsed with 25% ethanol as would be done in clinical usage. In Study 2, the same restorative materials (except PCN) were subjected to a rinse in either tap water (control) (N = 8) or 0.0018 M sodium fluorescein (N = 8) for 60 seconds followed by a 5-second rinse with tap water. For both studies the specimens were analyzed for overall color changes (delta E*) comparing baseline to immediately post dye exposure and then again after 1, 4, 24, and 48-hour storage under running tap water. In addition, an image of each specimen, illuminated under an argon laser light (HGM), was captured with a miniature charged-coupled device (CCD) color camera at the same time intervals when the color was measured. These images were analyzed for fluorescence using computer assisted methods. A software program then computed the mean and standard deviation of the fluorescence values for each image. The data were analyzed using repeated measures ANOVA.

delta E* values from baseline on specimens treated with either Pyrromethene 556 or sodium fluorescein were not significantly different from water at any time. The only exceptions were CGI specimens exposed to 0.01 M Pyrromethene 556 and RMGI exposed to sodium fluorescein which had a higher delta E* immediately after treatment, however this effect was reversed after 1-hour rinse. Mean delta E* was less than 2.69 for specimens treated with Pyrromethene 556 and less than 3.20 for specimens treated with sodium fluorescein after 1-hour rinse in water. When the mean fluorescence level, as determined by the computer, was averaged there was no difference between the Pyrromethene 556 treatments and control for RMGI, RSN and PCN after 4-hour rinse in water and, as time in storage increased, the fluorescence level decreased. CGI treated with 0.01 M Pyrromethene 556 was significantly more fluorescent even after 48-hour rinse in water. All specimens treated with sodium fluorescein were also significantly more fluorescent than control even after 48-hour rinse in water. It was concluded that exposure of these restorative materials to Pyrromethene 556 at 0.01 M or 0.0015 M or to 0.0018 M sodium fluorescein will not lead to any prolonged visually detectable color changes.