In vitro cytotoxicity of indirect composite resins: effect of storing in artificial saliva.

AIM: The aim of this study was to compare the cytotoxic effects of two indirect composite resins (Artglass and Solidex) on the viability of L-929 fibroblast cells at different incubation periods by storing them in artificial saliva (AS). MATERIALS AND METHODS: Disk-shaped test samples were prepared according to manufacturers' instructions. Test materials were cured with light source (Dentacolor XS, Heraus Kulzer, Germany). The samples were divided into two groups. The first group's samples were transferred into a culture medium for 1 hour, 24 hours, 72 hours, 1 week and 2 weeks. The other group's samples were transferred into a culture medium for 1 hours, 24 hours, 72 hours, 1 week, and 2 weeks after being stored in AS for 48 hours. The eluates were obtained and pipetted for evaluation onto L-929 mouse fibroblast cultures incubated for 24 hours. Measurements were performed by MTT (3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The degree of cytotoxicity for each sample was determined according to the reference values represented by the cells with a control group. RESULTS: Statistical significance was determined by ANOVA. Both groups presented lower cell viability in comparison to the control group at all periods. Storing in artificial saliva reduced cytotoxicity significantly (P < 0.05). Stored Artglass and Solidex showed similar effects on cytotoxicity. Nonstored Solidex samples were found more cytotoxic than Artglass samples. The cell survival rate results of 24-hour incubation period were significantly lower than those of the other experimental periods (P < 0.05). CONCLUSION: Storing indirect composite resins in AS may reduce cytotoxic effects on the fibroblast cells. However, resin-based dental materials continue to release sufficient components to cause cytotoxic effects in vitro after 48 hours of storing in AS.

Color stability of glazed and polished dental porcelains.

PURPOSE: The purpose of this study was to compare the visual and colorimetric color stability of two ultra low-fusing and three conventional low-fusing porcelains on both glazed and polished surfaces. MATERIALS AND METHODS: Twelve disks, 10 mm in diameter and 3 mm in thickness, were fabricated for each porcelain. Specimens were glazed using their specific glaze materials. For each type of porcelain, the specimens were divided into two groups: one group was immersed in methylene blue and the other group in distilled water as a control. The surfaces were visually examined for staining without magnification. Objective color measurement was performed for each sample using a Tristimulus colorimeter. After examining the color of the glazed specimens, glazed layers were removed from the surface of the specimens to simulate an intraoral environment. Then, porcelain polishing points and diamond polishing paste were applied. The samples were immersed again in methylene blue and distilled water, and after removing from the staining solution and distilled water, visual and objective measurements were performed again. RESULTS: Visually discernible stain was present on the polished groups of all five porcelains immersed in methylene blue, whereas the glazed group immersed in methylene blue showed no staining. No staining was observed with glazed and polished samples immersed in distilled water. The objective evaluation showed that the polished porcelain surface of all five porcelain products had statistically significant color deviation than the glazed surface in the same group after immersion in methylene blue. The results of this study show a statistically significant difference in color stability between the polished and glazed specimens. CONCLUSION: It may be concluded that the glazed specimens showed a better color stability, although the staining observed in the polished specimens was not clinically noticeable.