Effects of Sports Drinks on the Microhardness of Composite Materials

Objectives: The purpose of this study was to determine the effect of acidic sports drinks on surface hardness of polyacid-modified resin composite, microhybrid composite and nanofilled composites. Methods: One hundred sixty eight disc-shaped specimens (8 mm in diameter and 2-mm thick) were made for each composite. After 24 hours, all specimens were polished with Sof-Lex disks and the baseline microhardness was then measured using a Vickers hardness measuring instrument with a 200-g load for 15 seconds. After the baseline evaluation, seven specimens of each experimental group were immersed in the following storage solutions: distilled water (control), Powerade, Ixir, Gatorade, Burn, and Redbull for 1 week and 1 month, and microhardness values of each specimen was re-evaluated. Data were statistically analyzed by using two-way repeated ANOVA and followed by Bonferroni's multiple comparison test (á = 0.05). Results: Statistical analysis revealed that all storage solutions significantly decreased microhardness values of polyacid-modified resin composite, microhybrid composite and nanofilled composites at the different storage time (p<0.05). All materials tested had various softening characteristics depending on the types of storage solutions. Sports drinks significantly reduced microhardness for all materials, compared with the distilled water (p<0.05). Conclusion: The storage solutions tested and immersion time were significant factors on the reduction of surface microhardness of restorative materials. Distilled water storage had less effect on microhardness over time compared with the other solutions.