Influence of Cola-Based Soft Drinks on the Microhardness of Nanohybrid and Bulk Fill Composites

Abstract

Introduction: Bulk fill composites have been introduced in the past few years and appear to solve some of the disadvantages of conventional composites such as polymerisation contraction and the consequent marginal microinfiltration. Aim: To evaluate the surface microhardness of the Z350 and the Bulk fill composites when immersed in distilled water, for 24 hours, and immersed in Coca-Cola™, along with distilled water, for 30 days. Materials and Methods: Seventy two specimens from each composite were evaluated, being divided into two groups and kept in distilled water at 37°C, for 24 hours and, subsequently, submitted to the Knoop microhardness analysis. After performing the reading, 12 specimens from each composite were individually stored in distilled water and in Coca-Cola Classic™ at 37°C, for 30 days and, then, the Knoop Hardness Number (KHN) value analysis was performed again. Data were submitted to the statistical analysis applying the Kruskal-Wallis test and the Dunn’s post-test (p<0.05). Results: Immersion after 30 days in Coca-Cola™ and distilled water similarly changed KHN values for Z350 and Bulk Fill composites. The analysis between the composites showed statistically significant changes for the group immersed in distilled water, in 24 hours, as well as for the group immersed in Coca-Cola™, with higher KHN for the Z350 composite (57.69±4.15), (p<0.0001). Conclusion: The bulk fill composite presented lower microhardness values than the Z350 composite after immersion in distilled water, for 24 hours, and immersion in Coca-Cola™. However, the immersion in distilled water, for 30 days, did not show differences between the two evaluated composites.

Keywords

• acid solution
• dental erosion
• resin