AUTHOR=Farghal Nancy Soliman , Abu Shamleh Ayya , Al Hurmuzi Osamah , Mahmoud Okba 

TITLE=The effects of a carbonated beverage on the optical properties and microhardness of preheated bulk-fill composite resin restorations

JOURNAL=Frontiers in Oral Health

VOLUME=Volume 6 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/oral-health/articles/10.3389/froh.2025.1539527

DOI=10.3389/froh.2025.1539527

ISSN=2673-4842

ABSTRACT=IntroductionPreheating the high-viscosity forms of bulk-fill resin composites is recommended to enhance their flow and adaptability. Nevertheless, the impact of preheating on their characteristics upon exposure to carbonated beverages remains unclear. This study aims to evaluate the effect of a Cola beverage on the properties of preheated and non-preheated high-viscosity bulk-fill composite resins in vitro.MethodsForty disc-shaped specimens were prepared from each of BEAUTIFIL-Bulk Restorative (BB) and Filtek One Bulk-fill (FOB) composite resin, then divided into two groups (n = 20), either preheated to 68°C for 15 min or kept at room temperature before polymerization, then specimens were immersed in Alkozay Cola beverage for 30 days (3 periods of 15 min/day). Color stability (ΔE00), surface gloss (GU) and Vickers Microhardness (VHN) were recorded before and after the Cola immersion. The data was analyzed with Two-way ANOVA, Three-way ANOVA and Tukey's HSD post hoc test using SPSS software at 95% significance level.ResultsThe color change was significantly higher in BB than FOB in all groups (P < 0:001), FOB had a significant reduction in color change after preheating (P < 0.05) while BB had no significant change (P > 0.05). Preheating significantly increased the gloss of BB and reduced that of FOB (P < 0.001), however, Cola beverage significantly reduced the gloss of all the groups (P < 0.001). Preheating significantly increased the microhardness of both materials (P < 0.001), however, Cola beverage significantly reduced the microhardness of all the groups (P < 0.001).ConclusionAlthough the preheating of high-viscosity bulk-fill composites significantly improved their microhardness and improved the surface gloss of FOB, it did not protect both composites against the Cola drink attack. Preheated FOB showed improved color stability after the Cola immersion, but not to a clinically acceptable limit.