# Effect of immersion in different media on the color stability, surface roughness, and microhardness of flowable nanohybrid resin composites

## TL;DR

This study tested how different liquids affect the color, roughness, and hardness of dental resin composites.

## Contribution

The study provides new empirical data on how various immersion media impact flowable nanohybrid resin composites.

## Key findings

- Energy drinks caused the most significant discoloration and increased roughness in tested resin composites.
- All tested media reduced microhardness of the resin composites compared to the control.
- Polofil NHT Flow showed the highest increase in surface roughness after immersion in energy drinks.

## Abstract

To evaluate color stability, surface roughness, and microhardness of flowable nanohybrid resin composites following immersion in different media.

Polofil NHT Flow (VOCO GmbH), G-aenial Universal Injectable (GC DENTAL PRODUCTS CORP), and Tetric N-Ceram (Ivoclar Vivadent) were used. From each tested resin composite, 50 disc-shaped specimens (10-mm diameter × 2-mm thickness) were performed. Each group was categorized into five subgroups according to immersion media (n = 10): (1) control (without immersion), (2) artificial saliva, (3) coffee, (4) cola, and (5) energy drink. Color stability, surface roughness, and microhardness were evaluated. Data were analyzed through two-way ANOVA, Tukey’s post-hoc, and Pearson correlation coefficient tests (p < 0.05).

For color change, no statistically significant differences were observed among the resin composites regarding artificial saliva (p = 0.78), coffee (p = 0.93), and cola (p = 0.09), while there was a significant difference between them regarding energy drink (p < 0.05). The highest surface roughness mean value was recorded with Polofil NHT Flow, which showed an increase in surface roughness after immersion in energy drink (0.32 ± 0.06 μm) compared to the control subgroup (0.22 ± 0.08 μm). For all resin composites, there were significant reductions in microhardness with all immersion media in comparison to the control subgroups (p < 0.05).

For color stability, energy drink and coffee had the most negative effect on all tested resin composites. Energy drink caused the highest discoloration with G-aenial Universal Injectable and the highest roughness with Polofil NHT Flow. All tested resin composites showed a decrease in surface microhardness following immersion in all tested immersion media.