Effect of Modeling Liquids on Properties of Resin Composites

Objectives: Modelling liquids (ML) have been used to facilitate handling of resin composite restorations. This study aims to evaluate the properties of resin composites placed with the use of different ML.
Methods: Resin composite specimens (Nanofilled Filtek Supreme Ultra, 3M – NF; Nanohybrid Empress Direct, Ivoclar Vivadent - NH; Suprananomeric Estellite Omega, Tokuyama - SN), all in shade A1E, were prepared with the use of ML applied at 3 levels: control – without modeling (C), wetting resin – Ultradent (WR), modeling resin - Bisco (MR). A total of 9 groups (n=25) with 15 bar-shaped (2x2x8 mm) and 10 disk-shaped (ø 10x1.5 mm) samples were developed: 1-) NF/C, 2-) NF/WR, 3-) NF/MR, 4-) NH/C, 5-) NH/WR, 6-) NH/MR, 7-) SN/C, 8-) SN/WR, 9-) SN/MR. A polywave light-curing unit was used to light-activated 1 mm increments for 20 s. Flexural strength (three-point bending), roughness (optical microscope VHX-7000N, Keyence, Tokyo, Japan), and microhardness (µHV HMV-G31DT, Shimadzu, Tokyo, Japan) were assessed. Color stability was measured at baseline and after brushing and storage in cola dink using a spectrophotometer (Easy Shade V, Vita Zahnfabrik, Bad Säckingen, Germany). Kruskal-Wallis/Friedman tests were applied for flexural strength and ANOVA/Tukey were applied for roughness and microhardness (5% significance level).
Results: NF resin composite presented superior flexural strength in comparison with both NH (p<0.001) and SN (p<0.002). The addition of ML increased flexural strength for NH/WR and SN/MR, which were similar to NF/C. Two-way ANOVA showed a significant effect of the interaction resin composite/ML for µHV and roughness. Color stability of NH and SN were affected by the presence of ML, being Delta-E_oo of NH/WR and SN/WR greater than 3.
Conclusions: ML use does not impair the flexural strength of resin composites. Differences in surface roughness were observed in groups with ML. WR modeling liquid resulted in clinically observable staining of NH and SN composites.