The Impact of Artificial Aging on the Color Stability and Hardness of Nanocomposite Resin

Likai Wang,Yan Zheng

doi:10.3389/fmats.2021.722131

Likai Wang, Yan Zheng

Open Access

https://doi.org/10.3389/fmats.2021.722131

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Abstract

Objective: This study aimed to investigate the impact of artificial aging on the color stability and hardness of nanocomposite resin.Methods: Four nanocomposite resin materials were used: Filtek Z350 XT (FZ), Synergy D6 (SD), Grandio (GD), and Clearfil Majesty Esthetic (CM). Thirty specimens were created from each material, which were divided into three (A,B,C) groups of 10 specimens each. For each material, the values of visual lightness (L*), degree of redness and greenness (a*), and degree of yellowness and blueness (b*) of the specimens in group A before and after aging, as well as the hardness of the specimens in group B before aging and in group C after aging, were measured. The American Society for Testing and Materials (ASTM) G155 Cycle 1 standard was adopted to test the aging of the specimens. The color difference (ΔE00) value and hardness difference (ΔH) value of the specimens before and after aging were calculated.Results: Aging was found to have an impact on the ΔE00 values of the resin materials in each group (H = 17.6, p = 0.001), and the hardness of the specimens in each group after artificial aging was significantly higher than before aging (p &lt; 0.05). The difference in ΔE00 between the FZ group and the SD, GD, and CM groups was statistically significant (p &lt; 0.05). The FZ group had the highest ΔE00 values. There was no correlation between ΔE00 and the hardness change percentage after aging (r = 0.114).Conclusion: Among the four nanocomposite resins tested in this study, except for Filtek Z350 XT’s ΔE00 values (&gt;1.8) in the clinically unacceptable range, the remaining three kinds of resin ΔE00 values (&lt;1.8) were all in the clinically acceptable range. The hardness of the four nanocomposite resins increased after aging. The results of the present study revealed that there was no correlation between ΔE00 and hardness change percentage in the four nanocomposite resin materials after aging.

Highlights

Composites are popular restorative materials in dental practice (Vidal et al, 2020)
The results showed that the L* values of all the materials groups decreased after aging, and there was significant difference in the L* values among all groups (p < 0.05). a* value was increased in FZ, SD and GD groups, but decreased in CM group
The results showed that there was a statistical difference in hardness values H0 before aging among all groups (p < 0.05)

Summary

Introduction

Composites are popular restorative materials in dental practice (Vidal et al, 2020). The application of nanotechnology to composite resin has been an important recent advancement in the field as it has improved the biological properties of composite resin (Paravina et al, 2015), but researchers have been concerned about nanocomposite resin’s resistance to aging. The application of composite resins in dental restoration requires consideration of the resin’s mechanical, aesthetic, and clinical properties, which depend on its structure. Dental composite resins are composed of three materials with different chemical properties: an organic matrix, an inorganic filler or dispersed phase, and an organic silane or coupling agent to combine the filler and the organic matrix (Nasim et al, 2010). Nanocomposite resins emerged in the late 20th century They are composed of two or more kinds of materials, composited in at least one dimension, with nanometer sizes of 1–100 nm. The diameter of the filler can be reduced and its content and gradient distribution range increased, thereby reducing polymerization shrinkage and improving the mechanical and optical properties of the composite resin (Moszner and Klapdohr, 2004)

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