Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Mar 6;16(5):2130.
doi: 10.3390/ma16052130.

Effect of Hydrothermal Factors on the Microhardness of Bulk-Fill and Nanohybrid Composites

Daniel Pieniak  1   2 , Agata M Niewczas  3 , Konrad Pikuła  3 , Leszek Gil  2 , Aneta Krzyzak  4 , Krzysztof Przystupa  5 , Paweł Kordos  6 , Orest Kochan  7   8
Affiliations

Effect of Hydrothermal Factors on the Microhardness of Bulk-Fill and Nanohybrid Composites

Daniel Pieniak et al. Materials (Basel). .

Abstract

This study evaluates the effect of aging in artificial saliva and thermal shocks on the microhardness of the bulk-fill composite compared to the nanohybrid composite. Two commercial composites, Filtek Z550 (3M ESPE) (Z550) and Filtek Bulk-Fill (3M ESPE) (B-F), were tested. The samples were exposed to artificial saliva (AS) for one month (control group). Then, 50% of the samples from each composite were subjected to thermal cycling (temperature range: 5-55 °C, cycle time: 30 s, number of cycles: 10,000) and another 50% were put back into the laboratory incubator for another 25 months of aging in artificial saliva. The samples' microhardness was measured using the Knoop method after each stage of conditioning (after 1 month, after 10,000 thermocycles, after another 25 months of aging). The two composites in the control group differed considerably in hardness (HK = 89 for Z550, HK = 61 for B-F). After thermocycling, the microhardness decrease was for Z550 approximately 22-24% and for B-F approximately 12-15%. Hardness after 26 months of aging decreased for Z550 (approximately 3-5%) and B-F (15-17%). B-F had a significantly lower initial hardness than Z550, but it showed an approximately 10% lower relative reduction in hardness.

Keywords: bulk-fill dental composites; hydrothermal degradation; microhardness; thermocycling.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Schematic of the course of testing the dental composite samples.
Figure 2
Figure 2
The image of an indentation left by the Knoop indenter.
Figure 3
Figure 3
The results of Knoop hardness measurements for Z550 after aging in artificial saliva (AS) for one month. LC—light-cured surface of sample (top side of sample), NLC—non-light-cured surface (bottom side of sample), HK—Knoop hardness.
Figure 4
Figure 4
The results of Knoop hardness measurements for B-F after aging in artificial saliva (AS) for one month. LC—light-cured surface of sample (the top side of a sample), NLC—non-light-cured surface (the bottom side of a sample), HK—Knoop hardness.
Figure 5
Figure 5
The results of Knoop hardness measurements for Z550 after thermocycling (TC). LC—light-cured surface of sample (top side of sample), NLC—non-light-cured surface (bottom side of sample), HK—Knoop hardness.
Figure 6
Figure 6
The results of Knoop hardness measurements for B-F after thermocycling (TC). LC—light-cured surface of sample (top side of sample), NLC—non-light-cured surface (bottom side of sample), HK—Knoop hardness.
Figure 7
Figure 7
The results of Knoop hardness measurements for Z550 after aging in artificial saliva (AS) for 26 months. LC—light-cured surface of sample (the top side of a sample), NLC—non-light-cured surface (the bottom side of a sample), HK—Knoop hardness.
Figure 8
Figure 8
The Knoop hardness test results for B-F after aging in artificial saliva (AS) for 26 months. LC—light-cured surface of sample (the top side of a sample), NLC—non-light-cured surface (the bottom side of a sample), HK—Knoop hardness.
See this image and copyright information in PMC

References

    1. Siejka-Kulczyk J., Lewandowska M., Rokicki G., Szafran M., Kurzydłowski K.J. Degradation processes in dental ceramic-polymer composites. Kompoz. Compos. 2006;6:50–54.
    1. Finlay N., Hahnel S., Dowling A.H., Fleming G.J. The in vitro wear behavior of experimental resin-based composites derived from a commercial formulation. Dent. Mater. 2013;29:365–374. doi: 10.1016/j.dental.2012.12.005. - DOI - PubMed
    1. Ferracane J.L. Resin composite—State of the art. Dent. Mater. 2011;27:29–38. doi: 10.1016/j.dental.2010.10.020. - DOI - PubMed
    1. Elfakhri F., Alkahtani R., Li C., Khaliq J. Influence of filler characteristics on the performance of dental composites: A comprehensive review. Ceram. Int. 2022;48:27280–27294. doi: 10.1016/j.ceramint.2022.06.314. - DOI
    1. Shalaby S., Salz U. Polymers for Dental and Orthopedic Applications. CRC Press; Boca Raton, FL, USA: 2019.