Influence of Surface Finish on Flexural Strength and Microhardness of Indirect Resin Composites and the Effect of Thermal Cycling

Abstract

This study investigated the effect of surface finish and thermal cycling procedures on flexural strength and surface microhardness of three indirect resin composites, Artglass®, Signum®, and Solidex®. The specimens were prepared in sufficient number and size according to flexural and microhardness test requirements (n = 10). Scanning electron microscopy-energy dispersive x-ray (SEM-EDX) analysis was also used for studying the morphology, dispersion, and elemental compositions of fillers. The EDX results showed that Artglass contained 1.57% aluminium oxide (Al₂O₃), 53.29% silicon dioxide (SiO₂), and 2.62% barium oxide (BaO); Signum had 55.69% silicon dioxide (SiO₂) and Solidex had 44.99% silicon dioxide (SiO₂) of total mass. Artglass appeared to display the best flexural strength values under all the test conditions employed (range: 116.8 ± 32.18 to 147.8 ± 47.97 MPa), and it was followed by Signum (range: 93.7 ± 22.84 to 118.0 ± 33.45 MPa). Thermal cycling did not seem to have affected the flexural strength of Artglass and Signum (p > 0.05); however, it led to a significant decrease, from (110.5 ± 20.69 MPa) to 74.0 ± 13.30 MPa (p < 0.001), in the strength of polished Solidex specimens. While surface microhardness of the three materials increased by polishing (Artglass: 55.7 ± 2.64/74.1 ± 8.63 Vickers Hardness Numbers (VHN); Signum: 44.8 ± 3.12/60.7 ± 4.50 VHN; Solidex: 44.0 ± 2.31/53.4 ± 3.58 VHN for unpolished/polished specimens), thermal cycling had a deleterious effect on this property (p < 0.001).

KEYWORDS:

• Flexural strength
• Indirect resin composite
• Microhardness
• Surface finish
• Thermal cycling

ACKNOWLEDGMENT

Our thanks are extended to Professor Ali Fazil Yenidunya, Cumhuriyet University, Faculty of Science, Department of Molecular Biology and Genetics, for invaluable contribution in the preparation of this manuscript for submission.

Notes

*Data are disclosed by the manufacturers. **Seimenis et al. [14].

Bis-GMA: bisphenol A diglycidylmethacrylate; HEMA: 2-hydroxy ethylmethacrylate; UDMA: urethane dimethacrylate; EGDMA: ethyleneglycoldimethacrylate

n = 10 specimens per experimental condition.

^*Means labeled with the identical letters were significantly different by the Tukey's Test (p < 0.001).

The same capital letters in horizontal rows were the comparison of different indirect resin composites according to the same procedure; the same small letters in vertical columns for the same indirect resin composite according to the different procedures applied.

n = 10 specimens per experimental condition.

*Means labeled with the identical letters were significantly different by the Tukey's Test (p < 0.001).

The same capital letters in horizontal rows were the comparison of different indirect resin composites according to the same procedure; the same small letters in vertical columns were used for the same indirect resin composite according to the different procedures applied.