Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 27 Feb 2024

Effect of Radiant Exposure on the Physical and Mechanical Properties of 10 Flowable and High-viscosity Bulk-fill Resin Composites

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Page Range: 136 – 156
DOI: 10.2341/23-025-L
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SUMMARY

Objectives

To evaluate the effect of the different radiant exposures from a multipeak light curing unit on the physical and mechanical properties of flowable and high-viscosity bulk-fill resin-based composites (RBC).

Methods

Five flowable bulk-fill RBCs (Tetric N-Flow Bulk-fill, Ivoclar Vivadent; Filtek Bulk Fill Flow, 3M Oral Care; Opus Bulk Fill Flow APS, FGM; Admira Fusion x-base, Voco and; and SDR Plus Bulk Fill Flowable, Dentsply Sirona) and five high-viscosity bulk-fill RBCs (Tetric N-Ceram Bulk-fill, Ivoclar Vivadent; Filtek One Bulk Fill, 3M Oral Care; Opus Bulk Fill APS, FGM; Admira Fusion x-tra, Voco; and SonicFill 2, Kerr) were photo-cured using a VALO Cordless light (Ultradent) for 10, 20, and 40 seconds at an irradiance of 1200, 800, or 400 mW/cm2, resulting in the delivery of 4, 8, 12, 16, 24, 32, or 48 J/cm2. Post-gel shrinkage (Shr) was calculated using strain-gauge test. The degree of conversion (DC, %) was calculated using FTIR. Knoop hardness (KH, N/mm2) and elastic modulus (E, MPa) were measured at the top and bottom surfaces. Logarithmic regressions between the radiant exposures and mechanical properties were calculated. Radiodensity was calculated using digital radiographs. Data of Shr and radiodensity were analyzed using two-way analysis of variance (ANOVA), and the DC, KH, and E data were analyzed with two-way ANOVA using split-plot repeated measurement tests followed by the Tukey test (a = 0.05).

Results

Delivering higher radiant exposures produced higher Shr values (p<0.001) and higher DC values (R2=0.808-0.922; R2=0.648-0.914, p<0.001), KH (R2=0.707-0.952; R2=0.738-0.919; p<0.001), and E (R2=0.501-0.925; R2=0.823-0.919; p<0.001) values for the flowable and high-viscosity RBCs respectively. Lower KH, E and Shr were observed for the flowable bulk-fill RBCs. All bulk-fill RBCs had a radiopacity level greater than the 4-mm thick aluminum step wedge. The radiant exposure did not affect the radiopacity.

Conclusion

The Shr, DC, KH, and E values were highly correlated to the radiant exposure delivered to the RBCs. The combination of the higher irradiance for longer exposure time that resulted in radiant exposure between 24 J/cm2 to 48 J/cm2 produced better results than delivering 400 mW/cm2 for 40 s (16 J/cm2), and 800 mW/cm2 for 20 seconds (16 J/cm2) or 1200 mW/cm2 for 10 seconds (12 J/cm2). All the bulk-fill RBCs were sufficiently radiopaque compared to 4 mm of aluminum.

Copyright: 2024
Figure 1.
Figure 1.

The irradiance measured at each distance. A. MARC Resin Calibrator System; B. VALO Cordless LCU centralized over the MARC censor; C. Irradiance of 1200 mW/cm2 measured at 1 mm distance using 10-, 20-, or 40-second exposure times resulting the radiant exposures of 12, 24, and 48 J/cm2; D. Irradiance of 800 mW/cm2 measured at 5 mm distance using 10-, 20-, or 40-second exposure times resulting in the radiant exposures of 8, 16, and 32 J/cm2; E. Irradiance of 400 mW/cm2 measured at 13 mm distance using 10-, 20- or 40-second exposure times resulting in the radiant exposures of 4, 8, and 16 J/cm2. Abbreviation: LCU, light-curing unit.

Figure 2.
Figure 2.

A. The device developed to standardize in vitro radiograph studies; B. Specimen of each resin-based composite and the aluminum step wedge positioned over a phosphor plate; C. set of the phosphor plate, specimens and the aluminum step wedge positioned on the base of the developed device; D. The radiograph transferred from the phosphor plate to a computer using a digital scanner.

Figure 3.
Figure 3.

Logarithmic regression (logX) between the radiant exposure (J/cm2) delivered by the VALO Cordless LCU and the post-gel shrinkage values (%) for the flowable bulk-fill RBCs. A. Admira Fusion X-base; B. Filtek Bulk Fill Flow; C. Opus Bulk Fill Flow APS; D. SDR Plus Bulk Fill Flowable; E. Tetric N-Flow Bulk Fill; F. Logarithmic regression coefficient (R2) for all flowable RBCs. Abbreviations: RBC, resin-based composite; LCU, light-curing unit.

Figure 4.
Figure 4.

Logarithmic regression (logX) between the radiant exposure delivered by VALO Cordless LCU and the post-gel shrinkage values (%) for the high-viscosity bulk-fill RBCs. A. Admira Fusion X-tra; B. Filtek One Bulk Fill; C. Opus Bulk Fill APS; D. SonicFill 2; E. Tetric N-Ceram Bulk Fill. Abbreviations: RBC, resin-based composite; LCU, light-curing unit.

Figure 5.
Figure 5.

Logarithmic regression (log X) between the radiant exposure delivered by the VALO Cordless LCU and the degree of conversion values (%) for the flowable bulk-fill RBCs. A. Admira Fusion X-base; B. Filtek Bulk Fill Flow; C. Opus Bulk Fill Flow APS; D. SDR Plus Bulk Fill Flowable; E. Tetric N-Flow Bulk Fill; F. Logarithmic regression coefficient (R2) for all flowable RBCs.

Figure 6.
Figure 6.

Logarithmic regression (log X) between the radiant exposure delivered by the VALO Cordless LCU and the degree of conversion values (%) for the high-viscosity bulk-fill RBCs. A. Admira Fusion X-tra; B. Filtek One Bulk Fill; C. Opus Bulk Fill APS; D. SonicFill 2; E. Tetric N-Ceram Bulk Fill; F. Logarithmic regression coefficient (R2) for all high-viscosity RBCs.

Figure 7.
Figure 7.

Logarithmic regression(logX) between the radiant exposure delivered by the VALO Cordless LCU and the Knoop Hardness values (N/mm2) for the flowable bulk-fill RBCs. A. Admira Fusion X-base; B. Filtek Bulk Fill Flow; C. Opus Bulk Fill Flow APS; D. SDR Plus Bulk Fill Flowable; E. Tetric N-Flow Bulk Fill; F. Logarithmic regression coefficient (R2) for all the flowable RBCs.

Figure 8.
Figure 8.

Logarithmic regression (log x) between the radiant exposure delivered from the VALO Cordless LCU and the Knoop hardness values (N/mm2) for all tested high-viscosity bulk-fill RBCs. A. Admira Fusion X-tra; B. Filtek One Bulk Fill; C. Opus Bulk Fill APS; D. SonicFill 2; E. Tetric N-Ceram Bulk Fill; F. Logarithmic regression coefficient (R2) for all the high-viscosity RBCs.

Figure 9.
Figure 9.

Logarithmic regression (logX) between the radiant exposure delivered from the VALO Cordless LCU and elastic modulus values (MPa) for the flowable bulk-fill RBCs. A. Admira Fusion X-base; B. Filtek Bulk Fill Flow; C. Opus Bulk Fill Flow APS; D. SDR Plus Bulk Fill Flowable; E. Tetric N-Flow Bulk Fill; F. Logarithmic regression coefficient (R2) for all flowable RBCs.

Figure 10.
Figure 10.

Logarithmic regression (logX) between the radiant exposure delivered by VALO Cordless LCU and elastic modulus values (MPa) for the high-viscosity bulk-fill RBCs. A. Admira Fusion X-tra; B. Filtek One Bulk Fill; C. Opus Bulk Fill APS; D. SonicFill 2; E. Tetric N-Ceram Bulk Fill; F. Logarithmic regression coefficient (R2) for all high-viscosity RBCs.

Figure 11.
Figure 11.

A. Mean and standard deviation of the radiopacity of the 5 flowable RBCs tested; B. Mean and standard deviation of the radiopacity of the 5 high-viscosity RBCs. Different letters indicate where there was a significant difference between the flowable and high-viscosity RBCs, p<0.05.

Contributor Notes

*Corresponding author: 1720 Para Ave, Campus Umuarama, Block 2B, Room 2B24, Uberlândia, MG, Brazil, 38400-902; e-mail: carlosjsoares@ufu.br
Accepted: 27 Nov 2023
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