Flexure strength of methacrylate- and ormocer-based bulk fill resin composites: effect of material thickness and distance to photo-polymerization device

El-Askary, Farid Sabry; Botros, Sara Adel; Soliman, Zainab; Nassif, Mohamed Salah Abdelaziz; Özcan, Mutlu

doi:10.1080/01694243.2020.1816776

Cited by 6 publications

(10 citation statements)

References 24 publications

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“…This was a concern for highly-filled composites due to high light scattering at the resin/filler interface [ 8 ]. A lower degree of conversion on the bottom could cause higher flexion of specimens before fracture at the three-point bending test [ 29 , 46 ]. All tested materials were polymerized according to the curing protocol recommended by ISO 4049 and showed a high degree of conversion at the sample surface and a depth of 2 mm, with no statistically significant differences between the surface and the bottom of the sample.…”

Section: Discussionmentioning

confidence: 99%

Aging-Dependent Changes in Mechanical Properties of the New Generation of Bulk-Fill Composites

et al. 2022

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This study evaluated the behavior of a new generation of bulk-fill resin composites after prolonged exposure to an aqueous environment and accelerated aging in ethanol. Six bulk-fill materials were tested (Tetric PowerFill, Filtek One Bulk Fill Restorative, Tetric EvoCeram Bulk Fill, Fill-Up!, Tetric PowerFlow, SDR Plus Bulk Fill Flowable) and compared to two conventional reference materials (Tetric EvoCeram and Tetric EvoFlow). Flexural strength, modulus, and Weibull parameters were examined at three time points: 1 day, 30 days, and 30 days followed by ethanol immersion. Degree of conversion after 30 days, water sorption, and solubility up to 90 days were also investigated. Filtek One Bulk Fill had the highest flexural strength and modulus among the tested materials, followed by Tetric PowerFill and SDR plus. Flexural strength and modulus of high-viscosity bulk-fill materials showed higher stability after accelerated aging in ethanol compared to their low-viscosity counterparts and reference materials. After 30 days, the degree of conversion was above 80% for all tested materials. Dual-cure material Fill-Up! was the best-cured material. The water sorption was highest for Fill-Up!, Filtek One Bulk Fill Restorative, and Tetric EvoFlow, while solubility was highest for Tetric EvoCeram. After aging in water and ethanol, new generation high-viscosity bulk-fill materials showed better mechanical properties than low-viscosity bulk-fill and conventional composites under extended light curing conditions.

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Section: Discussionmentioning

confidence: 99%

Aging-Dependent Changes in Mechanical Properties of the New Generation of Bulk-Fill Composites

et al. 2022

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“…This experimental setup also allows for a distinction between the upper, better-polymerized part of the specimen in contrast to the bottom specimens with lower DC. In a recent innovative study by El-Askary et al [ 42 ], the 4 mm thick specimens for a three-point bending test were light-cured only from the top surface without the foil. However, the results obtained in that study were confusing since the obviously less polymerized specimens cured with an 8 mm distance from the light source obtained higher FS than the same material polymerized with only 2 mm distance from the light source.…”

Section: Discussionmentioning

confidence: 99%

“…It is suspected to permit higher deformation before brittle failure [ 45 ], leading to artificially increased FS. Unfortunately, the degree of cross-linking, DC, and FM were not measured in that study [ 42 ], so the conclusions were not unequivocal. However, our study design supported their assumptions as we found lower FM and DC in the bottom specimens.…”

Section: Discussionmentioning

confidence: 99%

Rapid 3 s Curing: What Happens in Deep Layers of New Bulk-Fill Composites?

et al. 2021

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This study assessed the influence of rapid 3 s light curing on the new generation of bulk-fill resin composites under the simulated aging challenge and depths up to 4 mm. Four bulk-fill materials were tested: two materials designed for rapid curing (Tetric PowerFill—PFILL; Tetric PowerFlow—PFLW) and two regular materials (Filtek One Bulk Fill Restorative—FIL; SDR Plus Bulk Fill Flowable—SDR). Three-point bending (n = 10) was used to measure flexural strength (FS) and flexural modulus (FM). In the 3 s group, two 2 mm thick specimens were stacked to obtain 4 mm thickness, while 2 mm-thick specimens were used for ISO group. Specimens were aged for 1, 30, or 30 + 3 days in ethanol. The degree of conversion (DC) up to 4 mm was measured by Raman spectroscopy. There was no difference between curing protocols in FS after 1 day for all materials except PFLW. FM was higher for all materials for ISO curing protocol. Mechanical properties deteriorated by increasing depth (2–4 mm) and aging. ISO curing induced higher DC for PFLW and FIL, while 3 s curing was sufficient for PFILL and SDR. The 3 s curing negatively affected FM of all tested materials, whereas its influence on FS and DC was highly material-specific.

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“…The main drawback of the mentioned study was the fact that the transparent film most likely hindered the polymerisation reaction in the lower 2–4 mm because the activated radicals could not initiate polymerisation in the lower parts of the sample and the chain lengthening could not progress in the lower parts. El-Askary et al investigated the FS of bulk-fill materials with a specimen thickness of 4 mm and a distance of 2 or 8 mm from the light-curing device [ 19 ]. Interestingly, they found that the FS was significantly higher for thicker samples cured at a distance of 8 mm from the light source than that of the 2 mm thick samples [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Proposition of New Testing Procedure for the Mechanical Properties of Bulk-Fill Materials

Macan,

Marošević,

Špiljak

et al. 2023

Materials

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This study analysed flexural properties, microhardness, and the degree of conversion (DC) of five bulk-fill composites under clinically relevant conditions (4 mm thick specimens) in comparison to 2 mm specimens according to ISO 4049. Additionally, the effect of rapid polymerisation on 4 mm specimens was evaluated after accelerated aging. DC was measured using Fourier transform infrared spectrometry at 2 and 4 mm thick layers, while flexural properties and Vickers microhardness were tested using 16 × 2 × 2 mm or 16 × 2 × 4 mm specimens. Three polymerisation protocols were used: (I) “ISO”: 2 mm thickness, 1000 mW/cm2, double-sided; (II) “10 s”: 4 mm thickness, 1000 mW/cm2, one-sided; and (III) “3 s”: 4 mm thickness, 2600 mW/cm2, one-sided. Mechanical properties were tested after 1 day, after 10,000 thermocycles, and after 10,000 thermocycles followed by a 7-day immersion in absolute ethanol. The “ISO” protocol produced a higher DC and microhardness of all materials. Elastic modulus was significantly higher for the “ISO” protocol compared to the 4 mm specimens. The differences in flexural strength for all polymerisation protocols were equalised after thermocycling and immersion in absolute ethanol. All tested materials met the ISO 4049 flexural strength requirement (80 MPa) for all polymerisation methods and all aging conditions. Rapid polymerisation achieved nearly optimal properties (ISO), except for elastic modulus, which was significantly reduced in 4 mm samples.

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Flexure strength of methacrylate- and ormocer-based bulk fill resin composites: effect of material thickness and distance to photo-polymerization device

Cited by 6 publications

References 24 publications

Aging-Dependent Changes in Mechanical Properties of the New Generation of Bulk-Fill Composites

Aging-Dependent Changes in Mechanical Properties of the New Generation of Bulk-Fill Composites

Rapid 3 s Curing: What Happens in Deep Layers of New Bulk-Fill Composites?

Proposition of New Testing Procedure for the Mechanical Properties of Bulk-Fill Materials

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