Evaluation of flexural modulus, flexural strength and degree of conversion in BISGMA/TEGDMA resin filled with montmorillonite nanoparticles

This study had as its main objective to evaluate the flexural properties (strength and modulus) and degree of conversion of a dimethacrylate resin containing different amounts of nanoparticulated clay Montomorillonite (MMT) as filler. A series of composites containing similar amounts (in volume) of barium glass particles was also tested as control data. Eight formulations with polymeric matrix-based BisGMA/TEGDMA (Bisphenol A Bis(2-hydroxy-3 methacryloxypropyl)Ether/Triethyleneglycol Dimethacrylate), four added with MMT and four added with barium glass in the volume concentration of 20, 30, 40 and 50 vol% were studied. The degree of conversion was determined using near-IR spectroscopy. Elastic modulus and flexural strength were determined by the three-point bending test. The dispersion of MMT nanoparticles was determined by means of X-ray diffraction and transmission electron microscopy analysis. The fillers montomorillonite and barium glass interacted with polymer matrix-based BisGMA/TEGDMA in a distinct manner. Although the addition of montomorillonite nanoparticles resulted in similar degree of conversion and higher elastic modulus values at all concentrations tested, only at the 20 vol% the flexural strength was statistically higher, compared to the control groups filled with barium glass. This could be related to the need of concentration optimization of montomorillonite for each type of polymer matrix in order to adjust or improve mechanical properties. The addition of low concentrations (<l 20% vol) of montomorillonite nanoparticles in dental composites resins – such as additive or hybrid filler – should be studied, aiming to the reduction of polymerization shrinkage, better mechanical properties and improvement of a new technology for future applications.

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Effect of Camphorquinone Concentration in Physical-Mechanical Properties of Experimental Flowable Resin Composites

BioMed Research International ◽

10.1155/2018/7921247 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10 ◽

Cited By ~ 2

Author(s):

Dayany da Silva Alves Maciel ◽

Arnaldo Bonfim Caires-Filho ◽

Marta Fernandez-Garcia ◽

Camillo Anauate-Netto ◽

Roberta Caroline Bruschi Alonso

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Flexural Strength ◽

Mechanical Strength ◽

Surface Hardness ◽

Degree Of Conversion ◽

Bending Test ◽

Resin Matrix ◽

Shrinkage Stress ◽

Depth Of Cure

The aim of this study was to evaluate the effect of camphorquinone concentration in physical-mechanical properties of experimental flowable composites in order to find the concentration that results in maximum conversion, balanced mechanical strength, and minimum shrinkage stress. Model composites based on BISGMA/TEGDMA with 70% wt filler loading were prepared containing different concentrations of camphorquinone (CQ) on resin matrix (0.25%, 0.50%, 1%, 1.50%, and 2% by weight). Degree of conversion was determined by FTIR. Surface hardness was assessed before and after 24 h ethanol storage and softening rate was determined. Depth of cure was determined by Knoop hardness evaluation at different depths. Color was assessed by reflectance spectrophotometer, employing the CIE-Lab system. Flexural strength and elastic modulus were determined by a three-point bending test. Shrinkage stress was determined in a Universal Testing Machine in a high compliance system. Data were submitted to ANOVA and Tukey’s test (α = 0.05). The increase in CQ concentration caused a significant increase on flexural strength and luminosity of composites. Surface hardness was not affected by the concentration of CQ. Composite containing 0.25% wt CQ showed lower elastic modulus and shrinkage stress when compared to others. Depth of cure was 3 mm for composite containing 1% CQ and 2 mm for the other tested composites. Degree of conversion was inversely correlated with softening rate and directly correlated with elastic modulus and shrinkage stress. In conclusion, CQ concentration affects polymerization characteristics and mechanical strength of composites. The concentration of CQ in flowable composite for optimized polymerization and properties was 1% wt of the resin matrix, which allows adequate balance among degree of conversion, depth of cure, mechanical properties, and color characteristics of these materials.

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THE INFLUENCE OF SiC COATING PROCESS ON THE PROPERTIES OF C/C COMPOSITES

Surface Review and Letters ◽

10.1142/s0218625x07010317 ◽

2007 ◽

Vol 14 (04) ◽

pp. 817-820

Author(s):

MIN HUANG ◽

KE-ZHI LI ◽

HE-JUN LI ◽

QIAN-GANG FU ◽

GUO-DONG SUN

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Failure Mode ◽

Flexural Modulus ◽

Pack Cementation ◽

Bending Test ◽

Carbon Composites ◽

Coating Process ◽

Three Point Bending ◽

Coated Carbon

SiC coating for carbon/carbon composites was prepared by pack cementation method. The effects of coating process on the microstructure and the mechanical properties of C / C composites were analyzed by SEM and three-point bending test, respectively. As the infiltrated Si improved the interfaces bonding during the coating process, the flexural strength and flexural modulus of SiC -coated carbon/carbon composites were both increased by about 10% than the naked C / C composites. In addition, the mechanism of the change of failure mode of SiC coated C / C composites and naked C / C composites was addressed.

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Influence of a Repeated Preheating Procedure on Mechanical Properties of Three Resin Composites

Operative Dentistry ◽

10.2341/13-238-l ◽

2015 ◽

Vol 40 (2) ◽

pp. 181-189 ◽

Cited By ~ 6

Author(s):

M D'Amario ◽

F De Angelis ◽

M Vadini ◽

N Marchili ◽

S Mummolo ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Vickers Microhardness ◽

Flexural Modulus ◽

Bending Test ◽

Resin Composites ◽

Three Point Bending ◽

Main Effect ◽

Dependent Variables ◽

Marginal Means

SUMMARY The aim of this study was to assess the flexural strength, flexural elastic modulus and Vickers microhardness of three resin composites prepared at room temperature or cured after one or repeated preheating cycles to a temperature of 39°C. Three resin composites were evaluated: Enamel Plus HFO (Micerium), Opallis (FGM), and Ceram X Duo (Dentsply DeTrey). For each trial, one group of specimens of each material was fabricated under ambient laboratory conditions, whereas in the other groups, the composites were cured after 1, 10, 20, 30, or 40 preheating cycles to a temperature of 39°C in a preheating device. Ten rectangular prismatic specimens (25 × 2 × 2 mm) were prepared for each group (N=180; n=10) and subjected to a three-point bending test for flexural strength and flexural modulus evaluation. Vickers microhardness was assessed on 10 cylindrical specimens from each group (N=180; n=10). Statistical analysis showed that, regardless of the material, the number of heating cycles was not a significant factor and was unable to influence the three mechanical properties tested. However, a significant main effect of the employed material on the marginal means of the three dependent variables was detected.

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Effect of Filler Content and Waiting time Before Light-Curing on Mechanical Properties of Dual-Cured Cement

Current Dentistry ◽

10.2174/2542579x01666190924180448 ◽

2020 ◽

Vol 2 (1) ◽

pp. 45-52

Author(s):

Ana C. de Assunção Oliveira ◽

Sandro Griza ◽

Rafael R. de Moraes ◽

André L. Faria-e-Silva

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Flexural Strength ◽

Waiting Time ◽

Filler Content ◽

Bending Test ◽

Resin Cements ◽

Three Point Bending ◽

Light Curing ◽

Curing Procedure

Objective:: To investigate the effect of filler content and the time spent before light-curing on mechanical properties of dual-cured cement. Methods:: Experimental dual-cured resin cements were formulated with 60, 65 or 68wt% of filler. The viscosity of experimental cement was measured using a digital viscometer. Bar-shaped specimens (25 x 2 x 2 mm) were fabricated, while the light-curing was started immediately or 5 minutes after the insertion of cement into the mold (n = 7). A three-point bending test was performed and the values of flexural strength and elastic modulus were measured. The Vickers hardness of fractured specimens was measured on the surface of the cement. Data from viscosity were submitted to oneway ANOVA, while the data from mechanical properties were analyzed by two-way ANOVA. All pair-wise comparisons were performed using Tukey’s test (α = 0.05). Results:: The experimental cement with 68wt% of filler showed the highest viscosity and those with 60wt% showed the the lowest viscosity. Irrespective of the time spent before light-curing, the cement with 65wt% of filler presented the highest values of flexural strength and elastic modulus. The addition of 60wt% of filler resulted in the lowest elastic modulus, while 68wt% of filler resulted in lowest flexural strength. Regarding the hardness, the cement with 68wt% of filler showed the highest values, while there was no difference between 60 and 65wt% of filler. Conclusion:: Filler content affected the mechanical properties of the experimental cement and this effect did not depend on the waiting time before the light-curing procedure.

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Chemical and Mechanical Properties of Experimental Dental Composites as a Function of Formulation and Postcuring Thermal Treatment

BioMed Research International ◽

10.1155/2018/9845427 ◽

2018 ◽

Vol 2018 ◽

pp. 1-6 ◽

Cited By ~ 6

Author(s):

Renata A. Esteves ◽

Letícia C. C. Boaro ◽

Flávia Gonçalves ◽

Luiza M. P. Campos ◽

Cecy M. Silva ◽

...

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Elastic Modulus ◽

Thermal Treatment ◽

Flexural Strength ◽

Low Cost ◽

Chemical Properties ◽

Degree Of Conversion ◽

Dental Composites ◽

Molar Ratios

This study evaluated the influence of formulation and thermal treatment on the degree of conversion, fracture toughness, flexural strength, and elastic modulus of experimental composites. Six composites were analyzed at BisGMA : TEGDMA molar ratios of 1 : 1 and 7 : 3 with filler at 30, 50, and 70 wt%. The degree of conversion was analyzed by Fourier transform infrared spectroscopy, fracture toughness was measured using the single-edge notched beam, and flexural strength and elastic modulus were measured with the 3-point bend test. For all tests, one-half of the specimens received thermal treatment at 170°C for 10 min. Data were analyzed by the Kruskal-Wallis or ANOVA/Tukey’s test (α = 5%). The 1 : 1 BisGMA : TEGDMA ratio showed higher properties than the 7 : 3 ratio. Although the material with 70% filler had a conversion lower than the one with 50%, it showed higher mechanical properties. The thermal treatment improved all properties in all materials. Therefore, the use of an equimolar ratio of BisGMA : TEGDMA can be paired with 70 wt% filler to design dental composites that possess increased advantageous physical and chemical properties. Furthermore, the simple and low-cost method of thermal treatment proposed for use in clinical dentistry has been shown to effectively improve the properties of all evaluated materials.

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Investigating the Mechanical Properties of ZrO2-Impregnated PMMA Nanocomposite for Denture-Based Applications

Materials ◽

10.3390/ma12081344 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1344 ◽

Cited By ~ 14

Author(s):

Saleh Zidan ◽

Nikolaos Silikas ◽

Abdulaziz Alhotan ◽

Julfikar Haider ◽

Julian Yates

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Impact Strength ◽

Flexural Strength ◽

Flexural Modulus ◽

Surface Hardness ◽

Bending Test ◽

Zro2 Nanoparticles ◽

Control Group ◽

The Mean

Acrylic resin PMMA (poly-methyl methacrylate) is used in the manufacture of denture bases but its mechanical properties can be deficient in this role. This study investigated the mechanical properties (flexural strength, fracture toughness, impact strength, and hardness) and fracture behavior of a commercial, high impact (HI), heat-cured denture base acrylic resin impregnated with different concentrations of yttria-stabilized zirconia (ZrO2) nanoparticles. Six groups were prepared having different wt% concentrations of ZrO2 nanoparticles: 0% (control), 1.5%, 3%, 5%, 7%, and 10%, respectively. Flexural strength and flexural modulus were measured using a three-point bending test and surface hardness was evaluated using the Vickers hardness test. Fracture toughness and impact strength were evaluated using a single edge bending test and Charpy impact instrument. The fractured surfaces of impact test specimens were also observed using a scanning electron microscope (SEM). Statistical analyses were conducted on the data obtained from the experiments. The mean flexural strength of ZrO2/PMMA nanocomposites (84 ± 6 MPa) at 3 wt% zirconia was significantly greater than that of the control group (72 ± 9 MPa) (p < 0.05). The mean flexural modulus was also significantly improved with different concentrations of zirconia when compared to the control group, with 5 wt% zirconia demonstrating the largest (23%) improvement. The mean fracture toughness increased in the group containing 5 wt% zirconia compared to the control group, but it was not significant. However, the median impact strength for all groups containing zirconia generally decreased when compared to the control group. Vickers hardness (HV) values significantly increased with an increase in ZrO2 content, with the highest values obtained at 10 wt%, at 0 day (22.9 HV0.05) in dry conditions when compared to the values obtained after immersing the specimens for seven days (18.4 HV0.05) and 45 days (16.3 HV0.05) in distilled water. Incorporation of ZrO2 nanoparticles into high impact PMMA resin significantly improved flexural strength, flexural modulus, fracture toughness and surface hardness, with an optimum concentration of 3–5 wt% zirconia. However, the impact strength of the nanocomposites decreased, apart from the 5 wt% zirconia group.

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

Materials ◽

10.3390/ma14030515 ◽

2021 ◽

Vol 14 (3) ◽

pp. 515

Author(s):

Danijela Marovic ◽

Matej Par ◽

Ana Crnadak ◽

Andjelina Sekelja ◽

Visnja Negovetic Mandic ◽

...

Keyword(s):

Mechanical Properties ◽

Raman Spectroscopy ◽

Flexural Strength ◽

Flexural Modulus ◽

Degree Of Conversion ◽

Resin Composites ◽

Three Point Bending ◽

Deep Layers ◽

Light Curing ◽

New Generation

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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Correlation between the Mechanical Properties and Structural Characteristics of Different Fiber Posts Systems

Brazilian Dental Journal ◽

10.1590/0103-6440201600377 ◽

2016 ◽

Vol 27 (1) ◽

pp. 46-51 ◽

Cited By ~ 18

Author(s):

Veridiana Resende Novais ◽

Renata Borges Rodrigues ◽

Paulo Cezar Simamoto Júnior ◽

Correr-Sobrinho Lourenço ◽

Carlos José Soares

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Cross Sections ◽

Structural Characteristics ◽

Flexural Modulus ◽

Testing Machine ◽

Correlation Coefficients ◽

Bending Test ◽

Fiber Posts ◽

Fiber Matrix

Abstract The aim of this study was to evaluate the flexural strength and flexural modulus of different fiber-reinforcement composite (FRC) posts and determine the correlation between mechanical properties and structural characteristics. Eleven brands of fiber posts were analyzed (n=10): Exacto Cônico (Angelus), DT Light SL (VDW), RelyX Fiber Post (3M-Espe), Glassix Radiopaque (Nordim), Para Post Fiber White (Coltène), FRC Postec Plus (Ivoclar), Aestheti-Plus Post (Bisco), Superpost Cônico Estriado (Superdont), Superpost Ultrafine (Superdont), Reforpost (Angelus), and White Post DC (FGM). The posts were loaded in three-point bending test to calculate the flexural strength and flexural modulus using a mechanical testing machine (EMIC 2000 DL) at 0.5 mm/min. Data were submitted to one-way ANOVA and Scott-Knot test (p<0.05). The cross-sections of the posts were examined by scanning electron microscopy (SEM). Correlation between the mechanical properties and each of the structural variables was calculated by Pearson's correlation coefficients (p<0.05). The flexural strength values ranged from 493 to 835 MPa and were directly correlated with the fiber/matrix ratio (p=0.011). The flexural modulus ranged from 4500 to 8824 MPa and was inversely correlated with the number of fibers per mm2 of post (p<0.001). It was concluded that the structural characteristics significantly affected the properties of the FRC posts. The structural characteristic and mechanical properties of fiber glass posts are manufacture-dependent. A linear correlation between flexural strength and fiber/matrix ratio, as well as the flexural modulus and the amount of fiber was found.

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Evaluation of New Hollow Sleeve Composites for Direct Post-Core Construction

Materials ◽

10.3390/ma14237397 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7397

Author(s):

Shinji Yoshii ◽

Sufyan Garoushi ◽

Chiaki Kitamura ◽

Pekka K. Vallittu ◽

Lippo V. Lassila

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Resin Composite ◽

Flexural Modulus ◽

Accelerated Aging ◽

Fracture Analysis ◽

Bending Test ◽

Outer Diameter ◽

Fiber Post ◽

Three Point Bending

The preset shape and diameter of a prefabricated FRC post rarely follows the anatomy of the root canal. To solve this problem, a new hollow sleeve composite (HSC) system for post-core construction was developed and characterized. A woven fiber was impregnated with two types of resins: Bis-GMA or PMMA, and rolled into cylinders with outer diameter of 2 mm and two different inner diameters, namely 1.2 or 1.5 mm. The commercial i-TFC system was used as a control. Dual-cure resin composite was injected into these sleeves. Additionally, conventional solid fiber post was used as the inner part of the sleeve. The three-point bending test was used to measure the mechanical properties of the specimens and the fracture surface was examined using an electron microscope (SEM). The HSC (1.5 mm, Bis-GMA) revealed a statistically similar flexural modulus but higher flexural strength (437 MPa) compared to i-TFC (239 MPa; ANOVA, p < 0.05). When a fiber post was added inside, all values had a tendency to increase. After hydrothermal accelerated aging, the majority of specimens showed a significant (p < 0.05) decrease in flexural strength and modulus. SEM fracture analysis confirmed that the delamination occurred at the interface between the outer and inner materials. The HSC system provided flexibility but still high mechanical values compared to the commercial system. Thus, this system might offer an alternative practical option for direct post-core construction.

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Influence of Light-polymerization Modes on the Degree of Conversion and Mechanical Properties of Resin Composites: A Comparative Analysis Between a Hybrid and a Nanofilled Composite

Operative Dentistry ◽

10.2341/07-81 ◽

2008 ◽

Vol 33 (3) ◽

pp. 287-293 ◽

Cited By ~ 33

Author(s):

E. M. da Silva ◽

L. T. Poskus ◽

J. G. A. Guimarães

Keyword(s):

Mechanical Properties ◽

Comparative Analysis ◽

Flexural Strength ◽

Hybrid Composite ◽

Clinical Relevance ◽

Flexural Modulus ◽

Degree Of Conversion ◽

The Other ◽

Lower Degree ◽

Resin Composites

Clinical Relevance The nanofilled composite presented a lower degree of conversion, flexural modulus and flexural strength than the hybrid composite. On the other hand, the two materials had a similar hardness. The light polymerization mode influenced only the degree of conversion and the hardness of composites.

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