Flexural Strength Of Composite Resin Research Articles

Effect of thermocycling on the flexural strength of two different composite filling materials: An in vitro study.

Flexural strength is the bend strength or stress which causes failure in bending of the material. Composite is the widely used restorative material in the era of esthetic dentistry as it provides better esthetic and mechanical support for both posterior and anterior teeth. The term "thermocycling" refers to the process of changing temperatures in the mouth. Thus, the aim of the study was to determine the effect of thermocycling on flexural strength in two different composite filling materials. Twelve samples of packable type composite filling material, among which four samples prepared were from Restofill l (Group 1) and four were prepared from Ivoclar Vivadent (Group 2) for the study. Bar-shaped composite resin specimens were prepared with dimensions of 2 mm × 2 mm × 25 mm. Then, the eight samples were subjected to a thermocycling process and four left as control. This was followed by the determination of maximum force by a universal testing machine, and then, the collected data were used to determine flexural strength using the formula. The determining flexural strength was analyzed using SPSS version 23.0 by Independent sample t-test. The mean flexural strength of thermocycled Restofill composite filling material is 6.73, whereas the nonthermocycled Restofill sample showed 5.58 and the mean flexural strength of thermocycled Ivoclar Vivadent composite filling material was 5.08. The difference was not statistically significant with P = 0.978 >0.05. The current study concludes that the flexural strength of the Restofill composite (Group 1) was higher than the Ivoclar composite (Group 2). Hence, thermocycling affects the flexural strength of composite resin.

Effects of alkalisation and volume fraction reinforcement of Bombyx mori silk fibre on the flexural strength of dental composite resins

Background: Composite resins are widely used in dentistry to restore dental caries. Recently, short fibre-reinforced composite (FRC) resins have been widely used for high-stress areas, especially in posterior teeth. Bombyx mori silk fibre is under research to reinforce dental composite resin as it has good mechanical properties. Purpose: This study aims to obtain the effects of alkalisation and silk fibre volume fraction on the flexural strength of FRC. Methods: Bombyx mori silk fibres were obtained from Perhutani, Pati, Indonesia. Samples were divided into two alkalisation groups (4% and 8%). Alkalisation of the silk fibres was conducted through the scouring process in NaOH, hydrolysis (30% H2SO4) and drying. Silk fibres were then reinforced in a resin matrix. The samples were subdivided based on the fibre volume fraction reinforcements, which were 0%, 5%, 10% and 15%. Each group of samples consisted of three specimens (n = 3). Flexural strength was measured using a universal testing machine. Data were analysed by two-way ANOVA (p < 0.05) and post-hoc least significant difference test (p < 0.05). Results: The results showed the flexural strength (MPa) means of the 4% alkalisation group were 169.31 ± 54.28 (0%), 76.08 ± 43.69 (5%), 107.86 ± 40.61 (10%) and 101.99 ± 10.61 (15%). The flexural strength (MPa) means of the 8% alkalisation group were 169.31 ± 54.28 (0%), 82.62 ± 22.41 (5%), 111.07 ± 32.89 (10%) and 153.23 ± 23.80 (15%). Statistical analysis by ANOVA indicated that the fibre volume fraction affected the flexural strength of composite resins. Conclusion: It can be concluded that the volume fraction of silk fibre increases the flexural strength of composite resins, although the strength is not as high as a composite resin without fibres. However, the alkalisation percentage did not affect the flexural strength of composite resins, and there was no interaction between alkalisation percentage and fibre volume fraction with the flexural strength of composite resins.

Physicomechanical properties of different nanohybrid composites after aging: color stability, flexural strength, and microhardness

Aim: To evaluate the physicomechanical properties of different hybrid composites (Charisma Diamond - CD, Aura - AU, NT Premium - NT, Opallis - OP, Filtek Z250 – Z250) after 6 months of aging in distilled water. Methods: Discs were fabricated and color measurements were performed after 24 hours and at 7, 30, and 180 days. Flexural strength was determined using the three-point bending test. For the microhardness test, the specimens were flattened to obtain polished and flat surfaces and indentations. The results for ∆E and microhardness were analyzed by two-way repeated-measures ANOVA and Tukey’s HSD test. The flexural strength results were analyzed by two-way ANOVA and Tukey’s test (α=0.05). Results: The ∆E values for composite resins varied in the following order: CD (3.54)a < Z250 (4.70)ab < AU (4.95)ab < OP (5.20)ab < NT (6.23)b. ∆E values were lower for 24 h (3.84)a < 7 days (4.43)ab < 30 days (4.93)b. The highest values were observed after 180 days (ΔE = 6.54)c. The flexural strength of composite resins varied in the following order: CD (89.17 MPa)a < Z250 (73.06 MPa)b < OP (60.30 MPa)c < NT (51.28 MPa)c < AU (23.77 MPa)d. Flexural strength values were significantly higher for 24 h (68.62 MPa)a < 180 days (51.40 MPa)b. The microhardness of composite resins varied in the following order: Z250 (112.05)a < CD (102.15)ab < OP (92.04)bc < NT (87.77)d < AU (87.68)d. Microhardness was significantly higher for 180 days (113.44)a < 24 h (78.21)b. Conclusion: The microhybrid (Z250) and one of the nanohybrid composites (CD) performed better. The color stability and flexural strength of all tested composites decreased with storage time.

Flexural strength of composite resin fabricated by various polymerization method

Flexural strength of composite resin fabricated by various polymerization method

Degree of conversion and biaxial flexural strength of composite resins

Degree of conversion and biaxial flexural strength of composite resins

EVALUATION OF POSTERIOR FIXED FUNCTIONAL SPACE MAINTAINERS MADE OF FIBER REINFORCED COMPOSITE: AN IN VITRO STUDY

Background: Fiber-reinforced composite (FRC) space maintainer is proving to give solutions for the limitations encountered with the conventional band and loop space maintainer. However, the longevity of FRC is a controversial aspect. Aim of the study: Evaluation of the reinforcing effects of glass fibers on the flexural strength of composite resin. Materials and Methods: Three groups of specimens were prepared using a white Teflon split mold; a control group of composite resin bars, one glass fiber reinforced composite bars and two glass fiber reinforced composite bars. Mean flexural strength values in mega Pascal (MPa) were determined in a 3-point bending test. Results: A significant difference in mean flexural strength between the three groups was found. Conclusions: Flexural strength of composite resins improved with incorporation of glass fibers, and increasing fiber volume led to substantial improvement in the flexural strength.

새로운 광증감제를 사용한 치과용 광중합형 복합레진의 기계적 특성

Purpose: The purpose of this study was to know the physical properties of UDMA dental composite resins containing two photosensitizers, PD, DA, as a photosensitizer instead of CQ. We want to know Remaining Double Bond(RDB) of UDMA unfilled resin and diametral tensile strength and flexural strength of composite resin containing PD and DA were compared with those of CQ, most widely used photosensitizer for dental composite resins. Methods: The RDB of UDMA studied by FT-IR spectroscopy increased with irradiation time. The composite resins were tested for their physical properties. The dental composite resins were made with UDMA as a monomer, silanized silica as filler, N,N-dimethylaminoethyl methacrylate (DAEM) as amine initiator, and one of the two kinds of new photosensitizers. Results: The relative RDB of UDMA was in the order: DA > CQ > PD but the physical properties of the composite resins show PD and DA with higher results compared with that containing CQ. The reason for the results is that PD and DA serve not only as a photosensitizer but also as a photo-crosslinking agent. Conclusion: PD and DA show as effective photosensizers, suitable for UDMA dental composite resin compare with a higher efficiency than CQ.

Flexural strength of a composite resin light cured with different exposure modes and immersed in ethanol or distilled water media

Aim:The aim of this in vitro study was to evaluate the flexural strength of a composite resin polymerized with three different modes of light exposure.Materials and Methods:The three different modes of light exposure were conventional, 600 mW/cm2/40s; soft start, 300 mW/cm2/10s + 600 mW/cm2/30s; pulse delay, 600 mW/cm2/1s + 60 s of waiting time + 600 mW/cm2/39s). Twenty samples were prepared for each polymerization method. Flexural strength (FS) tests were carried out with a 2 kN load at a speed of 0.5 mm/ min. All tested groups were submitted to analysis of variance (one-way-ANOVA) and Tukey's test (P < 0.05).Results:When stored in water, conventional and pulse delay groups presented higher FS values which were statistically different from the soft start group. When stored in 100% ethanol, conventional and soft start groups presented higher FS values which were statistically different from the pulse delay group.Conclusion:Different polymerization modes and immersion media can affect the physical properties (flexural strength) of composite resin.

Flexural strength of four adhesive fixed dental prostheses of composite resin reinforced with glass fiber.

To evaluate the flexural strength of two fixed dental prosthesis (FDP) designs simulating frameworks of adhesive fixed partial prostheses, reinforced or not by glass fiber. Forty specimens, made with composite resin, were divided into 4 groups according to the framework design and the presence of fiber reinforcement: A1 - occlusal support; A2: occlusal support + glass fiber; B1: occlusal and proximal supports; B2: occlusal and proximal supports + glass fiber. The specimens were subjected to the three-point bending test, and the data were submitted to two-way ANOVA and Tukey's test (5%). Group A2 (97.9 ± 38 N) was statistically significantly different from all other experimental groups, presenting a significantly lower mean flexural strength. The use of glass fibers did not improve the flexural strength of composite resin, and designs with occlusal and proximal supports presented better results than designs simulating only occlusal support.

Investigations in the correlation between Martens hardness and flexural strength of composite resin restorative materials

The purpose of this study is to verify the hypothesis that the hardness and flexural strength of composite resin restorative materials are correlated and similarly affected by accelerated aging. With four different composite resins (Tetric Evo Ceram, Synergy, Filtek Supreme, Quixfil), the effects of aging in distilled water at 37 degrees C or by thermal cycling (5 degrees C/55 degrees C) on Martens hardness and flexural strength were assessed. Flexural strength (n=12) was measured according to ISO 4049 immediately after light-curing and after 75 days of aging. Martens hardness (n=6) was measured in intervals up to 75 days. The results were statistically analyzed with one-way ANOVA, followed by a post hoc Bonferroni test. In all cases, the effect of aging on hardness could not be measured. The effect of aging on flexural strength was also not consistent, although it was found that thermal cycling affected flexural strength more than water storage. Martens hardness and flexural strength of composite resins are not correlated.

The Flexural Strength of Composite Resin Reinforced by Glass and Polyethylene Fiber.

The Flexural Strength of Composite Resin Reinforced by Glass and Polyethylene Fiber.

Experimental and computational approach for evaluating the mechanical characteristics of dental composite resins with various filler sizes

This study aimed to investigate the influence of particle size of fillers on flexural properties of dental composite resins by laboratory testing with computational analysis validation. Four kinds of silica fillers with mean particle sizes of 3.3, 4.3, 7.9, and 15.5 μm were used. Filler content was kept constant at 70 mass% (or 53.8 vol.%). The three-point bending test was performed with a constant loading speed of 1.0 mm/min, and a span length of 20 mm using an Instron machine, in order to measure flexural strength and modulus of composite resins with various particle sizes. Test specimens were 2-mm wide, 2-mm thick, and 25-mm long rectangular bars. Furthermore, a numerical simulation using three-dimensional finite element (FE) analysis was performed to investigate stress distribution in composite resins under loading. As a result, flexural strength decreased with increasing particle size of the filler of the composite resins ( p < 0.05). On the other hand, there was no significant difference in Young’s modulus among composite resins with various filler sizes ( p > 0.05). Moreover, FE analysis indicated that stress concentration increased with increasing particle size in agreement with experimental results of flexural strength. In conclusion, within the limitations of this investigation, we confirmed that flexural strength of composite resins decreased with increasing filler particle size. In addition, FE analysis was effective for evaluating stress distributions of dental composite resins with various filler sizes.