Flexural fatigue behavior of machinable and light‐activated hybrid composites for esthetic restorations

Abstract

Abstract:The purpose of this study was to determine the flexural strength and flexural fatigue strength of a machinable composite (GN-I) and three hybrid composites (Artglass, Estenia, and Gradia). Specimens (2×2×25 mm) were polymerized in a laboratory-photo-curing unit and then immersed in water at 37°C for 24 h, 6 months, and 1 year. After each immersion period, flexural strengths (4-PFS) were measured at a cross-head speed of 1 mm/min in 4-point bending (span = 20 mm; distance between inside loading points = 10 mm).The cyclic fatigue test was performed at 2.0 Hz on a fatigue tester. The staircase method was employed for flexural fatigue strength (FFS) using a 5,000 cyclic load limitation, 5 MPa stress increment, and 20 specimens for each material. Both 4-PFS and FFS of the machinable composite after all immersion periods were significantly greater than those of the three hybrid composites. The FFS results followed the same pattern as those of the 4-PFS.The Estenia material exhibited the highest 4-PFS and FFS after 24-h-immersion among three hybrid composites, whereas after 1-year-immersion, all three composites showed almost identical 4-PFS and FFS statistically. A strong correlation was observed between 4-PFS and FFS of the machinable composite and three hybrid resin composites.

Wear and fatigue behavior of nano‐structured dental resin composites

“…There are a number of additional factors that may affect fatigue limit in composites that remain to be addressed. Although the test frequency of 1.4 Hz used is within the range reported in previous studies (0.5-5.0 Hz) 4,24,27,31 and below the 2-Hz upper limit of the chewing frequency, 3 the effect of test frequency on fatigue-crack growth has not been characterized. Similarly, how nanoparticles may alter the kinetics of crack growth has not been documented to date.…”

“…Among other factors, the life expectancy of resin composites depends on the occlusion, because it induces wear and fatigue 2–4. Therefore, the resistance of nanoparticle‐filled materials to the loss of substance during sliding and to the propagation of microfractures through cyclic‐fatigue loading is of fundamental importance.…”

“…Among other factors, the life expectancy of resin composites depends on the occlusion, because it induces wear and fatigue. [2][3][4] Therefore, the resistance of nanoparticle-filled materials to the loss of substance during sliding and to the propagation of microfractures through cyclic-fatigue loading is of fundamental importance. Nevertheless, an understanding of how nanometer-sized particles can affect the wear and fatigue behavior of dental composites is yet to be thoroughly evolved.…”

Fatigue behaviour of biocomposites

“…Self-cure or light-activated polymerizable matrices typically contain one or more monomers, such as bis-phenol-A-diglycidyl dimethacrylate (bis-GMA), triethylene glycol dimethacrylate (TEGDMA), and urethane dimethacrylate (UDMA). Flexural S-N curves and fl exural fatigue limits have been experimentally measured for several commercially available dental restorative materials (Abe et al, 2005;Boberick et al, 2002;Braem et al, 1994 andMcCool et al, 2001;Yoshida et al, 2004). Fatigue failure manifests itself in dental prostheses and restorations as wear, fractured margins, delaminated coatings, and bulk fracture .…”

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

“…Brittle materials are much weaker under tension than compression; tensile strength is, therefore, considered to be a more meaningful parameter for the assessment of brittle materials, such as composites, especially in the presence of critical surface flaws [26]. It could also be worth investigating whether the method of surface preparation, per se, would affect the mechanical properties of ceromers.…”