Multiaxial analysis of dental composite materials

Abstract

Dental composites are subjected to extreme chemical and mechanical conditions in the oral environment, contributing to the degradation and ultimate failure of the material in vivo. The objective of this study is to validate an alternative method of mechanically loading dental composite materials. Confined compression testing more closely represents the complex loading that dental restorations experience in the oral cavity. Dental composites, a nanofilled and a hybrid microfilled, were prepared as cylindrical specimens, light-cured in ring molds of 6061 aluminum, with the ends polished to ensure parallel surfaces. The samples were subjected to confined compression loading to 3, 6, 9, 12, and 15% axial strain. Upon loading, the ring constrains radial expansion of the specimen, generating confinement stresses. A strain gage placed on the outer wall of the aluminum confining ring records hoop strain. Assuming plane stress conditions, the confining stress (sigma(c)) can be calculated at the sample/ring interface. Following mechanical loading, tomographic data was generated using a high-resolution microtomography system developed at beamline 2-BM of the Advanced Photon Source at Argonne National Laboratory. Extraction of the crack and void surfaces present in the material bulk is numerically represented as crack edge/volume (CE/V), and calculated as a fraction of total specimen volume. Initial results indicate that as the strain level increases the CE/V increases. Analysis of the composite specimens under different mechanical loads suggests that microtomography is a useful tool for three-dimensional evaluation of dental composite fracture surfaces.

Degradation, Fatigue, and Failure of Resin Dental Composite Materials

“…Assuming plane stress conditions for a thick-walled cylinder subject to internal pressure, the confining stress can be calculated at the interface between the inner wall of the ring and the sample during elastic deformation of the ring (Kotche et al, 2008). …”

The impact of long‐term aging in artificial saliva media on resin‐based dental composite strength

“…The resin consisted of a mixture of bis‐GMA, UDMA, TEGDMA, polyethylene glycol dimethacrylate (PEGDMA), and 2,2‐Bis[4‐methacryloxypolyethoxyphenyl] propane (bis‐EMA6) resins. The inorganic filler was comprised of non‐agglomerated silica (20 nm) and zirconia (4–11 nm) 10,11 . AEL contained 29.5% resin and 70.5% inorganic filler by mass.…”

“…The inorganic filler was comprised of non-agglomerated silica (20 nm) and zirconia (4-11 nm). 10,11 AEL contained 29.5% resin and 70.5% inorganic filler by mass. The resin contained bis-GMA and a proprietary polymer mixture, and filler was comprised of strontium glass and colloidal silica.…”

“…Therefore, deterioration of dental composite materials in oral environments needs to be examined. Prior studies have investigated the effect of water, acids, artificial saliva, and enzymes on the mechanical and chemical degradation of individual components of dental composites 6–11 . Resin‐based restorative dental composite materials are mainly comprised of two parts: a polymer matrix and filler materials.…”

Synthesis of Bis-GMA and UDMA Nanofibers for Reinforcing Experimental resin-composites: Influence on Degree of Conversion, Depth of Cure, Flexural Strength, Flexural Modulus and Fracture Toughness

“…Evaluation of strength-related properties of experimental and commercially available dental resin-composites are very essential for accepting such materials as restoratives materials. One good aspect of the flexural strength testing is that the material is evaluated under three main types of stresses; compressive, tensile and shear [35] . In the same stream, flexural modulus is an essential testing procedure to verify the capacity of a restorative material to serve successfully in the oral cavity.…”