title: Microfracture mechanisms of dental resin composites containing spherically-shaped filler particles.
abstract: The effects of spherically-shaped filler particles on bending strength, bending elastic modulus, and fracture toughness of resin composites were studied. The filler content was changed by 0, 20, 40, 60, and 70 wt%. Bending properties and fracture toughnesses were determined on three-point bending specimens. Acoustic Emission (AE), i.e., the elastic wave released from a localized source in the material, was detected by sensors of a high-sensitivity and low-noise resonance type during the fracture toughness test. Detected acoustic emission signals were analyzed for parameters such as amplitude, events, and locations. The fractured surface was examined by a scanning electron microscope. The bending strength and the fracture toughness showed almost the same trend in their increasing rates by filler content, but the elastic modulus showed a much higher increasing rate. A microfracture mechanism of the dental resin composites containing spherically-shaped filler particles is proposed based on the results obtained from the AE-releasing pattern, two-dimensional AE location, and fracture surface findings. In addition to the toughening effects of crack pinning and crack branching, which are observed in the usual commercial resin composites, crack-deflecting effects are confirmed in this new type of dental resin composites.
authors.affiliation: Department of Dental Materials, Dental College, Kyungpook National University, Dong-in Dong, Taegu, Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Park
authors.forename: Y
authors.initials: Y
authors.lastname: Imai
authors.forename: T
authors.initials: T
authors.lastname: Kishi
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D004548:Elasticity; D006244:Hardness; D006245:Hardness Tests; D008422:Materials Testing / Q000379:methods; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D013016:Sound
chemical_list: D003188:Composite Resins