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Objectives: Previous studies have reported the fractal dimension of dental ceramic fracture surfaces from mist and hackle regions. The aim of this study was to determine and compare the fractal dimensional increment between the mirror, mist, and hackle regions of lithium disilicate fracture surfaces.
Methods: Nine bar-shaped specimens were prepared from lithium disilicate glass-ceramic. One face of each specimen was indented using a Knoop diamond at 10 N followed by loading in 4-point flexure until failure at a loading rate of 12.6 MPa/s to avoid environmental slow crack growth. Fracture surfaces were replicated in epoxy, and an atomic force microscope (AFM) was used to scan the replicas. Noise in scans was reduced by Laplace transform filter. The FRACTALS software was used to determine the fractal dimensional increment (D*) by the Minkowski cover algorithm.
Results: Median D values (25 %, 75 % quartiles) from mirror, mist, and hackle regions were 2.14 (2.12, 2.14), 2.14 (2.12, 2.15), and 2.14 (2.12, 2.15), respectively. A multilevel mixed model with clustering on repeated measures showed that the fractal dimension between the mirror-mist (p = 0.51), mist-hackle (p = 0.90), and mirror-hackle (p = 0.43) regions are not significantly different.
Significance: Fractal dimension in mirror, mist, and hackle regions of the fracture surface were not significantly different in lithia disilicate glass-ceramics. Any portion of the primary fracture surface can be analyzed using fractal analysis to investigate the conditions present at the time of failure.
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http://dx.doi.org/10.1016/j.dental.2025.06.008 | DOI Listing |
Dent Mater
August 2025
Department of Biomedical Materials Science, University of Mississippi Medical Center, MS, USA. Electronic address:
Objectives: Previous studies have reported the fractal dimension of dental ceramic fracture surfaces from mist and hackle regions. The aim of this study was to determine and compare the fractal dimensional increment between the mirror, mist, and hackle regions of lithium disilicate fracture surfaces.
Methods: Nine bar-shaped specimens were prepared from lithium disilicate glass-ceramic.
J Prosthodont
June 2023
Department of Biomedical Engineering, The University of Alabama at Birmingham, Birmingham, Alabama, USA.
Purpose: To perform qualitative analysis using scanning electron microscopy (SEM) of fracture surfaces for ceramic and polymeric dental materials broken via standardized flexural and crunch-the-crown (CTC) tests.
Materials And Methods: Zirconia, glass-ceramic, and polymeric (Trilor; TRI, Juvora; JUV, Pekkton; PEK) materials were loaded using crowns for CTC tests, discs (zirconia and glass-ceramics) for piston-on-3 ball tests, bars (polymer) for 3-point bend tests, and bars (zirconia, glass-ceramics) for 4-point bend tests. SEM was used to characterize the fracture surfaces and identify fracture surface features (e.
Data Brief
February 2021
Univ. Bordeaux, CNRS, CEA, SAFRAN CERAMICS, LCTS, UMR 5801, F-33600 Pessac, France.
This data article reports a systematic fractographic analysis of SiC-based filaments aiming at stress intensity factors assessment. A total of 11 fiber types (as-received or chlorinated Nicalon® and Tyranno® of all three generations) where therefore repeatedly tensile tested to generate the fracture surfaces. The tensile strengths were found to be independent to defect location (surface or internal).
View Article and Find Full Text PDFPhys Rev E
June 2017
Department of Physics, Bar-Ilan University, Ramat-Gan, IL52900 Israel.
Mode-I fracture exhibits microbranching in the high velocity regime where the simple straight crack is unstable. For velocities below the instability, classic modeling using linear elasticity is valid. However, showing the existence of the instability and calculating the dynamics postinstability within the linear elastic framework is difficult and controversial.
View Article and Find Full Text PDFNature
January 2006
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 1-272, Cambridge, Massachusetts 02139, USA.
As the speed of a crack propagating through a brittle material increases, a dynamical instability leads to an increased roughening of the fracture surface. Cracks moving at low speeds create atomically flat mirror-like surfaces; at higher speeds, rougher, less reflective ('mist') and finally very rough, irregularly faceted ('hackle') surfaces are formed. The behaviour is observed in many different brittle materials, but the underlying physical principles, though extensively debated, remain unresolved.
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