Fracture toughness estimation for the TMJ disc

Abstract

J contour integral fracture toughness of the temporomandibular (TMJ) disc was estimated from a computational model based on fracture load data derived from experimental tests. The computational model involved a stress analysis of TMJ disc specimens with cracks oriented parallel and perpendicular to the primary collagen fiber axis within the intermediate zone of the disc. The results demonstrated differences occurred between crack orientations when an orthotropic model was used. Fracture toughness was much lower for a crack oriented parallel to the collagen fiber direction than that for a crack oriented perpendicularly. Thickness, crack size, and anisotropy ratio were observed as additional variables affecting the fracture toughness of the TMJ disc. Future model enhancements may be achieved by considering the poroviscoelastic nature of the TMJ disc.

Biomechanical properties of the mandibular condylar cartilage and their relevance to the TMJ disc

“…In the future, further explorations of tensile and compressive properties of the condyle are needed, and deficiencies with regard to the viscoelastic and biphasic models should be addressed to determine the material properties of the condylar cartilage. Although the TMJ disc (Allen and Athanasiou, 2006;Beatty et al, 2001Beatty et al, , 2008Beatty et al, , 2003Detamore and Athanasiou, 2003c;Kang et al, 2006;Koombua et al, 2006;Doblare, 2006b, 2007b;Snider et al, 2008) is more well characterized than the mandibular condyle in terms of biomechanical properties, more extensive data under a wide variety of conditions such as impact, high strain, degeneration, etc., are required for both. Establishment of biomechanical standards for condylar cartilage, the TMJ disc and other tissues of the TMJ such as the retrodiscal tissue, will provide necessary data for FEMs, provide validation standards for tissue-engineered constructs, and ultimately lead to a better understanding of TMJ biomechanics, which will ultimately have clinical application in the prevention (evaluating the implications of various activities), diagnosis (tracking motion and forces) and treatment (providing engineering design requirements) of TMJ disorders.…”

The fracture toughness of eggshell

“…Loading between flat metal plates, as carried out by other workers [5,7] creates high local stresses at the contact points. To Table 1 Typical values of Fracture Toughness K c and Young's Modulus E for Various Materials Data from [27] except the following: mussel shells [28]; nacre [17]; bone [18]; temporomandibular joint disc [29]; cartilage [30]; stratum corneum [31]. prevent this we used hemispherical cups (actually wooden egg cups) and placed a layer of low-stiffness foam between the egg and the cup to redistribute the contact forces over a large area.…”

A comparison of stress in cracked fibrous tissue specimens with varied crack location, loading, and orientation using finite element analysis

“…This test configuration was not included in the present work because it leaves the fibers unloaded, but it has been previously applied to spine ligament, tissue engineered cartilage, deep zone articular cartilage, and temporomandibular joint disc (Von Forell et al, 2014; Koombua et al, 2006; Von Forell et al, 2014; Oyen-Tiesma and Cook, 2001). Cracks did not extend in spine ligament (Von Forell et al, 2014), did extend in tissue engineered cartilage (Oyen-Tiesma and Cook, 2001), and also extended in a subset of articular cartilage specimens (Chin-Purcell and Lewis, 1996; Taylor et al, 2012).…”

“…Cracks did not extend in spine ligament (Von Forell et al, 2014), did extend in tissue engineered cartilage (Oyen-Tiesma and Cook, 2001), and also extended in a subset of articular cartilage specimens (Chin-Purcell and Lewis, 1996; Taylor et al, 2012). It was ambiguous whether the temporomandibular joint disc failed by fracture (Koombua et al, 2006; Taylor et al, 2012). This test configuration thus has a fair chance of producing crack extension, depending on the tissue.…”

“…Only a few publications report fracture toughness for fibrous soft tissue (Purslow, 1985; Stok and Oloyede, 2007; Chin-Purcell and Lewis, 1996; Oyen-Tiesma and Cook, 2001; Koombua et al, 2006; Beatty et al, 2008; Wu et al, 2006). Taylor’s review of these studies indicated that most did not actually produce fracture (Taylor et al, 2012).…”