Evaluating Anisotropic Properties in the Porcine Temporomandibular Joint Disc Using Nanoindentation
2010
Yuya, P. A | Amborn, E. K | Beatty, M. W | Turner, J. A
The objective of this study was to determine the viscoelastic properties present within the intermediate zone of the porcine temporomandibular joint (TMJ) disc using nanoindentation. A 50-μm conospherical indenter tip using a displacement-controlled ramp function with a 600 nm/s loading and unloading rate, a 3000-nm peak displacement with a holding period of 30 s was used to indent the samples. Experimental load-relaxation tests were performed on the TMJ disc to determine the response in three different directions; the mediolateral, anteroposterior, and articular surface directions. The experimental data were analyzed using a generalized Maxwell model to obtain values for short- and long-time relaxation modulus and of material time constants. The short time relaxation modulus E I values were 180.92, 64.99, and 487.77 kPa for testing done on the articular surface, mediolateral, and anteroposterior directions, respectively. Corresponding values for the long-time relaxation modulus E ∞ were 45.9, 14.97, and 133.5 kPa. The method confirmed anisotropy present within the central intermediate zone of the porcine TMJ disc due to the directional orientation of the collagen fibers.
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