The region-dependent dynamic properties of porcine temporomandibular joint disc under unconfined compression

In this study, the dynamic compressive properties in five different regions of the porcine temporomandibular joint (TMJ) disc are investigated over a wide range of loading frequencies. The aim was, thus far, to evaluate the regional difference and the frequency-related effect of the applied load on these properties. Eleven porcine TMJ discs were used; each disc was divided into 5 regions, anterior, central, posterior, lateral and medial. Sinusoidal compressive strain was applied with an amplitude of 1.0% and a frequency range between 0.01 and 10 Hz. The dynamic storage and loss moduli increase with frequency, the highest values being attained at the posterior region, followed by the central and anterior regions. Loss tangent, tan δ, ranged from 0.20 to 0.35, which means that the disc is primarily elastic in nature and has a small but not negligible viscosity. The present results suggest that the dynamic viscoelastic compressive modulus is region-specific and depends on the loading frequency, thus having important implications for the transmission of load to the TMJ.