RESEARCH REPORTS

Mandibular condylar cartilage functions as the load-bearing, shock-absorbing, lubricating mate-rial in temporomandibular joints. Little is known about the precise nature of the biomechanical char-acteristics of this fibro-cartilaginous tissue. We hypothesized that the fixed charge density associ-ated with proteoglycans that introduces an osmotic pressure inside condylar cartilage will signifi-cantly increase the tissue’s apparent stiffness. Micro-indentation creep tests were performed on porcine TMJ condylar cartilage at 5 different regions—anterior, posterior, medial, lateral, and central—in physiologic and hypertonic solutions. The intrinsic and apparent mechanical properties, including aggregate modulus, shear modulus, and permeability, were calculated by indentation test data and the biphasic theory. The apparent proper-ties (with osmotic effect) were statistically higher than those of the intrinsic solid matrix (without osmotic effect). Regional variations in fixed charge density, permeability, and mechanical modulus were also calculated for condylar surface. The present results provide important quantitative data on the biomechanical properties of TMJ condylar cartilage. KEy wORdS: temporomandibular joint (TMJ), condyle head, osmotic pressure, triphasic theory, micro-indentation