Effects of tissue-engineered articular disc implants on the biomechanical loading of the human temporomandibular joint in a three-dimensional finite element model

The purpose of this study was to evaluate biomechanical loading of the temporomandibular joint when using a biodegradable laminate implant to replace the articular disc and to test the hypothesis that the use of the implant reduces stress distribution in the condyle, implant, and glenoid fossa. A finite element model of a female human mandible, including the temporomandibular joint, which had two standard endosseous implants inserted bilaterally in the premolar region, was constructed from computed tomography scan images using a commercially available finite element software. The disc, condyle, and glenoid fossa were arbitrarily divided into five regions: the anterior, posterior, medial, lateral, and central. The disc was then replaced with a poly-L/DL-lactide biodegradable laminate. The finite element model was then used to predict principal and Von Mises stresses. The use of poly-L/DL-lactide implant resulted in remarkable reduction in Von Mises stresses (approximately threefold) in the anterior, central, and medial regions of the mandibular condyle in comparison with slight to moderate stress reductions in the corresponding regions of the implant and glenoid fossa. The mandibular condyle also demonstrated the largest total displacement in all directions followed by the implant and glenoid fossa. The use of an alloplastic implant such as the bioresorbable, poly-L/DL-lactide laminate to replace the articular disc reduces loading of the mandibular condyle rather than the implant and glenoid fossa. These findings lead to support the hypothesis that the mandibular condyle more likely functions as a shock absorber than the disc. The use of bioresorbable laminate implants might prove an efficient technique to replace the articular disc and promote normal function of the temporomandibular joint.