Inductive, Scaffold-Based, Regenerative Medicine Approach to Reconstruction of the Temporomandibular Joint Disk The TMJ disc is composed of soft cartilaginous material that acts as a shock absorber between the temporal bone of the skull and the lower jaw bone (the mandible) when the joint moves. Attempts to replace a diseased or degenerated disc by synthetic materials or tissues from other parts of a patient’s body have been unsuccessful or of only limited duration. However, Dr. Almarza and his collaborators report encouraging results for the regeneration of the TMJ disc in an animal experiment.
The team used extracellular matrix (ECM) material derived from pig bladders, which was shaped to model the TMJ disc and placed it into one of the sides of the jaw of dogs who had had both TMJ discs surgically removed, leaving the other side of the jaw empty as a control. (“Extracellular matrix” consists of materials and molecules in the ground substance surrounding various cells and organs in the body.) The ECM implant consisted of a powdered form of ECM sandwiched between layers of the same material. The authors noted that the same source material had been used successfully in a number of other areas of the body to promote healing and regeneration.
For six months, the joints were allowed to heal and regenerate. During that time the animals showed no sign of discomfort or major complications. After six months, the joints were evaluated for changes and newly formed tissue was examined. The new tissue was found to have many similarities to the normal TMJ disc in composition, structure and strength. The new tissue also protected the jaw surfaces from degeneration, compared to the empty control joints.
These results suggest that in the future biologic ECM tissue may be able to serve as a template for the formation of new, site-appropriate, functional TMJ disc tissue. While the results are encouraging, other test and experiments are ongoing to show the safety and effectiveness of the ECM device as a TMJ disc replacement.
Our thanks to Dr. Alejandro J. Almarza, Assistant Professor of Oral Biology and Bioengineering at the McGowan Institute of Regenerative Medicine at the University of Pittsburgh for writing a summary of his team's research for our readers.