EGYPTIAN TOTAL TMJ PROSTHESIS: A THREE-YEAR FOLLOW-UP OF 22 JOINTS

The TemporoMandibular Joint (TMJ) is the unique structure that facilitates the complex articulation of the mandible to the base of the skull, through its upper bony component the glenoid fossa and eminence. TMJ can be severely compromised both anatomically and functionally by many etiologic factors, including but not limited to: developmental abnormalities, ankylosis, destructive arthritis, comminuted fractures, locally invasive pathosis as ameloblastoma or bengin tumors as Keratocystic Odontogenic Tumor (KCOT), or even malignancies. Reconstruction of the TMJ has been subject to extensive research and a wide variety of materials. As is the case with most reconstructions, autogenous grafts both vascularized and none, as chostochondral, fibula, radial, iliac crest and even scapula and metacarpal grafts have been employed especially in children and adolescents. Needless to point out, the well-known disadvantages of such grafts as their unpredictable outcome and donor site morbidity. On the other hand, alloplastic TMJ prosthesis that were introduced to overcome the autogenous graft disadvantages, had a very disappointing and rather scandalous debut with materials such as: vitalium, Proplast-Teflon (PTFE), Polymethylmethacrylate (PMMA) and Polydimethylsiloxane (silicone rubber); all of which turned out to be rather destructive than reconstructive. After learning from our mistakes and having a better understanding of the destructive forces the TMJ can have on prosthetic materials, ultra high molecular weight polyethylene (UHMWPE) and titanium separately or in combination have been employed with better outcomes and less failures/reactions. Custom made TMJ prosthetics using CAD/CAM and Rapid Prototyping using different manufacturing techniques are essentially valuable in cases of mandibular resections with disarticulation following disfiguring lesions. Tissue engineering of TMJ on scaffolds (natural/synthetic) using stem cells and bioactive molecules are prospective solutions, yet further research is necessary. In this study, we are rather addressing destructive lesions that are limited to TMJ, where stock TMJ prostheses provide results similar to the more expensive custom made and tissue engineered reconstruction solutions.