Modular Endoprosthesis for Mandibular Reconstruction — A Thematic Research Study at the National Dental Centre Singapore

Introduction: A thematic research project was undertaken by the National Dental Centre Singapore to study the feasibility of using a novel modular endoprosthesis for reconstruction of the mandible. Successful application of this technique potentially eliminates the need for a donor site. Methods: Three sub-projects done in a monkey model are presented. In the first two sub-projects, a titanium modular endoprosthesis was inserted in surgically created defects for reconstruction of the ascending ramus and condyle; and body of the mandible respectively. In the third sub-project, a polycaprolactone scaffold with calcium phosphate (CaP) surface coating modular endoprosthesis was used for reconstruction of the body of the mandible. The animals were sacrificed at three to six months. Microcomputed tomographic and histologic analyses were done. Results: At the time of sacrifice, signs of infection were present in a few animals treated either with the titanium or the polycaprolactone endoprosthesis for replacement of the body of the mandible. None of the animals who received the ascending ramus and condyle titanium endoprosthesis had an infection. New bone formation was noted around the stems of the titanium devices and inflammatory reaction was much reduced from three to six months. For the polycaprolactone device, more de novo bone formation was seen in the group using Human-BMP-2. Conclusion: The use of a modular endoprosthesis for mandibular reconstruction seemed to result in a physiologic replacement of the lost part of the mandible, although the biomechanics of the system need further evaluation so as to improve its long term stability