Prefabricated 3D-Printed Tissue-Engineered Bone for Mandibular Reconstruction: A Preclinical Translational Study in Primate.

The advent of three dimensionally (3D) printed customized bone grafts using different biomaterials has enabled repairs of complex bone defects in various in vivo models. However, studies related to their clinical translations are truly limited. Herein, 3D printed poly(lactic-co-glycolic acid)/ß-tricalcium phosphate (PLGA/TCP) and TCP scaffolds with or without recombinant bone morphogenetic protein -2 (rhBMP-2) coating were utilized to repair primate's large-volume mandibular defects and compared efficacy of prefabricated tissue-engineered bone (PTEB) over direct implantation (without prefabrication). 18F-FDG PET/CT was explored for real-time monitoring of bone regeneration and vascularization. After 3-month's prefabrication, the original 3D-architecture of the PLGA/TCP-BMP scaffold was found to be completely lost, while it was properly maintained in TCP-BMP scaffolds. Besides, there was a remarkable decrease in the PLGA/TCP-BMP scaffold density and increase in TCP-BMP scaffolds density during ectopic (within latissimus dorsi muscle) and orthotopic (within mandibular defect) implantation, indicating regular bone formation with TCP-BMP scaffolds. Notably, PTEB based on TCP-BMP scaffold was successfully fabricated with pronounced effects on bone regeneration and vascularization based on radiographic, 18F-FDG PET/CT, and histological evaluation, suggesting a promising approach toward clinical translation.

Particulate Coral Hydroxyapatite Sheltered by Titanium Mesh for Localized Alveolar Rehabilitation After Onlay Graft Failure: A Case Report.

Reconstruction of bone loss in the alveolar ridge has long been challenging. Autologous bone grafts are considered as the "golden standard," while little research has focused on how to repair pronounced alveolar bone defects after autologous bone graft failure. The aim of this study was to detail a method based on the titanium mesh technique coupled with particulate coral hydroxyapatite to solve the onlay graft failure. With bone deficiency in the No. 11 and No. 24-25 regions, we harvested 2 autologous bone blocks for reconstruction. Two weeks after transplantation, the graft in the No. 11 region had healed uneventfully, while the graft in the anterior mandible became infected because of soft tissue dehiscence. After removal of the failed autologous bone block, pure coral hydroxyapatite stabilized within titanium mesh was used for alveolar rehabilitation. Six months later, the width of the local alveolar bone was evaluated. After the titanium mesh was removed, a biopsy was performed to study bone regeneration by micro computerized tomography and histology, following by a standard Straumann implant insertion. Although there was wound dehiscence 14 days after bone augmentation, repeated local rinsing and anti-inflammation therapy controlled the inflammatory reaction. The total horizontal bone gain was 4.2 ± 0.5 mm. Micro computerized tomography revealed that the closer the coral hydroxyapatite was to the host bone, the more was resorbed and the more bone regenerated. Histology showed mature lamellar bone structures, with evident residual coral hydroxyapatite. A 3-year follow-up revealed stable bone around the dental implant and successful function of the implant-born prosthesis. This study proposes that the method of particulate coral hydroxyapatite sheltered by titanium mesh is a promising solution in handling alveolar bone augmentation failure. More cases are needed for further research to form an efficient treatment procedure.