Orthodontic tooth movement in alveolar cleft repaired with a tissue engineering bone: an experimental study in dogs

Tissue engineering approaches have been successfully used in repairing bone defects and have become a viable alternative to autologous bone. The aim of the present study was to investigate if a construct of porous beta-tricalcium phosphate (β-TCP) combined with osteogenically induced bone marrow stromal cells (bMSCs) could repair alveolar cleft, and allow for subsequent orthodontic tooth movement in a canine model. Twelve alveolar osteotomy surgeries in six animals were made bilaterally and randomly implanted by (1) tissue-engineered bone complex of bMSCs/β-TCP (group A, n=4), (2) β-TCP alone (group B, n=4), and (3) autologous bone obtained from iliac bone (group C, n=4). Contralateral alveolar defects were created in one animal and left untreated to serve as blank control to observe spontaneous healing of the defects. Sequential fluorescent labeling and radiographic observation was used to evaluate new bone formation and mineralization in each defect. Orthodontic tooth movement was initiated 8 weeks after surgical operation for 12 weeks, and then the dogs were sacrificed for histological and histomorphometric analysis. Results indicated that the tissue-engineered complex with bMSCs/β-TCP dramatically promoted new bone formation and mineralization and achieved a favorable height of the repaired alveolar when compared with β-TCP alone, which absorbed severely. The overall effect of the tissue-engineered bone was equivalent to autologous bone; the physiological function of the alveolar bone was restored by allowing the adjacent teeth to move into the newly formed bone in the grafted region. This study demonstrated that the tissue engineering bone from the combination of β-TCP and bMSCs is a feasible clinical approach for patients with alveolar cleft and the subsequent orthodontic tooth movement.