Study of the timing of tooth movement after repair of alveolar bone defects by rabbit BMSCs combined with beta-TCP

Objective: To investigate the effect of tooth movement at different time after repair of alveolar bone defects with tissue engineering bone constructed by rabbit bone marrow mesenchymal stem cells (BMSCs) and beta-tricalcium phosphate (β-TCP).

Methods: Alveolar bone defect (6 mm×4 mm×8 mm) was made on the right side of 40 New Zealand rabbits, which was filled with tissue engineering bone constructed by BMSCs and β-TCP as experimental sides. Tooth extraction on the other side was performed as control. The mandibular second molars in both sides were moved mesially 2, 4, 8 and 12 weeks after surgery. The specimens were taken 4 weeks after exertion. The distance of mandibular second molar moved was measured. The periodontal tissues were observed after H-E staining. TRAP staining was performed and osteoclasts were counted in the periodontal tissues on the pressure side. BMP-2 immunohistochemical staining was used to observe the average optical density of periodontal tissue on tension side. The results were analyzed with SAS 8.0 software package.

Results: The distance of tooth movement, the amount of TRAP positive cells and the optical density of BMP-2 in the experimental side of the 2-week and 4-week groups were all significantly lower than those in the control side, while there was no significant difference between the 8-week and 12-week groups.

Conclusions: Eight weeks after repair of alveolar bone defect with rabbit BMSCs and β-TCP is an appropriate time for orthodontic tooth movement.