Orthodontic Tooth Movement In Alveolar Bone Defects Repaired With β-TCP/Bone Marrow:an Experimental Study In Rabbits

Objective:To evaluate if β-TCP alone or in combination with bone marrow could repair alveolar bone defects, and allow for subsequent orthodontic tooth movement in a rabbit model.Methods:1. Twelve New Zealand rabbits were used. The1st mandibular molars on each side were removed. The extraction sockets were expanded bilaterally to establish the experimental animal model of alveolar bone defects and randomly filled by β-TCP combined with bone marrow on one side (test group), and β-TCP alone on the other side (control group). All the defects were covered with a resorbable membrane (BME-10X). Six rabbits were sacrificed at the time12weeks, postoperatively. Sequential radiographic and histological observation was used to evaluate new bone formation in both group.2.12weeks after operation, by using the mandibular incisor as anchorage, orthodontic tooth movement was initiated8weeks to allow mesial movement of the2nd mandibular molars for the remaining six rabbits. The applied force was80g. Then, all the six rabbits were sacrificed for radiographic and histological analysis and the tooth movement distance was measured.Results:1. After the1st mandibular molars of rabbits were removed, The expanded extraction sockets didn’t have the ability to heal spontaneously. Then, the experimental animal model of alveolar bone defects could be established successfully.2.12weeks after surgical operation, the bone density was significantly (P<0.05) lower in control group than in test group. In addition, the newly formed bone area was significantly (P<0.05) less in control group than in test group.3. The2nd mandibular molars both in test group and control group moved into the alveolar bone defects repaired by β-TCP/bone marrow and β-TCP alone. In addition, the tooth movement distance was significantly (P<0.05) shorter in test group than in control group.Conclusion:1. Take New Zealand rabbit as the experimental animal, the experimental animal model of alveolar bone defects can be established successfully by removing the1st mandibular molars and expanding extraction sockets.2. The osteogenic effectiveness of β-TCP/bone marrow for alveolar bone defects is better than β-TCP alone and bone marrow can enhance the new bone formation.3. It is possible to move teeth into areas of alveolar bone defects previously repaired by (3-TCP/bone marrow and (3-TCP alone.