Objectives: Cleft lip with or without cleft palate are the most prevalent congenital craniofacial anomalies in humans. Secondary bone grafting is recommended if there is a persistent alveolar defect. Aim of the study was the evaluation of tissue engineered bone grafts in an artificial bone defect.

Methods and materials : Bone grafts were created using a synthetic hydroxyapatite-tricalcium-phosphate scaffold. The scaffolds were colonized with cells obtained from donor rats: undifferentiated mesenchymal stromal cells with and without cryopreservation (group 1/2, n = 18) and osteogen differentiated mesenchymal stromal cells after cryopreservation (group 3, n = 18). The bone grafts were inserted in critical size defects in the maxillae of 54 rats. In the control group (n = 18) the defects remained empty. After 1, 3 and 6 weeks the rats were sacrificed. The defect was evaluated radiological using cone-beam computed tomography with regard to the remaining defect volume. Sections of each defect were analyzed histomorphologically. Furthermore, the remaining defect diameter was measured. Statistical analysis followed.

Results: The application of tissue engineered bone grafts led to a pronounced bone formation at the defect margin. At all healing times, the remaining defect volume in the control group was higher compared to the other experimental groups. After six weeks the remaining defect volume was 0.0075 cm ³ (control), 0.0058 cm ³ (group 1), 0.041 cm ³ (group 2) and 0.0050 cm ³ (group 3). In all groups defect volume and diameter decreased with proceeding healing time. After six weeks, the remaining defect diameter was 2.69 mm (control), 2.67 mm (group 1), 2.39 mm (group 2) and 2.53 mm (group 3). The control group showed significant higher values for remaining defect volume and diameter in comparison to the other groups.

Conclusion: Tissue engineered bone grafts induce a pronounced bone formation in artificial bone defects compared to empty controls. The cryopreservation of the bone grafts before transplantation had no negative influence on defect healing.