Repair of bone defects by applying biomatrices with and without autologous osteoblasts.

QUESTION Is it possible to stimulate osteoconduction and osteogenesis to improve bone formation in critical-size defects in order to avoid bone grafting? MATERIAL AND METHODS Full thickness, critical-sized defects were created in the anterior mandible of 16 adult mini-pigs. The defects were filled with a new bioactive matrix (60% hydroxyapatite and 40% beta-tricalciumphosphate), produced by an innovative low temperature sol-gel-process (120 degrees C). The biomatrix was tested alone and in combination with cultured autologous osteoblasts. In a control group, periosteum was the only bone producing source. Five weeks postoperatively, the animals were sacrificed and the defects analysed macroscopically, histologically and radiographically. RESULTS The highest rate of new bone formation was in the biomatrix group without osteoblasts (73% of the former defect). The biomatrix was degraded at the same speed as new bone was laid down. In the control group, bone formation of only 59% was observed. Additional transplantation of autologous osteoblasts in combination with the biomatrix did not result in more bone production than in the control group(!). CONCLUSION This new bioactive calciumphosphate matrix seems to be a promising bone replacement material.