Effect of storage on osteoinductive properties of demineralized bone in rats

A requirement for the clinical use of demineralized bone is the possibility of storing the material without loss of its osteoinductive properties. Seventy-five 8-week-old male Wistar rats were randomly assigned to one of five groups of 15 rats each. Lyophilized demineralized allogeneic bone was prepared and implanted in the abdominal muscle either without prior storage (control group) or after storage for 9 or 14 months at -70 degrees C or 4 degrees C (four experimental groups). Bone formation in the implants was evaluated quantitatively 4 weeks postoperatively by measuring the strontium 85 uptake of the recovered implants. Storage for 9 months at both temperatures did not affect the osteoinduction, whereas storage for 14 months at both temperatures led to a statistically significant decrease in osteoinduction.