In-vitro and in-vivo study of periodontal ligament cryopreserved with a magnetic field.

INTRODUCTION: The purpose of this study was to examine the effect of a new cryopreservation method with a magnetic field on periodontal regeneration in vitro and in vivo. METHODS: Human periodontal ligament cells were frozen in 10% dimethyl sulfoxide by using a programmed freezer with a magnetic field. Cells were cryopreserved for 3 days at -150°C. Immediately after thawing, collagen type I and alkaline phosphatase gene expression were determined by real-time polymerase chain reaction. Incisors were extracted from 15-week-old Wistar rats and cryopreserved or dried for 3 days. Then the incisors were replanted into the same sockets. Ninety days after transplantation, they were observed under light microscopy. RESULTS: There was no difference in the messenger RNA expression of collagen type I between the cryopreserved and the control groups. The expression of alkaline phosphatase messenger RNA in the cryopreserved group was slightly decreased compared with the control group. There was no progressive root resorption in the teeth that were replanted immediately (control group) or cryopreserved. However, there was widespread root resorption and ankylosis in the dried teeth. CONCLUSIONS: These results show that a magnetic field programmed freezer can be successfully used for cryopreservation of teeth.