Experimental Study of Controlled Freezing Point Storage Method on Tooth Transplantation and Replantation

Purpose: Tooth transplantation and replantation are increasingly attracting attention in prosthetic treatment, because transplant and replant teeth possess periodontal ligament and are able to restore healthy and physiological occlusal function with better harmony. Although the prognosis of transplant and replant teeth depends on how well the periodontal tissue is stored, a method for long-term storage of periodontal tissue has not yet been established. Thus, the purpose of this study was to establish a long-term storage method of teeth for transplantation and replantation. Methods: It was transplanted by the extracted teeth that had been stored refrigerated, frozen, or at a controlled freezing point for 4-6 weeks, and comparatively investigated their prognoses based on tooth mobility, and on radiographical and histological findings. Results: The mobility of the teeth stored at a controlled freezing point for 8 weeks was grade 1, and the same as before extraction, whereas the mobility of the teeth stored refrigerated or frozen was grade 0. Radiographical observation showed ruptured periodontal spaces in the teeth stored refrigerated or frozen, but the teeth stored at a controlled freezing point had periodontal spaces throughout the circumference of the root. Histologically, ankylosis was observed between the alveolar bone and the dentin in the teeth stored refrigerated or frozen. In the teeth stored at a controlled freezing point, no ankylosis was observed, and fibrous connective tissue was regularly and functionally arranged between the transplant tooth and the alveolar bone. Conclusion: These results suggest that controlled freezing point storage allows long-term storage of teeth to be transplanted and replanted, and that this method of storage can be applied to clinical practice.