Effect Of Cryopreservation On Tooth Tissue

  1. Influence on the pulp: Skoglund et al believe that the original pulp tissue will be necrotic after autologous transplantation, and the restoration of the pulp mainly depends on the connective granulation tissue from the root tip, and only a small number of blood vessels and cells can grow into formation. Most of the new pulp tissue is formed into a bone-like matrix and dentin-like matrix, which then form a calcified tissue to fill the medullary cavity, leading to occlusion of the medullary cavity.

  Therefore, after the apical closed tooth is transplanted, the original pulp pulp is degenerated and necrotic, and the vascular connective tissue is difficult to grow into the medullary cavity through the apical foramen, which is more likely to cause absorption inside and outside the tooth. Autologous transplantation of apical foramen greater than 1 mm can reduce the risk of pulp necrosis and root resorption. After autologous transplantation long-term success rate statistics, the root tip development is too short, although a certain length of root growth can be obtained after transplantation, but ultimately Compared with normal teeth, in order to ensure the activity of the pulp and the length of the root, some scholars suggest that the timing of tooth transplantation is that the apex develops to the CDE but the apical foramen are in an incompletely closed period. The study found that the anterior teeth began to vascularize earlier than the premolars. It may be that the apical foramen of the anterior teeth are larger than the premolars and the connective tissue is easy to grow.

  After cryopreservation of the teeth, the pulp cannot maintain its original activity due to the complexity of the pulp tissue itself and the penetration of the antifreeze agent. In view of the fact that the success rate of autologous transplantation depends largely on the development of the root and the size of the apical foramen, some scholars have proposed that the cryopreservation of the root tip should be performed before the complete closure of the tooth, and the pulp removal and apical excision should be performed. Make the apical foramen relatively open. Experimental studies have shown that revascularization can still be re-acquired after dental pulp removal, and there is no statistically significant difference from the cryopreserved teeth or the immediately transplanted teeth. Skoglund et al. pointed out that vascularization can be regained after a simple root-cutting tooth transplant. Laureys et al. also pointed out that there was no significant difference in the vascularization process between the apical-cut teeth and the underdeveloped teeth.

  Secondly, a comparative study of cryopreserved teeth and immediate grafting found that after one week of transplantation, the newly harvested granulation tissue of cryopreserved teeth was similar to that of immediate transplantation, mainly containing macrophages, fibroblasts and connective tissue fibers. However, the surface of the acellular cementum layer in the frozen group appeared relatively rough, and the cementoblasts were relatively few.

  2. Effect on periodontal ligament: The protection of periodontal ligament in cryopreservation is the key to the success of autologous transplantation. Andreasen et al believe that the lesion area of ??periodontal ligament is more than 9mm, which is enough to make the periodontal ligament not regenerate after transplantation.

  The appearance of cementoblasts after transplantation indicates the health of periodontal tissues. According to the current study, in the transplanted teeth, the number of cementoblasts in the periodontal membrane of cryopreserved teeth and instantly transplanted teeth is similar, but the periodontal membrane repair process is relatively slow after freezing. There was no significant difference in the incidence of apoptotic cells in periodontal tissues after cryopreservation of the teeth. In addition, Temmerman et al. evaluated the activity of fibroblasts in the periodontal ligament after freezing, and found that the unfrozen and frozen periodontal cells have activity, growth potential and alkaline phosphatase activity, and the results show the growth potential of the periodontal ligament. Not affected by freezing treatment, although unfrozen periodontal cells showed weak alkaline phosphatase, the difference was not statistically significant. In addition, immunohistochemical measurement of the periodontal ligament cells stored in the dental tract indicates the ability to differentiate into odontoblasts and cementoblasts. Recent cases have shown that the frozen teeth can be obtained like normal periodontal ligaments. The same X-ray transmission, but its histological features have not been reported in the literature.

  3. Effects on dental hard tissue: Animal experiments show that after 1 week of cryopreserved teeth, the cementum-free layer is rough and alveolar bone formation is less, but with cementoblasts After 3 weeks, the periodontal and alveolar bone surfaces became smooth and flat, and the amount of alveolar bone formation was similar to that of the immediate implant group. The process of repairing the alveolar bone and periodontal ligament of the cryopreserved teeth was slower than that of immediate implantation, but the final repair results were not significantly different. The most common after transplantation is inflammation and alternative absorption. The inflammation of the root can be prevented by taking antibiotics all the time before and after transplantation. Many cases of retrospective studies have shown that the absorption rate inside and outside the teeth is low, but medullary calcification occlusion occurs after transplantation. . In addition, after experimental research on cryopreservation of isolated teeth, the hardness of the teeth was not significantly changed by hardness measurement experiments. Interestingly, when the teeth were placed in a culture medium that simulates oral temperature at 37 ° C, the hardness increased. trend.

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